Engine Diagnosis B8200 D950 Rings or Valve Stem Guides or Head Gasket or Injectors

[jimybud]

These are the issues with the engine:

Push rods on number one and number three cylinder are slightly bent.

Excessive smoke at all rpm levels, with the engine warm or cold.

Oil in the radiator, but no coolant in the oil.

Black gunk leaking out of the number one cylinder exhaust valve when the engine was running. There are indications of moisture near the intake valve stem/guide.

Number two cylinder, when performing a leak down test (approximately 90 PSI's of air) had leakage from the exhuast valve and also air into the radiator. There was moisture pitting on the head within this cylinder. I suspect water had leaked into the cylinder from the muffler. The cylinder does not show any pitting.

The compression on the cylinders was approximately 300 PSI's, with the number two cylinder a little less.

I did not detect any obvious damage to the head gasket.


This images are of the number one cylinder. Black gunk would leak from the exhaust manifold when the engine was running. The first photograph shows the build up on the outside of the engine.

this is also number one. This next one shows the buildup within the intake manifold. Please note there is a lot of buildup next to the valve guide.

This is also the number one cylinder is taken when the exhaust manifold is removed. This photograph is of the same cylinders above, but it shows the moisture on the exhaust valve guide. It is difficult to tell from the photograph, but the valve stem is fairly wet. It was not wet on the other two exhaust valves.

This is a photograph of the three injectors hooked up to test them. They seemed to discharge the fuel consistently. All three seemed about the same.

This next one is of the underside of the head. It is a bit difficult to tell, but the middle cylinder area is pitted, but only inside the round area. Not anywhere under the gasket. Cylinder one and three area cleaned up nice, in the photograph is is merely excess buildup.

Also, I took this photograph with the gasket still intact. I did not detect any obvious damage to the gasket. And again, there was not any pitting on the head under any part of the gasket.

I am debating what needs fixed.

I will have to perform some work to get the number two cylinder exhaust valve to seal better.

I am not sure how to diagnosis the number one cylinder excessive moisture.

I am assuming the a new head gasket will resolve the oil in the radiator. I am assuming it was coming from the number two cylinder as the leak test demonstrated such.

 

[jimybud]

Thank you for taking the time to respond, i was afraid I was not going to get any advice of feedback.

Could you also suggest what you would do with the piston rings/ or cylinders?

At this point I have removed the pistons and inspected the cylinder walls and ring wear.

I do not have a lot of practical experience to compare this with other engines, but It appears as if there is some wear as this is a slight ridge rim.

also, there is a larger gap on the compression and scrapper rings than on the oil control.

The end gap is about 50 on the compression and a bit less on the others.

If I had a new set of rings and inserted them into the cylinder, should the end gap be virtually the same for all three ring types (compression, scrapper and oil)?

I realize the compression ring gets more wear as it is closer to the detonation area but was not sure if that was the sole cause of the difference in size or if it had to do with the design of the rings.

 

[jimybud]

One other addition for diagnois of cylinder/piston rings.

Before I disassembled it, I removed the exhaust manifold and ran the engine. I took a piece of cardboard and tried to separate the three ports to determine if only the first cylinder was smoking (the one with the black liquid leaking from it). The best I could tell all three were cylinders were smoking to some degree.

 

[eserv]

One other addition for diagnois of cylinder/piston rings.

Before I disassembled it, I removed the exhaust manifold and ran the engine. I took a piece of cardboard and tried to separate the three ports to determine if only the first cylinder was smoking (the one with the black liquid leaking from it). The best I could tell all three were cylinders were smoking to some degree.

