water pump diagnosis/question

[1993]

i’m doing a coolant flush. already drained coolant twice and disposed.
now just trying to flush out sediment.

when i disconnect the hose going into the top of radiator, and turn engine on, there is no water flowing (radiator full).

is this normal?
also, i can’t seem to get any water coming out the bottom hose when pouring water in at the top of the engine (engine off). like it’s not getting past the pump?

 

[Dock Rocker]

https://youtu.be/ThjYW2DxXMg

Most likely your thermostat is holding everything up. This is a pretty good video on how to.


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[Action]

https://youtu.be/ThjYW2DxXMg

Most likely your thermostat is holding everything up. This is a pretty good video on how to.


Sent from my iPhone using Tapatalk

Why would someone paint the washer fluid reservoir and overflow tank black? What is all that crap around the washer fluid bottle / wheel well? I'm not talking about all the jerry rigged wiring there. Is that window screen covering the hood grill areas?

 

[Dock Rocker]

Why would someone paint the washer fluid reservoir and overflow tank black? What is all that crap around the washer fluid bottle / wheel well? I'm not talking about all the jerry rigged wiring there. Is that window screen covering the hood grill areas?

Those are all questions for the owner. But here are my guesses.

If you drive through a lot of brush / sage that screen keeps you from overheating and or cleaning your radiator all the time.

That’s probably an H1 washer tank. Some of them were black.

That’s a case for the jack up to the front of the wheel well and the Cadillac valve you are referring to as “crap”.


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[1993]

https://youtu.be/ThjYW2DxXMg

Most likely your thermostat is holding everything up. This is a pretty good video on how to.


Sent from my iPhone using Tapatalk

thanks, but shouldn’t i be getting some kind of flow when the top hose is off?
the truck seems to hold a steady temp when running on water in between flushes.
drove it around a bit to make sure.
so i’m guessing that it does circulate fine when zipped up?

or now i’m thinking that the thermostat is not opening till much later.
i know the gauges can be way off. but for reference...
i ran the engine on distilled water till the fan kicked on at 160, then i let it climb to 195 where it seems to stay.
does the thermostat not open all the way until i’ve been running at 195 for much longer?
the water at the base of radiator was cold after 10 min at 195

 

[Dock Rocker]

The fan should not kick on until 210. The thermostat unless it has been changed is a 190.


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[1993]

The fan should not kick on until 210. The thermostat unless it has been changed is a 190.


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based on your info, it would appear that both, the thermostat, and fan switch are faulty?
knd of like they’ve switched places logistically .
this truck has 8000 miles and nothing so far has appeared modified or replaced apart from tires and the new style controller under dash.
i drove it around a bit longer last night.
so based on the temp gauge, the fan kicks on and about 165 and basically stays on because the temperature finally plateaus at a gauge reading of 205.

i do feel like this truck gets up to temp super quick.
my 3500 5.9 cummins takes almost 3 times as long.
this kind of confirms that the thermostat has a delayed role

 

[Dock Rocker]

Never trust a military gage. If you are relying on the stock gage that’s probably your first issue.

The thermostatic switch is independent of the engine thermostat. If it’s coming on at the correct time, And you’ve given me no reason to think otherwise, then it is kicking on at 210°. It does not rely on the thermostat to make that decision.

Again if it’s a factory thermostat it is a 190° thermostat


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[KRedd]

https://www.steelsoldiers.com/showthread.php?171563-HMMWV-A1-Introduction. This explains the systems on the HMMWV.

 

[1993]

https://www.steelsoldiers.com/showthread.php?171563-HMMWV-A1-Introduction. This explains the systems on the HMMWV.

thanks. i know the gauges are not to be trusted, only get reminded every time i mention one of them.
however, since the temp gauge does move up the longer the engine is running, i figure it’s at least moving in the correct direction. maybe not accurate but still a functioning reference source.

so why would the fan kick on so much earlier than the thermostat opens?
seems like it should be the other way around.

the fan actually kicks on after about 10min after engine start(at abnot to be trusted gauge reading of 160) and stays on for the whole drive(maintaining a not to e trusted gauge reading of around 210).

seems to me that the radiator should be nice and hot befor the fan kicks on.
instead, the lower half of the radiator is still cool for a while longer.

 

[Thecaptain]

Correct functionality should be thermostat opens first - then fan kicks on. If that’s not happening your thermostatic switch could be failing and/or your thermostat could be on the fritz. The tms have some good procedures to troubleshoot the fan system.

Best

Cap

 

[ken]

In theory the thermostat should keep the engine around 190. The lower rad hose should be warm but not hot when driving. But when it can't dissipate the heat the fan should engage around 210. The fan should not come on at 165. The fan is controlled by the engines heat. Not the rad. So the rad could be cold as in the winter. For example my fan doesen't come on at all when it is below 50 deg outside. The switch is mounted on the drivers side coolant crossover just before the thermostat. The fan should come on and go off. Not come on after ten min and stay on for the whole drive. I would replace that switch on the cross over. I would also change the sensor for the temp gage. It is located right by the #1 exhaust port at the front of the drivers side head. This should
help with gauge accuracy. Also when the fan is on and stuck on it should not get above 190. With this condition the rad would be over cooled and the thermostat would regulate the temp.

 

[Milcommoguy]

Maybe bad temp sensor switch in water crossover? With fan engage, lots of air is moving, lots. Slow to or may not ever get up to thermostat opening temp.

Here in the Mojave Desert today, 109 outside. After a 6 mile drive, stop & go traffic, fan kicked in, ran about minute +/-, turned off. Six more miles repeat sequence. Seems normal to be. Military temp gauge like a slow windshield wiper. Up to 225, down to 190. Tracks fan cycling.

It's **** hot outside and this is normal summer HumV ride. Winters are different story.

Tell me I am normal, CAM

 

[Sharecropper]

After reading this it is pretty obvious that his thermostatic switch in the coolant crossover needs replacing. I need a new one as well. And idea where we both can find a new switch?

 

[Thecaptain]

I recently ordered mine from epay. Not a whole lot of options for that part. Good news is it’s probably the easiest repair you’ll ever do on your hmmwv

 

[1993]

After reading this it is pretty obvious that his thermostatic switch in the coolant crossover needs replacing. I need a new one as well. And idea where we both can find a new switch?

+1 on this inquiry. on my way home today i picked up a thermostat at a local auto parts place for $6.99.

but i forgot to ask about the thermostatic switch. would it be the same part on 12v 6.2’s? i’m sure id have to modify the connectors.

 

[Sharecropper]

I just bought a new HMMWV thermostat and switch on EBay. The thermostat was PN 14077122, NSN 6620-01-146-8006. The switch was PN 12338599, NSN 5930-01-237-7322.

Hope this helps.

 

[911joeblow]

Everything sounds OK in your system minus the fan switch as mentioned. I have seen so much crud in the system that it piled up behind the thermostat. So you might want to pick up a gasket and at lest pull the thermostat to take a look. You can also do a boiling water to test to make sure it is functioning well. But really I think the switch is going to fix you up.