Bubbles on dipstick...

[Hozer 88GTConv]

losing oil too. Bubbles on the dipstick? Isn't that a dead intake manifold leak giveaway in the lifter valley?

I think my used GT-40 intake is hosed up (i.e. warped, cracked...somethin'.)

Oh yeah, it's backfiring too on deceleration in gear. I'm thinking lean too boot. Probably intake related also.

Thanks...

[Dark_5.0]

I had absolute hell getting my Ported GT-40 lower to seal off with my Canfield heads so I can feel your pain. I had that damn intake on and off at least four times before I got it right.

what ended up fixing my problem was going from a felpro 1250 gasket to a felpro 1262 along with an @ssload of silicone.

I knew I had a problem cause I was making practicly zero vacuum at an idle. The 192cc runners on my heads swallowed the way smaller ports on my GT-40 lower intake I imagine you are having the same problem.

Bubbles can also mean you have too much oil in the engine. When you have too much oil the crank foams it up.

Good luck,

[Hozer 88GTConv]

I have had an oil consumption problem for a long time. Number 5 in particular. It fouls right away. The motor only has 20 k on it an I am thinking it could at least be this crappy fitting GT-40.

I have tried 1262's and 1250's probably 6 times over 18 month period.
I have also used grey rtv around the front and rear water jacket ports on both sides of the gaskets and the ports of number 1 and 5. Number 5 still fouls, almost immediatley.

It has great compression, and I just don't think it is a cracked ring. I just don't want to believe it is more like, b/c I don't want to pull the motor.

I got a set of 1262's and am thinking about getting a TFS intake just to see if that solves my issue.

Oh yeah, how much silicone did you put on? I only put a thin layer, i.e. 1/16th-1/8" around the ports. Thanks.

[mustangman65_79]

start it up, pull out the PVC valve, and see if u have blow-by coming out of the hole.

[Hozer 88GTConv]

should it be quite noticeable? i.e. push my thumb off the hole?

[Rev]

Originally posted by Hozer 88GTConv
losing oil too. Bubbles on the dipstick? Isn't that a dead intake manifold leak giveaway in the lifter valley?

I think my used GT-40 intake is hosed up (i.e. warped, cracked...somethin'.)

Oh yeah, it's backfiring too on deceleration in gear. I'm thinking lean too boot. Probably intake related also.

Thanks...

Doesn't seem to me that an intake leak woud cause dip stick bubbles. It would cause the oil cosumption and plug fouling though. It should make for poor idle as well shouldn't it?

Overfill is another possibility as Dark_5.0 said. I just don't believe an intake leak could cause the oil bubbles. But oil is getting into the combustion chambers somehow. Valve guides?

Rev

[Hozer 88GTConv]

I've had the heads off twice. Good guides, replaced seals twice too. Don't think it'd be cracked ring.

I'm gonna go with the intake.

Thanks...

[PKRWUD]

Dark 5.0
I remember that.

Hozer
What is the vacuum at idle?

There is an easy test you can do to verify if it is an internal vacuum leak from the intake to the lifter valley.

1) Hook up a vacuum gauge to the intake manifold.
2) Fully close the throttle plate by backing out the idle screw all the way.
3) Plug up the PCV valve opening.
4) Disconnect and plug any vacuum hoses attached directly to the intake manifold.
5) Disconnect the wire to the positive side of the coil.
6) Crank the engine and observe the vacuum gauge. From 3" to 7" of vacuum (at a minimum of 250 cranking rpm) is normal. A defective intake manifold gasket will give, in most cases, a zero reading.

[Hozer 88GTConv]

Yeah, I've gotten about 10 inches at idle. But it fluctuates of course. I wondering if the leak is only pronounced at one cylinder, it might not be noticeable.

Honestly, Dark's statement about his head ports "swallowing" the Gt-40's never occurred to me. When I take the manifold off this time. I am really going to examine the gasket position on the bottom of the intake and see if there is an obvious issue.

My suspicion is that the TFS heads do the same to my gt-40 intake.

I will test the vacuum again in a minute and post it. I am going to call TFS and see what they say, too.