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Kohler compression problem, post head gasket and valve adjustment
#1
T
Two_Putt
T
Two_Putt
Hello everyone, new to the forum
Kohler 20hp sv600 courage, ran good. During winter maintenance, replaced head gasket, exhaust port gasket, intake carburetor gasket, valve cover gasket and set valves, replaces push rods to appropriate valves. Cranked mower drove front wheels onto wheel stands and was dropping pto to install new drive belt. However when loosening pto bolt the crank rotated. Also, able to rotate flywheel by hand easily.
References to explanation using time on a clock is the flywheel set at 12:00 o'clock and the piston at TDC.
Cycle 1, TDC, adjusted valves(intake .005, exhaust .007), (down stroke), input valve starts to open just before bottom of stroke, exhaust valve closed.
Cycle 2(upstroke), intake valve finishes opening and closes TDC, exhaust valve remained closed.
Cycle 3(compression down stroke, supposedly), input valve closed. Exhaust valve begins to open, opens fully with slight tension remains on intake valve untill flywheel at 3 o'clock.
Cycle 4(upstroke), intake valve opens slightly and closes quickly, from 7-10 o'clock, exhaust valve closes at 10 o'clock
As I understand,
Cycle 1, TDC, down stroke, input valve opens.
Cycle 2, upstroke input valve closes and compresses air/gas.
Cycle 3, TDC, spark plug ignites down stroke.
Cycle 4, upstroke exhaust valve opens and closes at the top of the stroke.
Seems like valves acting like timing 180 degrees off? Installed new flywheel key. The only thing I can think of, is maybe the flywheel was rotated 180 degrees and push rods were installed on the back side of the valve cam/back of lobe on cam? Is this possible? New bolts and head gasket, can I take off the bolts and gasket and reuse without buying another set? Any suggestions and thank you.
Kohler 20hp sv600 courage, ran good. During winter maintenance, replaced head gasket, exhaust port gasket, intake carburetor gasket, valve cover gasket and set valves, replaces push rods to appropriate valves. Cranked mower drove front wheels onto wheel stands and was dropping pto to install new drive belt. However when loosening pto bolt the crank rotated. Also, able to rotate flywheel by hand easily.
References to explanation using time on a clock is the flywheel set at 12:00 o'clock and the piston at TDC.
Cycle 1, TDC, adjusted valves(intake .005, exhaust .007), (down stroke), input valve starts to open just before bottom of stroke, exhaust valve closed.
Cycle 2(upstroke), intake valve finishes opening and closes TDC, exhaust valve remained closed.
Cycle 3(compression down stroke, supposedly), input valve closed. Exhaust valve begins to open, opens fully with slight tension remains on intake valve untill flywheel at 3 o'clock.
Cycle 4(upstroke), intake valve opens slightly and closes quickly, from 7-10 o'clock, exhaust valve closes at 10 o'clock
As I understand,
Cycle 1, TDC, down stroke, input valve opens.
Cycle 2, upstroke input valve closes and compresses air/gas.
Cycle 3, TDC, spark plug ignites down stroke.
Cycle 4, upstroke exhaust valve opens and closes at the top of the stroke.
Seems like valves acting like timing 180 degrees off? Installed new flywheel key. The only thing I can think of, is maybe the flywheel was rotated 180 degrees and push rods were installed on the back side of the valve cam/back of lobe on cam? Is this possible? New bolts and head gasket, can I take off the bolts and gasket and reuse without buying another set? Any suggestions and thank you.
#2
B
bertsmobile1
B
bertsmobile1
remove spark plug take the rocker cover off, get a pencil, straw or similar to shove down the plug hole.
Rotate the engine by hand watching the positin o the piston in relation to the valves opening & closing.
Also note the position of the flywheel magnets that produce the ignition spark.
Do not worrry about what you may or may not have done wrong.
When you find what is happening at the wrong times it will become apparent.
Pretend some one just brought this engine to you to fix with the comment "it was working fine then my ******* decided it needed fixing and now it won't go at all."
Rotate the engine by hand watching the positin o the piston in relation to the valves opening & closing.
Also note the position of the flywheel magnets that produce the ignition spark.
Do not worrry about what you may or may not have done wrong.
When you find what is happening at the wrong times it will become apparent.
Pretend some one just brought this engine to you to fix with the comment "it was working fine then my ******* decided it needed fixing and now it won't go at all."
#3
reynoldston
reynoldston
Hello everyone, new to the forum
Kohler 20hp sv600 courage, ran good. During winter maintenance,
I would call this overkill if it ran good. This was your first big mistake.
