I think I have an exhaust leak, sounds like a train when I go more than 20% throttle. When I had it in the garage, I could not really replicate it, nor could I find an exhaust leak. When I am on the road, in gear, it makes the noise. In neutral it does not, barely any noise. It started when I floored it on the highway the other day. I put a stethoscope all over the top half of the engine, at idle, nothing sounded bad.

Is it the case that an exhaust leak is only/mostly loud when in gear? It is pretty bad when I drive it, but silent at idle or in neutral, nearly regardless of RPMs.

Any other ideas? I have to find a second person to put it in gear and rev the engine while I crawl around under it, but thought it would worth an ask to short cut the issue.
Thanks

 

Search on exhaust leak shop vac test.

 

Found at least one leak. great advice on the vacuum test. No leaks on the drivers side that I could see. I started soaking the joint w PB blaster in preparation for the battle. Does not look like too much of a pain to get at. Now to track down a gasket.

 

Great find. The engine may be tweaking side to side under acceleration and affecting the seal, which is why it's not as noticeable when in neutral.

 

When I had an exhaust leak at the exact same place, I found one of the nuts to have backed off about half way down the threads (but still seized somehow?). I tried to take it off to find a replacement size and the stud snapped trying to take it off! You may want to order a stud replacement kit before you take it off, as you likely will break at least one. If you break one, I'd keep the other 1-2 in place until it arrives. That way you can still drive it.

It's also worth checking your motor mounts. I'd be willing to bet this its the reason behind the leak. If your motor mounts are shot, odds are your transmission mounts are on the way out. If you need to order motor mounts try and avoid Britpart. I had one faulty one from them and its unfortunately common thing with them. Not a terrible job, but annoying.

 

Here is the link to the stud kit mentioned: https://extinctmotorsports.com/exhaust-studs I would recommend scoaking in Kroil at least 3 days before attempting removal.

 

After 4 days of pb blaster and the wax treatment,nuts came off with no trouble. Amazing. Used a ratchets strap to pull the exhaust down made it easier.

I got it back together, a still have a slight leak. Intalled the gaslet smooth side up. So it fit in the recess of the rxhaust.

I saw the trick about doubling up the gasket, should I try that or exhaust gasket sealing? The bolts are probably 50 ft lbs.

motor mounts still look super solid. No discernable wear.

Any suggestions?

Thanks again

 

@redrover75 Check very carefully for cracks below the flange in the Y-pipe, it is fairly common on Disco's as they age.

 

Thanks for the suggestion. I am really chasing this noise that sounds like a train under load. Nothing at idle. I still have 2 leaks now. The header and the original connection. Is it possible that the noise is from these exhaust leaks or should I be looking elsewhere. Honestly it sounds like it is coming from the top of the engine if I had to guess.

 

Remember to use copper spray on the gaskets before you install them.