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Topic
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My 1995 Astro van has an intermittent chirp somewhere in the belt drive.
Symptoms:
-seems to happen more when cold
-intermittent (not a constant squeal, more like an occasional chirp)
-happens most often when I have the brake applied (my van has hydroboost)
-when I hear it under the hood, it sounds kinda like its from the lower end of the belt drive.What I’ve done so far:
-replaced a blown idler mounted to the block; the bearing was shot and grainy
-replaced the belt. The old belt was a stretched gatorback with the belt info worn off (that old). I replaced it with a “new” gatorback belt which had older packaging. The belt seemed to be in “like-new” condition; I think the only defect was the outdated cardboard wrapper (probably why rockauto had them closeout’d).The tensioner seems to be good; the idler on it has a smooth bearing with no bounce during operation. The spring has plenty of tension! . It took a large 3/8″ breaker bar and some brute strength to work it during the idler job
I had a thread on this at astrosafari.com and beyond the idler and belt, we’ve gotten nowhere.
The only things in the bottom end of the belt drive is the engine pulley and the power steering pump. The power steering makes none of the “usual” power steering noises associated with a bad pump, which leads me to believe that it’s not the culprit.
The water pump has nothing leaking out of the weep hole, and it spun fine when I had the belt off last.
The alternator also spun fine. No charging issues to speak of either.
The A/C compressor spun ok IIRC… there is no reduction or increase in chirping with the A/C on or off.
Anybody have any suggestions?
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Replies
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One thing I would check is that all the pulleys align. Since the idler was changed I’d pay close attention to that one.
I’m pretty sure it’s on straight… It did the chirping routine before I did the idler/belt change (I did those to try to fix the noise).
I think the tensioner pulley is the issue. I popped off the belt to recheck things… the pulley bearing felt pretty grainy. Not as bad as the blown idler, but bad enough to imho warrant replacement.
Everything else was ok…
No luck… Still has the noise. @#$%!!!
I noticed that the fan blades shudder a bit when the noise occurs. Does that mean my water pump or fan clutch is hosed?
That should be easy to diagnose – and if it’s the fan clutch REPLACE it before the fan cuts loose into your radiator.
Grab one of the fan blades (engine off obviously) and check for any play. If you just see the fan moving but not the WP pulley then it’s the fan clutch. Next step is grab hold of the water pump pulley and check for play there.If there is any then the WP is at fault.
When I went to wiggle the fan, nothing budged. It’s an intermittent wobble apparently.
From what some of my Astro expert buddies tell me, it’s probably a water pump bearing. Ouch!
(Looks like I may need to get some cooling system tools).
If all goes to plan, Ill use a different car to get the parts/tools tomorrow and do the job in the afternoon.
Wish me luck, it will be my most involved auto job yet.
In the process of removing the water pump, I may have found the culprit.
turns out there is a bad spot in the fan clutch whete there is some serious play. it’s hard to find but I stumbled upon it when I went to pull the fan/clutch off the water pump.
Luckily I hadn’t removed the old pump yet (or bled the coolant), so tomorrow I’ll return the new water pump and replace the fan clutch.
I think I fixed it. Swapped the fan clutch, no more noise (so far).
Assuming the lack of noise holds (I’ll know when I drive to dinner in a few), here’s my conclusion:
Source of noise: Intermittently loose fan clutch.
Other issues found and fixed: Bad tension idler, bad fixed idler, Stretched/worn drive belt.
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