You can sometimes get away with reringing a diesel engine but not often! If you have "ridge rim" that you can feel with your finger then new rings will not seat very well . I wouldn't repair this engine without installing new sleeves. It probably doesn't need new pistons though if they measure up within limits.
seeing it has been consuming water and has bent pushrods it HAS been hydrolocking. this warrants close inspection for bent connecting rods. If you put it together with bent connecting rods you would have a " rebuilt" engine that is hard or impossible to start. You wouldn't like that!!
Ed

 

[eserv]

If this were my own tractor I would repair the head issues as Vic suggested and reassemble the engine with the original rings, get it running again and it likely will be satisfactory ( of course checking the piston protrusion! ) If it were a customers and I did that it would likely come back and bite my ass ! That is the dilemma we often find ourselves in in repair shops!
Ed

 

[jimybud]

This last comment gave me a bit of hope. I was just considering pushing it out of the garage bay and placing it in "storage" and pursuing finding a good used engine.

Given the option of using the the existing piston rings or replacing them with new one, are you suggesting that the new ones may not seal as well for this engine?

 

[eserv]

This last comment gave me a bit of hope. I was just considering pushing it out of the garage bay and placing it in "storage" and pursuing finding a good used engine.

Given the option of using the the existing piston rings or replacing them with new one, are you suggesting that the new ones may not seal as well for this engine?

Kinda yea! I think new rings would be wasted on the old cylinder liners and the original rings will likely seal better than new ones provided they go back into the same holes! 50 thou ring gap is a lot more than new rings but I've seen a lot worse!
Ed

 

[jimybud]

One continuing concern about reconstructing the engine, is that I did not discover anything unusual about cylinder one number and why it was emitting the black liquid out of the exhaust port when running. Sure it had excessive ring gap and a rig ream, but so did number two and three cylinder.

 

[eserv]

One continuing concern about reconstructing the engine, is that I did not discover anything unusual about cylinder one number and why it was emitting the black liquid out of the exhaust port when running. Sure it had excessive ring gap and a rig ream, but so did number two and three cylinder.

Put the pistons back in and check that all the pistons come up to the same height. If the engine has had water in that cylinder it could have a bent rod. This would cause the compression to be low on that cylinder causing it to not burn the fuel. This is not an uncommon situation on the Kubota engine ( or any diesel) when water gets into the cylinders.
ED

 

[jimybud]

The pistons all seemed to come up to the same height.

I guess I may not find out what was causing the black fluid leak in the number one cylinder.

I also took some gas and enveloped the top of the head around the valve guide seals to determine if there was any leakage. None was noticed.

 

[jimybud]

One other item I did notice before removing the pistons from the cylinders was the excessive oil residual on the cylinder walls when I cranked over the engine.

I am thinking the scraper rings were not doing their job.

 

[jimybud]

Reassembled the engine.

I cleaned up the valves as part of this process.

much less oil from the number one cylinder but still some leakage at the exhaust port. None at cylinder two or three.

also, no abnormal wear to the cylinder walls of number one as compared to 2 and 3. The rings also seemed to be the same as two and three.

with the engine running, and exhaust manifold removed I can a observe liquid that appears to be leaking from the top of the valve stem.

when I had the valves removed i did not notice any excessive wear on the valve seals, and the seals on all six of the valves seem to be about the same.

I also have read on the internet that valve seals are rarely the issue with a smoking engine.

Could the blow by inside the valve cover somehow be leaking past the top of the valve seal and causing this liquid? I can not figure how the oil is getting to the top of the seal. I checked and the bottom of the seal is not leaking.

I am open to replacing the seals, but was trying to first accurately diagnose why there is such leakage. I do not want to replace the seals and then find I still have the issue.

Other than the smoke the engine runs strong.

 

[E/S]

I am no expert but I'm wondering if there is a bad injector on #1 cylinder ?

E/S

 

[jimybud]

I forgot to mention that i also switched injectors one and three and did not notice any less moisture/leakage from the number one exhaust valve.

I appreciate the suggestion, no need to be an expert to provide solicited advice.

 

[jimybud]

The replacement of the valve oil seals reduced the amount of exhaust smoke and there is no longer any liquid leaking from cylinder number one exhaust port.

I was able to replace the seals by pressuring the cylinders with air to hold the valves in place. This allowed me to do the work without having to remove the head.

It was about a two hour job, no complications other than I did not have a very good tool for compression the valve springs; i merely used a 13/16 wrench and pushed them down with one hand will inserting the key with the other.