Alternator/belt squeal

[ALL500]

Hello from Toronto!

I have a pretty loud intermittent squeal on the front passenger's side after a mechanic changed my belt and alternator. The squeal is accompanied by precise flickering (and eventually dying) of all electronics.

I've already fried one battery and the mechanic says the new alternator checks out fine.
He says there is no problem with the car, but when I fried the old battery, it was in the middle of rush hour traffic and a long tow. Needless to say I am looking for a new mechanic.

I have narrowed it down to an alternator squeal from youtube videos, causing my alternator to not charge the battery properly. Can someone possibly help me confirm or deny this? The exact sound in my car is what I find on youtube with a belt/alternator squeal. It is a fast, very loud and high pitched squeal, that comes in bursts of a few seconds.

I am wondering what the exact belt is I should be getting, size/part number etc.

I am also wondering if there is a shorter belt I can get, to bypass the a/c compressor as that is shot and squeaking as well and for the time being, I don't mind no a/c.

When I bought the car, I am almost sure it had a shorter belt that bypassed the compressor, as there was no a/c compressor noise before this new belt was installed.

Either way I would like to bypass the a/c compressor until I can get the current one replaced and if someone could help me out with the exact size/part number for a shorter belt, it would be very much appreciated! Thanks!

 

[TerryA]

Sounds like you already know the answer to your problem. The mechanic should have questioned why the shortened belt was on the car. Somebody jury rigged the belt to bypass the compressor. Sounds like the mechanic just put on the correct belt without asking why it was "short-belted" in the first place. He does not want to do the work again without getting paid a second time.

If you want to continue driving with a shortened belt and no A/C you will have to get the old belt back and match it up at a parts store. Maybe someone on this board knows a part number for a short belt.

You need to find a competent Mercedes mechanic that is knowledgeable in these cars. One of our members in your area should be able to recommend a good Tech.

If you intend to keep the car and want it to be dependable and fun to drive don't use a guy in a Gas Station or from Pep Boys.

I hope you solve your problem soon.

Take Care

 

[ALL500]

Thanks terry, yes despite the presented expertise of the shop, I am doubtful and ended up there unintentionally. Any members who have recommendations are highly welcome (Toronto area). I'll continue my belt search until I get that compressor solved.

 

[J-Sauce]

Are you sure there was a shorter belt? I may be wrong, but I don't think it would be possible to bypass the AC compressor with it on the car. I believe a belt running from the crank pulley to the PS pulley would still hit the AC pulley. I haven't tried myself, but looking at the front of the engine, it does look impossibly tight.

Number one, if you do not know the brand of belt you got, I would recommend either genuine mercedes (aka contitech), or possibly dayco. Other brands just do not work as well, and will often squeak even when new. Though, your problem sounds more like (number two) a bad belt tensioner. What year is your car? If it is a 92 or early 93, you will have the manual style belt tensioner which is prone to going bad. If you or a previous owner have not replaced it in the last 60kmi, I would look into that next. The only two brands I can recommend for this part is OE mercedes and LASO. An easy way to tell if you have the old style or new style belt tensioner is to count the ribs on your belt. 8=old manual tensioner, 6=new.

 

[ALL500]

Thanks J-Sauce!

I will look into it to see what belt is actually on there, its a 1992. I will also look into the tensioner. But, is a bad belt or tensioner a culprit of the electricity cutting out to the exact time of the squeal? If I could record an audio waveform of the squeal, the flickering lights and power loss would correspond directly to the spikes it seems!

I know the battery is not charging properly at all. I don't want to fry another one.

Also, there is zero oil pressure, though I just changed the oil and no leaks. Bad gauge perhaps. The built in phone makes a tone through the speakers on start up now as well. Bad relay somewhere?

And... say the alternator is fine as the mechanic says... once the car is started, if I disconnected the battery, the car should still run off the alternator? It dies as soon as the batter is detached.

 

[gsxr]

Zero oil pressure is what appears when the wire to the sender is shorted to ground, and that wire is very close to the alternator (same harness). Sounds like something is messed up down there. And you may need to replace the lower harness... they are usually toast after 20 years.

J-sauce is correct, you cannot bypass the AC compressor (unless, possibly, it was removed from the engine). You can bypass the smog pump by installing the Euro idler pulley in place of the smog pump, but I very seriously doubt anyone did that.

