1993 Jeep Cherokee whistling...

[MJCfromCT]

Hi everyone,

I'm not sure, but I think this issue is related to the cold temperatures recently...When I start my Jeep, I'll hear a soft, low whistling noise, if I give it some gas, the whistling increases in "loudness" and in pitch, corresponding with the increase in RPM. I googled around for something similar, and actually found a YouTube video that pretty accurately depicts what is happening for me:

http://www.youtube.com/watch?v=N0w8x4Zcae4

As in this video, once the engine reaches a certain RPM, the noise goes from being very high pitched, to cutting off. If the engine drops below that certain RPM level (typically ~2000rpm), it resumes its whistling. It is quite loud, not only to me, but people on the street have turned around when they've heard it as well. Also, this happens not only when the engine is cold, but as it is making its way up to normal operating temperature (i've heard it from 0-200 degrees, 210 seems to be where it will stay at).

I'm not sure if this is of any importance, but watching the engine temperature, I noticed that when I hear this whistling, the temp drops by about 10 degrees or so. Its a slight move of the temperature needle, but enough to notice.

Does this sound like a vacuum issue? If so, where would be some good first places to go poking around looking for issues? I somewhat know my way around under the hood, having recently replaced the rotor, distributor cap, wires and plugs, but I'm unfamiliar with what I should be looking for if this is a vacuum or a belt-related issue. Thanks in advance for your help!

[knelleken]

your water pump can make a wine glass type hum, if it sounds like a turbo whisle,check out the i.a.c. valve.could be other stuff too, but i would be looking at the water pump because of the temp thing

[citizen@large]

Gunked up throttle body maybe? Mine whistles when I open it up to a certain point. then again, Mine's bored out too with a bored out spacer under it as well.

[MJCfromCT]

Thanks for the replies, I'll do some investigating and post back.

[SirXJ]

Hey-

My '94 does almost the same thing. Whistling at idle, but if I give it some gas, the whistle goes away.

I have idiot lights, so I can't check the temp, but I'm going to check out the IAC.

[AlohaBra]

Originally Posted by MJCfromCT

Hi everyone,

I'm not sure, but I think this issue is related to the cold temperatures recently...When I start my Jeep, I'll hear a soft, low whistling noise, if I give it some gas, the whistling increases in "loudness" and in pitch, corresponding with the increase in RPM. I googled around for something similar, and actually found a YouTube video that pretty accurately depicts what is happening for me:

http://www.youtube.com/watch?v=N0w8x4Zcae4

As in this video, once the engine reaches a certain RPM, the noise goes from being very high pitched, to cutting off. If the engine drops below that certain RPM level (typically ~2000rpm), it resumes its whistling. It is quite loud, not only to me, but people on the street have turned around when they've heard it as well. Also, this happens not only when the engine is cold, but as it is making its way up to normal operating temperature (i've heard it from 0-200 degrees, 210 seems to be where it will stay at).

I'm not sure if this is of any importance, but watching the engine temperature, I noticed that when I hear this whistling, the temp drops by about 10 degrees or so. Its a slight move of the temperature needle, but enough to notice.

Does this sound like a vacuum issue? If so, where would be some good first places to go poking around looking for issues? I somewhat know my way around under the hood, having recently replaced the rotor, distributor cap, wires and plugs, but I'm unfamiliar with what I should be looking for if this is a vacuum or a belt-related issue. Thanks in advance for your help!

I just watched this video. I think it could be the water pump, but to be sure you can use a stethescope or disconnect the serpentine belt for testing. I would also recommend the stethescope anyway for tracing it. An audible like that should be easy to find, unlike electronic problems which you can't see or hear.

[MJCfromCT]

A bit of an update,

I haven't been able to troubleshoot this in the past few weeks due to a death in the family, but I believe I found another piece of evidence that *might* point to the water pump: when I turn the key to on (not start), I hear what I believe is the fuel pump for a second or so, and sometimes I will hear a quick, high pitched whistle for about 1/4 second, that sounds very similar to the whistling that i've been hearing.

[dave92cherokee]

That would kind of eliminate the water pump because without the engine running the only thing that's doing anything is the fuel pump pressurizing the lines. Best way to check is to loosen the belt enough to slip it off one of the pulley's (usually power steering first) and then check all pulleys for any play or looseness that would indicate a worn bearing in the pulley. If everything checks out then put the belt back on and get it tensioned again and while the engine's running spray some belt dressing on the belt to see if the belt might be slipping or something.