Coolant Explosion

Hi all,

was driving the ‘80 CJ5 and someone told me I was spewing fluid on the road. Noticed I was indeed overheating and pulled over. When I got the radiator cap off, it was empty. I noticed that the thin black hose running off the drivers side of the radiator was not connected to anything where it ended near the front bumper (see photo).
As always, any help/advice is much appreciated.
John

 

That should be just a coolant over flow hose.
It would go to a recovery tank on a newer vehicle.
They normally just drained on the ground in the older vehicles.

 

X2.

You need to determine the cause. Was this a sudden thing, or long time in development?

When did you last check the coolant level?

 

Any gauges in the ' 80 ? ...... Or just lights, which are usually too late , btw

 

Know of any good YouTube videos or articles re: troubleshooting the issues?

It did have a very light leak before.

 

temp and oil pressure gauges

 

No need for you-toob. That's yore problem right thar.

Opening the hood more often is the first step. Folks who are used to new cars may not understand that in the old days, they required attentiveness as a routine responsibility.

Let's start with the easy stuff. How often do you check the coolant? (Are you aware that you should leave an inch or so space for fluid expansion?)

Then, how fast was it leaking down?

 

It is a wonder that we ever got by without Youtube prior to the interweb.

Pete is right. Slow leaks usually get worse, and when enough leaks out your engine will overheat for sure. So first find and fix the leak, should be easy to see where it is leaking. Then keep an eye on coolant level.

 

Hard to find leak when it’s empty. Should I just refill it and start it up to find the leak? Alternatively, should I just replace the original 43 yr old radiator instead? Thank you much.

 

I understand and I’m attempting to learn with no prior experience. Condescension noted though. Service manual says to check every 5 months - it was good 1 month ago when last checked. TSM also says to fill coolant to “1.5-2 inches below filler neck.” No note on how the F you measure it. Am I supposed to eyeball it or stick a ruler down there?

 

It is just an approximate type thing. If you get a little too much it will just squirt it out that little tube going down to the bumper. If you don't have enough you should notice a little higher reading on the temp gauge.

 

The coolant will expand in volume as it heats up, therefore by leaving the level down about 1 1/2" there is space within the radiator for it to accommodate the expansion.
Modern vehicles address this by use of a catch can. The heated & expanding coolant is directed into the catch can (also called the overflow reservoir, recovery tank, etc.) and retains it there until the vehicle is shut off, afterwards the coolant will cool down, shrink in volume and be drawn back into the radiator. The semi transparent catch can is often marked with levels indicating hot and cold and you can see the coolant level through the plastic tank. Many modern day vehicles actually have the radiator cap mounted on the catch can instead of the radiator.

If it were mine, I would refill the radiator to the appropriate level and operate the Jeep while monitoring the coolant level closely over a few warm up /cool down cycles to check for leaks. It also may be as simple as replacing a defective radiator cap. There are tools that can pressurize the cap to check it's relief pressure and the same tool has adaptors to pressurize the radiator to perform a leak down test.
You may be able to rent one at your local automotive parts store.
https://www.autozone.com/loan-a-too...stem-pressure-testing-kit-22-piece/449951_0_0

Here is a picture of the one I own, it is basically a hand pump and an adapter. back in the day there we not as many variations of radiator caps and related radiator necks so my old school tool only has one adapter.






Radiator caps do fail and if yours did that would be the best case scenario because it is relatively a inexpensive and easy fix to just replace it.
Good luck!

 

I apologize.

However it is a very real problem in society today that making the effort to develop 'problem solving' skills seems to be replaced by the urge to click on an app.

Owning an early Jeep is an ideal opportunity to practice some basic detective work. Think it through, one step at a time. Logic will be rewarded and self confidence gained.

Maybe the FSM said inspect every five months, but if so that was when the Jeep was new - half a century ago. Your choice to own an antique vehicle brings the need to monitor it with extra attention. Take pride in doing that.

 

If I were in your shoes, I would start by establishing some baselines and observing the patterns that follow. The first thing to know is how severe this problem may be.

Refill the cooling system to spec, with correct blend of coolant.

Run the engine a few minutes, while watching it carefully from above around and under. Look for any obvious leaks.

After it cools (!) re-check the level and top-off if needed. Sometimes a system needs to be "burped" after a re-fill.

Run again, and if all seems normal, drive it normally and gently for a while. Again, check the level often and look for clues if it diminishes. White exhaust fumes? Bubbles in the coolant with the cap off? Fluid ejected from the overflow? At what rate does the coolant loss occur? Temperature gauge behavior under different conditions?

DO NOT EVER REMOVE A RADIATOR CAP WHEN HOT! The sudden relief of pressure can cause the entire system to flash-boil. That is how the geysers in Yellowstone work. Seriously.

 

As several others have posted, that's not the place to start. Radiators do fail, but more likely the cause is elsewhere.
Pull the dipstick. Overfull can indicate a blown head gasket allowing coolant into the crankcase. Not likely since you have a visible coolant leak.
Conversely, combustion gases can over pressurize the cooling system, forcing coolant out the overflow hose. .

 

That's a good thing. Before your " Explosion " , You mentioned that you did notice the Temp gauge rising ? If So.....I agree with the other most knowledgeable fellas here. You may want to refer to your TSM regarding flushing your complete coolant system also. Could be a stuck thermostat or something simple like that ? Of Course, if your leak is found , it's only gonna get worse before that part is fixed, Eh

 

Your on it now...... Did you notice where ?

 

Did not the intermediates come stock with the coolant overflow tanks? The question in my mind is why it is missing and I'm suspect that the reason for that may have been it was blowing coolant all over under the hood. I would be running a compression check on this to check for a blown head gasket or maybe worse, a cracked head or block.

How long have you owned this Jeep?

 

Agreed.

But Baby Steps. Maybe it's just a tiny leak and wasn't noticed soon enough.

 

I think you have a plan, check the oil for water then fill up the radiator, run it and see if you can find a leak. I had a Grand Cherokee that would only leak after it was shut off. Without the engine moving coolant and the fan cooling it, it actually gets hotter for a short period after it's turned off causing the pressure to build up.