84 CJ Spewing Coolant

[Kappy415]

New member here, but i've been reading the forums for the past couple of months since I got my CJ. I feel like every problem I've had has been solved by the wise ones before me (), but I'm posting because I'm stumped and can't find the answer. Before I get to the issue at hand, I have a recently-acquired 84 CJ7 and I've been driving it around with no major problems. AMC 258 i6 / 4.2l I6 TF999 automatic Transmission , Dana 300 transfer, no major mods (yet). Heater core is bypassed, a new t-stat was installed a month ago, and PO said they installed a new water pump.

I went for a drive today, only about a mile. I came home, parked, and as I got out I saw steam coming from under the hood. Popped it and saw there was coolant leaking where the upper radiator hose meets the radiator. Thus began my journey:

- New hose and clamps. Still leaking
- New radiator cap. Still leaking
- Flushed radiator and overflow tank and added new coolant. Still leaking

BUT, I realized, I hadn't burped/purged the system after putting in the fresh coolant. So, I took off the radiator cap, turned on the CJ, and after about 1 minute, coolant comes gushing out the top. Coolant was EVERYWHERE. I then convinced myself the aforementioned mess was air purging from the system and the worst was behind me. I repeat the process with a careful eye towards the coolant level, and this time I make it 1.5 minutes before coolant comes gushing out the top.

The leak seems to only happen after I turn the car off so I'm hesitant to think it's a water pump or t-stat problem.

Any ideas?

 

[Petescj]

Upside down thermostat?

 

[Kappy415]

I took the housing off and looked. The thermostat was in correctly but when I pulled off the housing, i noticed it was dry - there was no coolant. So i'm thinking maybe it was stuck. Rather than test it, I'm just going to replace it and see if that fixes the problem. Thanks for the help! I'll keep you posted.

 

[Kappy415]

I installed the new thermostat and coolant is still leaking. When it leaks, sometimes it bubbles more than drips, and you can hear air pushing it out. I thought there could be a clog to the overflow tank, but after it cooled, I could see and hear coolant from the overflow being pulled into the radiator.

Not sure what to try next as this seems like a pressure issue but i've replaced the cap and the overflow is working correctly.

 

[Torxhead]

I am thinking you have air in the system causing the problem. I have heard of guys drilling a 1/16" hole in the thermostat to help bleed the air. You might want to take a closer look at that coolant leak and see if it is a hole in the radiator. If you question the thermostat you can put it in a pan of water with a meat thermometer and heat it up over a stove to watch when it opens.

 

[Lumpy Grits]

1/16" hole, at 12 0'clock in the t'stat flange works well.
When was the last time a full 'rod-out' was done to this radiator?
When you mix the AF. Use ONLY distilled water.
Also, the hose fitting on the radiator may need to be re-soldered.
What psi is your rad. cap rated at??
LG

 

[Fastatv]

Could this be a head gasket issue?

 

[CJim7]

What is your engine temp running at?

 

[Hedgehog]

Try pulling the thermostat altogether. No, I'm not saying to run without a thermostat. As a diagnostic step run the engine and see if the problem persists.

 

[KappysJeep]

I somehow managed to lock myself out of my newly-minted account (), but I didn't want to go silent on everyone. Appreciate all the help.

I inspected the radiator hose neck and couldn't see any holes. So I drilled a 1/16" hole into the t-stat at the 12 o'clock position and filled with coolant. I jacked up the front end and started the CJ with, cap off. After a few minutes, coolant came gushing out again. Turned off the engine and put the cap back on. Started up again, and sure enough, after a few minutes, coolant came out of the original leak, at the upper radiator hose.

I think, THINK, what's happening is the t-stat is opening when it reaches 190and pushing coolant back through the upper hose and is finding the fastest path out of the system: either the open radiator, if the cap is off, or the upper radiator hose connection, if the cap is on. I'm obviously still not sure why.... A little tired of cleaning up coolant, so I'm thinking of flushing the system with just water and opening up all of the connections to look for a clog.

