Low compression / weak cylinder

4wheelfurry · Dec 3, 2019

I have a 40hp 3cyl (2010 Massey with Iseki 81C 1.5L turbo) So over the course of about a year it slowly slowly developed a skip start and eventually became weak / slow burn / black fuel under load on one cyl. No noise and no other indication of an issue. Never ran hot and it only has 600hr on it. So I pulled a compression check cyl #3 is at 180psi. #1,2 at 400psi. So I popped up the rockers and shot shop air and it's blowing by into the crankcase. So I dropped some oil in the cyl and retested, sure enough compression shot back up to 400psi. I'm not a diesel guy i've wrenched on gas engines my whole life so my question is what could cause ring failure issue in one cylinder withought any warning? Some additional FYI I use it very little it sits most of the time, injectors pulled and inspected/cleaned and swapped around problem stayed in #3. Also all valves were in adjustment. I changed the oil this summer it looked fine no flakes and nothing has ever given me problems on the machine.

Agvg · Dec 4, 2019

Might be so easy that it needs to work hard, real hard over some time.

redman135 · Dec 4, 2019

Has this tractor been "run in"?
I would follow Avgv's advise and give the tractor some real work.

RickB · Dec 4, 2019

Poor coolant circulation around #3 overheated it and damaged the rings or scored the cylinder wall.
Putting it to work might not hurt it, if my long distance diagnosis is wrong it might help.

4wheelfurry · Dec 4, 2019

It has never ran hot and I keep check on coolant, everything is good on the coolant circulation end of it IMO.
It has seen it's share of hard work over the years however in the last year or two I haven't used it much.. I did have the fuel shut off solenoid go out on me so I pulled it and cut off the plunger and ran it like that a few times until my replacement came in. Can't see that as an issue. Fuel wise I have always changed my filter and always run off-road fuel, never a problem with that either...
I wonder if by oiling up the cylinder then running it if it will continue to hold proper compression? Guess that's my next try before removing the head and oil pan...

Shaneard · Dec 4, 2019

Can you run a bore scope down the injector hole and see if the cylinder wall is scarred? That may tell you if you have a broke ring, if you do running it won't help matters.

Also look in the radiator and see if there is any oil, I've heard of head gaskets failing and getting oil in the water but water in oil is more common.

mike48130 · Dec 4, 2019

Borescope it if you can. Amazon has some cheap USB scopes the would probably fit in the injector hole. Then run it hard for awhile and I would pour some solvent in that cylinder and let it sit just before the next oil change if you are having issues. I've seen rings just get gummed up and stick, so if you can get it cleaned some, it will probably work itself out.

4wheelfurry · Dec 4, 2019

mike48130 said:
Borescope it if you can. Amazon has some cheap USB scopes the would probably fit in the injector hole. Then run it hard for awhile and I would pour some solvent in that cylinder and let it sit just before the next oil change if you are having issues. I've seen rings just get gummed up and stick, so if you can get it cleaned some, it will probably work itself out.

This is what makes the forums so invaluable, I don't stay up with new tools and such as I don't do much wrenching anymore, I mechaniced for a living back when GM and Ford were beginning to introduce FI, it was mainly carbs and points/rotors ect lol.. I had no idea they now make scopes that can attach to your phone! So a scope is on order and I will go from there. Thanks all for the input!!

4wheelfurry · Dec 4, 2019

So after trying the oil trick today compression didn't hold and it even sounded a little worst after a few min of running so I went on and pulled the head. One medium and 2 or 3 light vertical scratchs in the cylinder pretty sure broken ring or piston or both... Now to figure out how to drop the front drive shaft to access the pan!

mike48130 · Dec 4, 2019

Well, that sucks. You might have to pull the front axle forward to pull the driveshaft.

rScotty · Dec 4, 2019

4wheelfurry said:
So after trying the oil trick today compression didn't hold and it even sounded a little worst after a few min of running so I went on and pulled the head. One medium and 2 or 3 light vertical scratchs in the cylinder pretty sure broken ring or piston or both... Now to figure out how to drop the front drive shaft to access the pan!

Good on you for pulling the head. Most of the time when I've had one cylinder go weak it's been a head gasket. How did that look?
rScotty

radios1 · Dec 4, 2019

4wheelfurry said:
So after trying the oil trick today compression didn't hold and it even sounded a little worst after a few min of running so I went on and pulled the head. One medium and 2 or 3 light vertical scratchs in the cylinder pretty sure broken ring or piston or both... Now to figure out how to drop the front drive shaft to access the pan!

that happening at 600 hrs. is very suspicious!. maybe a manufacturing defect?.

rScotty · Dec 5, 2019

4wheelfurry said:
So after trying the oil trick today compression didn't hold and it even sounded a little worst after a few min of running so I went on and pulled the head. One medium and 2 or 3 light vertical scratchs in the cylinder pretty sure broken ring or piston or both... Now to figure out how to drop the front drive shaft to access the pan!

