SMALL AIR PUMP MAKING NOISE AND GOING BAD

What chassis is it?

Roadmaster chassis

sounds like the electric air compressor that keeps your air leveling system supplied with air to keep the coach level. Thats if you have an air suspension leveling system.
Turn your air leveling off and it may stop. If it does then its confirmed.

the air pump fills a small tank with air so when your auto air leveling needs air it always has some no mater how long its been sitting.
if its running a lot you either have a leak or the pressure switch is bad and it just runs and runs trying to fill a already full tank.
if the pump is shot I don't think it is serviceable. could take it apart and see if there is any thing wrong with it.
if you want to shut it off there is a fuse for it in the side compartment.

Like Jerry said, it is probably the auxiliary air compressor for the leveling system. Mine is in the rear, but may be the same system. Mine is the HWH system. My compressor went bad and I found the identical compressor at Zoro.com Zoro Tools. They also had a rebuild kit for several small compressors like that. The one I purchased was the exact model number as the one I replaced.

Your leveling system checks periodically to see if it is level, and if not, it will relevel and the little compressor supplies air for that process. On mine, I believe it is supposed to check every 30 minutes or so. If you can remove the compressor and do a search for the brand and model number, it should be easy to locate. As another possibility, Monaco Coach will have one for you, but probably at a higher price. Hope this may help, Happy Trails Bert

I believe the pump is running but not pumping because of the noise. I figured it rattled itself apart inside. but I will check. its freezing cold outside and 45 in the shop so tomorrow il look for a fuse and see if I can turn the leveling system off and it stop the pump. ok ya know where a pump can be bought. mine rattles like a bucket of rocks/ thanks for the help.

Yours is in the front. Monaco changed it from the rear in 07 because of noise complaints while trying to sleep. Your air leveling system, adjusts your coach when you first push the button twice. Once leveled, the system goes to sleep. Every hour the computer "wakes up" and checks for level. If your coach is still level it simply goes back to sleep. If it needs adjustment, the air compressor kicks on to fill whichever air bag(s) needs air to relevel the coach. It then goes back to sleep for another hour etc. That said, you should hear a hum when the compressor kicks on and cycles. Unfortunately, because of it's location, your's is behind the front wheel, mine is in front of the duals, the three screws that fasten it to the frame have a tendency to become loose. The screw is fastened with a washer and a spring to allow some movement of the compressor as it cycles. These screws work their way loose and assuming you have all of them, they'll need to be tightened. I lost two and had to make my own replacements using materials I found at ACE Hdwe. I have no idea where you might be able to purchase them. I also did not take a picture of them when I had them off. Check to see if all the screws are there and that they are tight. Your noise will probably go away....Dennis

If the pump is running more and more and longer and longer, before you assume the compressor is bad, I would look at the pressure switch. They are inexpensive and very easy to change. It is located right near the compressor.

as soon as it warms up ill be on that pump like a hobo on a hotdog. yall have been so much help and the wealth of info on the rv net is priceless. I will let you know what I find in 3-5 hours

ITS OUT. IT MUNCHED ITSELF. AND IT COST OVER $7OO.OO IME GOING TO a pump shop tomorrow and see if he can rebuild it and I did check zozo or something like that and didn't find the pump or a kit. again I appreciate the help. I guess I can drive this coach if I have to with the pump off???? thanks mike