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Rebuilt 10hp Briggs Won’t Start
#1
G
Go-Rebels
G
Go-Rebels
So I replaced a bad Con Rod and installed new rings and am having problems getting the motor to start. This engine has been sitting for five years and I’ve finally got around to completing the rebuild. This is a 200000 seres OHV model that I bought new in 1993 in a Troybilt Chipper-Shredder.
After replacing the fuel line and old plug and cleaning the carb I was unable to get the motor to fire once after repeated pulls on full choke. But the engine would fire up and appear to run normally, albeit momentarily, with starting fluid. I removed the bowl, saw the fuel level to be normal, and found the main metering tube clogged with something (old gelled fuel or dirt?). I cleared that with a fine oxyacetylene torch cleaning wire and confirmed by shooting carb cleaner through the metering tube from the bottom. Then I reassembled tried to pull start the engine and experienced extreme backfire and numerous kickbacks coming through my pull cord running on gas. Clearly my timing seemed way off.
Today I have no time to work on it and am now planning ‘next steps’ for next weekend.
I’m thinking I next need to run a compression test to check timing. What should I expect from this engine?
If my flywheel is mistimed, like if the key is missing, then my timing would be way off. But I remember putting the key in the flywheel. I’ll need to disassemble to confirm.
I set the punchmarks on the cam and crank gear to be aligned per the punch marks. There’s no additional timing, correct? And the small removable cam driving gear on the crank can be reversed, correct? I didn’t check the removable gear to see if the alignment punches are identical on both sides.
Both push rods/rockers have 1-2mm of play after installation when not under load. I did not disassemble the rocker arms and did not check rocker play prior to disassembly. Is this much play normal? Prior to the con rod failure I never remember experiencing a backfire.
Thx for any advice in advance.
After replacing the fuel line and old plug and cleaning the carb I was unable to get the motor to fire once after repeated pulls on full choke. But the engine would fire up and appear to run normally, albeit momentarily, with starting fluid. I removed the bowl, saw the fuel level to be normal, and found the main metering tube clogged with something (old gelled fuel or dirt?). I cleared that with a fine oxyacetylene torch cleaning wire and confirmed by shooting carb cleaner through the metering tube from the bottom. Then I reassembled tried to pull start the engine and experienced extreme backfire and numerous kickbacks coming through my pull cord running on gas. Clearly my timing seemed way off.
Today I have no time to work on it and am now planning ‘next steps’ for next weekend.
I’m thinking I next need to run a compression test to check timing. What should I expect from this engine?
If my flywheel is mistimed, like if the key is missing, then my timing would be way off. But I remember putting the key in the flywheel. I’ll need to disassemble to confirm.
I set the punchmarks on the cam and crank gear to be aligned per the punch marks. There’s no additional timing, correct? And the small removable cam driving gear on the crank can be reversed, correct? I didn’t check the removable gear to see if the alignment punches are identical on both sides.
Both push rods/rockers have 1-2mm of play after installation when not under load. I did not disassemble the rocker arms and did not check rocker play prior to disassembly. Is this much play normal? Prior to the con rod failure I never remember experiencing a backfire.
Thx for any advice in advance.
#2
Scrubcadet10
Scrubcadet10
Well, with the compression release working properly on the cam, you normally get a reading of 90 pounds or less, just pulling the rope a few times.
what i would do, is with the rocker cover off, spin the engine by hand, and look for the Exhaust valve to bump after the intake closes, not open fully, just bump open a little bit, that will tell you if your ACR is working properly, or not, and i would also double check you have the correct valve clearance.
Clearance is 004 to 006 intake AND exhaust.
I'm not sure about the crank gear being reversed.
what i would do, is with the rocker cover off, spin the engine by hand, and look for the Exhaust valve to bump after the intake closes, not open fully, just bump open a little bit, that will tell you if your ACR is working properly, or not, and i would also double check you have the correct valve clearance.
