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Curtis
Curtis UltimaDork
9/6/18 2:56 p.m.
gearheadmb said:
Curtis said:

I think you have more going on than a tune up.

If it wasn't smoking, I would say ignition module or coil.  Leakdown test isn't necessary to confirm my guess... cracked ring, head gasket, or hole in a piston.

Also quite possible that TransMaro is right: Manifold gasket sucking oil from the bottom.

The internal intake leak fits the symptoms, but i hate to "throw one at it" since I'm not feeling vacuum at any at the valve cover holes. The more I think about the stream of smoke out pcv vent keeps leading my mind to a more insidious issue.

You won't feel vacuum at the valve cover.  Depending on ring seal, you'll actually get pressure.  Even with PCV hooked up, it doesn't generate enough flow to overcome crankcase pressure and make a vacuum.  On a fresh rebuild, maybe.

I would do a compression test first.  I know you said you handed it off to a pro, but that would be my next step.

gearheadmb
gearheadmb SuperDork
9/6/18 6:16 p.m.
Curtis said:
gearheadmb said:
Curtis said:

I think you have more going on than a tune up.

If it wasn't smoking, I would say ignition module or coil.  Leakdown test isn't necessary to confirm my guess... cracked ring, head gasket, or hole in a piston.

Also quite possible that TransMaro is right: Manifold gasket sucking oil from the bottom.

The internal intake leak fits the symptoms, but i hate to "throw one at it" since I'm not feeling vacuum at any at the valve cover holes. The more I think about the stream of smoke out pcv vent keeps leading my mind to a more insidious issue.

You won't feel vacuum at the valve cover.  Depending on ring seal, you'll actually get pressure.  Even with PCV hooked up, it doesn't generate enough flow to overcome crankcase pressure and make a vacuum.  On a fresh rebuild, maybe.

I would do a compression test first.  I know you said you handed it off to a pro, but that would be my next step.

My point was referring to the possibility of an intake gasket leaking vacuum to the crankcase. Every time I have seen that I have proved it by removing the oil cap and seeing if it sucked super hard. 

gearheadmb
gearheadmb SuperDork
9/18/18 11:45 a.m.

I got an update on this so i figured i would share it. The shop that was checking it out also suspected major problems, so after digging into it they found a head gasket blown between two cylinders and a burnt piston. 

tuna55
tuna55 MegaDork
9/18/18 12:06 p.m.
gearheadmb said:

In reply to AngryCorvair :

The float is black plasticy stuff, not brass, and seems to operate properly.

Yes, but does it float? I have had two of those on Q jets stop floating.

 

Check the timing for stability and do a compression check. We go from there.

tuna55
tuna55 MegaDork
9/18/18 12:07 p.m.
gearheadmb said:

I got an update on this so i figured i would share it. The shop that was checking it out also suspected major problems, so after digging into it they found a head gasket blown between two cylinders and a burnt piston. 

I added my own before reading page 2 and now I feel bad.

APEowner
APEowner Dork
9/18/18 12:43 p.m.
gearheadmb said:

I got an update on this so i figured i would share it. The shop that was checking it out also suspected major problems, so after digging into it they found a head gasket blown between two cylinders and a burnt piston. 

No amount of carb tuning is going to fix that.  I suspected that you were doing the right thing by sending that on.  Thanks for the update.

akylekoz
akylekoz Dork
9/18/18 1:13 p.m.

So how much does he want for a corvette with a dead motor?

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