ohthelawd

Okay, so for a couple of weeks, my 2006 E350 (41k miles) has made a chirping noise (like a h*rny cricket) at idle and low rpm (could also at higher rpm, but I wouldn't be able to hear it probably). Anywho, through reading the forums, visual and audio inspection, and a quick chat with a mechanic from a local reputable MB mechanic, I've pretty much decided that it's a bad bearing in the belt tensioner. So, anyone have experience changing one of these out?

If so, a few questions:

- How difficult was it? I do most of my scheduled car maintenance, but don't really dive into an engine often. I read a couple of threads on replacing the serpentine belt, so I understand how to get it out of the way, but I couldn't find anything on replacing the actual tensioner. Apologies if I missed one.

- Were there any special tools required? I'm assuming that I may need to by a Torx set of various sizes.

-From what I've read, this problem is generally with the bearing in the pulley of the belt tensioner. Can you just replace the pulley and bearing, or do you need to buy the entire tensioner unit?

-Can you guys recommend a reputable online dealer of MB replacement parts? I have a feeling I might be able to get a better deal there vs. vendors here in Alabama.

Thanks in advance for any help you can give!
Nathan

jimbo1mcm

Highlight my name and do a: Look for more posts. I have created a pdf dated 10-24-09 for the Removal and Replacement of Serpentine belt, pulleys and tensioner. Good luck. Let me know how it works for you. :Jimbo

ohthelawd

Thanks for the info, Jimbo.
After speaking with the MB tech again this morning, I think it may actually be the upper idler pulley, and not the tensioner. At least I'm going to try that first... seems like a little less effort (and $) than replacing the tensioner at this point. I'm hoping I can do this without having to remove the motor cover, fan shroud, etc. The MB tech said that the upper idler pulley is a real common thing for them to replace, and that he's personally done tons of them.

Thanks again!
Nathan

vettdvr

On my MB it was the upper idler. This is a small pulley turning very fast and puts lots of wear on the pulley. I bought a replacement at Autozone. Then I took the MB pulley apart and the bearing was identical in manufacturer to the OEM part. My guess is these are made by one supplier and sold to the car co's. The part was around $20 at AZ. I didn't order it online because I had pulled the belt for change at 78000 miles and found the idle pulley making noise. So I agree it is probably the idle vs. the tensioner.

ohthelawd

So I go to the MB dealer, and get the new pulley. Part number is 272-202-10-19, labled as a "sheave pulley". Getting the belt loose and the old pulley off was a breeze (thanks to these forums!). Put the new one on (hand tight, but pretty tight) and immediately notice that the ribs in the pulley are about 1/4" to 3/8" offset from all other pulleys. This can't be right.

The old pulley was "donut" style, and the bearing rested on a post molded into the engine block. This new pulley they've given me has a bolt built into the pulley itself with a metal dust cover on the front of the pulley. Called MB parts department, and the swear this is the correct part. I told them I needed the "upper idler pulley". Is this not correct? The only way this will work is if I really (and I mean REALLY) torque this thing into the threaded socket in the engine block. I'm thinking that this would actually "re-thread" the aluminum, and really don't want to go there. The pulley itself appears to the correct diameter and width... maybe I'm just afraid to damage the car beyond repair.

Any thoughts?

ohthelawd

Once I got the old pulley back on... the chirping went away. Imagine that.

jimbo1mcm

The part number, A272 202 10 19 appears to be the correct part number. Did you take off the dust cover and make sure it is centered and seated correctly before you screwed in the bolt? When I did mine, everything fit perfectly. Good luck. Occasionally, the part is incorrectly labeled. Let us know how it works out.

ohthelawd

Thanks for the info. The part was correct, and actually just needed to be threaded in further (I really only had it hand tight before). Unfortunately, I'm in a much worse position now. I got the pulley in, basically torqing it good and tight one handed. Got the belt back on, and went to give the pulley one last 1/4 turn to finish tightening it. Of course, it sheared the pulley bolt in half... $#%!!!!!

