108 overheat? smoking from breather cover.
 

I restored this 108 last winter and paid the local Case/IH dealer to overhaul the engine. Piston, rings, rod, valves. Cylinder was in spec (they said) so standard piston and rings were installed.

I put it all back together and have been using it all summer, cutting an acre or so every week. Engine seems stronger than it used to be, so I've been happy.

Until last week. After cutting for half an hour (heavy grass, working hard) the engine started to lose power and blowing lots of smoke out of the breather cover. Seems like the engine was working hard, but going nowhere, slowing down, but at full throttle. Barely finished cutting the grass, and put it away, not sure what was going on with it.

Today (a week later), it started fine, ran great for about a half hour (again, thick grass, but cutting it fine) and it started doing it again--losing power and smoking from the breather cover. So I shut it down. Went to go get the 1650 from the other house a few hours later to finish cutting the grass. Went to put the 108 on the trailer to bring home to fix. It started fine, no smoking, so I put it on the trailer. Now I have it home, so looking for ideas on where to start. Is it overheating? Or something else.

Sounds like it's happening when the pto's engaged and you're mowing? Does it still bog down and smoke after you disengage the blades? Grasping at straws, but maybe a pto, mule drive, or deck issue after warming up causing power loss. Of course, not so much if it still happens after shutting the deck down.........:bigthink:

Mouse nest? Grass clippings? Sounds like the engine is getting hot, :bigthink:

When it started doing this, my first thought was that the belt had come off a mule drive pulley causing excessive load on the engine. Or the deck was clogged up. But the smoking continues with the load removed (PTO clutch disengaged) when it does this.

The smoke out of the breather cover indicates excessive blowby, right? Why would this happen after using the tractor for a half hour?

Sawdust. Kind of sounds like the same problem I had with my 1200 after I refreshed it. Here is what I found out to be "my" problem. Maybe not yours. I had smoke and oil spewing out of my breather. I pulled the head and found it had "melted" and blew out the head gasket. I was running WAY lean because I did not adjust the carb correctly. Maybe take a look by pulling the head and seeing if you are burnt/melted and/or blown out gasket. I replaced the head and gasket, breather cover gasket, rubber grommit and filter, readjusted the carb to run a little/alot richer and have not had any problems.
Like I said this may not be your "fix" but a possible check.
Hope it goes well for you.
John

Sawdustdad, not saying this is the problem, but you could check the valve to tappet clearance. Something else to rule out. Just my :TwoCents:

So I spent some time today working on the 108. It started and ran fine. So I cut some grass, had to go out to the pasture to get some heavy grass to duplicate the conditions that caused the problem yesterday. After about half an hour it seemed to lose power again and smoking out of the breather again, so I opened the high speed jet to enrich the mixture and it regained power. So I think that might be the problem--running too lean, so when it's really hot, under heavy load it starts losing power. That seems to have solved the problem of power loss, but it's still smoking out the breather a lot.

The only way you get smoke out the breather is piston ring blowby, right?

you may want to put a cyl leak down tester on it. once you start getting smoke out the breather and losing power there's something wrong. if you don't have access to a leak down tester take the head off and check the bore. you will also get smoke out the breather if the rod starts to go tight on the crank. do you check the oil?

Yes. Even if the rod is getting hot and smoking it won't move more air, just make more smoke. The ONLY way it can have more air exiting out the breather is if there is more piston blow by. If the motor already got too hot from a lean condition, the damage is already done. Sorry man, it probably won't get any better on it's own. If it didn't score it too bad, it might go ahead and run, but if it was losing power, it was swelling the piston in the bore. If you want to, pull the head and look, but it has been my experience with engines that you probably won't see anything till you pull the piston out. Then you'll be like, "oh, there's the problem". It might make it worse to keep using it.... It may be fine. Your choice. But one thing is for sure, it got hot.

J-Mech ; everytime the piston travels downward you displace whatever cubic inchs of air the bore take's up in the crankcase. in the case of a K241 its 24 cubic inchs so your statement is incorrect. that's why there's a breather if it didn't your oil seals would start blowing oil out.

LOL, Yes, I know that. If you re-read my statement, I said "The ONLY way it can have more air exiting out the breather is if there is more piston blow by." Frank says as it gets hot, the blow-by got worse. The only way for it to have MORE air leaving is as I stated. He already said that he adjusted the carb and giving it more fuel helped his motor, so I think it's safe to assume that it was running lean. If a rod was binding on his journal, fuel would not have affected it AND it would start doing it within minutes of starting. Plus, a binding rod would not produce MORE air out the breather. I never do cylinder leak down tests. They are a waste of time. A compression check is sufficient. 90% of these motors won't hold compression long. They are too worn out. Half the time on here people post that their engine runs fine but only makes like 75 or 90PSI, as motors are concerned, I can't believe they will even start. I'm sticking with my scored piston diagnosis.

