1999 e300td alternator replacement - PeachParts Mercedes-Benz Forum

activ123 · #1 03-25-2007, 06:08 PM

The alternator pulley appears to be slipping (have no idea why one needs a "clutch" in an alternator pulley...) - I base this on the fact that the idiot message on the dash is intermittent. So I checked the dealer - they want almost $400 to put in a new pulley.

Dealer wants almost $700 for a new alternator, but I found one for $425. So here's the question:

Since the car has over 120K miles on it, should I go ahead and replace the complete alternator? (myself) Or should I get a new pulley and a new brush/reg kit and do it that way? (That's about $200 non-dealer sources)

My main concern is putting $200 into this alternator and then having the bearings in it go bad...

Also, are there any tricks to swapping the alternator? Any other parts that need to be removed? It looks crowded down there and the job needs to be deon from underneath. One of the rad hoses looks like it could cause problems.

Any advice and/or removal instructions would be appreciated.

thx

Andy

TMAllison · #2 03-25-2007, 07:52 PM

No clutch.

http://www.detali.ru/cat/oem_mb2.asp?TP=1&F=210225&M=606%2E962&GA=722%2E608&CT=M&cat=19T&SID=15&SGR=030&SGN=02

Sounds like you have a slipping or a old belt to me.

Drop the tension on the belt and examine it for glazed spots and then spin all pulleys by hand first to see if you can locate one with drag.

nhdoc · #3 03-25-2007, 07:54 PM

I was also getting an occaisional idiot light on my '98 at startup but found that a small leak at the t-stat housing was causing the belt to slip. I replaced the t-stat, seal, updated housing and, while I was at it put a brand new belt and tensioner spring on and it's been over a year with no lights. You may want to make sure your belt is in good shape, properly tensioned and most importantly that you don't have a leak at the thermostat housing.

jnc19610 · #4 03-25-2007, 09:00 PM

I haven't had the alternator out, but I've had a really good look at one.

As far as I can tell, it's two bolts from the front, and the alternator should slip back, down and out. (after taking the tension off the belt of course)

There are two E300's in my neighborhood. The other is a partner at my wife's law firm. I offer to work on that car from time to time. If I don't have enough time, then I'll help diagnose, and send them the right direction.

It is a 'very expensive' alternator. Yes, there is some sort of clutch in it.
Other than the clutch, I consider it a conventional looking alternator, that an average rebuilder could probably handle.

If you're anywhere near Lancaster County PA, I've had excellent luck with Weaver Bros, rebuilding an old (not quite unobtainium) 914/6 alternator. I think they could probably handle anything.

TMAllison · #5 03-25-2007, 09:22 PM

Quote:

Originally Posted by jnc19610

Yes, there is some sort of clutch in it.

Partner - Please help me understand where the clutch is on in the link above. I'm curious.

Mine has the Bosch unit with the #503 "freewheel" pulley. "Freewheel" means it has space to the inside of the multi-rib belt for a old style V-belt to ride so another accessory could be included.

McCool300TD · #6 03-26-2007, 04:15 PM

Hi

Firstly your alternator does have a freewheel type pulley or clutch people call it different things. The pulley works in one direction kinda like the chain sprocket on the rear of a bicycle and yes they do pack up. Mine did and i got it renewed pulley is about £40 or so you need a special tool to remove it. First link below will explain everything.

To replace the alternator :

Put car up on ramps at the front
Remove front accoustic shield 8mm socket 8no.
Remove middle section accoustic shield 8mm socket 4no.
Undo nut from tensioner 13mm
Take weight of tensioner with ext bar and withdraw the bolt to undo tension on belt.
From underneath remove alloy pipe that runs from turbo to intercooler (2 jubilee clips & 2no 10mm bolts)
Disconnect Battery (Becareful with radio code)
Pull off sleeve on heavy wire to back of alternator
Undo heavy wire 13mm
Undo light wire 11mm
There are 2 bolts holding alternator to engine i used hexagonal socket to fit the splined head on these bolts (cant remember size)
Withdraw bolts and remove alternator via the underside of car.

Reverse sequence for installation.

NB Charge pipe needs removed to get alternator off car.

Good Luck

McCool300TD

Few Links for you

http://www.peachparts.com/shopforum/showthread.php?t=164552

http://forums.mercedesclub.org.uk/showthread.php?t=23702

http://www.mbclub.co.uk/forums/showthread.php?t=28134

activ123 · #7 03-27-2007, 02:20 PM

Thanx for all the replies - your insight has likely saved me $$$! The wife drove it the other day and said the coolant level indicator came on too. (Now I recall that happening several months ago and I just topped it off forgetting it altogther)

I'll look for a coolant leak somewhere. Since this engine is differrent than what I am used to (GMC) I assume the tstat is under the top hose bib? (I'l look where nhdoc had the issue first)

thanx again!

McCool300TD · #8 03-27-2007, 02:31 PM

Hi

Your thermostat is just to the left of the water pump just above the alternator. (standing in front of the car looking at the engine).
Some of the early thermostats were part of the alloy housing and replacing these needs a thermostat and a revised housing. You will know when you unbolt ithe housing if the thermostat is seperate you need a new thermostat if it is part of the housing you need a new one. Not expensive from what i recall.

Good luck

McCool300TD

Parrot of Doom · #9 03-27-2007, 05:14 PM

The coolant level AFAIK is determined in the coolant reservoir. If the level in there drops, the warning comes on the dash.

I had the same problem, it turned out to be a rusty coolant pipe against the firewall, behind the engine. Fixed it by sleeving it with rubber and clamps.

nhdoc · #10 03-27-2007, 07:06 PM

If you are lucky you will see a leak above the alternator right where the thermostat housing attaches to the engine block. I needed to replace the housing and thermostat. The total cost was under $50 for all of the parts and it took less than an hour to replace it. Mine leaked very slowly, when cold only, so it will dribble a few drops out overnight, enough, apparently to work its way onto the pulley and cause it to slip when the car was started up.

Like I said, it's been over a year and no warning lights since I did that work...hopefully you'll be as lucky as me.

activ123 · #11 03-29-2007, 01:17 AM

Mine doesn't have a problem until the engine gets warm, then the battery charge indicator comes on and off. I looked for a leak but couldn't find one. I think I found the thermostat housing.

Is it possible the belt is just old (looks in great condition though) and these are two seperate issues? I did the leak check from the top of the engine only - I'll pull the sheilds this weekend and see what I can find.

nhdoc · #12 03-29-2007, 07:00 AM

The belt is always the first thing I'd check. It could be worn or glazed or stretched so far that it doesn't get good tension on it. You can replace it in about 15 minutes without pulling the fan off or anything. You just need to make sure you either have the path diagram or draw one before you take the old belt off.

TMAllison · #13 03-29-2007, 12:09 PM

If you stuff a 4' piece of twine down between the tensioner roller pulley and water pump you can tie it to the belt between the alt and balancer after you've positioned the belt, then you can "pull" the belt up through the tight spot and onto the tensioner roller pulley.....

Then it's only a 5 minute job.

sokoloff · #14 02-21-2023, 04:15 PM

Good info guys - thanks. I followed McCool's list in Post #6 and got it done. Took me awhile (I'm really slow), but all is done and the car seems to be running well. Time will tell if I missed anything.