I have another vacuum leak on the throttle body. This time where the throttle body meets the plenum. It has a new gasket (previous gasket was a beer box, which worked fine until I started messing with it and replacing the gaskets with OEM parts).

So I've tightened the bolts down and it's still leaking. Like I said: it was fine until I removed the old gasket and replaced this one in an attempt to find a previous intake leak.

Should I use RTV on this one? Can throttle bodies/intake plenum warp and cause leaks?

 

are you 100% sure it's leaking from there?

the coregated (spelling ) elbow coming off the throttle body there is renoun for ripping and leaking

 

I was pouring water all over my intake, and the engine started to sputter right as the water was poured over a certain part of the throttle body. It's not anything on the lower intake, it's definitely the upper portion where it meets the plenum. I knew it either had to be the 4 rubber hoses leaking or the gasket. So I kept testing with the water and was carefully pouring and spraying it at the hoses and the gasket area. It's definitely the gasket. Not sure where, as the water keeps trickling down the side I don't know if it's the top part, either of the sides, or the lower part.

 

Why were you using water?

 

It's safer than using gas......

 

Try spraying wd-40 on the TB butterfly linkage where it passes through the TB. It sounds like yours is worn. There have been cases of a warped TB but it's relatively rare.

 

Because I wasn't as thirsty as I thought, and while drinking it I was hearing the hissing sound I can hear from the cab. So I just dumped it on and found another leak.

So should I go ahead with the rtv ? Or is it a waste of time?

 

Remove the TB and check and make sure the mating surfaces are FLAT on the TB and the plenum. Some people still use a Roloc disc to remove gaskets and it's easier than you think to remove enough of the aluminum to create a wavy surface that will cause a leak.

You can tape a sheet of fine sand paper to a piece of glass and GENTLY move the TB mating surface in a broad circular motion. It'll show you any high or low spots, and you can also get it flat enough to seal using the same method. The plenum is a bit harder to check. Just make sure there is none of the old gasket material left on either side (especially around the studs at the plenum side). A new razor blade and a lot of patience is your friend, Roloc + power is the devil.

While the TB is off, also check the throttle shaft (the one that holds the butterfly inside the TB) for any play at the shaft bushing. It's a long-shot, but I have seen it.

The best "RTV" out there is the Perma-Tex Grey. It's closest to what most manufacturers use as OEM.

 

I removed the throttle body and was measuring for any warping. The throttle body is good and so is the intake plenum. But I noticed one more thing when removing the old gasket. There's some green/brown stuff stuck on the plenum. It looks like rust, but a lighter color. It's hard for me to say because I'm colorblind, but could it be rust? Is rust on throttle bodies a common thing? Or could it have formed because I had a vacuum leak for a few month?

 

I'd put the beer box gasket back in seemed to work in the past.

That probably worked because it is thicker than the OEM gasket. Try what Putneysmachine recommended. If you need to use a wee bit of sealant on the gasket, not too much it will tend to leak if overused...Just a light smear on each side of the gasket.

Not sure about the green/brown stuff could be a number of things but the plenum is aluminum and that does not rust.
However it will oxidize and if you want to get technical oxidization is rust...but all this is for another story. It could be old gasket material.

 

Stainless steel isnt supposed to rust either, but tell that to the first Delorean I ever saw in Florida. lol. I'm guessing it's old gasket material, so I won't worry for now. It's coming apart in a while anyway when I do the clutch, so in my spare time I guess I'll clean everything.