CJ2A Fuel pump and overheating

1945 - 196*, Willys CJ series, questions, discussions, regarding anything related to the post war jeep.®
ph@5200
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CJ2A Fuel pump and overheating

Post by ph@5200 » Tue Jul 14, 2020 4:15 am

My CJ2a is overheating, any idea why water would be spraying out between the water pump and the hose . This happens before it even gets hot. Have tighten the clamp but it seems like a lot of pressure.

Also could someone explain the glass bowl on my fuel pump? I have always seen the bowl on the bottom of pumps but on mine it is on the top. What is the purpose. Thanks.


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Re: CJ2A Fuel pump and overheating

Post by Scoutpilot » Tue Jul 14, 2020 8:33 am

"spraying out between the water pump and the hose" From around where the hose attaches to the pump? Sounds like an old or damaged hose or a cracked pump outlet.

The glass bowl serves two purposes. Obviously being able to see the condition of the fuel is good. The air bubble in the top serves to maintain pressure in the system. By the way. As long as the fuel level is above the brass screen the pump will function as it should.
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Re: CJ2A Fuel pump and overheating

Post by ph@5200 » Tue Jul 14, 2020 9:21 am

I replaced the hose and can't seem to find any damage to the pump. Could this be a stuck thermostat or bad radiator cap?

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Re: CJ2A Fuel pump and overheating

Post by Scoutpilot » Tue Jul 14, 2020 10:55 am

Is coolant flowing through the radiator? Do you have full circulation?
'70-'71 'A' Batt., 377th FA, 101AB
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'71-72 CHARLIE TROOP,
16TH AIR CAV, 1ST AVN BDE (AEROSCOUTS)
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ph@5200
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Re: CJ2A Fuel pump and overheating

Post by ph@5200 » Tue Jul 14, 2020 11:33 am

I hope coolant is flowing through the radiator I bought this radiator at a show last year. The jeep was over heating.

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Re: CJ2A Fuel pump and overheating

Post by Scoutpilot » Tue Jul 14, 2020 12:00 pm

Radiator Cap should be a 4 psi. Timing advanced too far will cause overheating. A too-lean mixture will cause overheating.
'70-'71 'A' Batt., 377th FA, 101AB
(Slicks and LOH's)(Col's LOH Pilot)
'71-72 CHARLIE TROOP,
16TH AIR CAV, 1ST AVN BDE (AEROSCOUTS)
LOW LEVEL HELL.
'46 CJ2A
'47 CJ2A
'48 CJ2A
'48 B1PW126
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ph@5200
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Re: CJ2A Fuel pump and overheating

Post by ph@5200 » Wed Jul 15, 2020 3:58 am

thanks, i will check this weekend.

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Re: CJ2A Fuel pump and overheating

Post by Rus Curtis » Wed Jul 15, 2020 5:21 am

From my experience, if it's leaking where the hose attaches, there will be evidence. You haven't shared what kind of clamp you're using. It could be the clamp may not be holding enough pressure on the hose. If you're cutting into the outer skin of the hose it's too tight. Crud build up (if not removed) on the hose or the pump attachment neck can prevent a seal. I disconnect the hose and look inside the hose for stains that indicate fluid is getting past the clamp. I also feel the contact surfaces for crud that might prevent a seal.

Are you sure it isn't the weep hole (I've been fooled into thinking a leaking hose connection in the past because of this)?

Removing the cap and observing the coolant at the top of the radiator will show if it's circulating. Also, the top hose will get hot when the thermostat opens - another sign of circulating. IF the thermostat is stuck, typically coolant blows out of the weakest link, i.e. the cap. This usually happens though after reaching temperature - where the thermostat should be opening. If you are observing flow through the neck of the radiator (cap removed) and coolant builds up and shoots out of the neck - that's another sign the thermostat is stuck.


Regardless of where the leak is, if the system can't hold pressure it can also over heat.
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Re: CJ2A Fuel pump and overheating

Post by ph@5200 » Sun Jul 26, 2020 4:14 am

I took the thermostat out and started the jeep. Took it for a short ride and it overheated again. Both hoses were hot.