Clearance is 004 to 006 intake AND exhaust.
I'm not sure about the crank gear being reversed.
#4
T
Tinkerer200
Without a model number I can not check but it would not be common for an OHV B&S engine to relieve compression via the EXHAUST valve except Vanguard series V engines.
I suspect improperly torqued flywheel nut/bolt has allowed partial shearing of key.
Walt Conner
T
Tinkerer200
Well, with the compression release working properly on the cam, you normally get a reading of 90 pounds or less, just pulling the rope a few times.
what i would do, is with the rocker cover off, spin the engine by hand, and look for the Exhaust valve to bump after the intake closes, not open fully, just bump open a little bit, that will tell you if your ACR is working properly, or not, and i would also double check you have the correct valve clearance.
Clearance is 004 to 006 intake AND exhaust.
I'm not sure about the crank gear being reversed.
Without a model number I can not check but it would not be common for an OHV B&S engine to relieve compression via the EXHAUST valve except Vanguard series V engines.
I suspect improperly torqued flywheel nut/bolt has allowed partial shearing of key.
Walt Conner
#5
G
Go-Rebels
Yes, my thoughts exactly! That's why I thought that I may have improperly assembled the push rod and lifter whereby I missed getting the bottom of the push rod seated in the depression in the top of the lifter. But I don't think that's possible given the clearance of the lifter moving in its bore.
With such clearance I would have imagines some damage, like a grossly bent push rod but that is not the case.
Would it be common to have a 20 year old OHV engine grow to such a clearance over the years??? I didn't exactly measure but its at least 1 mm (0.039 in). I never checked the valve clearance since this rebuild since the engine was quiet and ran very well.
G
Go-Rebels
1-2 mm of play is way out of spec. You need to adjust your valve lash
Yes, my thoughts exactly! That's why I thought that I may have improperly assembled the push rod and lifter whereby I missed getting the bottom of the push rod seated in the depression in the top of the lifter. But I don't think that's possible given the clearance of the lifter moving in its bore.
With such clearance I would have imagines some damage, like a grossly bent push rod but that is not the case.
Would it be common to have a 20 year old OHV engine grow to such a clearance over the years??? I didn't exactly measure but its at least 1 mm (0.039 in). I never checked the valve clearance since this rebuild since the engine was quiet and ran very well.
#6
G
Go-Rebels
Model is #205412.
I'm going to find some time tonight and check the key and verify that it's in place... or not.
---
Just a shameless plug for the Milwaukee tool company... this is my first rebuild project using their new stubby model #2555 3/8" impact wrench. Small and powerful, it cuts a bunch of time disassembling and reassembling making repeat work not so awful as if doing it by hand.
G
Go-Rebels
Without a model number I can not check but it would not be common for an OHV B&S engine to relieve compression via the EXHAUST valve except Vanguard series V engines.
I suspect improperly torqued flywheel nut/bolt has allowed partial shearing of key.
Walt Conner
Model is #205412.
I'm going to find some time tonight and check the key and verify that it's in place... or not.
---
Just a shameless plug for the Milwaukee tool company... this is my first rebuild project using their new stubby model #2555 3/8" impact wrench. Small and powerful, it cuts a bunch of time disassembling and reassembling making repeat work not so awful as if doing it by hand.
#7
Scrubcadet10
I only assumed it used the exhaust, since he said he bought it new in 1993.
I read that the EPA started making them relieve compression through the intake in the early 00's.
If any information I give is wrong, I'm more than happy for it to be corrected
Scrubcadet10
IWithout a model number I can not check but it would not be common for an OHV B&S engine to relieve compression via the EXHAUST valve except Vanguard series V engines.
I suspect improperly torqued flywheel nut/bolt has allowed partial shearing of key.
Walt Conner
I only assumed it used the exhaust, since he said he bought it new in 1993.
I read that the EPA started making them relieve compression through the intake in the early 00's.