I should clarify something--when it's hot there is more smoke coming out of the breather. I don't know if it's more air (than when it's cold) It's just not noticeable as smoke until it's hot.

Just curious do you know how to get a good compression test with the acr on these engines when i defeat the acr these start/gens are not quite strong enough with the full compression to get a true reading. Any suggestions? Id love to know how much my newly rebuilt 16hp has!!

I did notice last summer sometime that ring end gaps had to be adjusted when doing overhauls. they were always very tight almost nothing.
most people don't check it. I got a call from a fellow yesterday that had just overhauled a K321. it did pretty much what you explained. after taking off the head he found scoring in the bore that went up to where the top ring would travel to at tdc. no aluminum transfer in the bore. He had not checked the ring end gap.

there's not a good way to get a true compression test on a Kohler because of the ACR. I had a setup I tried for a while where I would take the spring off the ACR and use the starter cart off my puller to crank the engine over and get true readings off of used engines. I've never checked it on a fresh engine but decent used ones get around 140 with no ACR. a stocker puller motor can to 160, 170

there's nothing wrong with a leak down test if you know how to interpret the numbers. give's you an idea of how good the valves are as well as the ring seal.

:ThumbsUp: I'm good with all that!! That ring end gap is a good call! If they didn't check it when overhauled, that may indeed be the cause! :beerchug:

I had the same problem on my 100. It got hot and melted the head gasket.

I was going to take the 108 back down to the river and put it back to work, but maybe while I have it home I'll pull the head, see if anything is amiss, and pull the engine and have a look see in the crankcase. Maybe remove the balance gear while I'm in there and check the crank journal for any damage.

If your going that far, go ahead and pull the piston out and look at it. Just as well if your going to unbolt the rod.

Thanks, J-Mech, that's exactly what I did. And the results are in:

Cylinder is scored, and piston is scuffed up pretty bad. I mic'd the bore and it is at least .005 over the limit for a STD piston/rings. No evidence of any cross hatching in the bore. This is after the Case/IH dealer charged me $800 (yes, $800) to "overhaul" the engine. They said the cylinder was in spec and only needed STD piston, rod, valves, etc. Crank journal looks fine, as does the rod bearing surface. Lots of fine metal in the oil--aluminum from the piston I'm sure. Looking down the bore with the piston in it, you can see the rings all the way around the piston it is so loose in the cylinder.

Needless to say, it's in the back of the van and is going back to the dealer tomorrow. It's got all of 20 hours on it since the "overhaul."

Oh, no balance gear, no shaft for one either.

Thanks for the update!! Sorry that happened to you :( Hopefully, they will take care of it no questions asked!

Dealer has the motor. I expect they'll make it right under warranty. First thing the service manager did was check the scoring on the cylinder bore, looked at the well worn piston, and then looked at the rod journal bearing surface. I'm sure he suspected it was run without oil, but the journal bearing is perfect, so that's not a reason. It's always had the proper amount of oil in it. I think the bore was oversize when they put the STD piston in and it just flopped around enough to start wearing the piston skirt. Got worse quickly as time went on. 20 hours of run time, and it's toast. Will report back once he gives me a recommendation on repair.

Good luck sawdustdad. I hope they make it right free of charge!

Dealer called, said they are sending the block out to get bored oversize. Once they know whether it's .010 or .020, they'll order the piston and put it back together.

Thanks for the update!

X2! :beerchug:

Good to hear they are fixing it , but are they doing it for free ??

You said it is under warranty , but you probably know how some places can be !!

Some shops/parts stores make me want to :Explode:

That's what I was wondering too!

The service manager told the service clerk (while I was standing there) it was a company warranty job. I interpreted that to be "for free." I wanted them to assess the damage and tell me what the solution was rather than me telling them what I wanted them to do. That way, they are accountable for the outcome.

If the reason it failed was due to an oversize bore the first time around, and they didn't bore it oversize, then I didn't pay for that service then either. So, to be totally fair, I might offer to pay for the machining if they cover the new piston and labor. I don't expect something for nothing, but I did rely on them to do the work properly.

It will take about 3-4 weeks to get the engine back. Meanwhile, I'm dropping a spare K301 into the 108 to get it back to work. Will probably leave the 12hp engine in it. Might just put the 48 inch deck on it. I think that's too much for the 10hp but should be fine with the 12hp.