Urethane Alt mount bushings failed...

[Matt88S]

I replaced the alternator mount bushings here not too long ago, maybe two months? For some reason I used regular rubber for the alt, and urethane for the tension arm.

About a month ago I started getting some belt squeal, so I checked the belts, they were a bit loose. I thought it was odd, but figured the rubber alt mounts were settling in and egged a bit like they always do, so I just readjusted belt tension and went on.

Once again I started hearing a bit of squealing when cold or sometimes when I'd be releasing the clutch. I thought at first it was my harmonic balancer, but I marked the pulleys and the marks aren't moving.

The belts seemed a bit looser than I usually leave them, but they were still tight enough I didn't think they should be squealing. So I removed the AC compressor to inspect the water pump, and that's when I noticed the Urethane alt tensioner mounts were crumbling away and I could wiggle the arm back and forth.

The rubber alt mounts on the other hand, are still in perfect shape.

What gives? Is there something I should know about Urethane bushings? I thought they were supposed to be tougher than the factory rubber bushings? What would cause them to fail like that?

I'm peaved. I have to replace them now, (woot fun! ) plus I installed new belts when I did the bushings and they are probably toasted now.

[gotaquestion]

Originally Posted by Matt88S

I replaced the alternator mount bushings here not too long ago, maybe two months? For some reason I used regular rubber for the alt, and urethane for the tension arm.
...
What gives? Is there something I should know about Urethane bushings? I thought they were supposed to be tougher than the factory rubber bushings? What would cause them to fail like that?

At least you noticed them before you got stranded! I have replaced my rubber alternator mounts and tension arm with urethane as well...just haven't got the C900 started yet after doing that! I usually try to use the same type for each, as they could not mix well...the urethane are much stiffer, while the rubber ones have some give to them. It could be that having the rubber ones on the alternator caused some give that the urethane had to take! Being stiffer, then started to eat away.

Could also check that the water pump pulley has not been bent out of shape. Had one [*** EDITED ***] not tighten them right, and they loosened up, causing all kinds of problems, including worn and gone alternator mounts and a shot water pump pulley. Got stranded by that [*** EDITED ***]. Luckily not too far. Agree that it was not fun. Too bad that that [*** EDITED ***] liked listening to my C900 stereo with others and draining the battery till the C900 wouldn't start ... instead of working.

[Steve Corgan]

Matt,

I've installed the urethane bushings in two of my cars without any problems so far. My understanding is the same as yours, that they are supposed to be better. There must be something contributing to the premature failure. Is it possible the bushing material was defective?

[AUSSIE900]

Originally Posted by Steve Corgan

Matt,

I've installed the urethane bushings in two of my cars without any problems so far. My understanding is the same as yours, that they are supposed to be better. There must be something contributing to the premature failure. Is it possible the bushing material was defective?

Matt , Steve . I have also used Urethane (twice) , from Europarts , Believing them to be superior . I was staggered when I got less than 6 months in both cases ( once about 7 weeks ) , Perhaps there was a contributing factor or even some bad batches of material ? Regardless I have gone back to original rubber without issues . In both cases the material literally crumbled off . If it wasnt for the pain of shipping etc I would have been looking for replacements under warranty .

[Steve Corgan]

Originally Posted by AUSSIE900

Matt , Steve . I have also used Urethane (twice) , from Europarts , Believing them to be superior . I was staggered when I got less than 6 months in both cases ( once about 7 weeks ) , Perhaps there was a contributing factor or even some bad batches of material ? Regardless I have gone back to original rubber without issues . In both cases the material literally crumbled off . If it wasnt for the pain of shipping etc I would have been looking for replacements under warranty .

In that case I'm going to be watching mine closely. I got the bushings for my 90 car from the SaabSite about two years / 20k miles ago and they're holding up fine (I just went and checked them )

[IronJoe]

Yep, mine disintegrated rather quickly as well. I replaced with stock rubber.

[gotaquestion]

Originally Posted by AUSSIE900

Matt , Steve . I have also used Urethane (twice) , from Europarts , Believing them to be superior . I was staggered when I got less than 6 months in both cases

Not all Urethane is created equal!? Try better quality Urethane?

[Matt88S]

I went back with rubber, but in looking further for the cause I think my rear alt bearing is/has failed in my Alternator.

I'll know further tomorrow once I tear down the alt and take a look. Voltage output is fine, but it has some shaft play and I think the squealing was actually the bearing spinning.

Here is a picture of the urethane bushings if anyone is interested. That's the last time I go with anything other than OEM. I'm wondering though, if it doesn't withstand vibration/shock/compression as well as rubber?