I needed to change the intake manifold gaskets on my 91 TPI. Today I got it all together and after running it about 10 minutes noticed a big pool of oil coming from the rear of the engine pouring down over the transmission.

I'm assuming I didn't use enough RTV on the front/rear walls of the block. The GM service manual said a 3/16" bead that goes along the top of the wall and 1/2" up each head on the side, and I did just that. Next time around should I really just gob it on there?

Is a small gap, maybe 1/16" or less, between the block and intake manifold normal?

Can I re-use my intake manifold gaskets that were torqued and brought up to temperature once?

 

Yeah I goop the **** out of it and mine still leaks there a tad. I prob run like a 1/2" bead

My HSR has a bigger gap than that, it all depends on the machined surfaces and how well they mesh.

Matters how broke you are, personally I would reuse them if they are dry but my guess is the oil got to them a bit and you will have to replace them, better safe than sorry.

Best of luck Andy!

 

Did you also use a rubber gasket? Thats a no no.... they make it worse.

The bead should be pretty thick, 3/16s sounds ok, but there needs to be two big blobs at the corner where the block, intake, and heads meet.

Lastly, how long did you wait before you fired it up? You need to wait minimum 24 hours for it to dry.

 

It was probably 5 or 6 hours between sealing up the intake and starting the engine.

I used no gasket in those areas.

 

Did you replace the distributor gasket as well? I know its a stuipd question but its another place to check before you tear the intake apart.

 

I used the rubber ones on the TPI motor on my Vette and no leaks. On my '84 Firebird when I had it I used "Great Stuff" in the cheeze whiz cans and it worked great. It's been a while since I've done any wrenching but I'm pretty sure that the RTV stuff needs the surface to be super clean too before you put it on.

 

You were right vin, the gaskets are soaked with oil (normal right?) so i'll get new ones. It came apart pretty easy second time around, besides the coolant that I dumped into my crankcase . New gaskets tomorrow and time for round two.... any more tips for this noob?

 

As mentioned above make sure you put a solid chunk of silicone in the corners where the block and heads meet. I use at least a 1/4" bead of silicone on the front and rear surfaces, and it would be best to give it at least over night to dry before firing. Make sure your surfaces are clean (no old gasket material or silicone residue), and free of oil and other moisture. A little trick I like to use is to smear a thin layer of silicone on both sides of the water jackets on the side gaskets. This keeps them from moving around a lot during re-assembly and also helps make sure your water won't leak into the oil.

P.S. don't forget to torque your intake bolts from the center of the manifold out evenly on both sides.

 

Change your oil again too.

 

i dont mean to thread jack but i was reading this and i am about to do an intake job with my buddy on his 350 what should we torque the bolts down to ... i was told just tighten them down then another half turn if you dont own a torque wrench

 

Maybe it was 'the Right Stuff' gasket maker that Beltfed was referring to.... that stuff is expensive, but it works great.

 

GM Spec for a 91 TPI (aluminum intake) is 35 ft*lbs. I can't imagine any other SBC intake being significantly different.

 

I know this is an old thread. Will RTV copper work any good? It is a high temp and sensor safe. Also, Should I use the cork gasket that came with the set, or just toss it and use rtv. I am not trying to do this again as the superram gasket is like $46 or so and I wil need to wait a few more days.

Any tips?

 

Throw away the rubber gaskets for the front and rear seals and use a thick bead of RTV spread from one side to another. I don't know if the copper RTV will work or not, I've only used the black RTV that is always recomended (I prefer the "right stuff" gasket maker). Keep the gaskets that go on top of the cylinder heads and just use a thin smearing of RTV around the water jackets. This helps hold the gaskets in place while you put the manifold on, and helps ensure a seal of you water passages. There shouldn't be any cork gaskets on an intake manifold set, unless you are referring to an upper plenum gasket or some other. In which case keep the cork, just apply a thin layer of RTV to the mounting surfaces of the gaskets.

 

Acutually, the front and rear gaskets were cork... I used rtv, and got everything set, but some bolts did line up and i had to jerk it around a bit, so I am going to redo it. Better safe than sorry. I don't want to spend another 50 on Superram gaskets.

 

I don't recall ever seeing cork rail gaskets, or were you referring to the intake gaskets? I use the rubber seals and haven't had any problems. I put sealant at the ends just before installing the intake. You just have to lower the intake straight down where it goes and not attempt sliding it around. Just do a test fit before putting the sealant on so you can see exactly how the two surfaces align with each other.

If you want to use sealant, get the rail really clean (lacquer thinner works great) and lay down the bead. Let it dry for a while til it skins up real good and it will seal better IMO.

 

I've never seen cork gaskets on the front and rear seals, oh well, you got it with the RTV. Just remember that the RTV needs to be thick enough to push out of the seams a little when the intake is bolted on, and you should be good.