The air pump should be fairly quiet. Like, almost silent, but not quite. You should barely be able to tell it's engaged, over the noise of the engine at idle.
now THAT is weird!
Once it shuts off a few minutes after a cold start, it MAY turn back on randomly (even at full operating temp!), but often will remain off until the next cold start.
All the M119.97x air pumps should be interchangeable, I think, just match 6-rib vs 8-rib pulleys (they are different diameters, IIRC). There are some threads and videos about repairing / refurbishing the pump internals. Might be worth trying to open it up and clean it?
Could be coincidence. The pump not running isn't a problem. On a car without CEL (anywhere outside North America), if you disconnect the pump, the only result will be a fault code on pin 4 / LH module. The only purpose is to reduce emissions during the rich condition of a cold start.
Do I understand you correctly if I think you're saying that nothing besides the pump not working will happen if the pump has an issue? Ie, it won't seize to an extent that the belt an possibly other auxiliaries might be damaged?
If the pump is electrically disconnected, the clutch never engages, and the internal parts do not rotate. As long as the bearing is good, the pump would then act as an idler pulley. The concern would be if you leave it alone and it continues to get louder during operation, eventually it could seize or otherwise cause a problem.
Right, that's what I feared - or rather, I was hoping that it would disengage by design if/when it fails, instead of locking up and most likely damaging other components while doing so. I'll keep my ear on it and disconnect it if I hear an increase in sound.If the pump is electrically disconnected, the clutch never engages, and the internal parts do not rotate. As long as the bearing is good, the pump would then act as an idler pulley. The concern would be if you leave it alone and it continues to get louder during operation, eventually it could seize or otherwise cause a problem.
I wouldn't call that a bearing-related sound, but from your experience stuff can hit the fan without a more noticeable sound as well I guess.. I hope you're right, and will keep an eye on it for now - should be easy enough to disconnect in case it gets worseI've not wrenched on the air pump, but like to mention maybe a parallell in case it goes down; I had an AC compressor breakdown on my exLimited, where it fully seized. That means when the clutch engaged it released immediately due to the resistance in the locked up compressor. I always keep attention to strange noises in the car, so I was surprised when the AC mechanic told this and I hadn't noticed anything! But he said with an engine torque this high even at idle, it would hardly be noticeable, just a small dip in the idle before the clutch releases. So if the air pump breaks down/get seized, the clutch will release and no further harm occure - supposed the clutch and its bearing is fine.
I don't recall why I posted in this particular thread, but post #21 has images of the seized AC compressor:
Yes, as GSXR said, this is the classic moisture in the caps problem. This is a living problem and I was badly punished on this many years ago:
However, all are happy and that's the best part. And even better, it's been proved that the caps can be used for years. It's no reason to panick from burnt contact points and green goo inside, just clean them up and put them back again. The rotors are a bit different having other wear points.
That's interesting. My 500E has an occasional distinctive "clunk" when applying the throttle - which I've always (without any scientific evidence) put down to a worn differential. It can be avoided by gentle opening of the throttle.
Will do! I have good experience with the prop shaft rubbers on other cars, where I have also had to do the rear subframe mounts on some - hoping it won’t have to come to that though, but we’ll see..
That’s what I’m hoping as well - will inspect and let you know asap
Aha, from Steve of course! So he is still in business, haven't checked his site for years, I have to take a look.Oh, and I got them from MBenzNL in the Netherlands
He is very much in business still, although they are actually in Norway for vacation at the momentAha, from Steve of course! So he is still in business, haven't checked his site for years, I have to take a look.
Many thanks!
BTW - I hope the 500E poster arrived without any shipping flaws, and was up to your expectations?
His website got poached a few years back, and as he wasn't interested in paying the ransom for it he now relies solely on word of mouth and the occasional FB-post (where he still has a page). In other words, you won't find his website any more, and the best way to contact them is through MBenzNL@gmail.com or a message on FB. I might be ordering more stuff from them in the near future though, so perhaps we should join forces and save on shipping if you need parts as well.
