Radiator Fan

[enaberif]

Water pump pulley being smaller than crank pulley is normal.

From what I have read it's not. It seems it's normal for the crank pulley to be smaller or have them run in a 1:1 ratio.

With my water pump pulley being small it's turning faster that the crank which pushes coolant faster and I am thinking not allowing it to absorb heat and thus never getting warm enough.

I have tried to find what stick size is normal but I am unable to find that information.

[Don5]

I went out and measured my water pump pulley and it is 6 1/8 inch diameter. That is the OD of the pulley not down in the V. This has been on the truck since I bought it and I am sure it is the original one.

[enaberif]

I went out and measured my water pump pulley and it is 6 1/8 inch diameter. This has been on the truck since I bought it and I am sure it is the original one.

So your water pump pulley is smaller than mine.

What size is the crank pulley?

[Don5]

I went out and measured my water pump pulley and it is 6 1/8 inch diameter. This has been on the truck since I bought it and I am sure it is the original one.

So your water pump pulley is smaller than mine.

What size is the crank pulley?

I was afraid you were going to ask me that. I will go back out to the garage and try to measure. I don't know how exact this one will be. I will report back in a few.

OK near as I can tell mine is 7 inches. This is a two groove pulley. It is also a factory pulley that has been on the truck its whole life.

[Don5]

What kind of water pump do you have on it? Is it some high performance model or something? Mine was bought from O'reilly's last year.

[enaberif]

dang throws that theory out the window. guess it's back to the drawing board.

just a stock water pump as far as I know.

[Don5]

dang throws that theory out the window. guess it's back to the drawing board.

just a stock water pump as far as I know.

Sorry.  Just tryin to help.

[LTZ C20]

Well then beats the heck out of me. Hey brain storm idea! What happens if you cover say 1/3 of the front of radiator? Either vertically or horizontally. You probably have to pull the upper radiator support for this experiment but it's only 4 bolts.

[Don5]

I just keep coming back to the water pump. I think it is circulating coolant too fast. It is either the fan blade, the thermostat or the impeller in the water pump. I don't know.
Possible answers

The thermostat is opening too soon and engine can't get up to the correct temp.

The impeller is the wrong one and the water pump is circulating coolant too fast.

The fan blade is wrong size and spinning too fast- working too good.

I am probably wrong.


 

[LTZ C20]

So just thought I would update this thread.

With the new 6 blade fan, new hayden HD clutch fan and heater core I am unable to get my truck to proper temp

This is frustrating..

He mentioned he has an HD fan clutch. Is it possible the clutch is working to good just because of the way it's built. Maybe a for a 1 ton truck with a big block or something? Isn't his truck a 3/4 ton? Maybe switching to a new standard clutch would be better. Again, shot in the dark here.

[bd]

These may sound ludicrous, but (1) how are the heater hoses plumbed, and (2) what happens if you pinch off the heater hoses?

The proper way... 3/4 to pump

So does clamping off coolant flow through the heater have any effect whatsoever?

Haven't tried yet. Curious what this will accomplish?

Coolant flow through a SBC is radiator to water pump through lower hose - water pump to block water jackets - block water jackets into cylinder heads - cylinder heads to intake coolant crossover, thermostat and water outlet - water outlet to radiator via upper hose - through the radiator and back to the engine.  The heater hoses are connected to the intake water crossover and water pump.  Heater core plumbing bypasses the engine thermostat, routing coolant directly from the water crossover below the thermostat through a mini radiator under the dash and back to the water pump and engine. 

Have you ever pondered why the factory incorporated a 1/2" restriction into the 5/8" heater hose fitting that threads into the water crossover?  You posted that on a warm day ambient temperature is ~5° C (~40° F).  How do you suppose coolant bypassing the thermostat through the heater core might affect engine temp on generally cold days, especially if your engine is on the threshold of over cooling anyway, because of high heat rejection from a large radiator and high airflow?  If you or the PO replaced the 5/8" hose nipple with an open fitting, symptoms could be further exacerbated. 

Pinching a heater hose off to see whether it has any effect takes all of one minute.  It may have no effect at all.  But, until you try it, it remains an unknown.  All I'm attempting to do is offer you some assistance based on more than just a little experience.  Don't overthink it.

[enaberif]

a) will be doing the radiator cover up test tonight
b) will try pinching the heater line
c) whether I use the hd fan clutch or normal clutch same issue
d) two different fan blades used; same issue
e) if the thermostat was open I would see flow in the radiator which I do not.

The 5/8 nipple is supposed to have a restrictor? How does one know if it does?

[bd]

The 5/8 nipple is supposed to have a restrictor? How does one know if it does?

OE restricted fittings are steel and have unusually thick walls, creating an ID of approximately 3/8".  If the existing fitting is brass, it's not restricted.  If the fitting is steel, you'll need to remove the hose and inspect the ID of the fitting.  The restriction is visually obvious.  But, first, pinch off the hose to see if there is any effect on engine temp and whether it's worth pursuing.

[Don5]

That makes sense bd. I never thought about the fitting being changed out. That would explain why the coolant is circulating too fast thus the low temp. I know I would have never thought of the fitting. This problem is a real head scratcher for sure. I think several of us have learned a thing or two with this thread.

[timthescarrd]

So beyond running cool, is the engine doing anything weird?