I've seen lots of leaky head gaskets, some leaky valves, but rarely have I found broken rings. Minor vertical scratches in the cylinder wall are surprisingly common. I don't know what causes them. On the other hand, any time the head is off I now consider it normal procedure to have an automotive machine shop take a very light cut on the head to make it absolutely flat.

I've come to believe that a lot of cast heads have a little bit of manufacturing stress locked into them that shows up as warpage when a new engine is first run torqued down and run up to temperature. The gasket should be elastic enough to seal in spite of that movement, but that's not always the case. But once the head has aged and been flatted, it seems to last just fine.
rScotty

Shaneard · Dec 5, 2019

Have you ever used ether on this engine to crank it?

4wheelfurry · Dec 5, 2019

Shaneard said:
Have you ever used ether on this engine to crank it?

I have never however I loaned it out a while back and I suspect he did. The fuel solenoid went out while he had it, he was trying all sorts of things to get it up running not knowing what he was doing... I went and got it back going, needless to say I was not happy about he handled that situation but he was afraid I'd make him pay to repair it which the solenoid was not his fault. So I suspect that is the culprit to my situation now!
The head gasket was sealed up tight to the head and block, everything looked as it should. I plan to pressure was and clean the head Saturday I will put a straight edge on it once it's clean. I am going to go on and lap in the valves while its down too.
Today I will try to figure out how to drop the front drive shaft and pan, I will post an update once its completely down.

radios1 · Dec 5, 2019

4wheelfurry said:
I have never however I loaned it out a while back and I suspect he did. The fuel solenoid went out while he had it, he was trying all sorts of things to get it up running not knowing what he was doing... I went and got it back going, needless to say I was not happy about he handled that situation but he was afraid I'd make him pay to repair it which the solenoid was not his fault. So I suspect that is the culprit to my situation now!
The head gasket was sealed up tight to the head and block, everything looked as it should. I plan to pressure was and clean the head Saturday I will put a straight edge on it once it's clean. I am going to go on and lap in the valves while its down too.
Today I will try to figure out how to drop the front drive shaft and pan, I will post an update once its completely down.

ether these days have a lubricant to prevent washdown..

RickB · Dec 5, 2019

radios1 said:
ether these days have a lubricant to prevent washdown..

Some but by no means all. And most ether damage is caused by the violent explosion that occurs before the actual fuel injection timing, not cylinder washdown. Broken rings and melted and broken ring lands are not caused by a lack of cylinder wall lubrication.

rScotty · Dec 5, 2019

4wheelfurry said:
I have never however I loaned it out a while back and I suspect he did. The fuel solenoid went out while he had it, he was trying all sorts of things to get it up running not knowing what he was doing... I went and got it back going, needless to say I was not happy about he handled that situation but he was afraid I'd make him pay to repair it which the solenoid was not his fault. So I suspect that is the culprit to my situation now!
The head gasket was sealed up tight to the head and block, everything looked as it should. I plan to pressure was and clean the head Saturday I will put a straight edge on it once it's clean. I am going to go on and lap in the valves while its down too.
Today I will try to figure out how to drop the front drive shaft and pan, I will post an update once its completely down.

Is that a wet sleeve motor or a bored block type?
I'm a great believer in hand-lapping.

No,I don't like ether either. I almost didn't buy our JD310 (used with 6000 hrs) because it came is set up from the factory with ether injection. There's a place on the manifold to screw in an ether cylinder triggered by a solenoid from a button in the cab. I've never used it, but suspect that the previous owner used it a lot. The tractor had 6000 hours when I got it. Luckily, that engine is still tight, quiet, fuel efficient, and quiet and starts on the first crank. So maybe JD's ether start system doesn't inject enough ether to hurt. Or maybe this is just a blessed engine.

Which reminds me that I've still got an old German .22 cal. pellet rifle that uses ether to boost the velocity. I guess that makes it a diesel rifle.
rScotty

4wheelfurry · Dec 5, 2019

Piston is out. Broken second ring and middle lan. Which is quite unusual, pre-detnation usually effects the top ring and lan.. top ring and oil ring were both free and fine. No chunks missing or even big scratches to the piston beats all I ever seen. Assembly error perhaps? Anyway I have one bad push rod too so all parts ordered. Will clean this weekend and wait reassembly.