How do you tell a ccw from a cw water pump?

[Cardinal]

The 88 S10 with a 4.3L V6 which has a serpintine belt drive system has a bad water pump. I have a new water pump in the garage that is for a 4.3L with a serpintine drive system BUT it has gotten mixed in with other old style other rotation water pumps. How do I tell which one is the correct one?

[99s10327]

Take the back off and see what direction the fins are going

[Cardinal]

Want to avoid it but I'll guess that's what we'll have to do.

Anyone have a picture of a CW and a CCW water pump impeller that we can use as a reference?

[Cardinal]

We dodged the bullet of having to change the water pump. Found that the upper end of the lower radiator hose at the water pump end had a cut in it that leaked. Cut the hose back about 1.5", refastened, no leak.

[99s10327]

[TNFrank]

I may be wrong here but aren't all serpentine belt water pumps reverse rotation?

[sprint65]

Yes-
smooth pulley=serpentine belt & ran off of backside of belt (reverse rotation).
v-belt pulley or grooved serpentine pulley=standard rotation.

[Cardinal]

Externally, the GM long water pumps look the same. That's were the problem begins. If you don't put the correct rotation pump on an engine, then the coolant isn't pumped efficentily = overheating.

I was hoping that someone had taken a serpintine water pump apart and could tell me what the impeller looked like or post a picture of each kind of impeller.

[Telco]

Simple way, put the suction side in a bucket of water and spin it by hand. One direction should move a lot more water than the other direction. If you put a long bolt into one of the pulley holes it will make a convenient crank handle. You may need to put a hose on the outlet and submerge the pump to make this work.

[Cardinal]

Telco: THAT is THEE best solution to this (or anything, for that matter!) that I've heard in a long time! I can make an adapter to fit the face of the pump so that I can run it with a cordless drill too!

[hotrod80]

Besides the cordless drill/ removal check , i hear that the wrong pump will idle hot , cool down at slower speed like 20-30 mph , then slowly heat up as the speed increases due to the water pump not being able to keep up . I also read that the impellers are very similar in appearence and the casings are near identical . Some of the Reverse rotation pumps have a 50 mm center to center on the blade mount bolt pattern and some don't have the heater hose bung . Some also don't have the mount tabs cast in or they are not tapped for threads . Just some info i heard as I'm having problems with my 49' truck .

[Cardinal]

The serpintine belt driven water pump on the 4.3L V6 has a pulley flange that 1) has a completely different circumerence than any other water pump we have 2) has metric bolt holes 3) has NO provisions for heater hoses 4) no provisions for accessories at all.

The "extra" water pump we have on inventory that I think is a serpintine driven water pump has all of the above features so we're about 90% sure that it is a serpintine driven water pump BUT we're going to run it in a bucket of water to prove that it is or isn't. Never ASSUME anything.

[hotrod80]

Let me know how this goes as i understand it they will both pump water either direction Just not enough when backwards .

[smallblockchevy]

I have a Mid 70's Block and i'm planning on using the serpentine belt system off my 4.3 will the water pump be the wrong one?

[99s10327]

Just use the pump for the year 4.3 motor everything will be just fine