I spent all day today trying to drill the bolt to get an EZ-out bit in. No matter what size or type of bit I try to use, I can't get the hole deeper than about 1/8 inch... nowhere near enough for the bit to get a good grip. I've decided to give up tonight, and have the car towed to my local indie shop in the morning. I have never been so frustrated with an auto repair in my life, but I guess it's my fault for being overzealous with the wrench.

Not sure if the shop will be able to get the bolt out, either. If not, I may be in for a new water pump. This is going to cost a fortune. Furious.

On a better note, I now have about $100 of tools I didn't have previously...

vettdvr

Sorry to hear that. It is always the last 1/4 turn that does you in. You either have to use torque wrenches or have a very good feel for tightening bolts in aluminum. I did the very same job with no issues but I used a wrench to bring the bolt to seat and did not do it by hand. Also I never tighten a tensioner with the belt on.

jimbo1mcm

I use a torque wrench on all my work when there is a setting, but I couldn't find a setting for the bolt that holds the sheave pulley on. If anyone has it, could they post it please? Also, sorry for that extra turn and the problems it caused for you.

Clinton Horn

[
"Not sure if the shop will be able to get the bolt out, either. If not, I may be in for a new water pump. This is going to cost a fortune. Furious."

I applaud your efforts. Anyone who has spent much time on their car will admit that once in a while you just can't win. I replaced a heater core on a 70's GM car I once owned and it was not a job I would EVER tackle again. Still, if it was mine, I'd take the water pump off and ruin it with an easy out before I gave up. You need a tungsten bit if that bolt was hardened. You have to weigh your time and sanity vs. the agony of defeat. We have all been there.
PS I doubt the dealer will make much effort to salvage the part when selling you a new one is much more profitable and less liability.
Good Luck either way.

gnma

Easy for me to say don't be upset, but I applaud your efforts as the others have stated too. This went wrong, but guaranteed you will be $$$ ahead of the game by DIY work over time.

Also, you think the dealers get everything right the first time?

If you end up having the car towed, at least you did your best which was good enough - I think u'll never overtorque a bolt now, and u will always remember to tighten down, and then install the belt as one posted above - that knowledge alone is worth $$.

Good luck!

ohthelawd

Appreciate all the goodwill. Had the car towed this morning (free, thanks to GEICO). The local indie shop was able to get the bolt out, and they put the pulley and belt back. $85 out the door... I'll call this a relatively inexpensive lesson learned.

For anyone on the Birmingham area, this shop is Momentum Motorworks in Pelham. Highly recommended.

ohthelawd

Agree with Jimbo, too. I woud love to know the torque spec for this bolt...

jimmyp

I thought someone on the c32 forum said 14-15 ftlbs

vettdvr

Glad you got it solved but don't be afraid to tackle another.

Ok time for my story.

Car 1964 Ford Falcon 223 Cu In 6. Generator failed. I decided to rebuild it and the belt pulley needed to be pulled. Once that was off the rest was easy. Gen came off easy enough 3 bolts and the wires. Finally I removed the "big" nut to get the pulley off. Nope not a chance of the pulley moving. The nut was totally off. So I decided to just hold the pulley and tap on the end of the shaft to remove the pulley as I could not afford pullers. Well you know the rest of the story. The threads were damaged and the end of the soft metal shaft mushroomed. Guess how far you can shot put a failed mushroomed generator when your 25. UMMM

So breaking off a bolt really isn't the end of the world especially since it was in a removable part. If it were in the engine block another story.

Your $85 repair was still cheaper than my 1964 generator years ago.

So we have all done a dork it up once in a while. I published my MB story once,, that's the only chance you get to read it, ,

SZMB

I must have missed something here. Isn't your car still under warranty? Why spend your own time and money fixing the problem?

ohthelawd

...entered service in July 2005, so the warranty expired this summer.