Motor out and disassembled. As I suspected, I see nothing that appears wrong. Timing marks are lined up, rings installed proper direction, compression and oil rings have good tension, end gaps good. No out of spec measurements that I can see.

It appears to me the oil is coming from below as evidenced by the pistons being clean in certain areas. Thinking if from the intake, it would be uniform across top of piston. I do not know the brand of the pistons so guessing at the rings to use. The numbers do not reference to anything. Perhaps that is the problem but really do not know.

Anyone sees different don't be shy. I'm open to any and all ideas. I'll talk to the engine shop again on Monday but they are just as confused and have not seen this before.

I'm done. Looking for a new/used engine. I have taken this apart so many times and just keep spending money with no better results. Too bad, flanged top hat liners and all fully rebuilt again 800 miles ago

 

Hate rebuilding engines over the internet, because pictures do no justice and it's a hands on type of operation. But...the hone work on those cylinders looks way to aggressive (especially third one in picture)...but...it could just be the lighting, angle of camera or whatever...but...do you actually feel those hatch-marks with your finger nail? First cylinder seems to have some scoring, but it looks as though the hone marks go through them.

Rings on the one piston seem to be rounded, but could be photo...or this damn tablet. Pictures seem so much clearer at work on a regular computer.

Also, just breezed through the topic...and you say the compression was good....but what were the actual numbers...also, did you ever do a cylinder leak down test like suggested? And, do you remember your vacuum readings while running at idle?

That's a huge amount of oil in the cylinders, you'd think that one of the cylinder test would have given you more clues to the issue. If the engine had a lot of miles on it, you'd think the cylinders were wasted (ovaled out at the bottom of the stroke), but not with new liners. Very strange situation, but like I say...this is a case for measurements, eyeing the parts up close and experience.

Anyhow, hope you guys come up with something at the machine shop.

Brian.

 

What do the spark plugs look like?

 

How does oil wind up in the intake from a rings issue?

 

Exhaust ports were not coated with any oil but sooty. Spark plugs white ash in the electrode but heavy black elsewhere.

Cross hatch vey fine. So smooth can’t even feel it and looks like mirror when viewing. I’m generally knowledable on mechanically related stuff and not my first rebuild but I don’t have enough experience to understand what to look for and what I am seeing. Not often you get a chance to look inside an engine with 800 miles.

I agree the vertical scuffs on the cylinder wall are unusual so will inquire more on that. I know my pistons are .002 too small due to rehoning from the first rebuild for same oil burn problem. I’ve done this before and the shop has too so I don’t think it’s the cause.

Cold compression with intake off was 140-150. No leak down test

 

I suspected top end for the longest time. Tore it down to the intake valley 4 times. Concluded sucking from the valley area into the ports. Siliconed it up and when I tore it back down I could see it was dry on the contact surfaces so I ruled that out. Also a good imprint on the valley gasket itself.

Manifold pressure was 25 hg. High in my opinion. Stock cam.

The shop is suspecting during the exhaust/intake overlap some oil droplets are making it into the open valve. I have googled the problem and there are other cases of this with other makes of engines and using similar oil consumption but never a resolution. I suspect they gave up.

Problem is I don’t know if oil is getting flung somewhere it shouldn’t and making its way past the rings or it’s running down from the piston top after it’s been sitting. Shop says clearly from bottom/rings cause of clean spots on the piston which we saw with the bore scope.

 

Yeah, you'd think if the rings were bad...you'd see the same type of pooling on top of the exhaust valve...which I don't think you are? Hate jumping in at midstream, when I originally read this topic...you were battling the valley pan gasket...and just figured you get it straighten out or find a better sealant.

The pooling on top of the intake valves would lead me to believe valley pan was not sealed properly and oil was being drawn in on intake stroke, but you said you've tackled the gasket a few times now...with the same results. Me, I used ultra gray premetex with good success on the valley pans (2)...knock on wood. Not sure what you were using, but it almost looks cellular or foamy in nature.

Weird that this thing didn't smoke like an old freight train.

Anyhow, good luck with your diagnosis...and hopefully you find something of interest.

Brian.

 

25 is high, what does the intake system look like? Filter and duct work in good shape...no restrictions?

 

There are three test that I would normally do in a case like this, vacuum reading at idle (easy test), compression test (a bit more complex) and a cylinder leak down test (slightly more complex). These three test will give you a good "baseline" of the condition of your engine.

Normal vacuum readings mean the engine is "breathing" correctly.

Normal compression means the engine cylinders are making acceptable compression for creating ignition/power.

Normal leak-down tests mean the cylinder, valves, rings and other components are holding up there end of the deal.

After reading about the higher vacuum reading...I would have pursued this area of concern first, ruling out something simple. If the intake air system is plugged/restricted/modify it can cause oil to be drawn up around the rings. The cylinder is going to get "air" from somewhere on intake stroke.

I'd pop the tube off from air box to fender and look for obstructions. Darn mice can cause issues with such connections.

Just some after thoughts about the topic...and for those following along. These three tests are a must in proper engine diagnostics.

Brian.

 

Agree with your diagnosis steps. Compression was good and engine was making good power and smooth idle. So didn’t bother with leak down cause it wouldn’t help with oil control rings anyway.

No restrictions. Was reading off the OBD port. Wish I had used a gauge to verify. Odd thing is I tore it down cause it was burning oil when I purchased it. But not at this rate. Had 20k on the rebuild at that time.