Matt Harwood

Water pump packing

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27 minutes ago, Ben Bruce aka First Born said:

I am going to be a contrarian here.  I don't understand how the water pump can push too much water into the top of the radiator for it to handle. If the radiator can't handle it, how does the pump get enough water at the suction to push too much into the top? 

 

First off the pump is not a suction pump, it's a transfer pump.

It cannot push out more water than what's coming in.

Also pumps and radiators are designed to play together.

If the radiator can't flow the output of the pump there is a problem in the radiator.

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12 hours ago, Ben Bruce aka First Born said:

am going to be a contrarian here.  I don't understand how the water pump can push too much water into the top of the radiator for it to handle.

 

I'm an engineer, but not an automotive engineer, so my comments will be just my opinion.

 

I believe, in the case of my Pierce, that the pump was pushing a very large volume of water at speed, the radiator was taking it just fine.  It's actually a new core, as an incompetent radiator man decided the original core needed to be tested at 15 psi, but that's another story.

 

Thus, here we go down the road at speed, a lot of water velocity, boom, let off the gas and (particularly in free wheeling, I know, dangerous) some of the water KEEPS ON MOVING since the velocity is so high, even though the engine speed is greatly reduced.  So, some water is still moving at high velocity to the top of radiator, but the water pump is at a much lower rpm and thus not taking it away from the bottom of the radiator.

 

I believe this phenomena is only evident in a non-pressurized system.  A pressurized system would quickly self-equalize, and never generate enough force/pressure to overcome the cap pressure.

 

That's my story and I'm sticking to it.  I'm sure someone can argue about fluid flow and fluid dynamics and all that stuff (such as the water is at higher velocity at the very middle of the hose, and slower along the sides of the hose), but I'm not going there...

 

Matt, glad that suggestion helped, as I tell my son, you're mostly welcome.  I've had people look at me funny when I told them about the restriction, but the proof is in the pudding, and it worked for me.  Wonder how you get the proof OUT of the pudding??

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Firstly, I have noticed the IR thermometer gives odd results when held near the HT leads and distributor.

 

Secondly, when the water pump slows, the water slows too.When you stop pushing water under a low pressure the water flow stops pretty much immediately. The pump is pushing into the block and is fed from the radiator without significant low pressure on the inlet side because it is below the header tank. The water pressure (head) in the system is equal to the height from the pump to the bottom of the radiator inlet at the top plus the head lost in drag or friction through the system plus a little bit to move the water forward.

 

Water-hammer occurs when a flow is suddenly cut, for example by a tap or gate valve. Pressure in the water column will spike to a very high level very briefly and that pressure could be enough to break something or eject a little water if there is an escape route. But the water hammer is BEHIND the tap, not in front of it, as it would be when a pump suddenly slows. But our pump doesn't suddenly slow much, does it? When one lifts off the throttle, the engine keeps working at the same speed, slowing gradually, unless you put your foot on the clutch.

 

I wonder if Matt's Lincoln re-cored radiator has enough tubes? i.e. capacity. Is the radiator painted? If so, are the openings restricted by the paint?

 

Another thought is that the PO had been having similar problems and had done all the cleaning in trying to rectify them, hence the engine is apparently clean as a whistle inside. But is the radiator blocked? Taking its temperature all over the front while the engine is running might show a cooler (blocked) area. An IR camera would be an even better way to tell.

 

I am perplexed about Matt's problem too, not least because I have the same problem with my Dodge Brothers 8. In my case, the "lift off burp" occurred very occasionally at speed. But then, in May, it suddenly ejected a lot of coolant. It turned out the radiator was blocked. The shop showed me the blockage by wetting the radiator all over then running hot water through it. The blocked part stayed wet, the rest dried. But it still ejects coolant after the radiator was cleaned. I have scratched about a cup of mud from inside the cooling jacket and am nearly ready to put it back together. I can't imagine that little bit of restriction is enough to make it overheat, however.

 

I feel Matt's frustrations and am watching with interest!

 

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The fallacy in the argument that if the pump slows, the water flow slows, is that it's not a positive displacement pump.  It's a vane pump, which means water can flow through it even if the pump shaft is not turning.

 

Again, there's an entire science around water flow, fluid dynamics, fluid flow, coriolis effect, the list goes on....that's not the discussion here.

 

Antique cars.

 

If you have foaming, you're probably sucking in air at the water pump.  There's no other place that's under low pressure with a passage for air intake.

 

If you have overflow, then the cooling system is unbalanced, and one can blame radiator, water pump, and so forth...but the key is regulate the flow, and see if the problem goes away.

 

Not rocket science.  Oh, crap, maybe someone will bring up formulas and show it IS rocket science...

Edited by trimacar (see edit history)
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