epic 790 hydraulic pump fail, oil flowing from dip stic, bent connecting rod....and

[spruce Deere]

Been a longgg while since I last posted.... Get comfortable if interested in the following story.

So, had a hydraulic pump let loose and being they are bolted to the timing cover of the engine and driven from the engine from gears within the cover the hyd oil from the failed pump tried to relocate ALL of the hyd oil to the crankcase.... It did not all fit...

First, there was extreme exhaust smoke, laboring engine which at this point I shut off the engine. I had just started it and all this happened in less than a minute.

Second, Finding my way threw the horrible smoke I pulled out the engine dipstick and a fountain of oil erupted from the dipstick tube.

The only good thing is that the tractor is in my shop whisle all this went down, Checking the tranny/hyd. dipstick confirmed my thoughts on what just happened.

So, I had a used hyd. pump on hand and swapped out the pump on the tractor with it. I changed the engine oil and filter, Should be on a better path now...

As I started the engine on the tractor, I expected some more intense smoke and some rough running for a bit. Well, the smoke thinned but never did clear. The rough running start leveled into a straight-up misfire on the no.1 cylinder. I betcha, it fouled the injector I assumed. I pulled off the exhaust manifold and confirmed oily diesel crud from no.1 hole. the other two ports were dry.

Had a few days wait for a new injector and the puller kit. Then some brute force whaling on the puller to pull the old injector out I was once again met with a miss on no.1 cyl with the new injector? I spoke in a sailor style tongue as the cause of miss is discovered to be deeper now.

Day or two later, I pulled the head off the block. cylinders looked as they should for only having 1000 hrs, zero ridge cross-hatch marks very clear, but as I turned the engine over by hand no. 1 piston was NOT making it all the way to the top like the other two pistons did, bent rod. So I commenced to pulling the inspection plate off from the oil pan on the engine to remove said bent con rod.

Rod removal did go good. Rod was very obviously bent. bearings and crank journal completely fine.

891 clams at deere and a couple days wait got me a NEW hyd. pump, NEW connecting rod/W bearings, pin bushing and gaskets I need to put this project back together.

After getting everything from deere, I meticulously checked/assembled everything. All cylinders made it to the top of the stroke, Checked the valves for obvious damage, there good, checked push rods for bend, zero. Plopped the head gasket on the block, torqued the head down in the 3 step procedure, returned the push rods to there rightful holes, fiddled a while getting the rocker arm rack and push rods back together, rotated the engine and lined up timing marks on the fly wheel and got all of the valves set to .008 inch clearance. All tech data is right from the deere 790 repair manual I gladly purchased couple years back.

Leaving the rocker cover, water pump/radiator, exhaust manifold off, I fire tractor up. Rough at first typical smoke but still no.1 misfire.....

Anyone got any ideas on what I missed

 

[Roadworthy]

It may be a long shot but is the piston damaged or perhaps a cracked ring? Maybe a slightly bent valve stem? You obviously had a lot of pressure to bend the rod. Oil doesn't compress easily so obviously something else is damaged. Those are just guesses on my part. I was more fortunate when my hydraulic pump started dumping oil into the crankcase.

 

[berky]

Hate to say it, but I think you are going to have to tear it down again. I agree that something is either wrong with the piston (broken ring land) or the rings may be broken.

 

[Tx Jim]

I'll suggest to check compression pressure to determine if rings or intake/exhaust valve are leaking.

 

[aczlan]

I'll suggest to check compression pressure to determine if rings or intake/exhaust valve are leaking.

That is where I would start for sure.

Aaron Z

 

[dodge man]

You might check the head also. Warped, bad valve or valve seat.

 

[herm0016]

before you go for removing the head again, make sure your new injector is getting and spraying fuel, and check the compression.

 

[spruce Deere]

Thanks for the replies fellas. The new injector is getting fuel, I can crack the injector line to it, engine smooths out with the miss, tighten it back up a labored miss takes over.
Compression pressure test is what is next. I need to talk to my diesel dude to loan the adapter and guage.....
Good thing I will not really need the tractor till around March...Enthusiasm has wained a little.

 

[Sno]

Can you switch the injector to another cylinder and see if the miss switches to that cylinder, just to be sure the new injector isn’t the problem? I’m not that familiar with diesel troubleshooting, so if that is not a useful step, I’m anxious to learn why.

 

[spruce Deere]

I'm curious too sno. I might fiddle with it today... That is a good idea. The original injector took a good deal of banging on the puller to remove and I buggered the threads a little on the injector because of the adapter loosened a bit from the threads on the injector while pulling... pull an injector again, I'm gunna smack the puller a few times then put a wrench on the adapter to make sure all is good and tight