Calling All 2F Guru's and Engine Experts (2 Viewers)

[rlocke49]

Hey Folks!

I am hoping you can help me with some over-the-internet troubleshooting of a recently rebuilt 2F in my 60 series. Long (and sad) story short, the engine was rebuilt in May by a "reputable" shop, quickly developed an oil leak behind the cam plate and had to be pulled back out for warranty work. Reinstalled and ran for about 4k miles before starting to burn oil and smoke during engine braking down long grades, and in between shifts when the engine is cold (<40 degrees F). Tried the quick fix of the PCV System, seems to be functioning as intended - went ahead and threw in a new valve for the heck of it. Still smoking.

I pulled the spark plugs, cyl. 6 seemed to be the worst followed by cyl. 1. Compression test showed an even 150 PSI across the board. Spoke with the engine shop and decided to pull the head to check valve guides - apparently they were not replaced during the initial rebuild because they were "in spec". Valves felt loose to me, so the shop was happy to press in new intake guides and new seals (for every valve) under warranty. Another note, the piston tops were pretty carboned up as well, likely from the oil consumption but the truck was also running rich since I live at 7K feet above sea level.

Where I need your expertise is that the the engine is STILL burning oil and smoking during engine braking and in between shifts. The idea of pulling the engine again is a real bummer. Any idea where I should look next? Is it possible to have a carboned up oil ring but still have good compression numbers? Should I seafoam the hell out of it and see if that breaks things loose?

I really appreciate any and all advice!

Thanks,
Ryan

 

[OSS]

If compression is 150 psi across all cylinders, that’s good. Maybe one of the oil control rings on a piston isn’t doing its job. Maybe it’ll figure itself out. I’d just drive it. Put a lot of miles on it and keep an eye on the oil level. Don’t use thick oil. A rebuilt engine might be compared to getting a whole new set of dentures/ it’s going to take a while before chewing becomes normal again.

Mismatched valve oil stem seals (too loose) will cause the engine to burn oil too.

 

[pithicus]

I vaguely remember a couple of other post's about oil burning after rebuilds. Could this be something to do with the quality of the piston rings? I'm not sure what brand of rings are available/ recommended these days. I assume it;s not been badly overheated since the rebuild?

 

[rlocke49]

I vaguely remember a couple of other post's about oil burning after rebuilds. Could this be something to do with the quality of the piston rings? I'm not sure what brand of rings are available/ recommended these days. I assume it;s not been badly overheated since the rebuild?

Correct! never overheated since I've owned it and the machine shop has checked the head twice, apparently it is straight and not cracked.

 

[F226continental]

Just a note to anyone building an engine...

ALWAYS put in new valve guides, because guides are what the valve seat cutting machine centers itself off of. Guides tend to wear off center so therefore if you cut new valve seats with the machine set on an off center hole, guess what...

Your valve seat is now off center of where your valve would like to seat.

 

[rlocke49]

Just a note to anyone building an engine...

ALWAYS put in new valve guides, because guides are what the valve seat cutting machine centers itself off of. Guides tend to wear off center so therefore if you cut new valve seats with the machine set on an off center hole, guess what...

Your valve seat is now off center of where your valve would like to seat.

AMEN

 

[pithicus]

Was this a hone and re-ring , or a re- bore and new pistons? If the former. it may have been at the point where a re-bore was needed. It shouldn't burn any oil if done correctly. Even if the guides are worn, new stem seals should minimise the oil burning.
Also check none of the stem seals haven't popped up from where they are seated.

 

[rlocke49]

It was re-bored and new pistons were installed.

 

[pithicus]

It was re-bored and new pistons were installed.

You have a real mystery. Bad quality valve stem seals?

 

[rlocke49]

You have a real mystery. Bad quality valve stem seals?

Could be! I would be somewhat surprised since I have had 2 full sets of seals installed. Thanks for your input!

 

[Lead Head]

If they installed new guides, it's probably not the guides. Piston rings are likely worn for some reason, or maybe stuck. What is the oil consumption like?

I suppose you could try a bottle of something like Marvel's Mystery Oil to see if it frees the rings up (if they are stuck for some reason).

Are you sure its oil smoke and not "running too rich" smoke?

 

[rlocke49]

If they installed new guides, it's probably not the guides. Piston rings are likely worn for some reason, or maybe stuck. What is the oil consumption like?

I suppose you could try a bottle of something like Marvel's Mystery Oil to see if it frees the rings up (if they are stuck for some reason).

Are you sure its oil smoke and not "running too rich" smoke?

I am hoping for a stuck ring, just odd that I have such consistent compression. I think I will seafoam it and see if I can knock some of the carbon out. It was consuming about 1qt every 1000 miles before the new valve stems and seals were installed. Unfortunately it is definitely blue smoke which seems to stop once the engine comes up to temp.

 

[F226continental]

My bet is that your cylinders are glazed over, because rings didn’t seat.

Reason could be too slick a finish on cylinder walls, I’ve done that before. These engines seat rings with a rougher finish cylinder better

Or it could be totally a ring problem like OSS said earlier

 

[rlocke49]

My bet is that your cylinders are glazed over, because rings didn’t seat.

Reason could be too slick a finish on cylinder walls, I’ve done that before. These engines seat rings with a rougher finish cylinder better

Or it could be totally a ring problem like OSS said earlier

That would be a drag, that could be a pull the pistons and hone situation?

 

[pithicus]

I have heard using friction modified, or synthetic oil can cause a hard glaze when running in an engine.

 

[F226continental]

I use the cheapest non detergent motor oil at Wally World, then add zinc for flat tappet cams

 

[4Cruisers]

Don’t use thick oil.

Especially now that really cold weather is ready to set in up here in the next day or two - forecast for Friday night low is 13 degrees.

 

[rlocke49]

Especially now that really cold weather is ready to set in up here in the next day or two - forecast for Friday night low is 13 degrees.

Thank you! I have 20w-50 in it currently, on the recommendation from the builder that I should use High zinc stuff. Hopefully running it this long hasn't caused the issue. Would you recommend 5w-30 with a zinc additive?

 

[4Cruisers]

Thank you! I have 20w-50 in it currently, on the recommendation from the builder that I should use High zinc stuff. Hopefully running it this long hasn't caused the issue. Would you recommend 5w-30 with a zinc additive?

I use a zinc additive in the 3FE in my '86 FJ60, but I have fewer miles after my rebuild than you do. That reminds me that I'm ready for another oil change.

 

[rlocke49]

I use a zinc additive in the 3FE in my '86 FJ60, but I have fewer miles after my rebuild than you do. That reminds me that I'm ready for another oil change.

5W-30? Ill change the oil today if that's the case