If any information I give is wrong, I'm more than happy for it to be corrected
#8
M
MowLife
M
MowLife
After you rebuilt I would assume the clearance changed. A new head gasket alone will change the clearance. And yes after 20 years they would need adjusting. Valve lash adjustments should be a part of your yearly maintenance on mowers. I know your engine is not on a mower with frequent use so every few years it would be good to check the lash.
#9
G
Go-Rebels
Ah yes... the new head gasket is the reason.
Good call!.
G
Go-Rebels
After you rebuilt I would assume the clearance changed. A new head gasket alone will change the clearance. And yes after 20 years they would need adjusting. Valve lash adjustments should be a part of your yearly maintenance on mowers. I know your engine is not on a mower with frequent use so every few years it would be good to check the lash.
Ah yes... the new head gasket is the reason.
Good call!.
#10
G
Go-Rebels
G
Go-Rebels
Flywheel key was sheared. Neither my local Advance Auto nor O’Reilly’s had any keys so I needed to buy through Amazon Prime. Plenty of air fresheners but no square 3/16" keys. Sad.
I’ll set the valve train clearance before I next try to fire it up.
I’ll set the valve train clearance before I next try to fire it up.
#12
T
Tinkerer200
Don't know where you would have read that but not so. IF anything, they would want the compression released into the Intake to lesson pollutants released into the air.
I can send anyone a PDF of the Service Manual IF desired. Address below, put in proper format and remind me engine model number and what you want.
Walt Conner
wconner5 at frontier dot com
T
Tinkerer200
I
I only assumed it used the exhaust, since he said he bought it new in 1993.
I read that the EPA started making them relieve compression through the intake in the early 00's.
If any information I give is wrong, I'm more than happy for it to be corrected
Don't know where you would have read that but not so. IF anything, they would want the compression released into the Intake to lesson pollutants released into the air.
I can send anyone a PDF of the Service Manual IF desired. Address below, put in proper format and remind me engine model number and what you want.
Walt Conner
wconner5 at frontier dot com
#13
G
Go-Rebels
All my local stores (four of 'em) show either "Not Sold at this Location" or "Unavailable at this Time."
:thumbdown:
G
Go-Rebels
All my local stores (four of 'em) show either "Not Sold at this Location" or "Unavailable at this Time."
:thumbdown:
#15
T
Tinkerer200
Yeah, or Rural King sell it in 1 ft. sticks. However, these all will be hard steel keys which B&S has started using on some engines but doubt this one had steel key and I do not like using steel keys.
Walt Conner
T
Tinkerer200
Do you have a Tractor Supply or Ace Hardware? Both carry them
Yeah, or Rural King sell it in 1 ft. sticks. However, these all will be hard steel keys which B&S has started using on some engines but doubt this one had steel key and I do not like using steel keys.
Walt Conner
#16
G
Go-Rebels
Yes, I have a Tractor Supply that I called. They stated they didn't carry them. Anyway, I bought a foot long section of 3/16" square from NAPA. Price was $2.99, cheapest around. Go figure... NAPA the low cost seller!
G
Go-Rebels
Do you have a Tractor Supply or Ace Hardware? Both carry them
Yes, I have a Tractor Supply that I called. They stated they didn't carry them. Anyway, I bought a foot long section of 3/16" square from NAPA. Price was $2.99, cheapest around. Go figure... NAPA the low cost seller!
#17
G
Go-Rebels
Why would B&S ever use a hard steel key?
G
Go-Rebels
My old key was strongly magnetic, so it was steel rather than stainless steel. I don't believe the rod I purchased was hardened as it cut too easily. I suspect it was cold rolled steel, which is slightly harder than hot rolled steel, as the plated finish was too smooth.Yeah, or Rural King sell it in 1 ft. sticks. However, these all will be hard steel keys which B&S has started using on some engines but doubt this one had steel key and I do not like using steel keys.
Walt Conner
Why would B&S ever use a hard steel key?