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Re: CJ2A Fuel pump and overheating

Post by Rus Curtis » Sun Jul 26, 2020 5:22 am

You're leaving a lot of helpful information out.....

Is the hose still leaking? Did you check the weep hole? Did you observe the coolant circulating with the cap off? Have you flushed the system?
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Re: CJ2A Fuel pump and overheating

Post by ph@5200 » Sun Jul 26, 2020 7:07 am

the hose isn't leaking, checked the weep hole and it seems to be circulating. Haven't flushed the system yet.

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Re: CJ2A Fuel pump and overheating

Post by Joe Gopan » Sun Jul 26, 2020 7:12 am

Does the liquid taste sweet? Antifreeze tastes sweet. Depending how bad the leak, the waterpump will drip or spray from a hole in the bottom of the casting when the seal is worn, is it wet underneath where that square hole is? Am guessing that a new water pump will be the cure.
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Re: CJ2A Fuel pump and overheating

Post by Rus Curtis » Sun Jul 26, 2020 7:38 am

Joe Gopan wrote:
Sun Jul 26, 2020 7:12 am
Does the liquid taste sweet? Antifreeze tastes sweet. Depending how bad the leak, the waterpump will drip or spray from a hole in the bottom of the casting when the seal is worn, is it wet underneath where that square hole is? Am guessing that a new water pump will be the cure.
That has to be one of the worst ideas suggested. This is not a smart way to diagnose.
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Re: CJ2A Fuel pump and overheating

Post by Joe Gopan » Sun Jul 26, 2020 10:37 am

Way of life in 30's and later garages, shops everywhere.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO

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Re: CJ2A Fuel pump and overheating

Post by Rus Curtis » Sun Jul 26, 2020 11:27 am

To test antifreeze, get a tester, they are cheap:

https://www.amazon.com/Prestone-AF-1420 ... B000BOA9RY

They're available at every parts store and Walmart, etc. - and won't be unhealthy/dangerous to use. And while we're at it, the existence or absence of a certain ratio of antifreeze, i.e. the unhealthy taste-test, won't affect flow - it's irrelevant. It's just as easy (and healthier) to visually check for antifreeze. Green: Better. Brown: Worse. Clear: Absent. But again, irrelevant.

Back to troubleshooting for the OP.

Note: Everything below can be done with tap water from the hose. Once everything is working as it should, then you'll want to switch over to distilled water/coolant. There is absolutely no benefit to testing for leaks and operation with antifreeze. Right now, hose water is cheaper and easier.

ph@5200 wrote:I took the thermostat out and started the jeep. Took it for a short ride and it overheated again. Both hoses were hot.
How did the thermostat look? Rusted? Both hoses hot suggest at least some circulation however, steam coming out of the top of the engine into the top hose could also make that hose hot.
ph@5200 wrote:the hose isn't leaking, checked the weep hole and it seems to be circulating. Haven't flushed the system yet.
If your coolant is brown and dirty, there's nothing wrong with flushing it out and starting with clean water to check everything.
You confirmed no more leaking. The weep hole should never have any liquid leaking out - that's a sign of failure.

WARNING: Be careful removing cap from hot radiator (really any temperature on the gauge). Best to let it cool, or if impatient, place several rags over the cap and turn till the pressure vents - not all the way off. Step back and let it vent. Then carefully remove the cap.

Have you visually checked that the radiator is filled properly? Fill enough to cover the plates inside the radiator but leave about 2" at the top for expansion. Plates not covered? Need more water. Start engine and check for leaks again - visually with the cap off. This is where I check circulation - before driving anywhere.
....it seems to be circulating...

How do you know it's circulating? Watch through the neck for coolant movement. If it flows easily then it's possible there aren't any restrictions and also a possibility that the pump is pumping. If it backs up and rises to the top of the radiator, there may be blockage within the radiator. If it just sits or "trickles/oozes" by, the pump may not be pumping. Do this without being centered close over the radiator neck. IF there's a gush of steam or water that shoots out, you want to be offset by enough to move and not be injured - leave yourself some space.

Would like to know how this goes before creating tangents.
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