Ugh...are NAPA belts made of taffy?
 

I put a pair of NAPA belts on the alternator/water pump last weekend. I have driven the car about 50-60 miles since then and they have started squealing and needed adjustment twice since then. :mad:

At least I'm getting good at adjusting them...I just did it in about 7 minuets...in the dark...with no flashlight. :rolleyes:

Continental is the best brand to go with when dealing with MB applications.

Must be a problem with your belts. My NAPA belts are over a year old without any need for adjustments. They are starting to crack so I'll have to replace them come summer.

Agreed. The Continentals are metric sized. The NAPA, Gates and all others are not metric and don't quite fit the pulley properly.

This is noted especially with the a/c belt. The narrower Gates won't transmit the required torque properly without overtightening.

I've put about 40 miles on it since my first post...they need adjusting again. :rolleyes:

Guess I'll go with continental next time. I'm not ready to pull the fan and all the other belts so I can replace these quite yet....

I agree with Lance. I have no problems with my NAPA belts on my 300D. Is it possible they sold you the wrong belts? Sometimes they will list a preferred belt and when that is not in stock they have a substitute belt part number. They did that swap on me once with my 6.2L Diesel and it was a catastophe. The belt started squealing immediately no matter how tight it got it. It turns out the substitute belt was a hair narrower then the preferred belt.

TimK

Why pull the fan? Seems like an extra step.

You definitely don't need to remove the fan.

The last time I used NAPA belts they didn't last very long (maybe only 10-15K miles). I ended up buying a pair of belts from a dealer in MA and replacing them in a hotel parking lot. The NAPA belts appeared to be a little wider than the dealer belts, I suspect they don't quite fit the pulleys.

Hmm..I never tried putting the belt on over the fan. It just looked too small to fit. :stupid:

Not a problem, just snake it over one side then the other. Removing the fan is a PITA, this is much easier.

Luckily the fan came off easily...no rounded bolt heads.

The strange thing is I tighten the belts to 1/4" or so deflection, which stops the squealing, but after 30 or so miles the squealing returns and the belts are back to 3/4" of deflection. I am tightening up the alternator bolts after I adjust it, so it seems like the belts must be stretching.

That seems like a lot of stretching, are you sure the alternator's not moving? Is your adjuster bolt intact? Mine never really did that, they just wore out sooner.

Are belts hard to do on a 300D? Mine are all cracked, but it seems like there's not much room in there. Not like my friend's old Nova without A/C... so much room under the gigantic hood.

I'm fairly sure the alternator is not moving. My adjuster bolt is intact.

It only took me about 45 min to do mine...and that was with the extra fan removal step.. :o