#4
L
Lawnranger
First, ignore any useless comment(s) that insult your intelligence and offer ZERO help. Too many people won't/don't read every word of the OP's post to try to understand what is really going on. You have a better understanding regarding theory of operation of a four stroke engine compared to most people who come here looking for help so pat yourself on the back and answer the question in the next sentence.
If the engine started and you drove the mower up on stands/ramps then you know the engine is operating properly - Is this statement true???
By what you describe, you are rotating the crankshaft in the wrong direction as you observe valve movement. Try rotating the crankshaft the opposite way you have been and observe valve/rocker movement and see if the valves don't work the way they should. Then come back here and tell me what you discovered.
L
Lawnranger
Hello everyone, new to the forum
Kohler 20hp sv600 courage, ran good. During winter maintenance, replaced head gasket, exhaust port gasket, intake carburetor gasket, valve cover gasket and set valves, replaces push rods to appropriate valves. Cranked mower drove front wheels onto wheel stands and was dropping pto to install new drive belt. However when loosening pto bolt the crank rotated. Also, able to rotate flywheel by hand easily.
References to explanation using time on a clock is the flywheel set at 12:00 o'clock and the piston at TDC.
Cycle 1, TDC, adjusted valves(intake .005, exhaust .007), (down stroke), input valve starts to open just before bottom of stroke, exhaust valve closed.
Cycle 2(upstroke), intake valve finishes opening and closes TDC, exhaust valve remained closed.
Cycle 3(compression down stroke, supposedly), input valve closed. Exhaust valve begins to open, opens fully with slight tension remains on intake valve untill flywheel at 3 o'clock.
Cycle 4(upstroke), intake valve opens slightly and closes quickly, from 7-10 o'clock, exhaust valve closes at 10 o'clock
As I understand,
Cycle 1, TDC, down stroke, input valve opens.
Cycle 2, upstroke input valve closes and compresses air/gas.
Cycle 3, TDC, spark plug ignites down stroke.
Cycle 4, upstroke exhaust valve opens and closes at the top of the stroke.
Seems like valves acting like timing 180 degrees off? Installed new flywheel key. The only thing I can think of, is maybe the flywheel was rotated 180 degrees and push rods were installed on the back side of the valve cam/back of lobe on cam? Is this possible? New bolts and head gasket, can I take off the bolts and gasket and reuse without buying another set? Any suggestions and thank you.
First, ignore any useless comment(s) that insult your intelligence and offer ZERO help. Too many people won't/don't read every word of the OP's post to try to understand what is really going on. You have a better understanding regarding theory of operation of a four stroke engine compared to most people who come here looking for help so pat yourself on the back and answer the question in the next sentence.
If the engine started and you drove the mower up on stands/ramps then you know the engine is operating properly - Is this statement true???
By what you describe, you are rotating the crankshaft in the wrong direction as you observe valve movement. Try rotating the crankshaft the opposite way you have been and observe valve/rocker movement and see if the valves don't work the way they should. Then come back here and tell me what you discovered.
#5
T
Two_Putt
T
Two_Putt
Thank you for your responses.
My initial input was with the valve cover off with plastic tie inserted in the spark plug whole. Using the clock reference, the magnet on the flywheel is at 12:00 which is TDC and the magneto is at 11:00. The finished downs stroke the magnet is 12:30. All else is the same in my initial description. Briefly turning the motor over shows a clockwise rotation. I am easily able to turn by hand through all four cycles, the motor over clockwise and counter clockwise, no difference. This make sense because the valves in cycle 1 don't even open and on cycle two the input valve open, no possible way to build compression for cycle 3(ignition). And for Cycle 3 and 4 input or exhaust valve is open. I can see why no compression. Never have done a leak down test, but, you have to have compression to do it. Don't know how I had the power to drive onto the wheel stands, although it wasn't under the heaviest load, pto was not engaged. Just to be complete I also replace exhaust muffler gasket. All bolts were torque specific. I still thinking about pulling the push rods out, rotating the flywheel 180 degrees and re-installing then to see if it makes a difference. But will hold off to see if we can figure this out. Tlhanks Again.
