So, a couple weeks ago, I was driving on the highway around 70mph with the cruise control set, and all of a sudden got a "battery/alternator" warning in the MFD. I thought "that's odd" and cycled through the screens to check coolant temp, which was rising rapidly. "That's odd" went to "WTF?" and I immediately pulled to the shoulder and popped the hood.
First impressions weren't good - serpentine belt was off, and there was a perplexing spray of oil and coolant through the front of the engine bay. Looking around further, I saw that my LET Motorsports idler pulley sheared off of its mounting post, and was laying on the cross member towards the driver's side. I wondered "did the bolt break?" - nope, it's a 10.9 grade bolt (same grade/strength as the lug bolts I just sourced from Renntech, FYI) and it appeared brand new. Then I looked at the mounting post, which is integrated into the water pump housing - it was all chewed up, and the threads stripped (looks to be relatively soft aluminum).
In examining the LET idler pulley itself, the culprit became obvious - the NSK bearing in the pulley seized up. When this happened, the LET idler (for those that aren't aware, the idler is a hefty chunk of solid steel) apparently had more centrifugal force than the mounting post could stand, so much so that it sheared completely off its mount and ricochetted around the front of the motor, causing severe damage to other pulleys and the oil cooler (which, by direct impact, it cracked - causing the oil and coolant spray, plus some oil getting into the coolant system and vice versa).
For those that might not be aware, I have had LET's parts on my car for over 5 months and 8,000 miles - the car ran strong with no major issues, until this one. I was one of the earlier LET customers, and bought every LET part offered back in Feb 2008 (except plug wires). I have shared my positive experiences, and referred like-minded modders to LET. At my own expense (like many of us), I have run unbiased before and after dyno runs, and posted the information on MBW. I have logged many, many miles of data that I was happy to share with LET if it could improve their tunes in any way.
I contacted Jerry, explained the issue, and simply requested what they (LET Motorsports) would be willing to do for me as their customer, through this difficult experience. I received an apologetic but otherwise curt reply from Jerry stating "our warranty only extends to the part that failed - we'll send you a new idler pulley at no cost to you." It would be insincere for me to say that I wasn't disappointed to essentially be brushed off, after supporting LET through their infancy and spending thousands of dollars on their products.
The situation is straightforward: the LET-supplied NSK bearing in the LET idler failed, and directly damaged another guide pulley, the LET crank pulley, the water pump, and the oil cooler. The total bill of this repair? $1,826.85 - that doesn't include the $393 tow (of course, this type of thing would occur along the highway two hours from home...). I was also without my car for 1.5 weeks, because the oil cooler is an AMG specific part, and when one couldn't be sourced locally it had to be shipped from Germany. FWIW, I've still yet to receive a new idler from LET; so far I've only received a used, rusty ASP idler that my mechanic wasn't comfortable putting on the car.
LET is a great software tuner, and on MBW and elsewhere there are many positive reviews of their products and services (mine included) - however, too often the bad news isn't posted... I feel this info might be worthwhile for those considering their hardware vendor; "you pays your money and you takes your chances..."
Enjoy the pics...
water pump
Keller005.jpg
LET crank pulley damage (thankfully, mostly superficial)
Keller004.jpg

 

ASP idler sent

Oil cooler
misc019.jpg
Seized bearing
misc023.jpg
misc026.jpg

 

New water pump
misc034.jpg

New oil cooler
misc035.jpg

 

Due to their lack of communication with me, I already don't trust them. Posts like this remind me I was correct in my assumptions!

Failing hardware is understandable... lack of support in a small market with dedicated customers is not.

 

Oh great.
I just bought a 181 pulley.
Now what!?

 

AS LONG AS IT IS THE UPDATED WATER PUMP PULLEY YOU SHOULDN'T HAVE ANY PROBLEM.


I have been driving w/ mine for 5K and I generally drive hard and have been going to the drag strip once every three weeks or so. Last Wednesday I made 10 runs in an hour and only stopped once for 10-15 min. Before the last run of the evening.

 

Same thing happed to Lotus F1 and his ASP idler pulley - I wonder if they use the same bearing?
https://www.crossfireforum.org/forum...3&postcount=66

I tried to look at mine but can get the number off it..I'll pull it this weekend to see.

Lotus and your pullies are some damn rusty parts..

