Idler Pulley, '87 300d w124 603 - PeachParts Mercedes-Benz Forum

louie3va · #1 04-29-2014, 10:36 PM

When I purchased this vehicle, I noticed the belt was frayed and appeared to be sitting forward on the idler pulley. I replaced the belt and idler pulley with Dayco products and the lower tensioner arm with Febi. The new setup appears to be spinning the belt correctly, however the belt still appears to be resting forward on the idler pulley. any thoughts?

ah-kay · #2 04-29-2014, 11:07 PM

I am only speculating because I do not know for sure. There is a big washer behind the belt tensioner. It may be missing, hence the tensoner is bolted towards the engine by about 1/8". The idle pulley is bolted to the tensioner so it is also off by 1/8". It should not really matter as the belt is still wrap round the idle pulley over 90%. May be you can shim up the idle pulley ??

You can remove belt tensioner and take a look. It can be removed without removing the water pump pulley on the OM603.

jay_bob · #3 04-30-2014, 10:37 AM

I am about to undertake this job on my W124. I bought a Mylie belt tensioner 18 mos ago, and I am now regretting that decision to try to save about $50. I will try to get some photos when I attempt this, hopefully over this weekend, with a Genuine MB part.

To the general forum population: what's the best tool to use to get the fan bolt loose on an OM603, without having to remove the radiator? Sawed off Allen key, mini Allen socket, ?? I went to HF but they didn't seem to have anything that would work. It's an 8 mm, correct?

engatwork · #4 04-30-2014, 11:13 AM

There is a bushing in the tensioner "pivot" arm that wears out causing this issue.

louie3va · #5 04-30-2014, 11:19 AM

follow this thread, with pictures. thats what i did

http://www.peachparts.com/shopforum/diesel-discussion/312419-diy-1987-300d-serpentine-belt-tensioner-replacement.html

Quote:

Originally Posted by jay_bob

I am about to undertake this job on my W124. I bought a Mylie belt tensioner 18 mos ago, and I am now regretting that decision to try to save about $50. I will try to get some photos when I attempt this, hopefully over this weekend, with a Genuine MB part.

To the general forum population: what's the best tool to use to get the fan bolt loose on an OM603, without having to remove the radiator? Sawed off Allen key, mini Allen socket, ?? I went to HF but they didn't seem to have anything that would work. It's an 8 mm, correct?

ah-kay · #6 04-30-2014, 11:19 AM

Quote:

Originally Posted by jay_bob

I am about to undertake this job on my W124. I bought a Mylie belt tensioner 18 mos ago, and I am now regretting that decision to try to save about $50.

I am the other way round. I regret buying a MBZ part shipped from Germany instead of URO. The belt tensioner is such a simple design that there is no point to spend more money. It is just a pivot with a bearing inside. The bearing actually never turns, it just pivots. URO part would do fine in the next 20 years. You can also change out the bearings for $8 if you are as adventureous as I was - I did it on another car.

I did not remove the radiator when I changed out the belt tensioner. The only issue is that it is very difficult to push back the dust cover. I broke it so I left it out.

louie3va · #7 04-30-2014, 11:28 AM

I replaced the lower tensioner arm. I am not sure the bushing that youre speaking of. Are we talking about 2 different parts?

Quote:

Originally Posted by engatwork

There is a bushing in the tensioner "pivot" arm that wears out causing this issue.

Phillytwotank · #8 04-30-2014, 12:05 PM

Quote:

Originally Posted by jay_bob

I am about to undertake this job on my W124. I bought a Mylie belt tensioner 18 mos ago, and I am now regretting that decision to try to save about $50. I will try to get some photos when I attempt this, hopefully over this weekend, with a Genuine MB part.

To the general forum population: what's the best tool to use to get the fan bolt loose on an OM603, without having to remove the radiator? Sawed off Allen key, mini Allen socket, ?? I went to HF but they didn't seem to have anything that would work. It's an 8 mm, correct?

