oil coating inside of plenum - normal?

[rrubel]

Today I started pulling my engine apart (note to self: metal intake runner gaskets are S-H-A-R-P!). I noticed a lot of oil residue on the inside of the stock plenum and even on the back of the throttle body butterfly (but not much - just a little). The runners were black inside but dry, but the plenum itself was damp with an oily film. This can't be normal, can it? I'm pretty sure I have an intake manifold gasket leak (or two, or three) because I get oil pooling atop the manifold. Could this be the root cause of the dirty plenum? Or is there some other major issue that has just made itself known? The one other time I had these parts off, I don't remember what their condition was. This is an old car, with over 140000 miles on it, and those things were probably never cleaned.
Thanks...
[RICHR]

 

[Ken]

It's normal Rich. The oil comes from the crankcase breather and PCV. And if you use aftermarket valve covers and they aren't baffled well-enough, you'll find a LOT of oil making its way in there, believe me I know - been there done that.

 

[rrubel]

Ah... aftermarket valve covers! Not much baffle at all on mine. Explains a lot. Thanks!
[RICHR]

 

[Mart]

Hey Rich,

I'm just about to redo my intake and was wondering what gaskets did you use, I have a set of felpro ready to go, did you use silicone as well.

What it easy, how long did it take you?

Mart

 

[rrubel]

My situation is probably a bit different than yours - I'm installing a SuperRam, which mostly comes with its own gaskets (Mr. Gasket brand, which is Accel's parent company). However, I'm having the base gasket-matched to a Fel-pro 1205 or 1206 at the discretion of the porting expert.

I spent about three hours, all told, today. With the help of Mad-mic, we drained the oil and most of the coolant (need to do the knock sensor still). Removed the whole intake down to the manifold (which is still completely bolted in). Removed valve covers and distributor.

If you've never removed a TPI before, which I had not, you definitely want a good set of directions to follow. Rather than the Haynes manual, I'd suggest the December issue of "Corvette Fever" magazine, which details in words and pictures exactly how to replace the intake manifold gaskets. There are some definite tricks to getting at some of the bolts, too. Also, make sure you keep track of what goes where - different length bolts go into different places in the runners. The CF article, IIRC, has pictures and descriptions of what goes where.
[RICHR]

 

[ErnieN85]

Rich, take a lok at the bafel in the stock cover. You need something like it in the new one. there is so much oil flying around in there that you suck up a lot with the PCV system.
You will burn a lot of oil and foul up the o2 sensor with respect to the actual air fuel ratio. not to mention fouled plugs, plugged converter, all kinds of nasty stuf from burning too much oil.
It's a simple fix but needs done.

 

[rrubel]

Ernie, there is *a* baffle in place; with the PCV and breather hoses disconnected, I cannot see straight down to the rocker arms... it just doesn't seem as good as what was in the stock covers. These are Edelbrocks, so they're not completely generic knockoffs.

I do think I managed to find my oil leak... at least four of the manifold bolts were on barely finger-tight! Hm... a new phrase? "Loose bolts drain crankcases". Nah... not as good as the original.

Manifold comes off completely tomorrow (paused to buy new T-40 sockets...) and then water pump follows. I'm running out of room to store all the parts I'm taking off!

[RICHR]

 

[ErnieN85]

Glad to hear you have a baffel. when mine went togher the last time i had quite a leak in the #1 cylinde sucked a lot of oil & fouled the plug. the only other time I had a lot of oil was with lots of blowby (bad rings) so i don't think that is your problem, if your not using much oil it's probably normal

 

[rrubel]

The plugs looked good last time I changed them, though that was before the new valve covers. Didn't say I wasn't losing oil... just not via the exhaust!

[RICHR]