Intake Manifold Leak?

My jeep has lost all of it's power. i have a top speed of about 30mph. When I give it gas, I hear a loud whistling sound that sounds like an intake manifold leak. Could a bad gasket cause my jeep to lose all of it's power?

It very well could, that would be a vaccum leak. I would also check for any other vaccum leaks. good luck.

What year Jeep ?

Also, do you still have the cats?


Friends Dakota did this exact thing, replaced the cat and everything was great.

did you even pop the hood and look at it? you should be able to tell where the whistle is coming from if you look at it and hit the throttle on the throttle body....

If you are a carefull person you can spray some form of accelerant, like wd-40 to suspected areas. I have used propane before but that is very dangerous and should only be used in an emergency. If the idle changes you have found your leak.
I would inspect for a cracked/disconnected hose and then check the gaskets.
Jeremy

in2fords said:

If you are a carefull person you can spray some form of accelerant, like wd-40 to suspected areas. I have used propane before but that is very dangerous and should only be used in an emergency. If the idle changes you have found your leak.
I would inspect for a cracked/disconnected hose and then check the gaskets.
Jeremy

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Don't use WD-40 - use carburettor cleaner. It will burn off more quickly and cleanly than WD-40 (which is good for your catalytic converter, if it's still good.)

Does a clogged cat whistle? I've only run across a few, and none of them whistled - they just kept the engine from breathing well.

Spots to check for whistling would be the vacuum lines off of the throttle body (more common than you might think - especially with the MAP line, since that affects fuel metering,) the base of the throttle body, and the base of the EGR valve (if present. You don't say what year - which really does help us. The EGR valve was on 1987-1990XJ, and is located on the side of the intake plenum, near the brake master cylinder.) You may also have loose manifold screws - you can spray a fog of carburettor cleaner there to check as well.

The catch with carburettor cleaner is simple - if there is a vacuum leak, the fog will be drawn in via the leak and the engine will race briefly. Start with a "cold" engine (let it cool off overnight if possible,) as the intake is aluminum - and aluminum expands rather rapidly when heated, which can make the leakds seal themselves back up. The leaks could be more obvious when cold.

The throttle body lines would not seal themselves up at operating temperature, but you can usually spot those with a visual check if they're loose (since most of them are Nylon, you should also see them if they're broken. A patch can be made with rubber vacuum hose - get it to just slip over the Nylon line. You can use a bit of RTV black, applied to the outside of the Nylon line to help seal it. The use of clamps isn't recommended - too easy to crush the Nylon line and make things worse.)

Propane may also be used (in lieu of carburettor cleaner,) but it provides far greater enrichment and you don't get the visual cues you get with aerosol carburettor cleaner. So, the carburettor cleaner is recommended for this check. (Propane enrichment of a running engine can get a little dicey.)

sounds like a head gasket. this same kinda thing happened to my buddy's yota. it was a dog and wasn't running smoothly at all. but i could be wrong. good luck. hope i could help.

5-90 said:

Does a clogged cat whistle? I've only run across a few, and none of them whistled - they just kept the engine from breathing well.

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not saying it's the problem here, but a clogged cat can cause enough back pressure to force exhaust past the valves and out the valve cover. In a case like that, the problem tends to get addressed before that point as you can't keep it running very well from the polluted mixture-- but it CAN happen if you ignore a plugged cat long enough.:explosion

Sorry I didn't reply earlier, I'm in school. The cat isn't the problem because I had that punched out a month ago. I'll have to get some carb cleaner and see if I can find the leak. I'll keep you posted on where the problem is. Thanks

Shorty said:

not saying it's the problem here, but a clogged cat can cause enough back pressure to force exhaust past the valves and out the valve cover. In a case like that, the problem tends to get addressed before that point as you can't keep it running very well from the polluted mixture-- but it CAN happen if you ignore a plugged cat long enough.:explosion

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OK - that makes sense. I guess I just hadn't run across a clogged cat that had been neglected long enough for that to happen. I wasn't saying it was impossible - just that I hadn't run into it, and I wanted to know more (Hell - from what I've seen over the years, "that's impossible" is a phrase I try not to use very much anymore...)

5-90 said:

(Hell - from what I've seen over the years, "that's impossible" is a phrase I try not to use very much anymore...)

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ain't that the truth!

I used to run a service station off the Balto-Washington Pkwy and had a old Chrysler come "limping in" that had started "running rough" about twenty miles up the road and the converter was soooooo plugged, it sounded like a freight train comming off the exit ramp! The orange/white exhaust from the converter back to the engine kinda gave us a hint as to the problem!