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Discussion Starter · #1 · (Edited)
So I thought I should start a new thread for this one.

I have lost almost all power from my right cylinder. The engine will run on one cylinder and it sounds better on one cylinder than two. (this was checked by pulling the sparkplug wire off of the right spark plug and hearing a more consistent and healthy engine tempo.

Oil is all over the top of the right cylinder. It is also filling the air cleaner compartment and is dripping downward from there. Strangely I measured fairly good compression (see picture below, 120psi) but the dial indication bounces all around until I turn the engine off and the dial settles down to 120 as shown. I have a video of it.

If you have insights, Id appreciate them. The only thing I can imagine is a valve gap issue but Im not sure. Removing that large tin requires getting a wrench under the engine, not an easy maneuver. Id like to get some insights from those that know this engine before I start to tear it apart.
 

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Discussion Starter · #2 ·
At this point my next step will be to take off the head and see if there is something quirky with the valves, timing or a displaced valve stem guide.
 

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Discussion Starter · #4 · (Edited)
I did a search on " holed piston". That makes sense based on some of the the evidence, but it's still hard to explain the compression test measurements. I'll pull the head off this week and take pictures. I could be headed for a full rebuild on the engine. I'm devastated because I just installed dual brakes and 26×12 tires, and the starter relay. I never pushed this tractor hard but I've only owned it for one year so I cant know what that engine has been through.
 

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Don't be surprised if you find the head gasket blown, but still have decent compression. Blown head gaskets rarely show up as a loss of compression, believe it or not. At the GM dealers, I gave up trying to diagnose blown head gaskets with a compression test many years ago.
 

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Discussion Starter · #10 · (Edited)
I managed to pick up a leak down tester and things really got interesting..

the left cylinder (the cylinder that was able to run the tractor by itself was leaking into the crank case ( ouch !.. I could hear and feel the pressure from the crank case breather)

the right cylinder (the engine runs better with the right cylinder plug removed) had less of a leak but it was leaking out of the exhaust valve.

I have to decide what to do, Id like some advice, It seems that I can get this engine running fairly well again by just cleaning the valves and put off the rebuild until next winter. I dont imagine that there is any solution for the leaking into the crankcase on the left cylinder other than new rings.
 

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Paul, You REALLY don't need advise, you're on the right track! Pull the heads and see what's inside. Your "just cleaning the valves" could end up as replacing the valves and seats if burnt and your "other than rings" could end up as new pistons, re-bore and rings!

Pull the heads, inspect/measure and THEN make your decision. Bob
 

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Discussion Starter · #12 · (Edited)
Paul, You REALLY don't need advise, you're on the right track! Pull the heads and see what's inside. Your "just cleaning the valves" could end up as replacing the valves and seats if burnt and your "other than rings" could end up as new pistons, re-bore and rings!

Pull the heads, inspect/measure and THEN make your decision. Bob
Thanks Bob, not quite what I wanted to hear but it is the truth, .. and that is what I will do. I hate to say it but I have more fun working on the engine than I do mowing the grass, its just that I need to get this running so I can keep my neighbors happy too! I might just bring the JD212 over.
 

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I managed to pick up a leak down tester and things really got interesting..

the left cylinder (the cylinder that was able to run the tractor by itself was leaking into the crank case ( ouch !.. I could hear and feel the pressure from the crank case breather)

the right cylinder (the engine runs better with the right cylinder plug removed) had less of a leak but it was leaking out of the exhaust valve.

I have to decide what to do, Id like some advice, It seems that I can get this engine running fairly well again by just cleaning the valves and put off the rebuild until next winter. I dont imagine that there is any solution for the leaking into the crankcase on the left cylinder other than new rings.
hold up a second, you said you could fell the pressure from the crankcase breather, did you removed the dipstick and heard the oil bubling? also, did you make sure that both valve were fully closed when you did the leak down test?
 

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Discussion Starter · #15 · (Edited)
I had to hold the wrench on the PTO drive shaft 14mm bolt tightly and had to push against the pressure to keep it over TDC during the measurement.. so measuring was not that easy. Yes, I could hear the oil bubbling. But the rubber breather hose was putting out an unmistakable volume of air. It was a bit depressing. And I still haven't found a reasonable way to loosen that lower bolt holding the shroud in place. What were the engineers thinking when they put that bolt there ?
 

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I had to hold the wrench on the PTO drive shaft 14mm bolt tightly and had to push against the pressure to keep it over TDC during the measurement.. so measuring was not that easy. Yes, I could hear the oil bubbling. But the rubber breather hose was putting out an unmistakable volume of air. It was a bit depressing. And I still haven't found a reasonable way to loosen that lower bolt holding the shroud in place. What were the engineers thinking when they put that bolt there ?
Engineers HATE technicians. That is the only explanation I have come up with that makes any sense....... GM engineers had the bright idea of putting a six inch long bolt, that you HAD to remove to change the water pump on some of their front-drive v-6 cars, but, there was only about 2 inches of space to pull it out..... You had to drop the friggin' engine cradle to change a water pump... What should have been a half-hour job, turned into a six to eight hour job. And that was only ONE example of engineers booby-trapping cars for the techs..... Seems tractor engineers are the same way. :D (and who in their right mind puts a starter motor UNDER the intake manifold???????)
 

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Discussion Starter · #17 ·
I look at my starter tucked under the engine beside the frame rail and I think to myself, that is a stroke of diabolical genius!! ..

Ok , so I took the heads off tonight after work and just what I was suspecting, massive carbon build up on the valves but no significant gauling/scoring of cylinder walls. Pictures below. 1) I now realize at the very least I have to do a complete valve job. 2) I do not see any sure sign of a blown head gasket. 3) the cylinder walls don't look terrible, but they could use a honing.

So why the carbon build up, I have only had this tractor for one year and I always run my 4 stroke engines with 2stroke fuel/oil mix. I think there are positives to 2cyc fuel in 4 stroke engines but there are negatives too.

I think at this point, I need to decide if I am going to just do a valve job and out off the rebuild until next winter , or do I rebuild this engine now..
 

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I hate to say it but I have more fun working on the engine than I do mowing the grass,
Doesn't everyone?

You had to drop the friggin' engine cradle to change a water pump... What should have been a half-hour job, turned into a six to eight hour job.
Did not Jag XKE's have inboard rear brake discs? I remember reading changing the pads was an 8 hour job. Never owned one - that's just something I picked up.

So why the carbon build up....
If you have a lot of oil making its way into the cylinder - valve guides? - that would lead to carbon.
I'd guess the oil outside came from a bad valve cover gasket? You said no evidence of a blown head gasket.
 

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Did not Jag XKE's have inboard rear brake discs? I remember reading changing the pads was an 8 hour job. Never owned one - that's just something I picked up.
Yes, they did. I don't know if it took 8 hours to change them, as I never had to do it, but they did have inboard brakes. Hummer H1s also have inboard brakes all the way around. Stopping a Hummer H1 is strange because of the brakes; the axles end up working like torsion bars, so when you come to a stop, the truck sways fore and aft a few times. Very weird if you're not accustomed to it!
 
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