Mercedes engine with an air compressor mounted to it, when compressor is activated, belt bounces around violently, not activated, looks okay. have a video on my phone. belts do not last long in this condition. Any ideas would be great. Compressor is true to the other pulleys.
Tensioner been replaced? Is the compressor factory, or an add on? All the pulleys been checked for any bearing play or wobble?
Everything is factory, This model is mounted in a Unimog large vehicle. This compressor is the only component run on this belt from the crank shaft. Adjustments are made at the compressor. Yesterday was the test after extensive work making sure everything was spot on. I have a video on my phone that I could send you. He has had a lot of pros look at it, I have 25 years experience myself, just not on Mercedes. It looks great when the compressor is off but on the belt looks like its going into a death wobble. The belt is also from the manufacturer.
Yeah, I was asking generally to knock out the basics. I'm not familiar with those Mercedes engines, and especially not in Unimogs, and especially when it's an issue with a belt drive compressor in the generator section of the forum.
I know right! I have a reputation of being the king of funky things up here in Maine. Everything that no one can figure out comes to me. Eventually I will prevail! But this is an odd one. Could I send a vid to your email just to get another set of eyes on it? it shows at the beginning at rest, then the compressor turns on.
Does it smooth out when the RPM is changed? Or happen at idle only? Tried changing the idle RPM either direction? Old Ford diesel trucks used to have a v-belt that slapped around a good bit to the alternator. They usually ran fine like this, but occasionally would jump off, but not much you could do about it.
I relate to that, having an '86 F350 6.9idi with the slappy alternator belt as a daily driver. You either let it do its thing, or wipe out the alternator bearings if you do ever get it tight enough to roll smooth, haha.
Just because everything is OEM including the belt doesnt make it right . I would try a gates automitive (not industrial ) belt
I thought of an aftermarket belt, customer is very meticulous, wanted more input, thank you.
The belt as it turns out is a Gates belt, I was just looking at some of my pictures.
A photo might help . Is it a single A section belt ?
Is there any chance it is in fact pushing the driven pulley rather than pulling it? Or am I out to lunch here lol
A compressor has peaks & valleys of resistance. perhaps a less stiff belt would help to smooth the torque and the jumping. Another thought, lower the belt tension to let the rubber elements work.
Late to the party here. Are we talking air compressor or A/C compressor. I remember air compressor driving off camshaft on side of engine.
Air compressor belt, as soon as can figure out how, I will post pic/vid.
Could not put video on, 2672 is compressor idling, 2673 is compressor engaged.
Put a dial indicator on the compressor pulley. Bar the engine over. Looks like it's not running true by the photo blur. Do it at several places, edges, groove walls, etc.
These photos are actually after I got it true. It was not before. Now it looks good until compressor starts and starts fluctuating and not sure but looks like it makes contact with the frame. I tried to load a video but wouldn't let me.
Other than looking terrible , is the belt flapping causing problems ? Is it chewing up belts ? If it was a pulley problem I would still expect flapping when the compressor is unloaded . These compressors are hard to drive on 1 belt . From the pic ,the belt is loose under load due to belt stretch ,lack of tension or over loading . If you start the vehicle with empty air tanks ,is it as bad from the start ? Is it cutting out at the correct air pressure ?
Customer just came back inti the picture, he had bought a new compressor to try, I installed it, made sure it was true to the crank shaft, it does get chewed up when it hits the frame, starting out with empty tanks it jumps quite a bit, tanks full, it looks perfect.
Can you increase belt tension a little ? Is there room to put flat pulley under the flapping side , even to get a longer belt to fit the pulley in ? It is very tough work for 1 belt
Can you change the pulley on the compressor to a heavier one or add a steel disk to it to give more of a flywheel effect in an effort to even out the compressor pulses?
The belt is a little to tight as it is, I may have room for an extra pulley, I will have to take another look at the room, very tight quarters.
That is a much easier possibility, might be worth a try even if I have to have one made. I was wondering if there was a way to reduce the compression stroke of the compressor? (construction equipment experience, compressor not much) I see where you are going with pulley/flywheel effect. I did put the old pulley on the new compressor got the same results.
You might consider a harmonic balancer instead of a simple flywheel. It would be working in reverse of usual installation on an engine. Which brings up another thought. Is the harmonic balancer on the engine doing its job?
I dont know anything of the science of belt tension but as I work only on the same kit over and over, i find the best tension varies hugely from 1 application to the next . If it was my machine assuming it has a good quality compressor , i would keep squeezing the belt bit by bit until it steadied or split . That is just me and I could be slated for suggesting this .
I would be looking at the harmonic dampener on the engine. The rubber part of it may be failing. I had one that had actually allowed the pulleys and the steel weight to rotate out of alignment with the correct crankshaft position. I figured it out because the 0° timing mark was off when #1 piston was top dead center. I even put new timing gears in the engine before figuring it out.