1991 5.0 Heater Pipe Fitting

HotRodBlack

Active Member
Apr 24, 2017
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Hello guys I am trying to figure this out and am looking for a picture to confirm what I need to get to fix my leak

Leaking coolant from the heater pipe. Its spewing out from the fitting that is screwed into the intake manifold. I recently replaced my lower intake manifold, its an Edelbrock Performer. (The old one was warped and simply would not seal to my heads)

Leak started up about two weeks after the engine was assembled, I put it back together exactly as it was but it may not have been correct in the first place.

Like I said, it leaks from the fitting at the lower intake. Its as snug as I can get it but i can move the tube up and down. What I am trying to figure out is if there is supposed to be another fitting screwed into the manifold in between the line and the manifold. It would make sense, being that it's a flared line and fitting similar to a brake line. If that's the case, then a replacement tube will do the same thing.

If anyone has any pictures or information I would really appreciate it!
 
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It's a tapered pipe fitting into the manifold. In general the taper provides the seal the tighter you get it, but NPT fittings in general are not that great under higher pressures.

I'd try a pipe thread sealant and see if that helps. I'd also inspect your manifold in that area for cracks and such.

A new pipe would probably give you the same issues

You can see the red sealant uses on the threads.
IMG_4159.JPG
 
I take it the leak is coming from the threads and not the pipe fitting itself, like stated above, try thread sealent. If it is the pipe that is leaking around the fitting there is an o ring that is in there that can be changed but it's tricky.
 
Good catch. There's an internal o ring to allow the fitting to swivel while you screw it in. This can fail. I've never personally changed one, so unsure how this job would be done.

Verify it's the seal or the threads
 
I take it the leak is coming from the threads and not the pipe fitting itself, like stated above, try thread sealent. If it is the pipe that is leaking around the fitting there is an o ring that is in there that can be changed but it's tricky.

Yeah the coolant is coming out between the pipe and fitting, not fitting and manifold. I will deal with it. Its just so odd to me it was fine for weeks, and then all the sudden LEAKS!!!

It may be worth mentioning that while I cannot tighten the fitting any further, i can move the pipe up and down. I can also see that someone has cut the little eyelet off near the back, apparently they struggled? Maybe without this holding it in place the pipe moves around and leaks.

New pipe seems to be the solution. Thanks for the help boys