NEVER EVER EVER disconnect the battery while the car is running! You can kill the computers that way, or cause other serious damage!! The alternator needs the battery present to maintain a steady 12-14v. Remove the battery connection and the voltage can spike.

 

[ALL500]

I will take a look at that wire close to the alternator. I fortunately have a competent friend and mechanic on hand now. Apparently the alternator was fried the first time. After a rebuild, the squealing that I most wrongly diagnosed as a belt squeal turned out to be the starter engaging as the car was running. That burned out as was replaced. Then the car died yet again and the mechanic said it was the alternator, again. A subsequent test showed the alternator was fine (and my suspicion is it could have been in the first place). I received the car back electronically limping and my friend who has w124 experience simply cleaned the ground contact on the battery wire. ZERO problems for a week now and all windows work twice as fast...

 

[DerFuror]

... my friend who has w124 experience simply cleaned the ground contact on the battery wire. ZERO problems for a week now and all windows work twice as fast...

That's good news. Think of the additional diagnosis & repair cost your friend just saved you. Electrical system trouble shooting starts with the battery; its condition, connections & then moves toward the component exhibiting the symptoms. Ground connections are most often the cause.

Buy your friend lunch!

 

[ALL500]

Yes, I think I saved a ton and have a trusted and informed person to help me learn here, well deserving of a large steak meal. I'll check the forums for the service/repair manual.

 

[ALL500]

Uh oh. I spoke too soon. Just went around the block and the car cut out dead again in heavy traffic. Luckily it started right back up again and I made it home. GSXR, if you can tell me any more info about that wire to the sender, I'll take a look. I don't want to poke around blindly without my friend to help...

 

[gsxr]

Uh oh. I spoke too soon. Just went around the block and the car cut out dead again in heavy traffic. Luckily it started right back up again and I made it home. GSXR, if you can tell me any more info about that wire to the sender, I'll take a look. I don't want to poke around blindly without my friend to help...

Check the date code on the lower engine harness (which goes to starter, alternator, oil level sender, and oil pressure sender). There should be a label on the harness, where it attaches to the main power terminal, behind the CAN box. If the harness is original, the insulation is likely flaking off, and harness replacement would be a Very Good Idea:
http://www.500eboard.com/forums/wiki_index.php?title=Lower-Wiring-Harness

The oil pressure sender is located at the very bottom of the oil filter housing. Details and photos are here:
http://www.500eboard.com/forums/wiki_index.php?title=Oil-pressure-gauge

 

[DerFuror]

After a rebuild, the squealing that I most wrongly diagnosed as a belt squeal turned out to be the starter engaging as the car was running. That burned out as was replaced.

Do you happen to have a heavy car key chain (i.e. loaded up with all kinds extra keys & such?) A heavy key chain plus a worn ignition lock cylinder can create a situation whereby the starter will not disengage, gets spun by engine & burns things up.

If you determine the squealing is actually belt-related, take the belt off & turn by hand the various pulleys. The one that doesn't want to turn is the most likely culprit.

 

[ALL500]

Thanks gsxr, I will have a peak at both harnesses soon, though I am still reading up on how to access them both thoroughly. I assume I'll need a good set of stands and a floor jack asap.

DerFuror thanks, it was mentioned to me as a culprit of ignition issues, but I only have the starter and door keys on the chain. Quite spartan. The good folks over at the mechanic shop relieved me of $1300 that was burning through my wallet
One of the items replaced was the rear part of the ignition switch. Funny enough, my friend says its the front of this module that could stand replacing.

Unless those harnesses are fairly new, I assume it would be good measure to replace them when I get some $$. Any leads on someone/where as a source?
I'm about to do plugs/rotors/caps/ignition wires.

 

[500e500toronto]

All 500 where in Toronto are you located. S&S Motors at 645 Queen St E knows these cars in & out if you are still having issues.

 

[ALL500]

I'm just north of the downtown core, so S&S will not be hard to get to. I am getting a 4 CD set repair/service guide for the w124 tomorrow. I would like to know my car and learn about it, so if there is a job I am capable of handling, I would like to give it a try. If it gets too much or something I cannot handle, I will try S&S. I only ended up at that other place (Mortimer area)... not by choice. I am thinking a wiring harness might be a manageable job, bit finding one for the 500e might be difficult.

 

[emerydc8]

Are you sure there was a shorter belt? I may be wrong, but I don't think it would be possible to bypass the AC compressor with it on the car. I believe a belt running from the crank pulley to the PS pulley would still hit the AC pulley. I haven't tried myself, but looking at the front of the engine, it does look impossibly tight.

