Help!!! Loud Squeal, alternator locked.... 1985 300D - PeachParts Mercedes-Benz Forum

tobybul · #1 07-27-2008, 08:05 PM

.... from engine area. Just came back from 220 mile road trip on the 85D. Car ran just fine even with the ac on. Since it was just about due for an oil change, I changed the oil about 15 minutes after arrival. I usually like to change the oil while engine is still warm so most of the old oil drains out.

After changing the oil, I started the car and it started squealing kinda like a belt is slipping but even louder. I turned off the car right away. Checked around where the belts are and did not see anything unusual. Tried it a couple times more and does the same thing.

I'm stumped!!

Any thoughts or ideas?

TMAllison · #2 07-27-2008, 08:08 PM

Spill any oil on the fan belt while refilling it?

Are all acc devices spinning? None frozen?

forkintheforest · #3 07-27-2008, 08:09 PM

Check the ribs of the belts for cracking, just to make sure.
My ac belt would squeal intermittently. And then it was actually my alternator belt that snapped/broke/what have you.
Also make sure you get the right size belts if thats whats needed.
I hope its nothing major.

-Nick

tobybul · #4 07-27-2008, 08:17 PM

It does not appear to be any of the belts. As I said, I just got back from a 220 mile road trip and the car ran just fine. It actually starts well too. But I am totally stumped by the squealing!! I don't want to run the engine too long while I investigate. It sounds very loud and I do not know what i may be doing to it if I let it run too much

forkintheforest · #5 07-27-2008, 08:24 PM

Sorry, I'm trying to think what else could make a squealing noise.

tobybul · #6 07-27-2008, 09:59 PM

Alternator froze

Of all things!! I guess I should be thankful that it did not act up during my trip.

barry123400 · #7 07-27-2008, 10:16 PM

Why not take the alternator apart. Remove the bearings. Take them to a bearing supply place or altenator shop and get replacements. All that has happened is a bearing has failed in there. Very common. If unable to remove the bearings an alternator shop can do it for very little once you have the alternator apart.

You fellows are aware the slip ring can be replaced on these alternators as well. They see so many miles they sometimes have very deep grooves worn in them.

Actually this is a very cheap part. The problem comes after you install the new one. It has to be trued up on a lathe. I have been toying with the ideal of doing a general reconditioning on all my older alternators that are showing wear. Some may still be the original units for all I know. As is stated a lot comprehensive records with an old car are important.

pawoSD · #8 07-27-2008, 10:29 PM

Same thing happened to the one on my dads car a few months after he got it, he was just driving along at 30mph on Lake Drive.....so like 1400rpm or so.....and all the sudden loud squealing....his alternator had seized.

Interesting that it would happen to another dieseler so close by!

I just swapped out a 1 year old re-man alternator I got at Advance auto.....it had a bad bearing and voltage regular....the rotor was wobbling all over! I swapped in a German Rebuilt Bosch (from online) wayyyyy better! I'd strongly recommend using one of those.

barry123400 · #9 07-27-2008, 10:40 PM

There are a lot of chinese aftermarket bearings around these days. Quality and quality control is probably all over the place. Some rebuilders like them because they are cheap I imagine.

You can buy good bearings easily enough though. At some point in time the chinese bearings will be good in my opinion. For all I know they may already have a higher priced line right now that compare favorably. In smaller sizes even some chinese manufactures deffer and import japanese bearings for quality upgades of certain product.

tobybul · #10 07-27-2008, 10:47 PM

Quote:

Originally Posted by pawoSD

Same thing happened to the one on my dads car a few months after he got it, he was just driving along at 30mph on Lake Drive.....so like 1400rpm or so.....and all the sudden loud squealing....his alternator had seized.

Interesting that it would happen to another dieseler so close by!

I just swapped out a 1 year old re-man alternator I got at Advance auto.....it had a bad bearing and voltage regular....the rotor was wobbling all over! I swapped in a German Rebuilt Bosch (from online) wayyyyy better! I'd strongly recommend using one of those.

Pawo, did you get the reman Bosch from Advance also?

Diesel911 · #11 07-27-2008, 11:44 PM

Quote:

Originally Posted by barry123400

There are a lot of chinese aftermarket bearings around these days. Quality and quality control is probably all over the place. Some rebuilders like them because they are cheap I imagine.

You can buy good bearings easily enough though. At some point in time the chinese bearings will be good in my opinion. For all I know they may already have a higher priced line right now that compare favorably. In smaller sizes even some chinese manufactures deffer and import japanese bearings for quality upgades of certain product.

Speaking of Chinese bearings:My alternator had a rebuilt by BOSCH North Americia sticker on it. When I took it apart the Bosch rbuilt had Made In China bearings.
I priced bearings locally and they wanted too much for both the American made and Chinese made bearings.
I ended up buying some more Chinese bearings on Ebay due to the cost factor. Will see how it holds up.
It looks like when you buy a rebuilt alternator they are going to put the cheapest parts available in them.

pawoSD · #12 07-28-2008, 01:05 AM

Quote:

Originally Posted by tobybul

Pawo, did you get the reman Bosch from Advance also?

Nope, the only place you can get a German re-man is online like Fastlane or ********.....etc....the in store ones are all Malaysian junk. Expect to pay about a $40-50 premium for the good stuff online...+ the shipping to send the core back....but its worth it, since the store ones are worthless junk. My dad's SD is coming up on 4 years/45,000 miles on his....and its still smooth and quiet.

Squiggle Dog · #13 07-28-2008, 01:29 AM

If the alternator turns out to be fine, then it is probably the water pump. When the bearings on the water pump go out they start to bind and will slip and cause a squealing noise. This happened to my roommate's 1992 Mercury Capri and 1966 Mercedes-Benz 200.

You might notice a bit of a grinding noise as well. If you use a mechanic's stethoscope or a long extension against the water pump with the engine running and put your ear to the end of the instrument you should hear any possible grinding from the bearings.

tobybul · #14 07-28-2008, 10:59 AM

Quote:

Originally Posted by pawoSD

Nope, the only place you can get a German re-man is online like Fastlane or ********.....etc....the in store ones are all Malaysian junk. Expect to pay about a $40-50 premium for the good stuff online...+ the shipping to send the core back....but its worth it, since the store ones are worthless junk. My dad's SD is coming up on 4 years/45,000 miles on his....and its still smooth and quiet.

Pawo, do you recall if the alternator came with the pulley? and if not, was the old pulley reuseable/transferable?

Thanks

vstech · #15 07-28-2008, 11:01 AM

pulley should swap easy. you may need an impact wrench to get the nut off.