Export thread

Please forgive me if this is a stupid or redundant post. I have replaced a couple of FX850V engines because they eventually used so much oil. This FX691 is really just starting to get bad. (It has 1375 hrs) My question: is it possible to re-ring this engine by just removing the heads and bottom engine case (without removing the internals)? I have no reason to believe they is anything wrong that new rings and and a light cyl hone wouldn't fix. Any advice will be greatly appreciated.

Are you sure it is not just bad valve stem seals? I just did late last year Kawasaki v-twin with 3000+ hrs and the only thing I found was a badly worn oil pump and bad valve stem seals. The seals were the source of excessive oil usage.

When it comes to doing rings you need to spec out the cylinder to make sure that it hasn't ovaled and/or tapered. IF either then OS is necessary.

You cannot re-ring without removing the pistons from the cylinder. No offense but if you don’t know this, you probably don’t want to attempt on your own.

In a word, no. I'm not sure it's not just valve stem seals. I did have a bent exhaust pushrod about 400 hours ago. Would that give any indication of valve (or seal) issues?

txmowman said:

You cannot re-ring without removing the pistons from the cylinder. No offense but if you don’t know this, you probably don’t want to attempt on your own.

Click to expand...

I'm aware that the pistons need to come out. I was referring to the crank and cam shafts. Specifically, is there room to remove / replace and properly torque the rod cap bolts.

Well like Txmowman said things have to come apart. You can't even try to remove the crankshaft without taking the rod loose. Kinda sounds like you have no experience even working on an engine at all.

But yes the rod screws and caps has to come off while the crankshaft is still in place.

Bent push rod usually indicates a valve guide migration problem which bust the seal as the spring caps bottom out on the seals and the guides.

LawnWizard said:

I'm aware that the pistons need to come out. I was referring to the crank and cam shafts. Specifically, is there room to remove / replace and properly torque the rod cap bolts.

Click to expand...

Sometimes, you can unbolt the rod and pull it back enough to remove the wrist pin and then push the piston up the cylinder and out the top. I might only do this if I was replacing a piston on one cylinder only. If I am doing both, I would also remove the crankshaft.

txmowman said:

Sometimes, you can unbolt the rod and pull it back enough to remove the wrist pin and then push the piston up the cylinder and out the top. I might only do this if I was replacing a piston on one cylinder only. If I am doing both, I would also remove the crankshaft.

Click to expand...

Curious. How the heck are you installing the piston(s) from the inside the crankcase? I have always removed and installed them from the head side here. The only I install from crankcase side is on hand held two cycles.

I suggest the OP get a copy of the service manual and read it over before attempting anything.

StarTech said:

Well like Txmowman said things have to come apart. You can't even try to remove the crankshaft without taking the rod loose. Kinda sounds like you have no experience even working on an engine at all.

But yes the rod screws and caps has to come off while the crankshaft is still in place.

Bent push rod usually indicates a valve guide migration problem which bust the seal as the spring caps bottom out on the seals and the guides.

Click to expand...

Did you even read my post?

LawnWizard said:

Did you even read my post?

Click to expand...

Yes. Why do think I suggested you get a copy of the service manual and read it thoroughly. Most of the answers are in it.

Here is a source for the PDF copy.
https://mymowerparts.com/pdf/Kawasa...ASAKI-SERVICE-REPAIR-MANUAL-99924-2093-01.pdf

EXACTLY why I quit posting on this forum years ago! A simple question: can the pistons be removed, new rings installed and replaced without removing the crankshaft turns into "you shouldn't be doing your own work if you don't know that pistons have to come out" and "things have come apart"! Well, no shit! Sorry to bother the all-knowing.

StarTech said:

Are you sure it is not just bad valve stem seals? I just did late last year Kawasaki v-twin with 3000+ hrs and the only thing I found was a badly worn oil pump and bad valve stem seals. The seals were the source of excessive oil usage.

When it comes to doing rings you need to spec out the cylinder to make sure that it hasn't ovaled and/or tapered. IF either then OS is necessary.

Click to expand...

Thank you for actually reading the post and posting an intelligent reply. Appreciated!

LawnWizard said:

EXACTLY why I quit posting on this forum years ago! A simple question: can the pistons be removed, new rings installed and replaced without removing the crankshaft turns into "you shouldn't be doing your own work if you don't know that pistons have to come out" and "things have come apart"! Well, no shit! Sorry to bother the all-knowing.

Click to expand...

Sorry but this is common sense things. And we do deal with some pretty inexperienced people at times that have no business even having a wrench in hand. Matter of fact some of local techs don't need them either. Like the one that on two different engines didn't know what in the heck he was doing. First one had a blown head gasket but he told he needed a complete engine replacement. The second engine he called himself cleaning the carburetor by just removing the fuel bowl and cleaning the trash out of it when the whole fuel in side was full of grass. The business he works for lost that commercial customer to my shop.