#18
T
Tinkerer200
Well I misspoke. I meant hard steel as opposed to the soft metal key traditionally used by B&S for as long as I can remember. I did not mean hardened steel.
Walt Conner
T
Tinkerer200
My old key was strongly magnetic, so it was steel rather than stainless steel. I don't believe the rod I purchased was hardened as it cut too easily. I suspect it was cold rolled steel, which is slightly harder than hot rolled steel, as the plated finish was too smooth.
Why would B&S ever use a hard steel key?
Well I misspoke. I meant hard steel as opposed to the soft metal key traditionally used by B&S for as long as I can remember. I did not mean hardened steel.
Walt Conner
#19
G
Go-Rebels
I wonder what changed over time? I doubt that they ever used hot rolled steel, which is a little softer, as it needs to be somewhat dimensionally accurate to fit in the milled slot in the hub/shaft. Hot rolled steel has a wide dimensional tolerance and that might be too wide to guarantee a nice fit.
And if not steel, what other metal might they have used? Maybe stainless?
G
Go-Rebels
Well I misspoke. I meant hard steel as opposed to the soft metal key traditionally used by B&S for as long as I can remember. I did not mean hardened steel.
Walt Conner
I wonder what changed over time? I doubt that they ever used hot rolled steel, which is a little softer, as it needs to be somewhat dimensionally accurate to fit in the milled slot in the hub/shaft. Hot rolled steel has a wide dimensional tolerance and that might be too wide to guarantee a nice fit.
And if not steel, what other metal might they have used? Maybe stainless?
#20
M
MowLife
M
MowLife
I’ve never run across a stainless key for the crank to pulley. Hard steel is all I’ve seen and the aluminum key for the flywheel. I believe stainless would be too hard.
#21
B
bertsmobile1
B
bertsmobile1
The whole point of a key, apart from a Scotch key is to shear before the shaft / pulley / whatever breaks.
So the key used needs to be weaker than whatever it is protecting
Even drive keys like in the axel will shear before the axel breaks.
The flywheel key was designed as a safety feature when flywheels were smaller & lighter.
So on a walk behind, the cast zinc keys are needed.
On a belt driven ride on they are not needed from a purely engineering point of view because belts will slip or break
So the key used needs to be weaker than whatever it is protecting
Even drive keys like in the axel will shear before the axel breaks.
The flywheel key was designed as a safety feature when flywheels were smaller & lighter.
So on a walk behind, the cast zinc keys are needed.
On a belt driven ride on they are not needed from a purely engineering point of view because belts will slip or break
#22
G
Go-Rebels
G
Go-Rebels
Today’s quick update:
I had 30 minutes spare time to get the motor started but had a little trouble getting my 3/16" key to properly fit the key way. I needed to grind and file ~1/64" from the height of the key to get a good fit and 20 minutes later I was ready to give it a start.
I pulled once to lube things up with the ignition switch off and then proceeded to turn the ignition on and choke the carb. One pull later the motor fired, stumbling a little, and I took the choke off. The engine surged slightly in speed but only reached about half normal RPM while stumbling somewhat. Half a minute later I slowly released the clutch on the chipper shredder drive and the engine stalled and dies. I tried to restart but felt no tension in the pull cord. Either I sheared the flywheel key (again) or broke another crank (again). Times-up for today.
I’ll tear it down again this weekend to ascertain the current problem.
I had 30 minutes spare time to get the motor started but had a little trouble getting my 3/16" key to properly fit the key way. I needed to grind and file ~1/64" from the height of the key to get a good fit and 20 minutes later I was ready to give it a start.
I pulled once to lube things up with the ignition switch off and then proceeded to turn the ignition on and choke the carb. One pull later the motor fired, stumbling a little, and I took the choke off. The engine surged slightly in speed but only reached about half normal RPM while stumbling somewhat. Half a minute later I slowly released the clutch on the chipper shredder drive and the engine stalled and dies. I tried to restart but felt no tension in the pull cord. Either I sheared the flywheel key (again) or broke another crank (again). Times-up for today.