To answer the other questions:
- Rad cap is 16#
- Not sure about engine temperature as fixing the temp gauge is next on my list
- I don't think it is a head gasket issue because I'm not seeing smoke or bubbles, or oil in the coolant - that's what I would see right?
- I'm using a pre-mixed 50/50
- I have not done a rod out on the radiator but it appears the PO installed an aftermarket radiator and it looks clean (from what I can see)

 

[Torxhead]

Thanks for the update. New guys have been having issues getting back in so good luck with that. So why and just where is the coolant coming out of the upper radiator hose connection? Your assumption is right about the head gasket also. I see you stated that the heater core is bypassed, are the coolant lines routed so that the intake manifold gets coolant also? Here is a link to John Strenk's new gauge page for when you start working on your gauges:The new Gauge Page

 

[Hedgehog]

Eliminate one possibility and yes I know it's remote. Replace your radiator hose, yes I know it's new. Then there's this. Could the new water pump be pumping backwards? Occasionally we have found water pumps that are supposed to run with a serpentine belt installed on a regular belt drive engine. But, if the water is coming up and into the radiator, I'm sticking with the idea that you have a radiator hose with an internal leak. Now there is that possibility that your thermostat housing is compromised in some way ... a crack or a porous casting.

 

[mtnwhlr]

I thought about this but if it's turning backwards I think you would have a over heating problem not it over pressurizing. But I do understand your thinking that it has the water flowing the wrong way. It would be worth checking just to rule it out.

 

[Fastatv]

New member here, but i've been reading the forums for the past couple of months since I got my CJ. I feel like every problem I've had has been solved by the wise ones before me (), but I'm posting because I'm stumped and can't find the answer. Before I get to the issue at hand, I have a recently-acquired 84 CJ7 and I've been driving it around with no major problems. AMC 258 i6 / 4.2l I6 TF999 automatic Transmission , Dana 300 transfer, no major mods (yet). Heater core is bypassed, a new t-stat was installed a month ago, and PO said they installed a new water pump. " Quote ".
I read this a few times and want to be clear on some things.
- You had said that you drove the CJ around for a while with no major
problems. Not sure how long you drove it but, if you drove it on a few
trips, just several miles each, and did not have a overheating issue, then
this would indicate that the water pump is turning in the correct
direction.
- Next, If PO installed a water pump...IF , and now you have installed
maybe two T-stats ( or PO installed one of them ), doubtful the T-stats
are both bad. IF he installed a water pump and a T-stat, then he probably
had the over heating issue while he owned it. My guess is that your water
pump is turning in the correct direction, and the T-stat ( second one ) is
probably good ).
- It sounds to me like you have either a blockage in the radiator, or a leaky
head gasket. A leaky head gasket does not always allow coolant into the oil,
and it does not always allow highly noticeable coolant into the exhaust
system....most of the time yes, but not always. But I'm not saying for sure
its a bad head gasket...
- When you say the radiator looks clean....what does that mean? Are you
looking down into the Rad tubes and they appear to be open and free...the
few that you can actually see?
Here' my take. One, the water pump may have failed as the PO may have
put a super cheap one on ( and does the pump look new ). Or, you have a blockage in the radiator. Keep us posted.....

 

[Lumpy Grits]

Does this jeep have a fan-clutch?
How long has the new WP been in?
LG

 

[hole]

1st thought is wrong water pump (wrong rotation) and I would pull it to verify that fact if it were me at this point
2nd I'd make good and sure the lower radiator hose is not collapsing while running, make sure the coil spring is in it and/or not corroded out.
3rd How did PO bypass the heater core?

 

[Lumpy Grits]

"How did PO bypass the heater core?"

Easy-Just disco the 2 hoses at the firewall and connect'em together.
LG

 

[007]

"How did PO bypass the heater core?"

Easy-Just disco the 2 hoses at the firewall and connect'em together.
LG

That is how it should be done, but not necessarily how it "was" done, but that's probably not it anyway.

I think the V8's are more prone to this, but some of these need up on ramps in front when ran with cap off to be "burped" well.

You've been given good advice...in no particular order...

Lower hose issue? (just replace as cheap as the are)
Pump moving water? (don't be afraid to pull hose and monitor flow for a few mins)
Radiator blockage? (new radiators can block easily when loosened crud from block comes loose AFTER a flush or due to increase flow from a good radiator - been there)
Head gasket? (try some leak-down tests for an obvious issue)

Frustrating for sure, but one step at a time will find it...

 

[Lumpy Grits]

OP-what is the color of your engine's oil? Is it a 'milky color' at all?
LG

 

[Kappy415]

I checked the water pump direction (it was correct) and be heater bypass configuration (it was correct per LG above). So I finally took it to a rad shop and asked them to pressure test the system. As soon as they did, we found a pinhole leak. They soldered and re-rodded it. I reinstalled and all looks to be fine now. No more leaking coolant.

Thanks all for the help and sorry for the delay in getting back to you. Finally got back on via my phone


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