What's the diameter of the Stock H2Opump Pulley?

Also what type of H2O pulley can I use that is not stock....I am looking for a smaller one to spin the fan faster. Is GM the same?

 

Unless another member beats me to it I will measure mine tomorrow and let you know.

I am curious why you want to spin the fan faster, Do you still have the stock fan or has it been replaced with a non stock unit.

I ask because spinning the fan faster may actually create a problem........you will also be spinning the water pump faster. Its my understanding from the FSM that the water pumps on the F-Heads are high flow units to start with, If you turn it faster than the original design speed thats matched to the radiators maximum heat transfer ability its possible to circulate coolant through the radiator faster than it can dissipate the heat.

If I am not mistaken you can also pull air through a radiator to fast witch can contribute to overheating problems.

This modification may result in your engine slowly and consistently overheating.

I would stick with the stock pulley diameter and fan unless there are some members that have done this without any side effects.

 

I think physics would prove that increasing flow rate of coolant thru radiator will increase the cooling effect, not decrease it.

 

Physics might say that, but logic dictates that if you slow down the flow of coolant throught the radiator more heat will be dissipated by the cooling fins.:tea: Pushing it through too fast will not allow it to cool off, therefor every thing will get hotter. Like Phoenix in the springtime!
R)

 

The water pump pulley on my F-Head measures 4 5/16 inches in diameter +/- 1/32.

 

Increasing the flow rate thru the radiator will not necessarily cool the motor better. If the water goes thru the block to fast it will not have time to transfer the heat from the block. We see this all the time at work and have to throttle back the flow from our thermolators to give the water more time to transfer heat or the molds run way to hot.

 

Always interesting when physics and logic disagree. When you overheat just slow down so the air has more time to cool off the radiator. Wouldn't want to jam the air through so fast that it doesn't have time to cool it down. Wait, that never works.

Q = mc(Th-Tc) Works every time it's tried.

 

I hope the point I was trying to make was not misunderstood or misinterpreted, The coolant must remain in the engine block long enough to serve as a heat sink as Mcruff pointed out.
If it is circulated through the radiator to fast it will not dissipate enough of the absorbed heat and return to the engine partially heated for lack of a better analogy.
Whenever an off specification condition exists that allows this cycle to get a foothold it feeds off itself because the thermostat will gradually reach wide open and stay that way in a vain effort to draw "fully discharged" coolant back into the block thereby closing or partially closing the thermostat so it can remain there long enough to serve as a heat sink again. The result is gradual overheating.

As for the air volume / velocity issue I will agree that it would have to be a very extreme condition in an automotive application for this to be the sole culprit of overheating but the air must be allowed to absorb heat from the radiator in the same manner that the coolant absorbs heat from the block. The point I was trying to make is that moving air through a radiator any faster than necessary for complete coolant heat dissipation is not efficient, Turning the fan half again or twice as fast as you need to requires more power, More power requires burning more fuel, Burning more fuel generates more heat.......Heat we are already having trouble getting rid of thereby contributing to the overheating problem.
Hope this helps, did not mean to confuse anyone.

 

Thanks for all the replys....I should have been more clear. I was wondering what the stock pulley diameter of the 225 v6 is.(mine measures close to 7 inches while still on...not exact) Yes I still have cooling issues. I may ditch the flow kooler water pump and put on a stock one and go with a smaller pulley to move air better. I think the combination of the flow kooler and high speed pulley may move water to fast as McRuff indicated. I do not have the original fan on it....it is a 15 inch 7 blade fan, I may change that as well. My problem is at idle the fan does'nt move enough air and she heats up. I have already thought about putting a pusher fan in front, but don't really want to do that as it will impede air flow to the core. The tough part is finding the right combination that will work well at keeping my :v6: cool while crawling in low range for hours on end in the high Sierra.

 

:iagree: It does sound like you are facing radiator issues, A fan shroud will increase efficiency.......drastically in some cases as w3srl noted.
In your case I personally would still recommend staying with the stock pulley diameter ( keep the factory crankshaft to water pump ratio ) and if you want a little more airflow at idle consider a flex fan or the electric option that Don X noted.

