• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Boiling out at 220-230*

Starscream

Starscream

NAXJA Forum User
Location
Columbia, SC
Okay, I'm at a loss. I've searched and studied and can't seem to figure this out.

My Jeep will boil out most of my water through the overflow tank when it gets to around 220-230* when I shut it off. I realize that some water should flow back, but most of it boiling completely out isn't right.

I've replaced my water pump, temperature sensor, hoses, heater valve, radiator, cap, and fan clutch and it still is overheating.

My first thoughts are that my auxilary fan isn't working (I know it isn't, it only kicks on with AC) and that my radiator cap may be set for the wrong pressure (I'm not sure about this, I'll have to check my book). Even when I turn on the AC the fan doesn't seem to do much but stop it from getting hotter - it doesn't actually cool it down much at all.

I went to Uwharrie last weekend and since when it overheats it immediately loses most of my fluid, it makes for fun trail "repairs".

So... anyone have any ideas? I really need some help on this one - it's driving me nuts. I've tried everything I can think of except for drilling holes in my t-stat. Thanks in advance for the help.
 
thermostat....change it. mine was doing the same thing and changed it last week with a 195 degree one and now it runs down where it should and does not go above 205-210. it was going up to 230ish while waiting at a light. 5 dollar fix.
 
mk20rockeye said:
thermostat....change it. mine was doing the same thing and changed it last week with a 195 degree one and now it runs down where it should and does not go above 205-210. it was going up to 230ish while waiting at a light. 5 dollar fix.
Click to expand...
Ah, I forgot to mention that. I changed my thermostat also with a 195* opening. Thanks for trying to help out, though.

On another note, I was just reading through my repair book and it says that the I6 models don't have a radiator cap and that the overflow bottle has a pressurized cap. Mine has a cap and an overflow neck that goes to the bottle. That setup is for I4 and V6 models (according to my book).

What's going on?
 
Did you test it?

Oh...just noticed....you electric fan does not come on when the temp hits about 220? Fix that also, all bets are off until then.

Rev
 
What year XJ do you have?

Never mind I see it 96, it will have a cap because it is a open system, it does sound like your caps not holding.
You may need to do a pressure test and a sniff test.
 
Last edited:
Rev Den said:
Did you test it?

Oh...just noticed....you electric fan does not come on when the temp hits about 220? Fix that also, all bets are off until then.

Rev
Click to expand...
Ya, that's going to be tested along with the cap. The thing is - like I said above - that the fan doesn't really seem to cool it at all. It more or less just stops it from getting hotter and then it idles around wherever it was before I turned on the AC (to kick the fan on).
 
Well the XJ's without air don't even have a fan.
Your not plugged with bugs and weeds are you, it don't take much and no air will flow through the radiator.
 
Sounds like someone switched you over from a closed to open system. If so your cap may not be for that rad. I don't know my self if all Cherokee caps are the same or if the fill neck on your rad is the right one for a Cherokee (custom rad). That is a reach but stuff like that happens.
I would also bum an IF gun and check the temp around the engine.
I had the same problem when towing on hot days if I shut down right after a hard pull. Letting the engine run for 2 min after parked before shut down fix it for me.
Your E-fan should kick in at 230 or so. If your cap is wrong or bad it may be lifting before that temp hense the E-fan never kicking in. My E-fan almost never kicks in unless im towing or AC is on.
 
Last edited:
badron said:
Sounds like someone switched you over from a closed to open system. If so your cap may not be for that rad. I don't know my self if all Cherokee caps are the same or if the fill neck on your rad is the right one for a Cherokee (custom rad). That is a reach but stuff like that happens.
I would also bum an IF gun and check the temp around the engine.
I had the same problem when towing on hot days if I shut down right after a hard pull. Letting the engine run for 2 min after parked before shut down fix it for me.
Your E-fan should kick in at 230 or so. If your cap is wrong or bad it may be lifting before that temp hense the E-fan never kicking in. My E-fan almost never kicks in unless im towing or AC is on.
Click to expand...
Okay, are you saying that switching to a higher pressured cap (18lbs) would be a good idea?

I may just end up wiring in a stand-alone relay for my e-fan that automatically kicks on at 200 no matter what. It'd also help because if it every screws up in the future, all I have to look at is that relay and it's wiring.

What do you guys think? Is the relay a good or bad idea. I've been playing with going full electric for a while now.

EDIT: As far as closed and open goes, I think most '96s came with open systems. Someone correct me if I'm wrong.
 
Mine does this whenever there is air in the system.. Let it purge itself out, then when the coolant sucks back in, make sure the overflow never goes dry, or you'll get more air in it. Usuall takes me 2 - 3 times to get all the air out and then its fine.
 
so 16 psi is correct for the stock rad cap? stupid auto parts store told me 13 :smsoap: where do you find 16 psi radiator caps?
 
ok thanks maybe they will be smart enough to give me the right one
edit they list 13 psi on their site also. do I have to request a 16 psi cap?
 
Blue XJ said:
Mine does this whenever there is air in the system.. Let it purge itself out, then when the coolant sucks back in, make sure the overflow never goes dry, or you'll get more air in it. Usuall takes me 2 - 3 times to get all the air out and then its fine.
Click to expand...
Well usually when mine gets air in it's system it will begin to get hot within a few minutes. This began (today) after 3.5 hours of driving on the highway. I know for sure there will be air in it now since it's pumped most of the water out.
 
Just outta curiosity...when was the last time the entire system was backflushed...clogged water passeges can create symotons similar..
Also if you change the t stat install the FAILSAFE T STAT....the stat is designed so that if it does fail it will freeze open and not closed.......
 
Last edited:
Starscream918 said:
My Jeep will boil out most of my water through the overflow tank when it gets to around 220-230* when I shut it off. I realize that some water should flow back, but most of it boiling completely out isn't right.
Click to expand...

Your radiator cap is faulty. The idea of the cap (stock should be 16psi) is to allow the cooling system to pressurize thereby increasing the boiling point of the coolant to prevent cavitation (formation of bubbles) in the system. Each 1psi adds about 3*F to the boiling point so a 16psi cap raises the boiling point to ~260*F.
If your coolant is boiling away at a much lower temp., that means your radiator cap isn't holding pressure. Replace it with a new 16psi cap. If you can't find one from NAPA or Autozone, the stealership will stock one.
 
You must log in or register to reply here.

Similar threads

V
High temp woes
2
Replies
21
Views
413
Vitzaa
V
S
Issues flushing dirty coolant
2
Replies
29
Views
4K
fenns7
F
I
911: AC Panel Replacement, Coolant lines, Questions?
Replies
6
Views
1K
iamacynic37
I
Root Moose
Cooling System Reset (2000 XJ)
Replies
1
Views
1K
Rob Mayercik
R
J
XJ coolant overflow after engine is shut off
2 3
Replies
45
Views
7K
XJI6191
X
Back
Top