Hi all,

I bought a 2000 cherokee with 170k miles on it for a crazy good price. I was told that there was no coolant in it and that the waterpump was busted, so I had it towed up to my house, and over the holiday replaced the water pump, thermostat, thermostat housing and the serpentine belt.

I filled the radiator, overflow tank, and the engine block (through the thermostat housing) with 2.5 gallons of cheap green antifreeze, reconnected all the hoses and went for a drive. towards the end of the drive the engine temp got to over 210 and when i parked i saw steam hissing out of the general area of the thermostat housing (i think it was coming from the point where the upper hose connects, but i'm not sure).

This is the first time i've worked on a cooling system, so a few quick questions:

1) is the upper hose supposed to be filled with coolant when the engine is not running? I can feel the hose is empty.

2) how much antifreeze does the thing take? I read 3-4 gallons, but i could only fill two and a half before it started spilling everywhere.

 

Did you install the thermostat upside down? The coil should face the engine.

 

pretty sure I did it right, that's the only way it would fit. Will double check if i have to pull the thermostat housing.

 

I hope that the PO didn't over heat it too bad because your year has a faulty head(0331) and are know to crack when over heated. Have you check the oil to see if it looks milky because of water/coolant has mixed with the oil if it does you have a bigger job ahead of you.

 

the little coolant drained out when i was changing the water pump didn't have oil in it, but i will change the oil and take a look.

I replaced the upper radiator hose, but it occured to me that if the coolant is boiling over, does it mean that it's not circulating? could the radiator be plugged up?

 

Yes, the radiator could be plugged up. Or not. There are a lot of possible reasons for your problem. Guessing here and guessing there might get you to the source of the problem, but it's really much more efficient to take things step by step and TEST your way to a solution.

So, is the radiator plugged? Don't ask us - test it. Take off the lower radiator hose and run some water into the filler. Does it flow through?

If not, it's plugged. If it flows through, it's at least partially unplugged.

By the way, yes, your upper hose should be full. These beasties are famous for needing to be burped after having the coolant drained. Do that by parking uphill, if you can. Best is if you can have the left front tire on a car ramp.

Then run the engine enough to warm it up so that the t-stat opens. Now add coolant. You'll be amazed how much more goes in!

Once you've done that, try again to see how it behaves. You may need to burp it a few times.

But if you aren't 100% sure about the direction of that t-stat, make sure before you proceed!

 

thank you for the pointer on testing the radiator, i did not think of doing that.
the tstat is in right, i checked when i pulled the upper radiator hose.

 

There ya go. So, check the rad, burp it, and try again.

Keep in mind that test isn't the final word. If the radiator is badly or completely plugged, you'll know it, but it may still be pretty gunked up and still allow some water through. But it might not be enough for good cooling.

But it's an easy test, and it will at least rule out an extremely plugged radiator, so it's worth doing.

 

It's impossible to tell how many of the rows/tubes of the XJ rad r clear or plugged unless the tanks r separated from the core and that's best left to a rad shop. The cooling system will self-burp after seveal heat/cool cycles. When the motor is cold is the time to frequently check coolant level in the rad, keeping it full. The front of the motor is higher than the rear.....no need to jack-up/lift/raise the front end to burp. Rad must always be full to the top of the neck and the bottle should be about half full, motor cold.

 

^^^ X however many times it needs to be repeated (apparently at least once a day)!

'91+ XJs with open cooling systems do not have to be burped by doing anything special except filling carefully and checking levels as djb383 states above.

I would add that if you use some patience when filling, you will not have to add a great deal of additional coolant after the first heat/cool cycle. The faster you attempt to cram the coolant in, the more you will have to add in subsequent cycle(s).

 

Followed your advice and got the air out of the system. The truck is running right at temperature now.

thanks all.

 

If you lift that left front, you only need to fill it once. Multiple cycles not necessary.

But if you prefer that method, go for it.

 

Only way to not have multiple cycles is to not drive it. Lifting the front is not necessary....even once.

 

Suit yourself. I know what works.