1989 300E 99,900 miles

Rattle coming from the engine. Sounds like it is coming from the belt tensioner. Any thoughts about this?

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1989 300E

2005 Acura TL

2011 Hyundai Elantra Limited

Swing hard! Take chances!

The shock absorber between the engine and the tensioner has bushings that wear. With the engine running put your finger on the top of the absorber and see if the rattle goes away. This is a cheap part.

Nice low mileage 124.

I just did mine, on a 1994. Check and see if the bolt going through the tensioner is tight. If loose, it will rattle and you can feel the rattle coming through the water pump. Put your hand on the thermostat housing and you can feel it there. Checking the shock is also advised.

There's a lot of write up about replacing the tensioner. It took me about 2 hours total and did not have to remove the fan and clutch.

Thanks guys! I will check it out later this morning!

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1989 300E

2005 Acura TL

2011 Hyundai Elantra Limited

Swing hard! Take chances!

Yeah, the shock rattles up and down because the rubber bushing around the bolt hole has hardened and shrunk. Same thing happens to Bilstein shocks on the suspension as they age. As a temporary fix you can put a small o-ring around the upper bolt, and tighten it against the washer or bolt head. It will dampen the rattling until you can get a new little shock installed.

DG

How? the bracket infront of the tensioner goes behind the Fan/Fan clutch pulley

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99 Jetta Mk3
07 Jetta Mk5
89 300E W124
10 E 350 W212
08 C300 W204
Benz's aren't mine

Must be different on a 103 v. a 104. On my 104 everything can be removed with fan/clutch in place. You just have to rotate the fan to get between blades for the front bracket bolt closest to the block, and the top and bottom shock bolts. Sure, it would've been easier removing it but I didn't see a need for it as I was getting around everything pretty easily.

You can change the tensioner without removing everything on a M103 - however for a DIYer I would do it the long way.
Fan, pulleys and Y bracket have to come off.
If the tensioner shock is cactus may as while change the tensioner while you are there.

...eventually the belt gets loose enough to let the alternator slip under load conditions and operate in a slip and jerky motion. This has a detrimental effect on the regulator and the bushes. Mine broke a bush.
A squealing belt indicates the tensioner rubber has collapsed and the belt is running at tilted angle .
mak

please explain... I've done tensioners many times on 103's. Its impossible to replace the tensioner without removing the fan/clutch, and the pulley.
Theres a bracket in front of the tensioner. 3 bolts, 2 go through the power steering pump bracket the other one goes through the engine block, which is blocked by the fan, clutch and pulley. and the 19mm bolt that goes through the middle. You can replace the belt shock without removing the fan/clutch and pulley, but not the actual tensioner.

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99 Jetta Mk3
07 Jetta Mk5
89 300E W124
10 E 350 W212
08 C300 W204
Benz's aren't mine

Mike, I agree. And removing the fan clutch and pulley is a 10-minute job, assuming you have fabricated the little holding tool or have a properly sized allen wrench to substitute.
As stated, just replacing the shock on a 103 "can" be done by contorting around a bit, but more time and frustration will be consumed than just removing the fan.

Now, if the tensioner is original with 99k miles, you should consider replacing it.
I had one fail with zero warning, and when that happens, you are officially broken down and going nowhere.

DG

It certainly sounds like the tensioner, et al, is in closer proximity to the fan clutch than the 104...

...but as already noted, it will make easier. Especially on the 104, once you get the water pump pulley off it is very easy to get the pin through the hole of the back of the fan clutch pulley in order to seize it so that one can torque it on/off (this doesn't apply to the 103 as yo uneed the wrench DG describes).

On a side note...for you 104 people...if you replace the fan pulley bracket (that piece that mounts to the block, which the fan pulley and clutch bolt on to with an aftermarket Febi piece...the hole needed to stop the pulley from turning will not match up exactly and the MB tool cannot be used because the ID/OD tolerance is too tight. What works best is a small dogleg allen tool, the ones you buy in ppacks with all different sizes.

I digres...

Hmmmm............checked all the "visual bolts" and rubber bushings and everything seems to be in order. Possible something is amiss out of sight since it is a bit crowded down there..................

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1989 300E

2005 Acura TL

2011 Hyundai Elantra Limited

Swing hard! Take chances!