1989 YJ Wrangler- high pitched whine...

[ajdunning]

Hello-

I'm the owner of a rather noisy 1989 Jeep YJ Wrangler-here's the situation...

Had the engine rebuilt a while back, and had the feedback (emission) sensors removed, new carb installed... Over the past couple of months, I've noticed a high-pitched whining noise- usually starts after driving it for about five minutes. As I accelerate, the pitch of the noise decreases, and increases as I let off the gas. I was told it's more than likely a vacuum leak. After poking around under the hood (I'm pretty much a novice with this stuff, thank goodness for the Haynes manual), I've noticed that there's no line coming off the EGR valve, and dammed if I can figure out where it would go if it needs to be connected. Not noticing any pressure from it when I place my finger over the 'nipple'. Could the thing be faulty & need of replacement? Is it not hooked up due to the lack of a feedback sensor? The 'whining' noise in question seems to be coming from the rear of the engine, drivers side, closest to the firewall...

Any help with this matter would be greatly appreciated...

aj

 

[Cherokee07]

I have the same situation with my 1991 Cherokee (6 cylinder). Of course it's fuel injected, so it utilizes a Manifold Absolute Pressure (MAP) sensor to regulate fuel/air density.

Same things happens to me though....I accelerate and the whine cuts off, but immediately after letting off the gas, here it comes! Sounds like a tea kettle. I replaced the engine last summer and cleaned the intake manifold with carburetor cleaner and a steel brush. My PCV hoses have always kind been in bad shape. I've been told to clean the idle control valve (ICV). This thing regulates your throttle when you idle to give your engine gas and air to keep firing.

I don't know. I'm gonna try to replace those two things and see what happens. I'm kinda clueless as well, but If I have some sort of stroke of genuis I'll see if I can relay that to you before it fizzles out.

Good luck!

 

[Jeepz4Mee]

I had thed same problem with my 95 wrangler. It turned out to be the exhaust\intake manifold gasket. Not hard to replace and is cheap.

 

[Cherokee07]

So I replaced the idle control valve. It was about $50 and very easy to install on my '91 Cherokee. It dang near redlined for 2-3 minutes after I started it up because the valve was open and hadn't adjusted to the right idle RPM yet, but it flattened out.

However, no luck. The whine crept up almost immediately. I have all new gaskets so I don't think that's my problem, but I do appreciate the input. I think I may check the MAP sensor next. There has to be a vacuum leak somewhere.

Regards

 

[elevatorman]

Heres a thought,Is your jeep a stick? New Motor?? It is a very common mistake made when overhauling an engine with a manual trans to forget to lubricate (should be replaced) the pilot shaft bushing in the end of the crankshaft. A dry or worn bushing will create a whining noise and get louder as time goes by.
With the car in neutral it is generally noisy As a load(puting it into gear) is applied it will begin to make a little less noise or go away all together. Check that out and see if it may be the cause of your problem.
The downside is repair means pulling the trans for access. All this for a 3 dollar part

 

[SteelHeadz]

Aj, if you want to diagnose your jeep engine for a vac. leak, get a can of carburator cleaner. NOTE: Dont spray around an open flame or any source of ignition. just a warning. keep your face and body away from the area your spraying. with the engine running at idle, spray the carb. cleaner for just one second around the suspected area of the vac. leak . if the idle changes rpms(Fluctuates) then your either close or on the spot of the suspected leak. if not , move to a different area until you get all around the intake manifold to see if there are any vac. leak.

 

[jpp1221]

i had a similar problem with my 98 wrangler, it would whine real high till about 4th gear. I ended up having to rebuild my transmission and get a new clutch. Hopefully you don't have the same problem, but if it continues you might want to get it checked out. Goodluck

 

[ka041a]

It might be a bearing in your alternator,water pump, or some other device thats driven by a fan belt, or maybe the bearings in the distributor- i've seen that before too. there is a tool called a mechanic's stethoscope you can use to track down noises, they are not too terribly expensive. a vacuum leak is more of a hiss than a whine i think.
The egr is a valve that opens a passage between the intake and exhaust manifolds to let some exhaust gas into the intake air stream in order to dilute the air/ fuel mixture during acceleration in order to reduce the formation of oxides of nitrogen (nox). it is supposed to be T'd into the distributor's vacuum advance system and also have an electric valve operated by the computer in the line to stop it from working when the engine is cold. basically, it robs power from the engine just when you need it most and most people don't care about smog, so they just take the hose off and the thing just stays closed- inoperable. the clean air act of 1993 makes it a ferderal crime to disable any emissions control device, however, so use your own judgement. good luck, john

 

[1000]

hey whats up, i have a 95 wrangler with a 2.5 i had a crazy sqeeling noise from under hood. i thought it was the belt changed that so i sprayed some starting fluid a round thought it was a vacumn leak. located the spot it was near the intake manifold next to the engine. i noticed the bolt that secures the intake and exhaust manifold was gone put a bolt and washer in and the noise was gone. so check to see if that bolt is there my jeep did the same thing pressed on gas the noise would let up soon as i let go of the gas it came right back.. hope this helps..