 

Take a look here and you will see my set up. It is a brand new radiator.....
http://www.earlycj5.com/forums/showthread.php?t=56085

 

Excellent work !!! Very clean. I have been scratching my head on why an engine with a new radiator and shroud would exibit overheating tendencies at idle, I noticed in your pics that the fan itself is entirely engulfed by the shroud, If what little I know about this is correct not more than half of the fan pitch depth should be inside the shroud.

I cant tell for sure but it also looks like the shroud is nearly flat against the radiator, How much clearance is there from the radiator core to the flat part of your shroud.

The fan not only pulls air straight back but also throws a considerable ammout out radially around it, If the entire fan is inside the shroud this radially displaced hot air will be blown back inside of the shroud reducing the efficiency of the radiator by cancelling out a portion of its airflow. In essence the fan is trying to reverse the flow of a portion of the air it has just drawn through the radiator. This will actually to a point pressurize the inside of the shroud and reduce the amount of air that can be drawn through the radiator.

At higher fan speeds the fan may be able to pull enough air to provide some cooling but I would almost bet that it will run hot and possibly overheat out on the open road, At any given rpm the airflow will proportionately be compromised.

It would be like trying to cool your house with an evaporative swamp cooler without opening the windows far enough to let the air out, The house becomes pressurized and does not cool well even though the cooler is running full tilt.

By chance have you tried seeing if it will overheat at idle without the shroud.

The only other thing I know of that can cause overheating/coolant circulation problems in an otherwise up to spec system is a waterpump impeller that is incorrectly clearanced.

Hope this helps.

 

I checked the timing and it's dead on.

[/QUOTE]I cant tell for sure but it also looks like the shroud is nearly flat against the radiator, How much clearance is there from the radiator core to the flat part of your shroud.[/QUOTE]
The shroud sit 1/2-3/4 inch away from the core.

[/QUOTE]The fan not only pulls air straight back but also throws a considerable ammout out radially around it, If the entire fan is inside the shroud this radially displaced hot air will be blown back inside of the shroud reducing the efficiency of the radiator by cancelling out a portion of its airflow. In essence the fan is trying to reverse the flow of a portion of the air it has just drawn through the radiator. This will actually to a point pressurize the inside of the shroud and reduce the amount of air that can be drawn through the radiator.[/QUOTE]
This could be part of the problem as the shroud fully engulfs the fan.

[/QUOTE]By chance have you tried seeing if it will overheat at idle without the shroud.[/QUOTE]
I didn't have a chance to check that out.

[/QUOTE]The only other thing I know of that can cause overheating/coolant circulation problems in an otherwise up to spec system is a waterpump impeller that is incorrectly clearanced.[/QUOTE]
I will be changing out the flow kooler water pump for a stock pump.

Thanks for the input. I will keep updating as I find out what's going on.

 

Before you tear into the water pump or change the fan it may be worth trying to run it without the shroud, If the cooling efficiency improves it would indicate that all you need to do is refine the shroud design a little.

For what its worth any shrouds that I have paid attention to have about two inches between them and the radiator, The shroud on my 81 Cherokee does not even go all the way across the bottom. Just the lower corners, sides and across the top. The fan is just short of halfway into the shroud and has about an inch clear from the ends of the fan blades to the edge of the shroud.

Hope this turns out to be something simple.

 

Stock 225 V6 water pump pulley diameter...anyone?

Does anyone have a stock 225 water pump pulley lying around they can measure for me.

 

mine measures very close to 5-3/4' diameter.

 

That might explain part of the problem. Mine measures 7 inches. Anyone have an extra laying around?
Thanks for measuring Jim.
Ryan

 

I would agree. :v6:my shroud is up against the radiator and cover 1/2 the fan blades deep. I had my old radiator recored as 3X core. It actually runs a little cool even when in low range 1st gear.