Another problem rears its ugly head. Ahh, the difficulties of not being the original owner of a car.
I started my C4 (1990 L98) and noticed a suspect noise so I shut it off. It sounded to have the rhythm of a belt noise, so after I popped the hood that was the first place I looked. Sure enough, the front edge of the serpentine belt was frayed. After looking around a bit, I saw that the belt was way too far forward on the water pump pulley. Here are two pictures, one from each side:




After taking off the belt, I noticed that the water pump pulley seems to be about 3/16 too far toward the rear in relation to the pulley it's next to. What could possibly cause this? Maybe the PO put the wrong water pump on it?

Here's the work that's been done to the belt system (that I now of).
PO:
Water pump replacement

Me:
Smog pump replacement
Tensioner replacement
Belt replacement
Removed and re-installed AC compressor
Removed and re-installed water pump pulley

I put the water pump pulley back together exactly as it was when I took it off. The pulley went on first with the convex side outward, then the frisbee, then the four bolts.

I'd really appreciate any help you could give me.

EDIT: I ran it without the belt on, and the noise was gone. So good news there. I looked it up, and it seems the spec for an L98 water pump is a hub height of 4.594 inches. I measured mine with a tape measure, and it seemed to be be about 1/4 short of that.

EDIT 2: I came across something on the forum saying SBC had three hub heights - short, long, and one in between for Corvettes after about 1970. That sound right? If so, that makes sense because a mechanic probably replaced it with the short one, not knowing about the size in between.

EDIT 3: It sounds like short is 5.545", C4 size is 5.795", and long is 6.900". So I need one 5.795". I'm guessing this one from O'Reilly will work?
http://www.oreillyauto.com/site/c/de...keyword=cp5016
Is the heavy duty version worth it? I'm guessing it is higher flow or something? I can't seem to find the difference.
http://www.oreillyauto.com/site/c/de...eyword=cp5016h
They're 5.830", but I'm guessing 3 hundredths of an inch isn't too significant.

 

For the sake of possibly helping someone else in the future, here's the rundown as I understand it.

There are three sizes of pumps. Short, long, and C4. The Corvette used the short pump until the C4, when it went to a serpentine belt. The serpentine turned the pump the opposite direction than it previously turned, so they had to redesign the pump, thus the "C4" version. Because it turned backward, the C4 version is referred to as a reverse flow pump. The short pump, and as far as I know the long one, are not reverse flow.
Long story short, the PO's mechanic (I conjecture) thought this pump looked like a short SBC pump, so that's what he replaced it with. The result is the pump has been turning the opposite direction it should have, causing coolant flow to drastically decrease.

With the new pump not only does the pulley line up, but it actually is effective in cooling the engine! No more overheating for me.

 

The L98 is NOT "reverse flow" -

SBC water pumps are clockwise rotation, counter-clockwise rotation and typically long and short. When replacing any SBC water pump hub height needs to be confirmed and I have a friend that depending on the source of the water pump won't install before confirming the impeller is a match for the removed pump. Particularly if you want to supply "your own".

Reverse flow cooling is the LT1/4 cooling.

It's good that your new pump purchase seems to have corrected your cooling issues and pulley alignment but it's NOT quite as simple as you assumed. If the radiator hose fit then there was an assembly issue.

The Edelbrock SBC application chart is pretty complete and can be used to compare if a person had questions. The Edelbrock also notes the different inlet size of the C4 pump which is actually a telling dimension by itself.There are others but this one is a good read:

http://www.edelbrock.com/automotive/...formance.shtml

Yes everyone can maybe learn from your experience but you might want to maybe not rush to your "interpretations".

There's no telling what the PO's mechanic installed, a white box pump, a reman pump, the one he was supplied with but he did fail with the "confirmation" before install.

 

Thanks for correcting me. Your post is certainly more factual and accurate than mine. I was aware the LT1 is reverse flow; the term I was looking for was reverse rotation.
I'll have to remeasure my old pump and do some research to see what I had, but looking at the chart it seems pretty idiot-proof given a certain pilot shaft diameter (which I believe corresponds to pulley and frisbee hole size) and hose diameter.

 

My first thought was that someone did not install the spacer that goes between the pump and the pulley. But, glad you got it all worked out.

 

When I saw it I thought I'd just put it back together wrong, too. I never seem to have the easy problems.