I also question the other poster about how he is installing the piston and rings from inside the engine when normally they are install from cylinder head side using a ring compressor.

StarTech said:

Sorry but this is common sense things. And we do deal with some pretty inexperienced people at times that have no business even having a wrench in hand. Matter of fact some of local techs don't need them either. Like the one that on two different engines didn't know what in the heck he was doing. First one had a blown head gasket but he told he needed a complete engine replacement. The second engine he called himself cleaning the carburetor by just removing the fuel bowl and cleaning the trash out of it when the whole fuel in side was full of grass. The business he works for lost that commercial customer to my shop.

I also question the other poster about how he is installing the piston and rings from inside the engine when normally they are install from cylinder head side using a ring compressor.

Click to expand...

Reading the post BEFORE posting a smart-ass response is not asking too much. I am not a 'certified" small engine mechanic or I wouldn't be on here asking questions, however I clearly stated that I planned on removing the heads and case bottom. The question was quite simple. It just seems some people would rather belittle and show off their superior intelligence than simply answer the question.

StarTech said:

Sorry but this is common sense things. And we do deal with some pretty inexperienced people at times that have no business even having a wrench in hand. Matter of fact some of local techs don't need them either. Like the one that on two different engines didn't know what in the heck he was doing. First one had a blown head gasket but he told he needed a complete engine replacement. The second engine he called himself cleaning the carburetor by just removing the fuel bowl and cleaning the trash out of it when the whole fuel in side was full of grass. The business he works for lost that commercial customer to my shop.

I also question the other poster about how he is installing the piston and rings from inside the engine when normally they are install from cylinder head side using a ring compressor.

Click to expand...

FWIW, I have replaced head gaskets, carbs, crank seals, etc. on V twins and completely rebuilt weedeaters and chainsaws as well as small block Chevy engines (which do NOT require the crank and cam shafts to be removed to replace pistons and rings).

LawnWizard said:

In a word, no. I'm not sure it's not just valve stem seals. I did have a bent exhaust pushrod about 400 hours ago. Would that give any indication of valve (or seal) issues?

Click to expand...

StarTech said:

Curious. How the heck are you installing the piston(s) from the inside the crankcase? I have always removed and installed them from the head side here. The only I install from crankcase side is on hand held two cycles.

I suggest the OP get a copy of the service manual and read it over before attempting anything.

Click to expand...

Didn't write anything about installing pistons from inside the crankcase. You can remove the head, pull the rod/piston down far enough to disconnect the piston from the rod. Push the piston back up and out through the top (head) side. Install new rings and install back into the cylinder as normal and connect the rod. Does that make more sense?

Even the main crankshaft bearings don't require the crankshaft removal on those Chev engines. But i can no longer can get the machine work done locally as all those shops are gone now. So I have to acquire a pre-built short block. I would rather do it myself as I can change the specs as I require instead having to tear a rebuilt block down to do it.

LawnWizard said:

EXACTLY why I quit posting on this forum years ago! A simple question: can the pistons be removed, new rings installed and replaced without removing the crankshaft turns into "you shouldn't be doing your own work if you don't know that pistons have to come out" and "things have come apart"! Well, no shit! Sorry to bother the all-knowing.

Click to expand...

You're the one that started your post with "Please forgive me if this is a stupid or redundant post". Sorry that you are now butthurt.

txmowman said:

Didn't write anything about installing pistons from inside the crankcase. You can remove the head, pull the rod/piston down far enough to disconnect the piston from the rod. Push the piston back up and out through the top (head) side. Install new rings and install back into the cylinder as normal and connect the rod. Does that make more sense?

Click to expand...

Yes it makes more sense. But that is just more difficult done that way. So much easier just the unbolt the rods and push the piston and rod out and back in.

StarTech said:

Even the main crankshaft bearings don't require the crankshaft removal on those Chev engines. But i can no longer can get the machine work done locally as all those shops are gone now. So I have to acquire a pre-built short block. I would rather do it myself as I can change the specs as I require instead having to tear a rebuilt block down to do it.

Click to expand...

Correct

txmowman said:

You're the one that started your post with "Please forgive me if this is a stupid or redundant post". Sorry that you are now butthurt.

Click to expand...

How is being bothered by smart ass answers from "experts" who can't even read the original post being "butthurt"? My butt is just fine, yours?

Come on guys take a step or two back and try to calm down. This is no place to be a PITA in each other backside. Meanwhile I head out to the doctor's to get a finger up mine today. How embarrassing to have a woman doctor to do it. Just it is a man doctor to do it to woman.

