I think there is crack or gasket leak in exhaust manifold.
If it is a crack, how to find it and where is it usually? Is it visible?
Thanks.
It makes noise when engine is cold.

 

Should be visable.

 

sounds funny but works 4 ft pc of hose one end on ear other end move all around manifold

 

A trick an old indian (Cherokee) taught me:

Use a shop vac with the hose installed at the other end, where it blows instead of sucks. Insert the hose in the tail pipe, and using duct tape seal it in. Remove air filter box. Mix up a solution of liquid dish soap and water, or use kids bubble stuff - you know, the stuff you dip a circular piece in it then blow through it to get bubbles (LOL), and put it in a squirt bottle. Get a mirror and flash light. Start the shop vac blowing up the exhaust pipe then squirt the soap/bubble solution all around the exhaust manifold. If it's cracked it will blow air out and create bubbles. Look for them.

Worked for me. Found one small crack I couldn't see before.

 

Thanks, I'll try hose and vacuum tricks.

 

what do you plan to do if you find a crack? if you have good reason to believe there is a crack, why not just swap out the manifold?

 

You can also use some seafoam, thought I had a small crack till I poured some in my brake booster to air intake hose. It looked like someone set up a smoke machine in my engine compartment.

 

Sorry to thread jack but this made me think about when I did a sea foam treatment.
I have a very loud tick that I have always assumed was an exhaust leak/crack but when I did a sea foam treatment the white smoke only came out of the tail pipe, so what else might this tick be?
Also that shop vac and bubble thing is genius.

 

Now that's "thinking out of the box". Really ingenious. I wonder if you held your hand over the TB and sprayed the solution around the intake manifold and TB you'd find intake leaks as well. Reasoning that the air pressure would back up through any open exhaust and intake valves.

 

Same thing we do on dirtbikes haha. Never even thought about doing it with the jeep.

 

Reasonable. Somewhere in the mix (153624) there will be an int/exh valve overlapped so there may be airflow in the intake manifold. Give it a try.

I really didn't learn this from an old Cherokee indian I used this technique when I was an aircraft mechanic working on six cylinder opposed aircraft engines.

 

I was thinking about trying something similar with my compressor and the boost leak detector I built to find intake leaks after the turbo on my Talon. The vacuum cleaner trick looks easier and lowers the risk of over pressuring. Thanks!

 

this is how i found my crack lol