oil in itake

[Grbmaverickmo]

A friend of mine is having a oil prob with his 428 it has CJ heads with a 406 T-bird trip intake. It is getting oil into the intake we changed gaskets twice using two diff companys thinking it was pulling oil in that way but no change. The other weird thing is it is pulling vac at the valve covers not blow it actually pulls in on both valve covers with PCV unhooked. I was thinking cracked intake but we cannot see anything. Any body ever see something like this before? Thank you for any ideas on this

[SE2839]

Were the heads milled and or block decked? Pretty common that the intake will not fit correctly allowing vacuum to suck in oil into cylinders but not sure that that would explain it getting inside the intake itself. Bad valve seals would also allow it to pull oil into the cylinder but again I would not expect to see it inside the intake. Both could explain vacuum at the valve cover though. No oil restriction to the top end flooding the rocker/valve springs could be allowing oil to be sucked in by the PCV valve. Check intake fitment, check that seals are installed correctly and look at how much oil is getting to the valve train.

[fe66comet]

I have seen that with huge blow by but it would smoke like crazy.

[My427stang]

A friend of mine is having a oil prob with his 428 it has CJ heads with a 406 T-bird trip intake. It is getting oil into the intake we changed gaskets twice using two diff companys thinking it was pulling oil in that way but no change. The other weird thing is it is pulling vac at the valve covers not blow it actually pulls in on both valve covers with PCV unhooked. I was thinking cracked intake but we cannot see anything. Any body ever see something like this before? Thank you for any ideas on this

If you have vacuum at the valve covers with the PCV disconnected, then you are right, something is leaking.  Bottom of the intake at the gasket, or the intake itself is about all it can be, unless he has something silly like a vacuum line hooked to the other valve cover where a breather should go.

If there is vacuum with everything unhooked from the v/c, I;d be pulling the intake looking at gasket imprints, and if I didnt find a smoking gun, I'd have the intake Zyglo'd

[cjshaker]

Can you be more specific about the oil in the intake? Is it visible inside the intake ports, or just the heads intake ports? Is it visible in the plenum under the carburetor? Is it actually oily residue or is it just black looking powdery residue? Does the engine smoke? These things will help track down the culprit.

Things to look at:
The gap between the intake to block surface with NO bottom gasket on. Too small a gap will hold the intake up when using a bottom gasket.
Mating surface between the head and intake ports needs to be parallel. If they're not the gaskets can't seal right.
Might want to take a look at the exhaust crossover also. If all else checks out ok, you may need to pull the baffle off the bottom of  the intake and take a close look there.

[machoneman]

FE head gasket tabs, designed for OEM intake gaskets to be held in place on the production line, often interfere with later gaskets and can actually hold up the intake itself, leading to a massive leak. Bend them out of the way of cut them off.

See pic of intake gasket: note at the bottom edge  two small L-shaped tabs. They hook into steel OEM type head gaskets that have a protruding tab to prevent the intake from slipping down during assembly. Nice touch but they often interfere with aftermarket intake gaskets and prevent a good seal. Bend or cut as noted either the tabs from the head gasket or the intake tabs. 

http://www.bob2000.com/fegskt02.jpg

[thatdarncat]

Have the heads been ported? Common for some porters to remove the bump under the long rocker shaft bolt - the one that connects to the oil passage. Oil gets pulled into the intake port around the threads of the bolt.

[Grbmaverickmo]

Ok what happened everything ran fine for a few weeks then it started smoking alot I mean alot. We pulled the plugs and they were all soaked in oil so we pulled the carbs and there was oil in the intake alot and every runner so we thought gasket sucked we tried changing them after 10 min same thing that's when we discovered the pulling vac on both valve covers. I`m not sure if heads are ported, didn't look I can ask him though. Also gona check intake clearance without gaskets but we use silicone and it didn't bottom out but I will check it anyway. This is weird. Thanks guys

[cjshaker]

It sounds to me as if the bottom of the intake is cracked somewhere around the plenum area. Once it heats up, the crack may be opening and pulling oil into the intake. It would also explain vacuum at the valve covers, but it seems it would have to be a fairly significant crack.

[Grbmaverickmo]

Ok we checked clearances on intake to head and block they were good going by the FE book. So we tried a Performer RPM and it did the same thing after a few minutes of running its pulling oil into the intake and making alot of vacuum at the valve covers. We are stumped so the motor is coming out and were gona recheck heads and rings. Any ideas on other things to check while its apart that would do this?? As always Thanks for any help

[machoneman]

Check that the 2nd ring isn't upside down and the oil ring expanders aren't overlapped or otherwise messed-up.

[RJP]

Bad valve guides in combination with too much oil to the heads will do what you have described. Pull the heads to check before going to the trouble of pulling the engine.

[machoneman]

Good points all.

Do all 16  valves actually have valve seals installed?

Heard of some weird shops that skip the seals altogether to promote increased stem oiling.....who knows why! Some builders leave off the exhaust valve seals which may make some sense in hard-running race engines.....but never on a street engine IMO. 

[RJP]

Good points all.

Do all 16  valves actually have valve seals installed?

Heard of some weird shops that skip the seals altogether to promote increased stem oiling.....who knows why! Some builders leave off the exhaust valve seals which may make some sense in hard-running race engines.....but never on a street engine IMO.

Street engines should have seals on all 16 valves. I have done several engines where I did not install the exhaust seals. All were high performance engines used in V-drive boat applications that were spun into the 7500+ rpm range. A couple of the engines were turbocharged as the exhaust pressure is it's own oil control. Valve stem lubrication is more important than a small wisp of smoke.

[63gal427]

I had a similar problem with my 427 which had been rebuilt.  The spark plugs were oiling up, and on inspection, there was oil in the intake and on top of all the pistons.
A strip down of the engine revealed that 2 of the pistons had the second ring upside down.  So instead of scraping the oil down the bores, they were pushing oil into the combustion chambers.