Looks like your tensioner is bouncing a lot and not doing its job. Shot or out of adjustment?

 

Your tensioner is outside its recommended operating range, as seen at 1:18. This will result in low belt tension, which sure won't help your problem! Here's what it should look like:



Have you tried using the correct sized crankshaft pulley yet?

 

I had noticed that before and even when I put the new tensioner on the marks were in the same location. I believe that's because the AIR Pump was removed several years ago. that would sit between the tensioner and ALT. With that in place it would raise the tensioner into the correct position. Many 84's remove the AIR pump and run a shorter belt. Been done for years.

I'll have to think this one thru... my upper radiator line now runs over the belt since the HSR upgrade a few years back. In the photos I posted prior to the video you will see where I place a temporary pulley in place. The problem with that it vibrated noise thru the exhaust at idle.


Just noticed your question and the answer is NO, I'm trying to avoid using that pulley. It creates another issue of trying to get the belt on and around it. For some reason its always sat very close to the crossmember. Even after the new motor and motor mounts were installed.

 

Can you go select a belt at your parts store that is a few mm shorter?

 

I use a 81.5 in belt, picked up a 81 inch and it won't fit on

 

Could maybe a "loose" air-gap on the AC clutch create an intermittent issue that wouldn't result in an inoperable compressor but erratic enough to cause your problem?

 

I did look into the air gap a couple of days ago. Learned about it thru you tube..haha. Anyways it did fall within spec.


Heres a thought with my belt routing issue that seems to a possible culprit.

On a 85, accessory locations are the same as the 84. A SBC is a SBC. I think both water pumps go in the same direction. So could I in theory re route my belt using the 85 guide? and get a 85 tensioner along with the Air pump delete kit?

 

Here's an '85 routing from the FSM for you to gather comments regarding your thoughts.

***Just realized I've an L83 also

 

I think that's a great idea. Having the tensioner pulley ahead of another "loaded" pulley is dumb, IMO. IDK why GM did that on the '84. Their first foray into serp belts? Anyway, I feel that "slackest" part of the belt system is between where the belt leaves the driving pulley and engages the first driven pulley with a load. In your case, that is the Crank pulley to WP pulley. That is where the slack should be, and where the tensioner should be. As it is, in the '85.

 

I don't think the GM engineers were so dumb. Their system has worked fine in my '84 for 240,000 miles! And you throw rocks?? Were they supposed to know that qws would want to defy their attempts to keep our air clean?

 

Sorry, "dumb" may have been harsh. I wouldn't have put it where they did (in '84) though.

 

Its funny I never thought about the tensioner marks until Hot Rod Roy brought it up. I've tried a new tensioner about a year and half ago and the marks fell in the same place as this one did.

Once I thought about it I realized that the 84's tensioner relies on the AIR Pump to keep it in the correct position. But since I did the engine and went multi-port its difficult to put anything there with the TB and using the upper radiator hose.

The advice given out over all these forums for the 84's Air Pump Removal is to just use a small belt, which is true you can use, however its not the correct way to do it. You will find that the belt will need to be replace every 1-2 years due to stretch... in turn effecting Alternator Voltage. I know because I had this problem.

Once investigating the belt pattern of the 85, I realized that all the accessories are in the same location as the 84 and that's the belt pattern that should be used once removing the 84 AIR pump.

The Mod really is easy, will cost a few bucks but I think would be well worth it in the end.

Parts needed
85 AC bracket with tensioner-simply remove the 84's bracket
Possibly would need to relocate PS Reservoir and use the 85's with new hoses.

85 Air Pump delete pulley- may or may not be needed.

Once I do this I'll know if the reservoir and delete pulley are needed. (May wait till this winter to do)

Measure the belt length and your done.

Thanks guys for your help in identifying my problem.