Ok, my 99 trooper which has been taken care of its whole life has started making a new noise this week. When going down the highway what sounds to be an electric motor of some kind kicks on and runs for about 30 seconds and then kicks off. Repeats about a minute later. The noise sounds like some sort of electric motor or compressor kicking on and off. It is not real loud and my wife didn't even notice it. She says it is all in my head. Any ideas on what this could be.

Also, I have seen a lot of talk on the web lately about changing or tightening the EGR. What exactly does the EGR do? Does it need changed every so often. I change my PCV valve on a regular basis. So far I have not experienced an excessive amount of oil burning. One experince where it was realy low but I had just had the oil changed at an iffy lube place.
Thanks for any info

Ok, my 99 trooper which has been taken care of its whole life has started making a new noise this week. When going down the highway what sounds to be an electric motor of some kind kicks on and runs for about 30 seconds and then kicks off. Repeats about a minute later. The noise sounds like some sort of electric motor or compressor kicking on and off. It is not real loud and my wife didn't even notice it. She says it is all in my head. Any ideas on what this could be.

Also, I have seen a lot of talk on the web lately about changing or tightening the EGR. What exactly does the EGR do? Does it need changed every so often. I change my PCV valve on a regular basis. So far I have not experienced an excessive amount of oil burning. One experince where it was realy low but I had just had the oil changed at an iffy lube place.
Thanks for any info

Sounds like your clutch fan; mine's famous for being real loud too. I doubt that the noise would be related to EGR.

Forgot to add, if your clutch fan has never been noisey and all of a sudden is, I'd check to make sure it's not going out.

Mine's been loud since the day I drove off the lot.

check to make sure your air selector is not set to defrost. The defrost setting, with fan speed 1-4 will cause the ac to run too even if the ac button is not on. Also, it could be a ABS pump. Yank the ABS fuse and drive it for a couple of days and listen for the sound. Yanking the fuse, will not effect your brakes. It will only turn off the ABS system.

The EGR recirculates exhaust gases back into the throttle body area. No need to change it. Just clean it out once a year. For a write up how to clean it check my FAQ link below.

-Ryan

If it is the ABS pump is that an easy fix. Is something I could do or should I take it to the dealer? Also, when changing the fuel filter is there a certain brand I should use? Is OEM really better?
Thanks

if u have an external fuel pump it could be that, cause that's what mine was doing

The noise you are describing sounds like the a/c compressor cycling on/off as it should. That makes kind of a whirring noise. Keep in mind the a/c compressor will cycle when the windshield defrost is selected.
G/luck
Joel

I am with Rodeo on this one try removing your belt see if the noise continues, if it goes away re install your belt and try to determine if it is in fact your compressor. Sounds like a slipping clutch.

Also forgot to add that I recently had my trans mode switch replaced as my transmission was shifting real screwed up. Still shifts hard. Could this have anything to do with a slipping clutch? Also replaced spark plugs with Bosch platinum 4s a while back before I found this forum and new any better. It seemed to run ok with them. If I am not having any problems with them should I replace them with the OEM plugs to be safe?
Thanks