StarTech said:

Yes it makes more sense. But that is just more difficult done that way. So much easier just the unbolt the rods and push the piston and rod out and back in.

Click to expand...

I was just trying to answer the question and look where that went. If I would have posted best practice, someone else would have posted something else. Like LawnWizard wrote…”a simple question”…
Sorry LawnWizard, didn’t mean to offend, like I started off by commenting originally. I don’t know you or your abilities.

I have a slightly different question which I find a bit concerning
These FX series engines can take a beating and what worries me is why you have gone through 3 of them.
How many hours before it started to use too much oil ?

bertsmobile1 said:

I have a slightly different question which I find a bit concerning
These FX series engines can take a beating and what worries me is why you have gone through 3 of them.
How many hours before it started to use too much oil ?

Click to expand...

If i remember right, weren't these the ones that had issues with the air filter sealing properly?

Scrubcadet10 said:

If i remember right, weren't these the ones that had issues with the air filter sealing properly?

Click to expand...

Nope that is the FR/FS series which is why I asked the question
AnFX should have a Donaldson air filter

bertsmobile1 said:

Nope that is the FR/FS series which is why I asked the question
AnFX should have a Donaldson air filter

Click to expand...

I was going for the same thing. OP has gone through several. Dirt getting by the air filter causing this? Most air filters require grease around the edges to help seal the elements off from grit and grime. Haven't seen one good design that makes me feel like the air is actually getting fully filtered. Skim coat of grease inside the intake tract will attract grit as well. Add an oiled foam pre-filter while you are at it.

With these small engines a lot think it’s the rings, but in most cases it’s not! It’s usually the exhaust valve not closing all the way. You have to remove the valves and clean them up. Pay attention to the exhaust as you will find on the stem close to the valve, that the carbon has built up and then it can’t go all the way into the guide. This is know as stem lock. It prevents the valve from closing.
Get the valve out and put in a drill that is in a vide. Spin the valve and use a 120 grit sand paper or emery cloth to remove the carbon. Be careful of the valve face (the part that goes against the seat.) I find that I stand at the end of the valve and make a 45 degree gentle movement on the face a few times just to clean it up. Get about a 3 inch wire wheel for the drill and clean the cylinder head. Where the seats are, I take a 1 inch cone wire brush on the drill and go into the seat area a few times and this wil clean up the seat area. Hope this helps. I’m sure your oil consumption will disappear!

He might live where it's hot, and is just cooking valve seals out of them, possibly ...

First you examine the external engine to see if any oil is leaking. Lots of times the governor oil seal goes bad and leaks oil that may drip down on the exhaust and smoke considerably when the engine is first started. If you see oily dirt around the rear of the engine that is the reason. Clean off the dirt and put a piece of tissue underneath the little governor seal and check it hours later to see if oil dripped onto it or you may just see it dripping first off. It gets soft and spongy over time and deteriorates. It is cheap and easy to change. Also, small engines have what most refer to as an engine breather which works like a PCV valve on a car. This releases some amounts of oil when pressure builds up in the crankcase and if the breather is working properly this oil drains back and recirculates into the crankcase. If it goes bad the oil will end up in the combustion chamber and smoke oil. This is an inexpensive part often located under a small metal plate on top of the crankcase under the flywheel which must be removed to replace it. The plate will probably have three small screws holding it down. Sometimes this breather is located inside the valve cover. Check your local parts store for more info or look up a diagram of your engine on the net and see where it is located and get the part number. Rings usually last for years without much problem. I would not tear down the engine unless you are certain the rings are the problem. Bad compression could be from rings or valves or both. As mentioned in previous post valve stems/seats/seals could be a possible culprit. The breather which is usually made of just a flexible piece of plastic that loses flexibility is a common problem. If your engine smokes that would be the first thing I would replace because it is cheap and eventually will probably need replacing anyway.

StarTech said:

Come on guys take a step or two back and try to calm down. This is no place to be a PITA in each other backside. Meanwhile I head out to the doctor's to get a finger up mine today. How embarrassing to have a woman doctor to do it. Just it is a man doctor to do it to woman.

Click to expand...

Oh my god...I thought I was the only one. I see her every 6 months. She's relentless...I put her off every time. I tell her I just had it done last month or it's on the calendar for next month with my other doctor. But recently, she called my bluff. There should be a law.

just dump more oil in it till you have it "sussed out"...run what you brung!

