M1009 engine buzzing

[richter1978]

My1985 m1009 which I've now had for a year makes a metallic buzzing sound somewhere between 900-1400 rpm (a guess with no tach) in park N and 1-3. At idle it will sound more like a chain clanking. I have searched for and found good things to check. I checked the flexplate and bolts, found no cracks or loose bolts, tightened starter heat shield, rebuilt IP, rebuilt injectors. Vehicle runs great otherwise. Under the hood it sounds like the noise might be coming from left side alternator/power steering/valve cover. I'm not sure if any one of these can make a noise like this. Before the IP rebuild I was convinced that it was making the noise.

 

[doghead]

Check your air filter housing for vibration(put your hand on it with it running) and or, check your throttle cable to see if it is touching the hood. Both Will cause a loud obnoxious vibrating noise in a certain low RPM range

 

[richter1978]

Thank you Doghead, I have checked those as well and both are secure. I have had the loose air filter cover before, that is a bad noise. Thanks again.

 

[doghead]

Climb under and look closely at your motor mounts. See if you have metal to metal contact from the rubber sagging.

 

[richter1978]

Alright, Doghead motivated me to go take a look. One engine mount looks like it may be makeing contact, so I put a thin piece of carboard between mount and frame, but the noise was still there. Decided to pull the alt. belts, to isolate the ringing/buzzing, noise still there. Went to loosen steering pump and noticed that the upper mount was missing it's nut. Found a replacement, noise gone! Thank you for the quick replies and the motivation.

 

[doghead]

Glad you found it!

 

[91W350]

Another good source is the starter brace, they rattle like a chain at lower rpm and we really need them to be tight. Glen

 

[mr.travo]

Had the same problem. Whoever installed the last power steering unit did a crappy job! A bunch of the nuts were loose and I was missing a nut that tied in to the bracket as well.

 

[wired1000]

I had this exact problem... though it was probably my own fault... I recently re-tensioned all my belts and must have missed that one nut when re-tightening.

 

[mr.travo]

Ya, the power steering is a BEAST to get tight and crank down by yourself. I have done one by myself and I am not excited about changing all my belts next week.

 

[wired1000]

It is!!!! It feels like it doesn't rotate correctly... wtf