My initial input was with the valve cover off with plastic tie inserted in the spark plug whole. Using the clock reference, the magnet on the flywheel is at 12:00 which is TDC and the magneto is at 11:00. The finished downs stroke the magnet is 12:30. All else is the same in my initial description. Briefly turning the motor over shows a clockwise rotation. I am easily able to turn by hand through all four cycles, the motor over clockwise and counter clockwise, no difference. This make sense because the valves in cycle 1 don't even open and on cycle two the input valve open, no possible way to build compression for cycle 3(ignition). And for Cycle 3 and 4 input or exhaust valve is open. I can see why no compression. Never have done a leak down test, but, you have to have compression to do it. Don't know how I had the power to drive onto the wheel stands, although it wasn't under the heaviest load, pto was not engaged. Just to be complete I also replace exhaust muffler gasket. All bolts were torque specific. I still thinking about pulling the push rods out, rotating the flywheel 180 degrees and re-installing then to see if it makes a difference. But will hold off to see if we can figure this out. Tlhanks Again.
#6
B
bertsmobile1
B
bertsmobile1
That will make absolutely no difference as each pushrod sits on its own cam.
When it looks like the valve is closed, try to rotate the pushrod.
If you can not turn it around then the valve is not fully shut.
My gut feeling is you set the valves then ran the engine which compressed the gasket so now the valves are too tight.
Or conversely the gaskets have settled a little bit so it is leaking at the head gasket .
If you sit in front of the cylinder & rotate the engine clockwise you should be able to work it out.
Piston near TDC, inlet opens, piston drops so cylinder fills up with fuel
Near BDC inlet closes then reopens just a little before TDC to release compression
This is the tricky bit.
Valve lash too big & no decompression occurs
Valve lash too small and complete decompression occurs.
Piston swings through TDC, magnets align spark happens & you go into power stroke as piston goes down
The near BDC exhaust opens and piston rises to expel exhaust gasses till the top of the stroke when the inlet opens & the cycle repeats itself.
Turning the engine with the pushrods in or out can not affect the timing.
Only removing & replacing the cams themselves can change the valve timing.
When it looks like the valve is closed, try to rotate the pushrod.
If you can not turn it around then the valve is not fully shut.
My gut feeling is you set the valves then ran the engine which compressed the gasket so now the valves are too tight.
Or conversely the gaskets have settled a little bit so it is leaking at the head gasket .
If you sit in front of the cylinder & rotate the engine clockwise you should be able to work it out.
Piston near TDC, inlet opens, piston drops so cylinder fills up with fuel
Near BDC inlet closes then reopens just a little before TDC to release compression
This is the tricky bit.
Valve lash too big & no decompression occurs
Valve lash too small and complete decompression occurs.
Piston swings through TDC, magnets align spark happens & you go into power stroke as piston goes down
The near BDC exhaust opens and piston rises to expel exhaust gasses till the top of the stroke when the inlet opens & the cycle repeats itself.
Turning the engine with the pushrods in or out can not affect the timing.
Only removing & replacing the cams themselves can change the valve timing.
#7
T
Two_Putt
T
Two_Putt
Just an added note. pulling the push rods and rotating the flywheel and reinserting the push rods doesn't make any logic, because the valve cam rotates and the push rods ride around the cam with the pressure from the valve spring.
#8
B
bertsmobile1
That is what every one has been trying to tell you
B
bertsmobile1
Just an added note. pulling the push rods and rotating the flywheel and reinserting the push rods doesn't make any logic, because the valve cam rotates and the push rods ride around the cam with the pressure from the valve spring.
That is what every one has been trying to tell you
#9
T
Two_Putt
T
Two_Putt
Thank you bertsmobile1,
First, I checked the torque on head bolts at 30 lb ft, all good.
Second, I pulled the head, found both valves leaking(water with air in intake and exhaust port, bubbles)
.
Third, I lapped and seated the valves, no more leak.
Fourth, I don't really understand the cycle/valve relationship on this motor. However, I inserted and marked the push rods at TDC, this was my observations where the push rods would push out of the cylinder/case, there by, would be pushing on the rocker arm, opening the specific input or exhaust valve. And, the push rod retreating back into the cylinder/case, which would be closing the specific input valve or exhaust valve and both of these in relation of position of the piston. Using the magnet on the flywheel is TDC at 12:00 and the magneto sets at 11:00. The motor runs clockwise.
TDC-where both valves could be adjusted, input and exhaust valves are closed. 12:00 is the piston at TDC and 6:00 the piston is BDC.
Cycle 1, 12:00-6:00, down stroke, from TDC,
Input valve starts to open at approx. 5:00 Exhaust valve closed
Cycle 2, upstroke
Input valve open Exhaust valve closed
Cycle 3, down stroke
Input valve closed Exhaust valve open from 12:00-closes in cycle 4 at 7:00
Cycle 4, upstroke
Input valve closed Exhaust valve open-closes at 7:00
Input valve opens briefly at 7:00 and closed at 10:00
My evaluation cycle 1, Ok, although input valve should have started opening from TDC.
cycle 2, If the input valve is open until cycle 3 where it closes at 12:00 and it was suppose to fire at 11:00, then no compression.
cycle 4, Where the input valve briefly opens and closes, valve spring compresses approx. 1/2 the distant s of a normally compressed open intake valve.
