Water pump modification

[Richard in Anaheim CA]

The old girl runs fine up hill and down, cool or hot weather as long as I don't exceed about 45-47 mph. Faster than that it starts to burp out rusty water all over the hood and windshield, slow down, it's back to OK. I have an OD so would like to drive about 10 mph faster.

A friend recommends cutting 1/3 off the water pump impeller blades but i'm hesitant. I haven't had to do that for the last 50 years, why now?

What do you think?

Richard
Anaheim CA

[Drive Shaft Dave]

I am thinking radiator restriction, how old is your radiator? Maybe time to try a radiator flush. The vinegar solution has been tried on here with good sucess.

[mleder]

You might search a post from Tom Wesenberg and his vinegar treatment to his cooling system. He found a lot of accumulated rust was removed from his engine. I think he found things to run better and mentioned that he thought a hot spot near one of the cylinders became more normal. Maybe (and it would only be a guess) there is a constriction in the water passages in the block due to accumulated rust and the water circulation is backing up at your higher speeds?

[quickchange]

Would it be anything to do with the large breakfasts on a recent tour??
Sounds like restriction in radiator, Do you run a thermostat ??

[Richard in Anaheim CA]

You guys may all be right but I specifically was interested in your opinion of grinding off 1/3 of the impeller length. I have heard of it before.

I run a 170* thermostat, have a 5.5 head and a radiator only 5 years old and have tried those tricks in my others A's in the past, dish washer soap, vinegar etc. It's kind of nice smelling that "salad" as I drove along.

Derek, no tinny for you.

Richard

[Mike V. Florida]

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Originally Posted by Richard in Anaheim CA

You guys may all be right but I specifically was interested in your opinion of grinding off 1/3 of the impeller length. I have heard of it before.

Some swear by it. If things get worse once you do it, it only costs a little to replace the impeller with new.

[Tom Wesenberg]

The impellor pumps plenty of coolant, and you should still be OK with grinding some off. A radiator only 5 years old shouldn't be blocked, unless some rust flakes came loose from the block and have plugged the tops of some radiator tubes. That's what happened to me. It wouldn't hurt to remove the radiator and flush it upside down to see if any junk comes out. How many rows of tubes in the radiator?

Sometimes an engine and/or radiator sets with open holes while the car is being worked on. Rodents just love this for nest making.

[59mgaguy]

The reason you grind of some of the impeller is to slow down the flow of the coolant passing through your radiator. Too fast of a flow does not allow enough time for the coolant to lose heat.

[Ray64]

Have you worked on the timing lately? My car had the same issues and it was because I had the timing retarded just a wee bit. Above 40mph and she blew water out all over th place. Slowed down and all was good

[Purdy Swoft]

Originally Posted by 59mgaguy

The reason you grind of some of the impeller is to slow down the flow of the coolant passing through your radiator. Too fast of a flow does not allow enough time for the coolant to lose heat.

I've been grinding the tips of the impeller for years with good results. Ford knew that the model A water pump, pumped too much, The earliest pumps had five blades. the first mod was to change to three. In 32 the problem was solved with an improved design.

[1931 flamingo]

What's the cap/gasket like. Even if it starts puking it shouldn't get on the hood, it should go down the o/flow tube.
Paul in CT

[AL in NY]

Richard, I have a similar problem with my Model A. I have a 5.9 head, thermostat, newly recored radiator, and OD transmission. I run a temperature gauge and no matter what gear (3rd /OD) or what speed, if I put my foot hard into the accelerator, the temperature gauge starts to climb immediately and will force coolant out the overflow when the temperature goes to 210-220(I'm running 50/50 water antifreeze). If a get out of the throttle, the temperature immediately starts to decrease.
Here is what I think is happening. The amount of coolant in the engine block is only about one gallon. That amount of coolant doesn't have a lot a heat capacity, and with a modified engine you are creating more heat then the coolant can carry away when you really step down on the accelerator hard. If a local hot spot develops and vaporizes the coolant, the pressure created by this vapor forces coolant out of the overflow and not down through the radiator as in a pressurized system, so the overall efficiency of the system is reduced.
I'm thinking of trying a pressurized system so I will be able to use the extra horsepower I have built into my engine without worrying about overheating under "full power" conditions.

[msmaron]

have you allowed the radiator to "seek" its own level and then leave it alone..I had the same issues, and after that I have never had to touch it again, it is down about 1/4 of a gallon and I run a 180 thermo and it is fine, even here when it is in the 90's

[BrianM]

I put on a new leakless ball bearing water pump when I installed my 6:1 head. The instructions clearly explain the need for grinding down the impeller blades. Basically, newer repro radiators have smaller diameter tubes than the original ones. As the system is not closed, the water piles up on top of the core and goes out the overflow tube.

I thought I'd try the new pump "as is" first. I filled the radiator & let it blow out the excess. Eventually it reached a stable level just above the top of the core tubes. I then pulled the pump and ground down the impellers to have a smooth radiused edge. I suspect I may not have done a full 1/3 reduction, but didn't want to overdo it on the first try. The new stable level is about 3/8" higher than before. The engine runs cool with a 160 degree thermostat & I've experienced no overheating issues at all, even in 90+ degree weather at cruising speeds around 55. I may grind more off the blades, but am in no hurry to do so.

[markyb]

I saw this info regarding grinding the pump vanes on Snyder's notes, especially recommended with repro radiators due to smaller bore core tubes. Can anyone provide more details on what the core looks like on an original radiator vs. a reproduction? Are there more tubes with smaller bore size? I will be changing my water pump to the Snyder ball bearing unit and as Brian referenced, I hesitate to take too much off the vanes unless necessary. I tore up an engine due to high speed cruising and pushing out too much coolant, tough lesson learned.

[John Kuhnast]

Had same problem. Try 2 1/2 gal. instead of 3 gal. Worked for me. Runs cool.

[john in illinois]

The first thing I would check is why you have rusty water. Engine rust cuts down heat transfer and can plug radiator. I have a standard vane pump and never loose coolant.

John

[Brendan]

why not put in a restrictor in the upper radiator hose I put 2 freeze plugs into the water pumps of my V8 Ford for the same reason. I drilled a hole in them . and it slowed down the water. I think it is better then grinding the impellers. what if you grind one to small and through the pump out od balance

[Jim Brierley]

Grind a little off and see how it works. Running higher than stock compression should not be making more heat, it should be less because the engine is now more efficient, turning more heat into power instead of out the pipe and into the water.