8mm hex key + 8mm deep socket + breaker bar + a bit of tape

Then switch to that hex key + box end spanner set up to do several revolutions.

just as depicted in that one thread to break the fan bolt loose. Getting it all the way out was the trick. No matter what tool you choose to use at some point before it is all the way out it will hit into the radiator.

I turned it out the last inch or so with my fingertips and got it started in like that too. Dont forget to clamp the fan pulley with some vise grips while you break the bolt loose. Helps to have a helper hold those vise grips in place while the other twerks.. i mean torques.

louie3va · #9 04-30-2014, 12:36 PM

To add to this, when you're turning the fan bolt by hand at the end, your helper will likely have to hold the fan in position to allow the bolt to turn freely and not bind.

Quote:

Originally Posted by Phillytwotank

8mm hex key + 8mm deep socket + breaker bar + a bit of tape

Then switch to that hex key + box end spanner set up to do several revolutions.

just as depicted in that one thread to break the fan bolt loose. Getting it all the way out was the trick. No matter what tool you choose to use at some point before it is all the way out it will hit into the radiator.

I turned it out the last inch or so with my fingertips and got it started in like that too. Dont forget to clamp the fan pulley with some vise grips while you break the bolt loose. Helps to have a helper hold those vise grips in place while the other twerks.. i mean torques.

vstech · #10 04-30-2014, 01:00 PM

short throw 8mm allen key... with a 10mm deep socket on the end with an extension on the socket to use as leverage... and a pulley holder. the belt is NOT tight enough to hold still while you break the bolt loose.

jay_bob · #11 04-30-2014, 01:08 PM

That's what I seem to remember when we did this back in the fall of '12. I couldn't remember if we had the radiator in or out at the time.

I got to run back to HF and grab a pulley holder, forgot that when I went there last weekend. I think I have the rest of what I need.

vstech · #12 04-30-2014, 01:11 PM

yeah, you need to get the fan shroud out of the way first of course... you still have the stock shroud IIRC... it can sit on the fan while you remove the fan... I'm doing it all over on my 87 wagon today... belt shredded itself... I HOPE she did not damage the head driving with no belt... it was VERY COLD out, so that may be my saving grace...

Phillytwotank · #13 04-30-2014, 02:00 PM

back to Lou's question tho.... i know he really needs the peace of mind on this before he takes his new benz out on a long trip.

I cant see how it really matters that little 1/8 inch gap on on the idler pully. The pully and tentioner are new and both are straight and solid. no wobble or wiggle whatsoever in the belt. just that little gap.

Is that a real problem? does he need to find something to put behind that pully to even it out?

OM603 · #14 04-30-2014, 02:36 PM

Quote:

Originally Posted by jay_bob

I am about to undertake this job on my W124. I bought a Mylie belt tensioner 18 mos ago, and I am now regretting that decision to try to save about $50. I will try to get some photos when I attempt this, hopefully over this weekend, with a Genuine MB part.

To the general forum population: what's the best tool to use to get the fan bolt loose on an OM603, without having to remove the radiator? Sawed off Allen key, mini Allen socket, ?? I went to HF but they didn't seem to have anything that would work. It's an 8 mm, correct?

The Stahlwille very short 8 mm Allen head 3/8" socket specifically designed for the task, cost about $15 from Samstag tools, sometimes it's cheaper on eBay

Mercedes Benz Short 8mm Hex Bit for Cooling Fan Clutch | eBay

OM603 · #15 04-30-2014, 02:41 PM

Quote:

Originally Posted by ah-kay

I am the other way round. I regret buying a MBZ part shipped from Germany instead of URO. The belt tensioner is such a simple design that there is no point to spend more money. It is just a pivot with a bearing inside. The bearing actually never turns, it just pivots. URO part would do fine in the next 20 years. You can also change out the bearings for $8 if you are as adventureous as I was - I did it on another car.

I did not remove the radiator when I changed out the belt tensioner. The only issue is that it is very difficult to push back the dust cover. I broke it so I left it out.

The sealed ball bearing assembly the tensioner pivots on is pretty rare and difficult to find for less than about $40, do you have a source for the one you obtained?