New rebuild pumping in oil on one cylinder

[d_boyce]

This is a 964 engine that's just gone through a new rebuild with new pistons and cylinders.

On initial startup the engine began smoking pretty heavily a few moments after startup. I pulled the intake manifold to check and see if I over-filled the oil tank and was possibly drawing oil--it was dry. What I did see was a puddle of oil sitting on top of one of the intake valves and noticable oil residue in the intake port. I dried out the port and restarted it with the same results.

The oil was somewhat black with assembly lube which leads me to beleive that it was drawing it through the valve stem from the area where lots of assembly lube would have been present.

I stepped back from the project for contemplation.

My number one suspect is that the intake valve stem seal may be missing. It seemed like too much oil on the intake port for a broken ring but I plan on doing a compression check.

I welcome any thoughts or comments.

-doug

[john walker's workshop]

lots of race cars don't run stem seals, at least on the intake, and they don't smoke. new guides right? valve stems weren't tapered or worn out? did you put an hour on it to see if it stopped smoking?

[NevenM]

Doug

Go back a bit, if the oil is being sucked down the guide it must be
pooling at the rocker end, have you pulled the covers and had a look?

Neven

[Wayne 962]

Hmm, without more info, I'd say the smoking is normal? Recently rebuilt motors are not environmentally friendly until they are broken in...

-Wayne

[adomakin]

any news doug??

Andy

[d_boyce]

I'm pretty sure this will turn out to be a ring problem--stay tuned.

I should mention that the amount of oil that was pumped into the exhaust was enough to form a puddle at the joint between the headers were it leaked out. Made me think I had a main seal leak--funny in retrospect.

The motor is out. I just need to round up some friends to help me lift it on to the stand.

-doug

[d_boyce]

Turns out that I got the wrong rings for one piston.



I did verify the gap on the first three I installed.

-doug

[john walker's workshop]

damn!

[ChrisBennet]

Wow. I don't check every ring. Maybe I should. Does everyone else?
-Chris

[adomakin]

i do now!

[Doug Zielke]

Originally posted by ChrisBennet
Wow. I don't check every ring. Maybe I should. Does everyone else?
-Chris

Another lesson learned.
Thanks for posting, d_boyce.

[asphaltgambler]

Did the ring packaging/box look like it had been opened before?

[cgarr]

Should this not have been caught when the parts were match weighed ??

Craig

[NevenM]

Check, Measure, Check, Measure and never assume

Neven

[asphaltgambler]

Sound like the luck I've been having as of late. Thought I was the only one. Most recent example of 'good' luck. I'm a tech at a highline shop. A good customer brought his BMW 740I in for repairs. Check engine light was on. Scan the ECM and diagnosis revealed leaking intake end and manifold-to-head gaskets. This is a common problem. Fairly straightforward fix. Pays about 3 hrs.


R&R the intake and replace the end seals and the manifold seals. Being very carefull I clean the intake port sealing area and then use a shop vac to vacuum the small debris up.
Put it all back together, turn the key, the engine fires and almost immediately crunching noise, followed by a bang. Engine stops. Trace noise to #8 cylinder. Piston is NOT moving, broken!! Intake valves bent! Boresope revealed 6mm bolt inside combustion chamber and extensive cylinder wall damage. These engines are all aluminum and have the Nikasil coating.

Now I must mention that when I remove any components I always put all hardware in sub-groups. There is a small number of bolts and nuts removed and all were accounted for...............completely. The 'errant' bolt was either sitting there near the opening that was left by some previous repair or...........

This is a 4-cam 4.4 all aluminum V-8, 4 valves per cylinder with tons of electronic controls. I already pulled the engine and have taken that cyl head off. Now trying to locate a block or long block. Needless to say all my labor is free and it may cost some $$ out of my pocket for the parts. That was my week last week. Life just sucks sometiimes.

[michaelgrasso77]

There you have it folks - some times it just F*****G sucks.

[efhughes3]

Wow, as I prepare for my upcoming rebuild-this is eye-opening. Definitely a lesson here. I'm sorry you had to experience this.

[Wayne 962]

Something like 1000+ parts go into an engine. Even if you have .1% failure rate or .1% out of spec, then you will have a large catastrophic failure. Don't assume the parts are correct from the factory, and also don't assume they're clean...

-Wayne