Sometimes, you can do a lot of things but often it's just not worth it. Sure, in some engines you might be able to rotate it to bottom dead center enough to actually try to slide a wrist pin or the circlips out to slide the wrist pin out of the piston and then push it back up and pull the Piston out or up enough to remove the rings but not often and you're increasing the level of difficulty and that increases the chances for error or something just not getting in the right place and having a catastrophic failure later. It's not pretty what a wristpin rubbing against the wall of a cylinder can do.
What kind of oil are you running in it? Usually it's the intake valve guides and seals that use oil as compared to the exhaust so you might just pop the spring and retainer off of that one and add an extra umbrella style seal on top of it which could eliminate most if it's leaking there.
Also the oil... Fully synthetic oils tend to find ways to disappear and get used more than conventional oils. I would be running a straight HD 30 in that.
I know others will roll their eyes but I have had great luck with one particular product in the entire line of them known as snake oil restore engine treatment.
I have used this in many engines and small engines at a good strong 20% of crankcase capacity and sometimes pushing 25% probably and I have had great results.

StarTech said:

Curious. How the heck are you installing the piston(s) from the inside the crankcase? I have always removed and installed them from the head side here. The only I install from crankcase side is on hand held two cycles.

I suggest the OP get a copy of the service manual and read it over before attempting anything.

Click to expand...

I have done this several times and it is not very hard. First off There is two ways I have done this. I remove the pin from the piston and only one ring from the pin. I put the piston back in using a ring compressor then push it to the bottom of the cyinder just enough for the pin to go back in then I put the ring in holding the pin. The I ease the cylinder back down on the piston. But you have to be very carefull doing this.
The second way is if the cylinder has a tapper on the bottom which most do have. You can take your fingers and compress the rings as you slide the cylinder down. I have done this several times when the piston had to came back down to far and exposed the oil rings before the pin would go in.
I do this when there is no problem inside the engine and just reringing the piston. If there is any damage to the piston or the cylinder a complete rebuild would be in order. The rings are harder than the cylinder wall so if you are careful they will not be damaged. I have never heard of the piston has to be inserted from the top side.
I have rebuild several twin engine mowers and never had a problem. Any engine with new rings if not broke in correctly will start using oil. My customers have been running engines I rebuilt like for years with no problems. Just because it is a redneck way does not mean it is a bad way. My father was a master mechanic and showed me several short cuts that work but is not in manuals.

Dreaded said:

I have done this several times and it is not very hard. First off There is two ways I have done this. I remove the pin from the piston and only one ring from the pin. I put the piston back in using a ring compressor then push it to the bottom of the cyinder just enough for the pin to go back in then I put the ring in holding the pin. The I ease the cylinder back down on the piston. But you have to be very carefull doing this.
The second way is if the cylinder has a tapper on the bottom which most do have. You can take your fingers and compress the rings as you slide the cylinder down. I have done this several times when the piston had to came back down to far and exposed the oil rings before the pin would go in.
I do this when there is no problem inside the engine and just reringing the piston. If there is any damage to the piston or the cylinder a complete rebuild would be in order. The rings are harder than the cylinder wall so if you are careful they will not be damaged. I have never heard of the piston has to be inserted from the top side.
I have rebuild several twin engine mowers and never had a problem. Any engine with new rings if not broke in correctly will start using oil. My customers have been running engines I rebuilt like for years with no problems. Just because it is a redneck way does not mean it is a bad way. My father was a master mechanic and showed me several short cuts that work but is not in manuals.

Click to expand...

I appreciate what you are saying, however you have to remember the target audience .
I also appreciate that in a full time workshop the situation is vastly different to in the shed of a very much amateur .
In my workshop I can ( usually ) do a full & proper diagnosis so end up knowing exactly what needs to be done and if I am busy limit the job to just that .
However I do like to do most jobs the long way so I can do things like examine to bore & pistons fully which is difficult to do with the rod still in the engine .
So while you pappys short cuts are a valid way of working , they are for discussion amongst professional or fully competant engine rebuilders and not on an open public forum where the bulk of the people are total novices.
As you know the rods on these engines are quite frail and easily twisted or bent by people whacking the pin with hammer .
I have a box full of pin clamps ( somewhere ) to push pins out without damage but I doubt that any standard home owner would have them.
Also there is a big difference between working on a vertical twin & a car engine.
By the time the engine is pulled from the mower , sump is off , head is off & rod cap is loosened /off there is not much to be gained by not pushing the piston all the way out .
Again if there is 20 more to be done then yes the 5 to 15 minutes of time saved would be significant but on a single one off job not really .

StarTech said:

Come on guys take a step or two back and try to calm down. This is no place to be a PITA in each other backside. Meanwhile I head out to the doctor's to get a finger up mine today. How embarrassing to have a woman doctor to do it. Just it is a man doctor to do it to woman.

Click to expand...

Meanwhile I head out to the doctor's to get a finger up mine today. I go on Monday.. Fun, fun..

I don't even change my own oil anymore - not because I can't but because I don't have to. But let's be honest, this stuff is not brain surgery. I can't imagine the OP couldn't find a youtube video to walk him through what he needs to do.