Based on the shop diagram here, I agree.

EDIT: Maybe if someone actually did that, the compressor would run backwards, causing the back side of the belt to slip on the A/C pulley and squeal.

 

[jouniu]

Attached document have some information about belt lengths.

 

[ALL500]

Thanks emerydc8, that diagram clears things up. However, Jouniu, I am confused again, as per the last diagram on the .pdf here, it looks like the belt IS bypassing the A/C compressor?

As a side note, my heat is now always on, despite the fan being off and all vent options only blow through the front vents. I'm not sure if that has to do with this however, I should post the topic in another section...

Didn't have these dang issues until I let that indy shop hack at it :/

 

[clarkz71]

Thanks emerydc8, that diagram clears things up. However, Jouniu, I am confused again, as per the last diagram on the .pdf here, it looks like the belt IS bypassing the A/C compressor?

No, it's showing both versions with and WITHOUT an A/C compressor

.

 

[gsxr]

That last image in the PDF is showing the later 119.98x engines. The belt lengths shown may not work on a .97x engine.

 

[ALL500]

Oops, ok gotcha, thanks. Well eventually, sooner than later, I will have to figure out what to do with it, as there is still a bit of noise for the first min or two after warm up...

 

[ALL500]

Well, I've been cruising around in a *brand new* 1987 300D since I last spoke here. It's parked next to my 500E, I'm sure they speak to each other at night. As spring will be here soon, I'm planning on re-opening the case of the stalling and noise on the 500E. Turns out the noise on start up is the bearings in the air pump (thing with the triangle in it).
Currently meditating on the DIYability of this, feel free to break my peace...

The more important issue is the stalling. It's at the point now where I can start the car just fine, though as I let it sit and idle, the rpms lower slowly and in about 30-45 seconds the engine dies. Always starts back up right away. Only thing I can do to prevent this is giving it a little gas. If I turn the wheel left or right (car stationary) the lights/electrics dim and if I do it too fast the engine cuts out.

My power steering pump (or line) is definitely leaking, though I'm not sure if this is any indication that the pump its self is bad?
The car also stalls in the 20-40mph range. It stalls in a straight line at this speed. It also stalls when cornering (especially downhill).

I stopped driving the car the last time I went down a 2 lane twisting hill and lost the engine, power steering and brakes. The wheel actually locked up before I could grind the car to a stop (with two feet on the brake pedal), 12 inches short of the concrete side-wall. Better than 12 inches from oncoming traffic.

I like James Dean, but I'm not a big enough fan to meet him. I've read a 19 page thread on the stalling topic and countless other threads and no one has seemed to actually reach a conclusion on the issue? If I am to buy a code reader, my questions will be: where from/what type/how do I read codes?

Also sometimes, I remember, after gunning it, all the dash would light up like a Christmas tree. I installed new plugs/wires/rotors/caps (after said issues) and before I put it away for the winter. Notwithstanding the aforementioned, it made the car drive faster

GSXR, the lower wire harness - I jack the car up and look for some wires attached to the alternator? The links you provided (Can Box?) are down at the moment.

 

[gerryvz]

First of all, you MUST replace both your upper and lower wiring harnesses BEFORE you do anything else, if they have not been documented as being replaced.

Once you do that, then you can start resetting and pulling codes. There are several HOW-TO articles and threads here that detail how to build a code reader and how to pull codes.

But first, you need to ensure that the electrical flow to your engine is correct. If the harnesses have been done, then you have a baseline for further diagnosis and repair. The ETA (also can be a victim of bad wiring) would be a logical next step once the harnesses have been done. The 500E harness price has dropped in recent years, so there is NO better time than now to get them and replace them. It's a DIY job on both, although the lower harness is a bit of a pain in the butt to do.

Let us know when you have those jobs done (or confirm that at least the upper harness has been replaced), and then we can start you moving to the next step.

 

[gsxr]

Gerry, why are the Wiki links in post 6 not working...?

 

[gerryvz]

Gerry, why are the Wiki links in post 6 not working...?

what links of which you speak?

 

[gsxr]

what links of which you speak?

Oooops. Sorry - make that post #11 above.

 

[ALL500]

Gerry, is this a plastic guide rail attached to the upper harness in question? And the lower one is underneath the car, passengers side? Would you have a recommendation as to where/who to get a harness from, OE or aftermarket?

