Maybe wrong water pump?

[68 Greenie]

Okay guys I'm sure you know by my other threads the problem Im having. You know the gauge climbing up and up and up. I just got to thinking that this is a 86 block but I'm running the ole v-belt system on it could I have the wrong water pump? Im sure in 86 it was a serpentine system which runs the opposite way. Right? This may be why the gauge climbs when im driving down the road and cools as Im idling. Just hit me. Let me know what you guys think. Thanks guys this site has been really helpful.

[AussieinNC]

Are you using the old water pump off your previous old engine...v belt style...

or are you using a water pump that came on the 86 engine?

86 on engines use serpentine belts, that require a reverse rotation water pump...

Using a reverse rotation pump on a v belt drive engine will have the water pump cavitating and reducing flow as engine speed increases....

Just buy yourself a new standard rotation pump...just make sure the drive flange length is correct...there are short and long pumps...

[Larry Weaver]

I know on some jeeps there were 2 dif pumps with different rotation. Dont know if GM did stuff like that but its an idea.

[57taskforce]

I thought the serpentine setup came around in 88?

[silverstreak]

Watch the rotation of the pump with the engine running then remove the pump and take the plate off the back to see which way the impeller is flinging the coolant.

[AussieinNC]

There is a difference in the pump flange height between standard rotation and reverse rotation "short" pumps....

As you are using a v belt, your short pump should measure 5 5/8" from mount to fan flange face

If you have a reverse rotation pump, it will measure 5 13/16" from mount to fan flange face...if your pump measures like this, it needs to be replaced.

See image below...