I’ll tear it down again this weekend to ascertain the current problem.
#23
T
Tinkerer200
T
Tinkerer200
"On a belt driven ride on they are not because belts will slip or break" (soft key needed)
I disagree slightly they are needed to protect against shade tree mechanics who do not use a torque wrench to tighten flywheel. Running with improper tightening will eventually destroy crank and flywheel with steel key.
Walt Conner
I disagree slightly they are needed to protect against shade tree mechanics who do not use a torque wrench to tighten flywheel. Running with improper tightening will eventually destroy crank and flywheel with steel key.
Walt Conner
#24
T
Tinkerer200
T
Tinkerer200
In your original post you just say you replaced a bad connecting rod. You do not say anything about why rod was bad and what you did about checking, repairing the crankshaft throw. Generally just replacing a bad con. rod doesn't do it. Sounds like rod off again.
Walt Conner
Walt Conner
#25
M
MowLife
M
MowLife
I removed the flywheel key in my racer mower 2 years ago for timing purposes and it hasn’t slipped yet. I’m leaning towards the rod.
#26
G
Go-Rebels
The rod broke into half a dozen pieces when it was fast idling under no load to the engine. A piece punched a hole in the thin wall cast aluminum block and it took me a few years to get around to welding that up (that was a bigger project than the rebuild itself!) Initially I was a little surprised that the rod failed as I regularly changed the oil over its 20 year life and checked the oil level prior to every time I ran the chipper. But I've since learned that the con rod is a weak point in the overall design.
Sorry, I don't understand what you mean by 'crankshaft throw.' The crank appears undamaged and the con rod bearing surface is clean and OD measures in-spec. Upon reassembly I could move the crank and piston by hand and everything felt normal through the compression stroke.
Tonight I'll pull the plug and drop a long weld rod into the cylinder to see if the piston moves.
G
Go-Rebels
In your original post you just say you replaced a bad connecting rod. You do not say anything about why rod was bad and what you did about checking, repairing the crankshaft throw. Generally just replacing a bad con. rod doesn't do it. Sounds like rod off again.
Walt Conner
The rod broke into half a dozen pieces when it was fast idling under no load to the engine. A piece punched a hole in the thin wall cast aluminum block and it took me a few years to get around to welding that up (that was a bigger project than the rebuild itself!) Initially I was a little surprised that the rod failed as I regularly changed the oil over its 20 year life and checked the oil level prior to every time I ran the chipper. But I've since learned that the con rod is a weak point in the overall design.
Sorry, I don't understand what you mean by 'crankshaft throw.' The crank appears undamaged and the con rod bearing surface is clean and OD measures in-spec. Upon reassembly I could move the crank and piston by hand and everything felt normal through the compression stroke.
Tonight I'll pull the plug and drop a long weld rod into the cylinder to see if the piston moves.
#27
G
Go-Rebels
G
Go-Rebels
Regarding the steel/stainless/zinc key issue...
Stainless 304 bar has a tensile strength of 73 ksi.
Low carbon steel has a tensile strength of 64 ksi.
Cast zinc has a tensile strength ranging from 40-60 ksi.
Forged crankshafts generally have a tensile strength of 100-110 ksi.
Stainless 304 bar has a tensile strength of 73 ksi.
Low carbon steel has a tensile strength of 64 ksi.
Cast zinc has a tensile strength ranging from 40-60 ksi.
Forged crankshafts generally have a tensile strength of 100-110 ksi.
#28
M
MowLife
M
MowLife
Good info on the keys. Hard to believe the rod would break if it did in such a short time and no load. I’ve only broke one rod on a rebuild at idle and it was because I forgot to put the oil pump gear in.
#29
B
bertsmobile1
Point taken I still think like an engineer so the "offending post" has been modified.
