Thetastycat

Hey all - 95 XJ w/4.0. Just replaced manifold gasket and I'm hearing something that sounds like an exhaust leak, but I just can't seem to find it. Block bolts were all still tight except the bottom middle - with my new Gibson headers you can't actually fit a socket over the bolt head, so it's open-end wrench only, so I did my best. I did the old trick of shop-vac on 'blow' in the tailpipe and spray the exhaust with soapy water and look for the bubbles; I'd have sworn it was coming from the collector but can't get a bubble out of it anywhere. Even got a fresh gasket for the collector but if I can't find a leak there, why bother. It's hard to get the spray bottle all the way to the bottom manifold bolts, but again couldn't see any foaming like I have before.

Anyway, here's the video:


Wondering if possibly it's something else? Sure seems to sound like an exhaust leak, and it rises and falls along with the sound of the exhaust coming out of the tailpipe - who knows.

Possibly useless backstory - XJ has 295k on it, PO put a motor from a 97 in it. When I got it, two of the manifold bolts were missing and gasket was leaking, so I got some Gibson ceramic headers and put them in since I was doing a new gasket anyway. I used non-factory bolts and washers to replace the missing two, and it leaked, even after I ordered and installed factory replacements. Got a Rem-flex gasket, put it in, and now still hearing something suspicious. It DOES get worse when the engine is up to temp and I stomp the gas.

Honestly after now installing the header twice if I can't find it, I'm about to just take it to the exhaust shop and pay whatever. Sure appreciate any ideas!

ETA: Also need to replace the noisy throwout bearing, but it's nowhere near as loud as whatever this is...

JonRedcorn

That things got all that work done and the stock steering setup!? Anyways sounds like there might be a bit of a leak but it doesnt sound too bad I wouldn't worry about it.

Thetastycat

Yeah, sure is - I'm putting in a HP 44 soon so I'm going to do it then. Yeah, it's not too bad in the vid but it definitely gets worse as I drive - and I just hate to have a leak at all after everything I've done, you know?

Thetastycat

OK so UPDATE - after spraying it everywhere with soapy water and finding nothing, I took it by my mechanic, who is an awesome old boy that knows his stuff. He said he could barely hear it and not to worry about it - but since I JUST did most of the exhaust, I really wanted it right.

SO

I did the old Seafoam trick - got the motor warm and poured 1/2 of a Seafoam into the intake, shut it off, waited 20 minutes, and fired it back up. Tons of white smoke out the tailpipe, and just a very small bit in the engine bay - of course my dumb *** waited until it was dark, and I had a headlamp on, and it's amazing what those bright headlamps pick up that you wouldn't otherwise see. Nothing visible underneath or at the manifold gasket, either on the top or bottom sides. Eventually I noticed that some white smoke was coming out of the exposed throttle body, so I put the air hose back on it and didn't see any more smoke. SO, it's entirely possible that the very small amount of smoke I saw was coming from there.

So.................I guess I don't have an exhaust leak after all? I mean it makes sense that there might be extraneous noise that could sound like an exhaust leak. At this point I guess I just drive it for a while and see if it gets worse?

I kind of wish I'd found one so I'd be able to get to the bottom of it, but on the other hand knowing I did the header install right is also nice.....I guess?

Thetastycat

Drove it a good bit again today - at first, no leak-ish sounds, then got the motor hot and sure sounded like an exhaust leak, then a bit later, nothing. I'm as lost as last year's Easter egg

Thetastycat

Well update - finally took it to my local exhaust shop where they figured out there was a bad weld in the header, right where all 6 come together. Of course I can't get a pic of it while it's installed, so Gibson is making me pay for a whole new header, then when I send them the bad one back they'll determine whether it's faulty or not and then give me my money back. Or not. I'm not thrilled