How do you find exhaust leaks

[derekf]

I've got a persistent header leak that I can only hear at medium-throttle cruise. Nothing I've done has corrected it, although after I take it all apart and put it back together it's a little better for a couple of days. It sounds like the problem is the passenger side bank.

This is on my daily driver 98 Z28, previous owner had put headers of unspecified brand on it and I'm guessing he had the same issue as he left the exhaust cutout open at all times.

I've swapped the gaskets over to the Percy's gaskets without it helping. Access is tight so in order to go through and tighten up the bolts I've got to remove/replace the AIR and EGR -- it's possible that they are the leak, but I'm not seeing any soot trails or anything like that.

So - if a header leak doesn't seem to be leaving any visible signs, and can only be heard under load, how do you track down where it's coming from?

[HILROD]

I've had bad luck with the percy's gaskets to try and seal a known leak. The best thing for leaks is two, (doubled up) graphite/steel header gaskets. Make sure to run the car for a bit and re-torque. If the flanges are already bent up, you might have to remove the headers and bend them straight, maybe even weld them. I,ve chased leaks for a long time on a few cars, almost always with cheaper brand headers. The hardest to find were a couple that leaked between the middle cylinders, underneath. All the full metal gaskets, aluminum and copper, seal O.K. and don't blow out, but normally won't seal troublesome leaks.

[MrQuick]

Get yourself a mechanics stethoscope with a metal tube attachment. Have someone you trust and depends on you for survival put the car in gear and ride it a bit to get some load on it.

Go around with the tube.

Make sure you don't forget to check between the collector tube area.

[derekf]

The best thing for leaks is two, (doubled up) graphite/steel header gaskets. Are these the ones that are steel on one side? If that's the case, how do you put them - the two steel sides facing each other, or steel/graphite/steel/graphite?

Get yourself a mechanics stethoscope with a metal tube attachment. Have someone you trust and depends on you for survival put the car in gear and ride it a bit to get some load on it. Car's a manual and the wife can't drive a stick (and the boy would likely run me over just to try to inherit the car). Looks like I'll be trying HILROD's plan.

[HILROD]

I was talking about actual header gaskets, Mr gasket, Fel Pro, and others make them.

[derekf]

So that's the normal header gasket material?

[Damn True]

How about a canary?

[Patrick]

How about a canary?

That's great!!

Stethoscope works best.

[BonzoHansen]

Someone covers up the tailpipes while running - listen for the noise.

[BulldawgMusclecars]

This method is a little unorthodox, but works. Get some Seafoam, unplug a vaccum line (the one for the brake booster works well), and dump some in per the instructions. You'll get a nice white, stinky smoke coming out the exhaust, including anywhere you have a leak. Easy.