B
bertsmobile1
"On a belt driven ride on they are not because belts will slip or break" (soft key needed)
I disagree slightly they are needed to protect against shade tree mechanics who do not use a torque wrench to tighten flywheel. Running with improper tightening will eventually destroy crank and flywheel with steel key.
Walt Conner
Point taken I still think like an engineer so the "offending post" has been modified.
#30
B
bertsmobile1
Thems very rough figures and we are talking shear strength for keys and torsional shear strength for the crank not tensile strength.
Next a lot of mower cranks are cast malliable iron not forged as the latter are about 6 timed the price of the former.
That was the real problem with the Kohler Courage engines.
At some point the forged cranks ( found on the Commands ) got replaced with the cast crank with corresponding heavier counterbalance and a whole different set of vibrations
B
bertsmobile1
Regarding the steel/stainless/zinc key issue...
Stainless 304 bar has a tensile strength of 73 ksi.
Low carbon steel has a tensile strength of 64 ksi.
Cast zinc has a tensile strength ranging from 40-60 ksi.
Forged crankshafts generally have a tensile strength of 100-110 ksi.
Thems very rough figures and we are talking shear strength for keys and torsional shear strength for the crank not tensile strength.
Next a lot of mower cranks are cast malliable iron not forged as the latter are about 6 timed the price of the former.
That was the real problem with the Kohler Courage engines.
At some point the forged cranks ( found on the Commands ) got replaced with the cast crank with corresponding heavier counterbalance and a whole different set of vibrations
#31
G
Go-Rebels
Is it common for these cranks to fail on these engines?
G
Go-Rebels
Of course these are rough figures and, yes, we're talking shear strength of the key versus shear strength of the crank (their is no such thing as "torsionsal shear" strength; it is just "shear" strength.) And of course we can get a good estimate of the shear strength of steel by multiplying the tensile strength by 0.6 so we're still talking apples to apples. The tensile strength of cast malliable iron is all over the place ranging from 65ksi to over 130ksi. Who knows where my crank is at? The only way to tell for certain what I have is to do a hardness test on the crank. I'll save that for another time...Thems very rough figures and we are talking shear strength for keys and torsional shear strength for the crank not tensile strength.
Next a lot of mower cranks are cast malliable iron not forged as the latter are about 6 timed the price of the former.
That was the real problem with the Kohler Courage engines.
At some point the forged cranks ( found on the Commands ) got replaced with the cast crank with corresponding heavier counterbalance and a whole different set of vibrations
Is it common for these cranks to fail on these engines?
#32
G
Go-Rebels
G
Go-Rebels
I checked for piston movement this morning by dropping a weld rod through the spark plug hole and found the piston moving up and down! The tension on the pull cord is erratic through the pull stroke with the plug in place, but not like going through a normal compression cycle. But I'm getting tension on the cord today where I had none a few days ago.
I'm thinking now that I may have a combinaton of a balky pull cord spring mechanism and a dirty carb that needs a good cleaning. I'll check the flywheel key again this weekend. Remember, this motor sat for years before I got around to installing the new crank.
On another point... how is the carburetor removed from this engine? I removed the two nuts that hold on the air filter backing plate and thought I could just pull the carb off the threaded studs (the studs with the male 'star' ends) but found it stuck. I tapped the carb body with a plastic hammer, thinking it was stuck to the gasket but no luck. It's not coming off! Any help would be appreciated.
I'm thinking now that I may have a combinaton of a balky pull cord spring mechanism and a dirty carb that needs a good cleaning. I'll check the flywheel key again this weekend. Remember, this motor sat for years before I got around to installing the new crank.
On another point... how is the carburetor removed from this engine? I removed the two nuts that hold on the air filter backing plate and thought I could just pull the carb off the threaded studs (the studs with the male 'star' ends) but found it stuck. I tapped the carb body with a plastic hammer, thinking it was stuck to the gasket but no luck. It's not coming off! Any help would be appreciated.
