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Video - A/C noise from Alternator??

rlb

rlb

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My 1994 2500 suburban with a 5.7 TBI makes a strange buzzing noise when the AC is on. Only between 800-1000 RPM. Not below or above. Varies with RPM, at the end of the video it gets worse when I crack the throttle slightly by hand. Sounds like it is coming from the alternator, but goes away when the A/C is turned off??

Possibly the Tensioner is worn out? looks okay. Alternator bearings worn out maybe?

No belt squeal and the belt looks fine. Smooth and quiet with the AC off.

Here is the video.

[video=youtube;9LYc9zfhByA]https://www.youtube.com/watch?v=9LYc9zfhByA[/video]
 
Remove snake belt and spin each spinny thing by hand. Note any roughness and noise. Check PS fluid level. Sounds like it's on the driver side. AC on, loads the entire accessory drive. Start engine belt off to rule out the engine making the noise itself.
 
Got to messing with it this morning. Convinced the noise was coming from the alternator so I went to remove it. Lo and behold, the alternator mounting bolt (right most one as seen in video) was about 1/2" too short and had only engaged the first 3 threads, subsequently stripping them out. I'm going to get a longer bolt and clean the threads up with a tap.
 
Everytime I see one of these 6.5 noise videos, they all sound the same. Just a noisy engine.

With all the rust, where does this one live?
 
Big T said:
Everytime I see one of these 6.5 noise videos, they all sound the same. Just a noisy engine.

With all the rust, where does this one live?
Click to expand...

Its a 5.7. North Carolina.

Not much rust on the truck. The rusty water pump in the video is literally 2 months old. Bought as a 'new' pump from O'reilly auto parts. Didn't think to paint it. The exhaust manifolds are rusty too but that is not really unusual.

If you want to see rust.. I hunt and fish with a friend all the time who is in a rod and gun club on the coast. They buy 4-5 year old gasser crew cab long bed 2500 pickups and fit em up for surf fishing. These trucks sit at cape hatteras national park for 10 months out of the year. Sell them 4 years later for $2000. Totally rusted out.

I fixed the messed up bolt, didn't fix the problem though. I did find the issue... actually the power steering pump. If you grab the PS pulley and swing it back/forth there is play. At just the right RPM with the right load combination, it chatters.
 
I changed the power steering pump today and can confirm that it was definitely the problem. Who knew a bad power steering pump would manifest itself as a noise that only occurred when the A/C was running.
 
Beware Cardone re-manufactured pumps. Mine leaked like a sieve from the reservoir. Connections were fine but it leaked out all of the fluid when sitting over the weekend. It was the reservoir that was not attached correctly and leaked from the pump/reservoir seal area.

I pulled the defective pump out yesterday and waiting on another one to arrive tomorrow. Trying my luck again with a Cardone pump because I could find no suitable other option.
 
rlb said:
Beware Cardone re-manufactured pumps. Mine leaked like a sieve from the reservoir. Connections were fine but it leaked out all of the fluid when sitting over the weekend. It was the reservoir that was not attached correctly and leaked from the pump/reservoir seal area.

I pulled the defective pump out yesterday and waiting on another one to arrive tomorrow. Trying my luck again with a Cardone pump because I could find no suitable other option.
Click to expand...

X2! A1-Cardone is a very limited life repaired pump.
I suggest a in line filter on the return hose to keep the debris down.
http://www.aaesteering.com/rebuild-...ine-magnetic-power-steering-fluid-filter.html
 
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