Vac Leak

Jun 10, 2004 6 Replies

Ok...here's a question? My jeep has a vac leak somewhere around the firewall. I've checked and looked all over the place but can't find it....and to make things worse you can only hear it when your on the highway (quits when you exit and stop to check lol)and let me tell ya....its a loud one! Stranger yet is sometimes you can see smoke rising from the dash lol. Anybody have an idea?



Brian



88 YJ
4.2 I6

Your heater control is vacuum. The line hooks up on the drivers side of the control up under the dash I think.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Brian wrote:

If you have power brakes, check the vac. fitting and hose. That comes straight off the manifold.

Yeah thats happend to me before but this is on the engine side of the firewall. Plus its hurting the performance of my engine big time....sounds like the valves are opening late. It pops and sputters for about a mile or two after I exit the highway and then clears up? There are some vac switches behind the air cleaner? What are those for?

Brian

88 YJ

On the engine side eh.

I would be checking the PCV line and solenoid behind the carb for a loose or broken hose and then I would be spraying carb cleaner at the base of the carb and along the intake to head mate up. If you have leaks the cleaner will burp the idle.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Brian wrote:

On YJs there's a vacuum line running from the manifold to a heating system flap motor on the pasengers's side. See if it's come off.

spray wd 40 around and when you hit the vacumn leak, the engine speed will surge. john

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