#33
B
bertsmobile1
Been a long time since I did any of this stuff in the lab but the shear strengths as measured with a Charpy or Izod were a lot lower than the rotational brittle failures what ever they were called..
An yes it will depend upon what grade of malleable iron the crank was made from .
And for that matter , the forged cranks are probably a fairly low grade steel as well when you consider the price of a crank.
Most of the failed cranks I get my grubbys on have failed on the PTO end, usually a brittle failure initating at the root of the retaining bolt hole.
Never seen a journal let go but then I have not been doing this for all that long.
We had some one here a while back with a classic fatigue failure but can't remember if it was a crank or a spindle.
Interesting units Kilograms / Sq inch ?
Usually if the end of the carb mounting studs has been formed into a torx head then the stud has a lip or boss on it to hold the cab in place so the whole stud needs to come out.
Having said that the only parts list I have for a 205412 shows the number of a plain stud and to check any further we need the 4 digit code number, there were a lot of variations of the 205412 model.
And some of those engines have a rod that is handed so it is possible to fit it upside down and have it foul on the crankcase.
B
bertsmobile1
Of course these are rough figures and, yes, we're talking shear strength of the key versus shear strength of the crank (their is no such thing as "torsionsal shear" strength; it is just "shear" strength.) And of course we can get a good estimate of the shear strength of steel by multiplying the tensile strength by 0.6 so we're still talking apples to apples. The tensile strength of cast malliable iron is all over the place ranging from 65ksi to over 130ksi. Who knows where my crank is at? The only way to tell for certain what I have is to do a hardness test on the crank. I'll save that for another time...
Is it common for these cranks to fail on these engines?
Been a long time since I did any of this stuff in the lab but the shear strengths as measured with a Charpy or Izod were a lot lower than the rotational brittle failures what ever they were called..
An yes it will depend upon what grade of malleable iron the crank was made from .
And for that matter , the forged cranks are probably a fairly low grade steel as well when you consider the price of a crank.
Most of the failed cranks I get my grubbys on have failed on the PTO end, usually a brittle failure initating at the root of the retaining bolt hole.
Never seen a journal let go but then I have not been doing this for all that long.
We had some one here a while back with a classic fatigue failure but can't remember if it was a crank or a spindle.
Interesting units Kilograms / Sq inch ?
Usually if the end of the carb mounting studs has been formed into a torx head then the stud has a lip or boss on it to hold the cab in place so the whole stud needs to come out.
Having said that the only parts list I have for a 205412 shows the number of a plain stud and to check any further we need the 4 digit code number, there were a lot of variations of the 205412 model.
And some of those engines have a rod that is handed so it is possible to fit it upside down and have it foul on the crankcase.
#34
G
Go-Rebels
Remember that the hardness testers measure the deformation (displacement) of a hard tip (ball or diamond) pressed into the surface of a metal using a calibrated load. Then we use conversion tables to estimate the tensile strength, and then multiply by 0.6 to estimate the shear strength.
"ksi" = Thousands of pounds per square inch
I've got a female TORX socket set that I haven't used in over 10 years. I guess there's a first time for everything.
BTW, my 4-digit engine code is -0120-E1
Thanks for all the help!
G
Go-Rebels
It's interesting that the "brittle failures" often mentioned are really classic fatigue failures where a small crack is formed at a stress concentration then progresses throught the cross section over many cycles.Been a long time since I did any of this stuff in the lab but the shear strengths as measured with a Charpy or Izod were a lot lower than the rotational brittle failures what ever they were called..
An yes it will depend upon what grade of malleable iron the crank was made from .
And for that matter , the forged cranks are probably a fairly low grade steel as well when you consider the price of a crank.
Most of the failed cranks I get my grubbys on have failed on the PTO end, usually a brittle failure initating at the root of the retaining bolt hole.
Never seen a journal let go but then I have not been doing this for all that long.