 

[gerryvz]

That does appear to be the case. There is a comprehensive Wiki entry on the upper wiring harness that should provide approximate pricing.

http://www.500eboard.com/forums/wiki_index.php?title=Upper-Wiring-Harness

There is no such thing as an "aftermarket" harness. It is ONLY available as a factory part.

Your best bet would be to go with a factory parts source - either MB of Gainesville (just do a search for "Lionel Rutter") or the MB Classic Center (do a search for "Tom Hanson").

Depending on whether you have an early or later car, you should be able to get the upper harness for under $475 (1992 model) or $400 (1993 and later), shipped. That price is dramatically lower than it has been in the past, so it is an EXCELLENT time to purchase a new upper harness.

Also, you can double click on the photo in the Wiki entry to get a blown-up size of the photo. You should be able to see the plastic channel that you have pictured above.

Cheers,
Gerry

 

[gerryvz]

Oooops. Sorry - make that post #11 above.

I am just not sure what you mean, Sir.

 

[gsxr]

Thanks for fixing!

 

[ALL500]

Well I tried driving her again. She was fine, fine, fine, oooh fast, fine fine, beautiful, stoplight - dead. Electronics seemed all good, but just a click on start up, no action. Towed home. And this: https://vimeo.com/125644405

 

[Maui]

Wow, that doesn't sound good.

 

[ALL500]

It is most definitely not music to my ears.

 

[J-Sauce]

Gerry is right, your lower harness needs replacing. My car had very similar symptoms and the harness was completely shot when I removed it. Replacing it with new cured it completely.

Have you replaced your smog pump? That's another thing I've done more than once with my 500E. The noise they make when bad is very similar to the one your car is making in the video. The clutch on that pump can engage and disengage based on engine RPM. It sounds like you either have:

a) A bad smog pump clutch bearing. When the clutch engages, the pump spins on it's internal bearings instead of the clutch bearing and the noise goes away.

b) The air tubing going from the pump to the exhaust may be cracked and broken or missing. The noise may instead be air escaping through the tubes instead of being pumped into and deadened by the muffler. This would be the case of the pump spins at idle and would explain why the noise goes away when the engine is reved.

Try repeating the experiment in your video and keep your eye on the CENTER of the smog pump clutch. See if the noise correlates to a stopped center or a spinning one. If it does not appear to be related at all, check the AC clutch for a bad bearing as well using the same method.

 

[J-Sauce]

As for the car stalling, I have one very stupid question, but it must be asked, and one not so stupid question.

Are you running the car without an air filter?

Have you checked the car for vacuum leaks? And be honest. We've had 2-3 folks here lie on this question only to end up sending everyone on a wild goose chase when they simply didn't THINK their car had a vacuum leak, but didn't bother actually CHECKING.

 

[ALL500]

Thanks J-Sauce, yes as a matter of fact I do have a shot air pump. It spins for a minute or so after start up then disengages. It emits a grinding noise like sand in rollerblades, very pleasant and musical actually. This noise - the video does not do it justice - is a cheese grater of death noise that screams from the inner bowls of the earth, discombobulating the soul. It's really loud. And it's coming from the rear-ish of the engine on the passenger's side. Sounds to me like someone put ball-bearings in my oil.

I make sure I keep the air filter on and I've ruled out large particles being sucked in, at least in my ownership. It was apparently well taken care of before me, apparently by Barry Gibb, so the story goes. I have not checked for vacuum leaks, beyond my modest abilities, apparently I need a cigar and then some voodo. I've ran many a w124 through the wild and beyond (vacuum lines haw haw haw) and as long as the engine is duct taped to the engine bay, they've never failed me. Except this M119... and another...

 

[ALL500]

Also, the lower wiring harness? That huge, giant 100 pound thing, with the billions of connections? THAT'S what needs replacing??

 

[Klink]

Thanks J-Sauce, yes as a matter of fact I do have a shot air pump. It spins for a minute or so after start up then disengages. It emits a grinding noise like sand in rollerblades, very pleasant and musical actually. This noise - the video does not do it justice - is a cheese grater of death noise that screams from the inner bowls of the earth, discombobulating the soul. It's really loud. And it's coming from the rear-ish of the engine on the passenger's side. Sounds to me like someone put ball-bearings in my oil.

