1989 Jeep Comanche

WCLAUSON

MEMBER
1989 JEEP

I just purchased a 1989 jeep comanche, it has a 4.0l straight 6 with 145000 miles. I bought the truck to haul dirt bikes around but the noise is driving me crazy. I initially thought it just idled high and would go down once it warmed up. No luck. I think I have a leak in the exhaust system but cannot figure out where it is. How can I isolate and fix the noise if it really is the exhaust? What steps should I take first, change out the gasket in the manifold, JB weld the pipe leading into the muffler? I'm really lost at this point and do not want to drop a lot of $$ into it. Any advice on where to begin or try first would be appreciated. Thanks.

Monday, October 29th, 2007 AT 11:43 PM

3 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Get yourself a 2ft conduit pipe use it as a doctor's ears and start at the exhaust manifold and listen very carefully while an assistant plays with the gas pedal-you should hear a puffing noise every time an exhaust valve opens and work your way thru to the back.

You sure its not the heat shield you hearing.

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Tuesday, October 30th, 2007 AT 12:15 AM

WCLAUSON

MEMBER
2 POSTS

Raz,

Thanks for the reply. I'm no expert with cars so I really couldn't say what it is. My friends who have some experience are telling me it's an exhaust problem based on my description alone, (one owned an 88 Comanche with similar problems). The previous owner, who was mechanically inclined, didn't know why it made so much noise either, but drove it everyday without a problem. My wife is 3 feet up my butt for buying it in the first place so, I'm trying to keep the money going out to a minimum. I hope it's not the heat shield, that would require replacing the whole manifold right?

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Tuesday, October 30th, 2007 AT 1:00 AM

RASMATAZ

MECHANIC
75,992 POSTS

Check 1st where the leak is-back in my old school days-we dont buy them, we use the roasting pan to shield lol-no joke, just shape it up and clip it on.

Or maybe the heat riser between the exhaust manifold and exhaust pipe-they do make a lot of racket if it goes-bouncing around in there like nobody's business.

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Tuesday, October 30th, 2007 AT 1:05 AM