Technical What symptoms would you have if you put a reverse flow water pump on an early sbc?

I'll go ahead and apologize now for the O/T question but my wagon, which I just recently got running, hasa cooling issue. The PO stuck a center bolt v/c , pre-vortec sbc in it. It has a serpentine belt setup off of a 94ish Suburban. Around town it does fine, but get out on the hwy and it runs about 230 degrees.


This has started me on a quest to diagnose the problem. I think the owner has installed a reverse flow water pump on a traditional flow block. Have you guys ever seen this happen? If so, please tell me about the symptoms. I need to get this done before the St. Louis Hot Rod Hundred. It's a 9 hour drive and I don't wanna be stranded.

Thanks

 

There is no such thing as a reverse flow block. Same engine can use either pump, as long as the drive is correct for the pump.

 

Ok, that's good to know. I don't have a clue about these newer blocks. Thanks.
I just wanted to make sure because I am removing the electric fans etc and putting a clutched mechanical back on it, but I didn't wanna dump a bunch of money into something that I would end up removing later down the road.

 

As badshifter says the blocks are the same. It still could have the incorrect pump for the drive system. I had an issue with a standard V-Belt system and to learn if it was the incorrect pump I removed the top hose and the thermostat. Then filled the block and rad through the thermostat housing and started the motor without the hose on it. The pump pulled the water out of the block and purged it up and out the top hose fitting. That told me the pump was for the serpentine belt system and the pump to work correct should be turning the opposite direction. I would think you could do the same process to learn if your water pump is correct for the belt system on your motor.
The Wizzard

 

Right, on traditional small blocks both rotations work on same block, with most serpentine setups needing the reverse. I think you are worrying about something that applies only to LT engines, which reversed the flow through engine... that stuff won't go on the regular small block so will not be the problem.
On the real small block pumps, though, I do not know for sure how to tell rotations of pumps...I assume it would be obvious from impeller if you had one of each to compare.

 

Odometer takes miles off. Otherwise, no change.

 

This is a mid 80's motor I think.
It def is a reverse flow according to this.
http://www.flowkoolerwaterpumps.com/info/standard_reverse_rotation.html

 

Huh? Unless I'm totally senile, you just look at them.
Std flow has the lower hose on the left (drivers side.) Reverse flow on the right.

 

You have arrived .

With a serpentine belt the WP is built to spin the opposite way, it's not verse flow it's reverse rotation. There was a very brief run of reverse flow cooling the cooled the heads first but it's way different.

The symptoms would be little to no flow because the impeller wouldn't be spinning thru the water in such a fashion to push it thru the block

 

you can take the back cover off to check the direction of flow as the water is pulled from the center of the pump and pumped to the block and the impeller will have holes behind the direction to relieve cavitation if its sheetmetal ( this is standard rotation ) and the cast impeller is easily determined , I have gotten rebuilt units that were serpentine and boxed for v belt usage . and the water often will try to flow backwards in the radiator ( top row should have a little dribble coming out of it while the motor is running if the bypass is hooked up ) or if you have a heater or puke violently out the fill when it gets warm and the stat opens and then it will surge if its running reverse

 

Gotcha. Reverse rotation. I was confused by the ones way back that were rerouted.

I just wanna make sure I order the right fan.

 

yea like said before the only reverse flow stock motor is the late LT series and its driven off the cam by a spline drive or electric motor and you have several more hoses to hook up on it too , if you saw the pump you would know right away . as it has no snout .

 

Sorry, I was looking at this pic the Roothawg linked to, & not even thinking that was pic of a a Ford style pump. LOL



OK gimme my sign....

 

Thanks guys. I'll get my shroud and fan ordered.

 

The direction of flow is the same, the impeller blades are different, for the reverse rotation pumps. The wrong pump will work, it will pump water the correct direction, it just won't work as well as it should.

 

Here is a reverse flow, note the different impellers. I used a LWP standard rotation on my SBC for clearance and ran a V-belt, not reverse flow serpentine, A small tutorial .

 

I'm really bummed after driving it yesterday. I got most of the bugs worked out and then this cooling issue. The under hood temps are way too high. I couldn't touch the valve covers. The radiator felt warm but not as hot as my valve covers. I am thinking this electric fan just gets in the way at highway speeds.

The PO bought an aftermarket oversize aluminum radiator and this electric fan. Not sure if the radiator is an ebay China special or what....

I spend more money undoing what this guy did previously. Ugh....

 

Don't forget that if the water pump is running in reverse you will need a fan with reverse pitch blades or your ordinary fan will be trying to blow hot air back out through the radiator raising the water temp even higher. Ralphie

 

Double check your tune, your timing too but verify your timing marks first with a piston stop test.

Electric puller fan shouldn't get in the way but a pusher can. If its heating up going slow that's probably the fan. Heating up on highway is going to be water flow, insufficient radiator or not enough advance in the timing.

Check your pump impeller or just go get one for serpentine belt. Check your hoses and make sure you have at least loops not blocked ports.

 

I'm picking up a new water pump (reverse rotation) just to make sure. It's only an hour of my time and I can be sure that I have a new w/p coming out of the gate. The PO was kind of a cheapskate and I find things that he has done, that I would have bought new....and end up usually doing just that.

I thought about dropping a 180* thermostat in it while I have the antifreeze drained, just for giggles. I don't wanna throw too many parts at it, so I can at least try and figure out what happened.

I am with you on the fan direction....I am changing one thing at a time, hoping not to invest my 401K in it.

 

squirrel has your answer. The motor is turning in one direction, but the pumps are designed differently . The impeller is designed to push the water. If it is turning the wrong way the impeller is "cupping" the water. In plumbing situations this can cause cavitation and greatly reduced flow.

 

I'll keep you posted.

 

i think they made a reverse flow water pump and a regular flow water pump on the serpentine set up. one has a smooth pulley and the other has a ribbed pulley . depending on how the belt is routed will determine which way the pump turns

 

Out of curiosity, was the long GM water pump more durable? Or was it just long for clearances & fit-up?

 

Yes, you are correct moonshiner.

 

230 degrees isn't hot for mid 80's. Bought a new '84 Z28 H O 305 that run that all the time. Took me some time to get use to it.

 

I changed the water pump and thermostat last night and took it for a drive, it was averaging around 200. I'll take it out when it gets back up to 90* and see what happens.

 

any updates on this?

 

Funny, you should ask. I sold the wagon, but the problem ended up being a swap meet electric fan. It made all kinds of noise, like it was really moving the air, but really it was just in the way. I put a clutch fan on it with a shroud and the problem went away.