We had some one here a while back with a classic fatigue failure but can't remember if it was a crank or a spindle.
Interesting units Kilograms / Sq inch ?
Usually if the end of the carb mounting studs has been formed into a torx head then the stud has a lip or boss on it to hold the cab in place so the whole stud needs to come out.
Having said that the only parts list I have for a 205412 shows the number of a plain stud and to check any further we need the 4 digit code number, there were a lot of variations of the 205412 model.
And some of those engines have a rod that is handed so it is possible to fit it upside down and have it foul on the crankcase.
Remember that the hardness testers measure the deformation (displacement) of a hard tip (ball or diamond) pressed into the surface of a metal using a calibrated load. Then we use conversion tables to estimate the tensile strength, and then multiply by 0.6 to estimate the shear strength.
"ksi" = Thousands of pounds per square inch
I've got a female TORX socket set that I haven't used in over 10 years. I guess there's a first time for everything.
BTW, my 4-digit engine code is -0120-E1
Thanks for all the help!
#35
G
Go-Rebels
G
Go-Rebels
Another interesting design point... why does B&S put a small tension spring in parallel with the fixed governor rod that runs from the carb lever to the governor mechanism located on the plate that is mounted over the cylinder? Is it meant to take up any clearance in the mounting holes of the fixed rod?
#36
B
bertsmobile1
B
bertsmobile1
It is a dampening spring to prevent hysteresis with throttle variations.
It must be needed but I see a lot of engines come in without it or with it stretched a long way & I don't notice any difference to the engine operation between the old one & the new one.
It does make a bit of a difference on the bigger Honda engines.
When I am in off peak times I will download the pars list ( you should have done the same ) from Briggs then get the stud number and plug that into one of the online parts retailers web site & see what it actually looks like.
It must be needed but I see a lot of engines come in without it or with it stretched a long way & I don't notice any difference to the engine operation between the old one & the new one.
It does make a bit of a difference on the bigger Honda engines.
When I am in off peak times I will download the pars list ( you should have done the same ) from Briggs then get the stud number and plug that into one of the online parts retailers web site & see what it actually looks like.
#37
G
Go-Rebels
G
Go-Rebels
Today’s update:
Checked the flywheel key and sheared it again. This time I actually followed the spec and torqued the nut to 100 ft-lb with a new key. I took great care to torque the internal fasteners to spec but got lazy tightening the flywheel nut.
Lesson learned.
Choke, pull start and it fired right up, running well like it did years ago.
Then I found oil dripping from the engine coming from my crappy weld where I tried to TIG weld the block... probably a couple tablespoons over fifteen minutes run time. Too much to ignore. Next I need to remove the engine from the chassis and lather up the weld repair with some high temp JB Weld. I should have just JB Welded the block in the first place. I’ll re-tighten the head bolts while my hands are dirty too.
Checked the flywheel key and sheared it again. This time I actually followed the spec and torqued the nut to 100 ft-lb with a new key. I took great care to torque the internal fasteners to spec but got lazy tightening the flywheel nut.
Lesson learned.
Choke, pull start and it fired right up, running well like it did years ago.
Then I found oil dripping from the engine coming from my crappy weld where I tried to TIG weld the block... probably a couple tablespoons over fifteen minutes run time. Too much to ignore. Next I need to remove the engine from the chassis and lather up the weld repair with some high temp JB Weld. I should have just JB Welded the block in the first place. I’ll re-tighten the head bolts while my hands are dirty too.
#38
Russ2251
Russ2251
The regular JB Weld will be fine. The high temp stuff is overkill.
#39
B
bertsmobile1
B
bertsmobile1
If that flywheel key goes again you might need to dress the groove in the crank then lap the flywheel to the crank with some fine valve grinding paste
#40
G
Go-Rebels
G
Go-Rebels
Yup, that’s what I picked up. It’s good to 550F.The regular JB Weld will be fine. The high temp stuff is overkill.