** EDIT **

Could someone with a ASP setup confirm the part number on the idler bearing - I'll look up the specs on the bearing supplied with mine and see what the duty cycle and max RPM are.

Perhaps a bearing upgrade is possible; if a better one is availible. Not much to press fit it in.

 

Tighed1, I have the 181mm pulley and have had no trouble with it at all. I have a new 115.3" gator belt to install to take a little of the tension off the tensioner. It seems pretty tight with the new pulleys. Maybe the extra revs we are putting on these peripheral devices is taking its toll. A little less pressure might relieve some of the stress on those bearings. There was a write up a few weeks back of an ASP ideler going out also. Maybe we should all be pulling our belts off and checking the bearings on things once in a while to look for sticky or loose/worn bearings.
You can get the 115.3" belt in standard style also.

Install it and ejoy.

MikeR

 

That sucks! I hate to hear about stuff like this happening. I was about to put a 185mm LET pulley on. I know I have to get a replacement for the water pump as I have one of the original designs, but this adds a new dimension to the issue. What size belt were you running? I may have to look for a remount on the idle.

 

Very strange..I just had the same problem.
Last night my idler pully bearing seized. Upon a quick inspection I did mot notice any major damage. Looks like the bearing seized and the bolt holding the idler backed out, idler dropped on the pan and threw the belt.
Left a message for Jerry earlier today, waiting to hear back, maybe on here is better.

*Edit - mine was not rusty looking at all - just completely locked up.
Also when an checked the factory idler - same basic part number but different manufacturer, factory was a Timken.

 

The bearing shown is a 6303Z (single Z) I may upgrade to a 6303ZZ for luck. ZZ means double shielded, single Z indicates single shield. The bearing shown in F1s thread looks like a single shield.check the specs. Paste in the below link?http://www.vxb.com/page/bearings/PRO...D=183288529512

 

Mine was 6303z - but has sheilds on both sides.

 

I have the renntech kit I and I have been hearing a bearing noise coming from the engine, I wonder if this is it?

 

Checked NSK site and they do not even list a 6303z..
Bearings listed are 6303,6303DDU, 6303NR, 6303VV, abd 6303ZZ.
The ZZ looks to be the correct bearing, as both sides have a sheild.
If this is the correct part, the bearing is listed as "Speed Limit" (grease) 15000 rpm

 

Being that I've not purchased a pulley system yet... looks like I might be going the code 3 route

 

Interesting - I'm looking at my stock idler pulley and the bearing is marked with a "6303 C3" and the green seals are stamped with "6303 RDD" but with a different type of seal then the bearings used on the LET or ASP (they look impervious to debris)

Now - if "speed limit" is 15,000 RPM - then we have a problem Houston!!

The stock idler pulley is approx 90mm
(178 / 90) = 1.978 * 6,000 engine RPM = 11,667 idler bearing RPM
(181 / 90) = 2.011 * 6,000 engine RPM = 12,067 idler bearing RPM
(185 / 90) = 2.056 * 6,000 engine RPM = 12,336 idler bearing RPM - No problem here.

The LET idler pulley is approx 60mm (and if the ASP idler is the same size):

(178) / 60) = 2.967 * 6,000 Engine RPM = 17,800 idler bearing rpm
(181) / 60) = 3.017 * 6,000 Engine RPM = 18,100 idler bearing rpm
(185) / 60) = 3.083 * 6,000 Engine RPM = 18,498 idler bearing rpm

Can someone verify the ASP idler pulley size and bearing used?

Looks like someone didn't do any math and just copied the OEM bearing part number...

 

If the idler is spinning over 15,000 rpm! Everyone is gonna have a problem, with any pulley set up! Just a matter of time. This is not good!

 

Except the stock setup:

(155 / 90) = 1.722 * 6,000 engine RPM = 10,333 idler bearing RPM

We may need to identify a new bearing - or perhaps re-install the stock Idler pulley and get a larger belt

A new bearing would be cheap and easy (less then $20) - but then the stock idler and a new belt might provide better wrap around the SC?

 

SKF makes one the right size, but it is an open design, not sealed.
Have not found any seals that have "higher" rmp ratings.
RPM is rated to 19000 rpm
Part #6303 JEM

 

Hi guys,

interesting. I will check my ASP-Idler pulley this evening when I get to my car and post the results...