Vacuum pump problem? Hopefully...

[lotik]

The problem first started with the altenator vibrating excessivly. After replacing the altenator, I go to turn on the A/C and there is a loud squeeling noise. So no I figure the clutch/compressor is going out. I shed out the 300 bucks for new compressor/dryer/etc. I get all of changed out and the noise is still happening when the A/C is on. Now it seems as if it is the Vacuum pump. It looks as if the pully on the pump locks up and causes the noise. I can't come up with anything else. Anyone had any experience with this situation? Can i test the vacuum pump? By the way I assume it is the vacuum pump from other threads I have read. Its directly under the A/C compressor?

Truck Specs:
1994 GMC 1500 Z71
6.5 TD

I would really like to get it fixed with the next purchase since I basically wasted 300. :/

[More Power]

Yes, in the 1992-95 model 6.5's, the vacuum pump is located somewhat below the A/C compressor.

You have a couple of options for repair.... 1- First detemine whether the vac pump is bad, if so replace it. 2- Eliminate the vac pump entirely by installing a heathdiesel.com Turbo-Master wastegate actuator (non vacuum), then install a 1992-93 model year serpentine belt.

Contact www.usdieselparts.com (http://www.usdieselparts.com) for either a new or reman vacuum pump assy.

Jim

[garre1tt]

Are you sure it is not the hormonic balancer?

Michael D

[lotik]

I'm not 100% sure of anything right now. I changed the harmonix balancer about 6 months ago.

How can I determine if the pump is bad?

Would you recommend a new pump or the actuator for heathdiesel.com?

[Warren96]

Can you disconnect the fan belt and turn the vac pump by hand? You can do this with all the belt accesoies.(fan-alternator-AC-vac pump-power steering-idler pully-did i leave anything out?) Just remove the fan shroud first.

[markelectric]

I would eliminate the pump, Use the turbomaster and a serp belt off a 93. This eliminates a bunch of known and soon to be shown to you problems.

I did this to both 94s when I had them. Never was sorry....

[lotik]

I removed the fan belt and attempted to turn the pully on the pump.Standing in fron of the motor looking at the engine. The pully will turn counterclockwise fairly easy. When turning it clockwise it is pretty hard. But it will turn. The only wierd thing about this is that it only happens when you turn the A/C on.

[N9Phil]

How is your belt tensioner? It seems to me that if it only happens when the air conditioner is on then the belt might be slipping under the load of the air conditioner.

N9Phil

[BobND]

I removed the fan belt and attempted to turn the pully on the pump.Standing in fron of the motor looking at the engine. The pully will turn counterclockwise fairly easy. When turning it clockwise it is pretty hard. But it will turn. The only wierd thing about this is that it only happens when you turn the A/C on.


I can't see why the pump would be easier to turn one way than the other. It is simply a diaphragm operated by a roller cam. Perhaps there IS something worn out inside the pump.

[stingthieves]

It turns the same clockwise or counter. Order yourself a new pump WITH the pulley from John Kennedy!

[lotik]

Hrmm.. seems that the problem was fixed with a new belt. SImple enough. I'm guessing the older one was worn out?

[More Power]

There's a tech article in the new Member Archive linked in my signature that discusses the belt tensioner, and indicates what to look for.

Jim

[lotik]

Well it wasn't the belt. It seemed to fix it temporarily. I have since changed the belt tensioner which also did not remedy the problem. I gues the only thing left is the vacuum pump. :confused: