Cooling issue

[Caman96]

Some pumps can turn either direction but many cannot. The Flowkooler 1974 and the cheaper GMB high volume clone I recently bought sold on RockAuto both have an aluminim straight bladed impellor. Flowkooler has both CW and CCW listed as rotation. I bought the GMB pump to put on the 1987 as the pump I put on it was leaking. Pump came off the 350 in my 97 and worked well on it at the time and then sat around the shop for a few years. Have not put on the GMB pump yet because the 2006 era Autozone Duralast heavy duty pump stopped leaking after a few heat cycles and a little run time. Never would have guessed that one. It was not leaking on the 97, sat around a while, leaked without even having pressure on it, heat cycled a few times and has not leaked a drop since, go figure. FWIW, Flowkooler small block pumps with cast iron bodies atleast are GMB pumps with a high volume impeller. GMB high flow pump I bought was identical.

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As soon as I posted that, I started wondering if they did make them with straight “blades”. Seems like they’d be less efficient.

 

[L31MaxExpress]

As soon as I posted that, I started wondering if they did make them with straight “blades”. Seems like they’d be less efficient.

The straight blade impeller design works incredibly well. When I flushed the heater system on my 97 with the 383 swap I put a garden hose into the pumps heater return inlet and directed the outlet into a 5 gallon bucket. Heater return hose looked like a fire hose spraying water, old gunked up dexcool and sediment out of the heater cores, aluminum lines and hoses into the bucket at idle.

 

[1998_K1500_Sub]

As soon as I posted that, I started wondering if they did make them with straight “blades”. Seems like they’d be less efficient.

The straight blade impeller design works incredibly well.

I wonder if there's some other reason why the straight-blade impeller seems uncommon (at least, from what I've seen).

Guess #1: Perhaps a straight-blade impeller is more prone to cavitation under certain conditions.

Guess #2: <ditto> has odd flow characteristics over the engine operating range (GPM vs. RPM), or at least "less desirable" characteristics.

Guess #3: (your guess here)

 

[Caman96]

Boat propellers are curved for a reason, my guess would be it’s a more efficient design.

 

[L31MaxExpress]

Boat propellers are curved for a reason, my guess would be it’s a more efficient design.

Not necessarily. Straight vane can be more efficient especially given the Flowkooler impellor design is closed. Flowkooler made a sheetmetal disc at one point that rivited on to the stock impellor and their pump were just a stock pump with an added disc. They have since designed their own billet impellors for basically every pump they sell and many are of a vastly unique design depending on engine type. I have also seen some SBC pump designs with more thinner blades to the impellor. 8 straigh vanes vs 6 curved vanes. Most SBC replacement pumps have a stamped sheetmetal impellor.

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[L31MaxExpress]

Being frugal at one point I actually used a soup can lid to rivit on an inexpensive GMB 8 bladed replacement pump like the one in the picture. Helped cool down the 1980 Corvette when I had it.

 

[1998_K1500_Sub]

Boat propellers are curved for a reason, my guess would be it’s a more efficient design.

^^^ And there's a reason why a water turbine has the shape it does.

Ditto for a torque-converter pump, and turbine, and stator...

and a jet engine's compressor and turbine stages, and...

and...

I'm pretty sure that the proof has been in the pudding for many, many years.

Pumps are designed as they are, for a reason.

I'm thinking laminar flow is one of the objectives, among the many.

Ditto, the characteristics of the medium, e.g., density, compressible or incompressible,...

@L31MaxExpress observations possibly (probably?) coincide with pumps that were not optimal to begin with, e.g., the impellers weren't enveloped by an appropriate housing and/or the impellers were of fundamentally poor design (functionally, not perhaps economically $).

I'm reminded of those $18 bathroom ventilation fans that consist of a straight-bladed plastic "fan"...


Below: Illustration of a Francis water turbine

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[Schoolbusleo]

Hey guys, I'm looking for a hand here I've had my head wrapped around this for months and have gotten no where hopefully someone here can help, I've got a 90 Scottsdale that I had built the motor in, decent cam and some heads off a 84 Vette, well it didn't make the truck real practical so I pulled the 305 out of my elcamino and slapped that in there, well I've had a really sporadic cooling issue it just gradually gets hot, I can't seem to figure out why, and it has crazy line pressure, so I park that till I have time and decide to finish the motor in my Scottsdale which is a bored over 350 with 305 heads and the edlebrock performer tbi cam, it runs emasculate better than anything I own honestly, well now I'm having the exact same issues cooling wise, crazy line pressure and slowly gets hot, heater core hoses are hooked up, both water pumps are spinning in the correct direction and Im about 90% sure it's not heads or head gaskets (on the scottsdale at least) im at my wits end with these things ive got countless hours into testing and screwing with it with no changed out come, hopefully someone here can point me in the right direction

If you have been having this issue since you’ve redone the engine & you think the heads are fine how about checking those intake gaskets, some have really small holes for the cooling ports & some don’t have holes at all, make sure they match your intake & head setup.