Maybe ACR(automatic compression release inside the case).
Actions,
1. Considering reusing bolts just purchased for current head gasket, also not sure if I should buy a new head gasket, what do you think?
2. Hoping after putting on the head tomorrow, I will have compression, but, not confident per above compression/valve observations.
3. Once I adjusted the valves, I will repeat you suggestion of rotating the push rods through the 4 cycles. Sorry, didn't mean to write a book, lol
4. Since I am a newbie, should I have opened this thread under kohler engines, should I ask administration to move it? Thanks
First, I checked the torque on head bolts at 30 lb ft, all good.
Second, I pulled the head, found both valves leaking(water with air in intake and exhaust port, bubbles)
.
Third, I lapped and seated the valves, no more leak.
Fourth, I don't really understand the cycle/valve relationship on this motor. However, I inserted and marked the push rods at TDC, this was my observations where the push rods would push out of the cylinder/case, there by, would be pushing on the rocker arm, opening the specific input or exhaust valve. And, the push rod retreating back into the cylinder/case, which would be closing the specific input valve or exhaust valve and both of these in relation of position of the piston. Using the magnet on the flywheel is TDC at 12:00 and the magneto sets at 11:00. The motor runs clockwise.
TDC-where both valves could be adjusted, input and exhaust valves are closed. 12:00 is the piston at TDC and 6:00 the piston is BDC.
Cycle 1, 12:00-6:00, down stroke, from TDC,
Input valve starts to open at approx. 5:00 Exhaust valve closed
Cycle 2, upstroke
Input valve open Exhaust valve closed
Cycle 3, down stroke
Input valve closed Exhaust valve open from 12:00-closes in cycle 4 at 7:00
Cycle 4, upstroke
Input valve closed Exhaust valve open-closes at 7:00
Input valve opens briefly at 7:00 and closed at 10:00
My evaluation cycle 1, Ok, although input valve should have started opening from TDC.
cycle 2, If the input valve is open until cycle 3 where it closes at 12:00 and it was suppose to fire at 11:00, then no compression.
cycle 4, Where the input valve briefly opens and closes, valve spring compresses approx. 1/2 the distant s of a normally compressed open intake valve.
Maybe ACR(automatic compression release inside the case).
Actions,
1. Considering reusing bolts just purchased for current head gasket, also not sure if I should buy a new head gasket, what do you think?
2. Hoping after putting on the head tomorrow, I will have compression, but, not confident per above compression/valve observations.
3. Once I adjusted the valves, I will repeat you suggestion of rotating the push rods through the 4 cycles. Sorry, didn't mean to write a book, lol
4. Since I am a newbie, should I have opened this thread under kohler engines, should I ask administration to move it? Thanks
#11
M
motoman
M
motoman
two putt, Glad the useless sniping is over. Probably well to replace head gasket. Waiting to hear your success and happy holiday!
#12
reynoldston
reynoldston
First, ignore any useless comment(s) that insult your intelligence and offer ZERO help. QUOTE]
Makes perfect sense to me. Just like a new engine for next spring.. Yes ZERO help from me.
#13
B
bertsmobile1
Check which valve is what.
Looks like you are mixing up the intate & exhaust valves
B
bertsmobile1
Thank you bertsmobile1,
First, I checked the torque on head bolts at 30 lb ft, all good.
Second, I pulled the head, found both valves leaking(water with air in intake and exhaust port, bubbles)
.
Third, I lapped and seated the valves, no more leak.
Fourth, I don't really understand the cycle/valve relationship on this motor. However, I inserted and marked the push rods at TDC, this was my observations where the push rods would push out of the cylinder/case, there by, would be pushing on the rocker arm, opening the specific input or exhaust valve. And, the push rod retreating back into the cylinder/case, which would be closing the specific input valve or exhaust valve and both of these in relation of position of the piston. Using the magnet on the flywheel is TDC at 12:00 and the magneto sets at 11:00. The motor runs clockwise.
TDC-where both valves could be adjusted, input and exhaust valves are closed. 12:00 is the piston at TDC and 6:00 the piston is BDC.
