Bullitt6283

If I recall correctly, the idler pulley on the passenger side of the block is the same pulley number and held on with the same bolt. Perhaps a trip to a salvage yard would solve the bolt problem.... ..

A quick online search for N808102-S437 shows several sources for this bolt. Here's one: https://www.tascaparts.com/oem-parts/ford-idler-pulley-bolt-n808102s437 . .

. Does your engine have a 6-rib belt or a 8-rib belt? Somewhere around the 1999 timeframe there was a change. Later models have the 6 rib belt. My vehicle is a 2016 Ford E450 chassis and the V10 gas motor and the 6 rib serpentine belt. The bolt I used is p/n N808102 S437 Pulley is (Motorcraft YS-385) #1L2Z-8678-AD. .

Great News Cheers!

I did a bit more investigation.... According to the RockAuto listings, Ford went from a wider 8-rib belt for 2001 and earlier V10s, to a 6-rib belt in 2002 and up. This may help explain why the second idler pulley disappeared in about the same time frame.

Glad you asked... 1. The UBS (unstable belt syndrome) has evidently existed undiscovered for some time. The UBS noise sounds a lot like spark knock and most owners thought that is what it was. Many motorhome owners have tried to diagnose the UBS noise issue themselves, or have taken their RVs to Ford Service who were unable to solve the real root cause. These motorhome owners are a conservative bunch, and would prefer a formal pronouncement from Ford that adding the idler pulley is an appropriate course of action. 2. I play with a highly modified Ford Mustang Bullitt, and I am very familiar with the "Law of Unintended Consequences". This Law becomes troublesome when a car is modified for a good reason, but the modification causes an unforeseen issue which can be worse than the original problem. So, for my motorhome, which I hope continues to be very reliable, I am concerned that adding the idler pulley may cause another problem. After all, the pulley had previously existed, and then it was removed. Why?? Cheers, Ron .

In order to gain engineering insight into the belt noise and 'omitted pulley' subject, I contacted Ford Help and the Ford Performance Techline. I also contacted the Motorhome Customer Assistance Center. None of these sources could help me. .

Is there a person, or a group, who may be able to lend some insight to the issue described in this posting? This appears to be an issue which has existed since 1999. Thank You. .

That is my intention. I am wondering, however, if there could be a reason why the pulley was omitted on recent motors. Was there an issue, or was it purely a cost-reduction. .

I have a 2016 Jayco Class-C motorhome built on the E450 cutaway chassis with the V10 motor. I've been chasing a noise for a long time, as have been many other 2011-2019 E450 (cutaway) motorhome owners with the V10 motor. It sounds like spark knock, but better fuel does not help at all. There is a history of owners taking their vehicles into the dealer for a diagnosis, but the problem remains unresolved even after belt/pulley/tensioner replacement. One of the owners on the Jayco website found the issue. VIDEO: https://youtu.be/Oa6cr2dFkPE --> As it turns out, there is serpentine belt instability on these motors. <-- Further, it was discovered that prior to 1999 there used to be an additional idler pulley mounted between the PS pump and alternator, the area where the belt is fluttering. The threaded mounting boss still exists. Why was this pulley deleted??? Can I safely put one back on???