Any ideas why gas powered air compressor vibrates under load?

[Brian Elfert]

I just bought a used Coleman Powermate gasoline powered air compressor. The problem is it runs like a swiss watch at idle, but when it goes to full power to compress air it vibrates pretty bad.

The engine is Briggs Vanguard series. The engine and the unit look almost brand new. I haven't checked for a broken motor mount or anything yet.

What should I be checking to get rid of the vibration? I bought it for one project and could probably live with the vibration, but it would still be nice to fix it.

[Bill LaPointe]

Check for loose bolts on compressor and engine. Check belt for "hump" from not being used. Remove belt from engine and see if engine vibrates without load. Probably one of the first two , though. Good luck.

[Brian Elfert]

I didn't get around to removing the belt yet. I gotta figure out how the guard comes off first. Good suggestions. I'll see what happens this weekend.

[Brian Elfert]

This is an old thread now, but I finally got around to working on the compressor. It has been so cold and rainy I haven't felt like working on it.

Anyhow, the thing works like a fine Swiss watch with the belt removed. The belt wasn't fully tensioned and it appears to have some issues. It was also the wrong length per the manual. I just called NAPA and ordered a new belt for about $10. I hope to have the compressor up and running tomorrow. You have no idea how happy I am that it isn't a bad engine!

I would like to meet the guy who designed the belt guard to tell him just how stupid the design is. The bolts fall down into the guard when they come out. I have no idea how I will get them back in. If they fall out of the socket the guard has to come off to get the bolt back out.

[Russ Filtz]

Wonder if a link belt would work good on that? If it can smooth out a table saw, should handle a compressor!

[Brian Elfert]

I got the new belt from NAPA last night and the compressor works great with the new belt in place. No vibration now. Thanks to Bill who recommended checking out the belt.