Cycle 1, 12:00-6:00, down stroke, from TDC,
Input valve starts to open at approx. 5:00 Exhaust valve closed
Cycle 2, upstroke
Input valve open Exhaust valve closed
Cycle 3, down stroke
Input valve closed Exhaust valve open from 12:00-closes in cycle 4 at 7:00
Cycle 4, upstroke
Input valve closed Exhaust valve open-closes at 7:00
Input valve opens briefly at 7:00 and closed at 10:00
My evaluation cycle 1, Ok, although input valve should have started opening from TDC.
cycle 2, If the input valve is open until cycle 3 where it closes at 12:00 and it was suppose to fire at 11:00, then no compression.
cycle 4, Where the input valve briefly opens and closes, valve spring compresses approx. 1/2 the distant s of a normally compressed open intake valve.
Maybe ACR(automatic compression release inside the case).
Actions,
1. Considering reusing bolts just purchased for current head gasket, also not sure if I should buy a new head gasket, what do you think?
2. Hoping after putting on the head tomorrow, I will have compression, but, not confident per above compression/valve observations.
3. Once I adjusted the valves, I will repeat you suggestion of rotating the push rods through the 4 cycles. Sorry, didn't mean to write a book, lol
4. Since I am a newbie, should I have opened this thread under kohler engines, should I ask administration to move it? Thanks
Check which valve is what.
Looks like you are mixing up the intate & exhaust valves
#14
T
Two_Putt
T
Two_Putt
Have found the issue with valves opening 180 deg off. I identified my intake from Cub Cadet part manual as being on the left, facing the lawn mower from the front bumper. However looking at the Kohler Engine manual diagram for 20hp courage sv_600.0009, shows the intake valve on the right. Once I rotated the motor through the 4 cycles, looking at the intake valve on the right, the valves opened correctly. Please understand this is the first motor top end that I have dissembled. I now realize that by looking exhaust port and intake port on the head, I should have caught on sooner.:confused3:
With the fixed leaking valves, I found it harder to turn through the compression cycle, as it should. After putting the motor back together, during initial cranking it would not turn over completely, battery is good. I plan on taking the valve cover off and check the rocker arm clearances. With Christmas around the corner, I may not get to it until after. Merry Christmas everyone.
With the fixed leaking valves, I found it harder to turn through the compression cycle, as it should. After putting the motor back together, during initial cranking it would not turn over completely, battery is good. I plan on taking the valve cover off and check the rocker arm clearances. With Christmas around the corner, I may not get to it until after. Merry Christmas everyone.
#15
T
Two_Putt
T
Two_Putt
After difficulty of motor to turn over, found both valves to be way out of tolerance. Once adjusted .005 on intake and .007 on exhaust valve on compression stroke(end of cycle two, TDC), success. Motor cranks and running great. Don't have to choke the motor to start.
Just a little side issue, FYI. My Cub Cadet LT 1045, throughout working and pushing the mower around, the relief valve on the transmission stopped working, the transmission was stuck in gear, worked once, stopped again. The linkage appeared to be opening and closing the relief valve. Since the transmission is maintenance free, my last option was once all was put back together, I pushed the drive/forward pedal. Initially it seemed to travel almost its entire pedal travel distance and then the transmission kicked in, after that, it drives correctly and the transmission relief valve is now working fine. I now can pull the transmission relief valve and take it out of gear for pushing. What luck, figured the relief valve was stuck or bound some how and the hydraulic pressure during the drive pedal depression, corrected the valve position. Was due to something going my way.:dance1:
I wish to thank everyone for your help and participation. I believe this site/forum has a mixed levels of technical knowledge and abilities from people willing to take time from their day and help those of us trying to fix our broken stuff, ourselves. Thanks again!
Just a little side issue, FYI. My Cub Cadet LT 1045, throughout working and pushing the mower around, the relief valve on the transmission stopped working, the transmission was stuck in gear, worked once, stopped again. The linkage appeared to be opening and closing the relief valve. Since the transmission is maintenance free, my last option was once all was put back together, I pushed the drive/forward pedal. Initially it seemed to travel almost its entire pedal travel distance and then the transmission kicked in, after that, it drives correctly and the transmission relief valve is now working fine. I now can pull the transmission relief valve and take it out of gear for pushing. What luck, figured the relief valve was stuck or bound some how and the hydraulic pressure during the drive pedal depression, corrected the valve position. Was due to something going my way.:dance1:
I wish to thank everyone for your help and participation. I believe this site/forum has a mixed levels of technical knowledge and abilities from people willing to take time from their day and help those of us trying to fix our broken stuff, ourselves. Thanks again!