Hey everybody. I've done the search more than a few times trying to get to the bottom of this problem with my friend's 97 420A.

To preface,
The crank pulley is not warped or cracked. I have been alternating between two good pulleys that I have to ensure that this is not the issue.

The crank pulley is torqued to 105 lb-ft. I've come across this spec more than once, so I doubt this is the issue.

The alternator belt always stays on track.

The car recently received the updated(?) thicker tensioner pulley. The bearing in said pulley seems fine.

Both belts are tight as hell. And the p/s pump is clocked to the position which would make it tighest.

On startup, the belt will jump off of the A/C compressor 1 rib. It will run there just fine for a few days if he's lucky. Then the belt shreds.

Normally, I would just eliminate A/C or P/S since he would be up for it. Unfortunately, he needs P/S since he got shot in the arm last year and I doubt that he could turn the wheel as needed if the belt were to break.

Any suggestions?

Well, a correction. The accessory belt is still tracking fine on the P/S pump and crank, but is one tooth toward the tire on the A/C compressor.

The alternator belt is one tooth off toward the motor.

WTF is going on?

Originally posted by TomInSC
To preface, The crank pulley is not warped or cracked. I have been alternating between two good pulleys that I have to ensure that this is not the issue. The crank pulley is torqued to 105 lb-ft.

I had my first struggle with our stock crank pulley, when I did my t-belt change back in '03. When I put it back on, I must've had is slightly crooked because from then on, my ps/ac belt would do exactly what you describe. I removed the pulley and re-installed it many times, but same issues. I eventually went down to a 4-rib belt so that it would stay on(in one piece). When I did my full rebuild last year, I bought an underdrive pulley that isn't a press-fit and bolts using the 3 crank gear threaded holes, and have not had a problem since. I realize you say that yours it proper and torqued, I just thought I would throw my $.02 in.

Dirt, thanks for the quick reply. I'm almost convinced that it is a crank pulley issue now that alternator belt is off too.

Do you mind telling where you got your UDP? Brand? Etc?

Most people swear by the AFX UDP available through Howell, here is a link

http://www.howellautomotive.com/index.asp?PageAction=VIEWPROD&ProdID=345

Some people use ebay to get cheaper ones but they are questionable.

thanks murray,

I've seen that AFX pulley and I was considering it as a possible solution, but I'd like to find the kind that Dirt was describing.

From the looks of the AFX pulley, it looks like it still attaches with an interference fit on the crank. I noticed the three holes off center.. and it looks like they're there for the purpose of using a harmonic balancer puller, and not to bolt to the crank.

any insight?

I clicked on the link in your sig, Dirt. And I found the pulley manufacturer. I'll be ordering it for him after the holidays and post here again with the results. Thanks for your help, guys. :)

UPDATE:

I ended up acquiring a UDP from customcargrills.com at the suggestion of DirtMcGirt.

This has solved the problem and the engine is now running great with no signs of slip after several tests during startup, idle and hard driving.

Thanks again everyone for the help and I definitely recommend this product to help with belt slipping issues.

Glad to hear you got that solved.

I'm curious about the UDPs. Now, if I'm not mistaken, the original part serves a dual purpose as both crank pulley and harmonic balancer, correct?





Now, my question is, by using the UDP aren't you running without a harmonic balancer?

Also, just to put my $.02 in here, since the original harmonic balancer/crank pulley has no bolt holes to assist in removal and the removal procedure is to basically pull it off by pulling on the outer ring (ie pulleys) this could easily cause this misalignment everyone is talking about here. The outer metal pulley portion is not directly connected to inner metal section, but rather is friction fit with what amounts to a large rubber band between the two parts.

Good, you noticed. I see maybe someone tried it on that pulley pictured? ( its missing a chip on the top right).

thats why your suppose to attach the puller to the Inner lip...

Most good UDP are made from solid billet blanks, the stock one is cast. As a result the new pulleys are pretty damn close to balanced.

I had my crank balanced with the UDP, hardly noticeable, they did shave a bit but you cant even tell anymore where they did.

Yeah, I can see where a good balancing job with the udp in place would certainly help.

On my pulley, I knew with 236k miles on it the rubber in the middle had probably seen better days and I was going to replace it anyway. So, I tried getting it off with my gear puller. It's too big to grab anything in the middle. But it was being a PIA! So, last night (after my last post) I went to the auto parts store and got a "loaner" harmonic balancer puller designed for the job. WOW! It never ceases to amaze me what a difference the right tool for the job makes! All the years I've been working on cars you'd think I'd have learned by now...LOL!

For the record and search purposes. Over tightening the belt can cause the same problem with the belts.