Diesel recall - engine belt idler pulley bolt

[Stockx5]

My Idler pulley bolt broke today. yea gonna have some fun pulling the old one.

what is concerning is that the recall was done at 50,700 Miles. it was replaced with "updated" part # 12318574809

now at 116,000 the bolt broke again. so 66,000 miles on the bolt does not seem right.

Does anyone think a decoupler/clutched alternator pulley would elongate the life of the bolt on the idler pulley?

assuming the right torque procedure is followed on the new bolt.....

[Stockx5]

Originally Posted by Lambeau

Same thing happened to me at 145K miles but BMWNA covered it for me because the decal was never placed in the door sill indicating the recall was performed.

If I had to replace it myself like you, I would personally use a stud with Loctite instead of the bolt. Once you get the bolt out, measure the total length including the bolt head and contact ARP for a stud to replace it. You'll have to determine the thread count. With an ARP stud there will be much less chance of it loosening like a bolt would and it would hold secure forever.

The bolt is an M10x1.5 on the end that goes into the alternator.
and the inside thread on the head of the bolt is M8x1.25
the screw that goes trough the pulley is a M8x1.25 of course

Called ARP and they do not have:
a M10 with a head nut like the one we have.
a M10 x M8 that one could use as a 2 size bolt
any M10's above 4 inches ( I might be wrong )

the only way that I found would be to buy a class 12 threaded rod from Grainger with a tensile strength of 174,000 PSI

https://www.grainger.com/product/FAB...1-50x1m-25DL67

Cut it the size of the stud and find a pulley that would allow an M10 trough it's inside diameter. Our pulley is 80mm OD and obviously the ID would have to be at least 10mm to allow the M10 to pass trough.

then you would just put a nut at the end of it and there you have it.


But I cannot find any such pulleys. So to take on this project one would have to be OK with going with a larger or smaller diameter idler pulley. Not sure if that is a good idea.


Just leaving this here in case someone wants to tinker with it and come up with a final solution.

[jeeperbrad]

For the guys that have removed the broken bolt. Do you have any tips or tricks to help remove it? Mine was replaced at 23K and broke at 98K saturday on my 2011.

[Stockx5]

Originally Posted by jeeperbrad

For the guys that have removed the broken bolt. Do you have any tips or tricks to help remove it? Mine was replaced at 23K and broke at 98K saturday on my 2011.

When I did this the torque wrench I borrowed from O riley was defective. So I broke the replacement idler pulley bolt right after I removed the previously broken bolt. So I did this twice in succession the second time it was really tight in there!

To get the broken bolt out you need to remove the radiator fan shroud and radiator.

then a low profile hammer that will allow you to get more swing, most hammers i have have too long a back end to allow any swing. as well as a chisel that I cut about 3 inches long. then proceed to hammer away extremely hard without damaging the radiator fins.


the bolt will come out about 2 inches from the back of the alternator. then I bouoght a 22 inch long sawzall balde to cut it from a distance.

for tightening i used 36lb torque + 170 degrees turn

instead of the recommended 36lb torque + 190 degrees on the updated tsb

the bolt has no risk of coming loose from what I can tell since it had lock thread on it. And you only weaken it by over tightening it.

Id be curious to see if you can get away with much less torque on it to extend the bolt life.

[smassey321]

Originally Posted by Stockx5

the bolt has no risk of coming loose from what I can tell since it had lock thread on it. And you only weaken it by over tightening it.

Id be curious to see if you can get away with much less torque on it to extend the bolt life.

The recall mentions that the original bolts were backing out and that is what was causing them to break. Perhaps they did not have the thread lock like the new ones.

[TriX5]

The last posting in this chain came only a few months before the NHTSA issued a second recall on the same item for the E70 35d. Mine was done under the original recall in 2012. (I looked at the parts diagrams and failed to understand the moronic design, reinforcing my decision not to buy any other BMW for the next few years.)

A few weeks back my wife went by the dealer in Portugal for something else (which true to style they failed to address) however, they did come up with recall number two on this. At first I wondered if there was a problem with the fact that the car changed continents and they were about to perform the same recall again but it is actually recall nr. 2 for the same item that is being proposed.

I am bringing mine in tomorrow to have it done, curious if anyone on the Xoutpost has been in for "round 2" on the idler pulley recall?

[josiahg52]

Yes, it is a second recall for rhe same assembly and part from several years ago. Need to get mine done. I like the idea of getting a replacement bolt from ARP. If the problem is the bolt backing out and snapping, that seems like an easy fix.

[FunfDreisig]

When I recently took our 2009 35d in to replace the steering rack, our dealer insisted on replacing the idler pulley bolt, even though they had replaced it once before on a recall and I had replaced it again just a few months back. Maybe the third time’s the charm?

[TriX5]

Dropped it off this morning for the recall (and received a Renault 3-cilinder as a loaner.....ugh). According to the SA, they replace the two piece arrangement where the pulley bolt screws in to the head of the alternator bolt (!) with a single bolt that holds both.

Before I dropped it I read the (4) engine codes (which prompted a CEL a week or two back) and apparently the DEF valve had stuck open and caused some displeasure but the codes did not come back on the 30 minute drive to the dealership.

We'll see when I go pick it up what they come up with. These guys are usually a bit lost as the US version does not equal the '09 Euro version....

The M2 Competition in the showroom looked very sweet!

[FunfDreisig]

Originally Posted by TriX5

Dropped it off this morning for the recall (and received a Renault 3-cilinder as a loaner.....ugh). According to the SA, they replace the two piece arrangement where the pulley bolt screws in to the head of the alternator bolt (!) with a single bolt that holds both....

Huh??? Maybe you need a new SA

I’m pretty sure the bolt covered by the recall is #5 in the attached diagram. FWIW I replaced parts #1, 2, 4 and 5.

https://xoutpost.com/bmw-sav-forums/...ine-noise.html

And none of the bolts involved fit your SA’s description.

Funf Dreisig