I make sure I keep the air filter on and I've ruled out large particles being sucked in, at least in my ownership. It was apparently well taken care of before me, apparently by Barry Gibb, so the story goes. I have not checked for vacuum leaks, beyond my modest abilities, apparently I need a cigar and then some voodo. I've ran many a w124 through the wild and beyond (vacuum lines haw haw haw) and as long as the engine is duct taped to the engine bay, they've never failed me. Except this M119... and another...

That Satan's meatgrinder sound is probably your starter being engaged when the voltage differential between the various shorted wires in that lower harness gets harmonically aligned by bad juju! Replace your lower harness before your car burns to the ground. Seriously! Look what happened to Barry Gibb's house in Nashville!! Coincidence? I think not. Replace your lower harness or your car won't be staying alive. This isn't jive talking, and I'm not starting a joke...

 

[Klink]

Also, the lower wiring harness? That huge, giant 100 pound thing, with the billions of connections? THAT'S what needs replacing??

It's not quite that bad...

 

[ALL500]

Yes, YES! I seem to remember someone, somewhere, sometime mentioning that it sounded like a starter trying to engage as the car was running. Maybe that explains why the electronics seem ok but the car is now not starting? Fried starter too?? O cursed, wretched beast of the lower circle of harnessness, I evoke though to be cast out and banished to the nether-regions, never to beget to this realm again. Ahem. Is this what I'm after:

http://www.ebay.ca/itm/MERCEDES-W12...993-/121397706745?hash=item1c43ddfff9&vxp=mtr

 

[ALL500]

I never knew that about Barry, he's the last one left! Well I've got a message for you, ever since this 500 stepped into my life, it's been too much heaven. I hope to get this sorted before the first of May.

 

[ALL500]

Ah, I saw the working links for the upper and lower harnesses. So I take it that this is NOT what I need: (what the hell is this?)

But rather this: (Upper)

And This: (Lower)

 

[nocfn]

glad mine are done. Also glad to learn from this and many others on this board!

EDIT - checking up on the procedure since I shamefully admit that indeed, my lower needs replacing, and that I would correct the record. Sometime before GVZ strokes out from travel, we may assist each other on this dastardly task.... stay tuned....

 

[Klink]

Ah, I saw the working links for the upper and lower harnesses. So I take it that this is NOT what I need:View attachment 39932 (what the hell is this?)

But rather this: View attachment 39933 (Upper)

And This: View attachment 39934 (Lower)

That's exactly right, you've got it figured out. There's a little more to it then simply adding a can of BG to the gas tank, but it's nothing like the horror of the first picture, which is the main vehicle/engine management interface harness.

This not so excellent adventure will not have done the starter any good, but it's spirit probably has not yet flown. It's no tragedy, anyway, as you can find a Bosch exchange for a reasonable price, or have a competent automotive electrical rebuilder go through it. That wouldn't be a terrible idea, and it's easier to route the new wiring harness into place with the starter removed, but R&R of the starter itself isn't too much heaven. Figure on a lonely day or lonely night getting this all accomplished. Right now, you're paying the price of love, as it's certainly not as much fun as a night on Broadway, but once it's all done you should be dancing...

 

[Klink]

I never knew that about Barry, he's the last one left! Well I've got a message for you, ever since this 500 stepped into my life, it's been too much heaven. I hope to get this sorted before the first of May.

Well, hold on! I think we can keep your enthusiasm aive for longer than one more hour...

 

[Maui]

If you are not mechanically inclined or one with little patience I would recommend buying the lower harness from MBCC or Gainesville and taking it to a COMPETENT indie mechanic to have it replaced. It is not a fun job, as simple as it may look compared to the upper. Given a choice I'd rather do 20 uppers over one lower.

 

[Klink]

Given a choice I'd rather do 20 uppers over one lower.

Any professional mechanic that has done the jobs will say the exact same thing, Ken.

 

[gerryvz]

Great ... I'm getting ready to do my lower E500 harness. It's like, my NEXT project.

Well, thankfully the photos I post in the HOW-TO won't record the curse words I'm sure I'll be saying....

 

[Glen]

Any professional mechanic that has done the jobs will say the exact same thing, Ken.

I'm far from a professional but after doing two lower harnesses and a few upper harnesses over the years, I absolutely agree 100%.

 

[gsxr]

I've done the lower harness several times now, and Ken & Klink nailed it. The funnest part is where the metal bracket won't fit between the block and the trans dipstick tube so you may need to loosen that to make room. Can't wait for the How-dee-do from Honch!