overheating and blowing resevoirs along the way.

I have a 1990 Laredo Automatic blah blah blah.

just put new thermostat, lower hose and resevoir with new hoses going to it. just did my headgasket3 weeks ago.

Driving around town and even going on the highway locally for short periods of time (30-45min) the jeep drives awesome.. never overheats etc etc. stays at 210 or below usually.

recently we were taking a trip to Somerset, PA and the highway to there is very hilly and mountainous.

my temp guage stopped working and is MAXED out passed red... even when off and cold. bout 1 1/2 to 2 hours into the trip, i started noticing a coolant smell. we pull over and i open my hood and my resevoir cracked and started shooting steam out of it.

im confused as to why my shit keeps overheating when on long trips like this? could it be my radiator having mud on it?

also why would my temp guage randomly stop working and read passed red?

Mud on a radiator :shiver: does not conduct heat very heat very well.

Temp sensors do go bad. Get A dealer one, the after market ones don't seem to read correctly. Check the connector on the Temp sensor too, if it is dirty or loose it defaults on the gauge to high temp maxing the gauge out.

We need more details on the the rest.

x2 with Ecomike.

Air flow through the CLEAN and CLEAR radiator allows for the exchange of heat. MUD is a great insulator--note the use of adobe construction in the Southwest.

On a closed system, such as your Renix XJ, the PRESSURE bottle is essential, without maintaining pressure on the system you will boil sooner.

so what u guys are saying is the bottle popped cuz my rad wasnt flowing good enough...

i ordered a new bottle and will clean my radiator good when it gets here..

but my temp guage problem is still wierd.. it was working Fine until the day of the trip..

could it be my water temp sensor located on the block?

Is your thermostat functioning, I would replace it any way.
How old is your radiator cap, these should be checked yearly and replaced every few years.
Clean the radiator, outside whenever dirty, as recomeded by coolant mfg or more often.
Is your temp OK after replacement of reservoir? These are required for the system to work correctly?
Sender and or gauge may have been damaged or failed, and need to be replaced? Why, because parts break, wear out and Just Fail.

Shred Bro Gnar Rad said:

so what u guys are saying is the bottle popped cuz my rad wasnt flowing good enough...

i ordered a new bottle and will clean my radiator good when it gets here..

but my temp guage problem is still wierd.. it was working Fine until the day of the trip..

could it be my water temp sensor located on the block?

Click to expand...

Q1: Yes, and it also probably popped becuse it is squeezed between the hood and shelf too much, due to Jeep design flaws. Some have lowered the bottle shelf bracked to correct this.

Q2: Once again, read post #2. It is the sensor on the top of the head, near the drivers side firewall. Clean the connector and retest it, then if cleaning and tightening the contacts does fix it, replace it with a dealer temp sensor.

93gc40 said:

Is your thermostat functioning, I would replace it any way.
How old is your radiator cap, these should be checked yearly and replaced every few years.
Clean the radiator, outside whenever dirty, as recomeded by coolant mfg or more often.
Is your temp OK after replacement of reservoir? These are required for the system to work correctly?
Sender and or gauge may have been damaged or failed, and need to be replaced? Why, because parts break, wear out and Just Fail.

Click to expand...

Reread post #1, it has no radiator cap, 1990 Renix, has the puke bottle, plastic bottle and cap.

His does not sound like a bad thermostat.

t-stat is brand new. im gonna go check the stuff ut old me to mike and ill reply later with whats goin on. my new bottle is on the way so it should be here prob couple days.

:viking: Hay soooo.

i took off the temp sending unit and clean it up and put it back on and voila temp guage star ts reading. i ordered a new one anyways.

stiill want to figure out why my jeep overheats on highways with hills....

i hope its just a dirty rad.

Yeah, check your PM.

The main reason you would over heat at highway speeds or under load is lack of circulation, either circulation of coolant, or enough air passing over the rad to cool the coolant. At highway speed, even on hills, you should have plenty of airflow (unless your rad is caked with mud). The other thing to look at is circulation of coolant. This would be restricted either by a clogged rad (inside) or cooling system in general. When's the last time you did a complete flush n' fill??

Thing 3 is an ineffective water pump.

Thing 4 is the pressure bottle and/or cap (I know it doesn't have the traditional cap, I mean the cap on the bottle). That plastic cap can crack, lose it's seal or just generally take a dump. No pressure = lower boiling point = overheat.

yea thanks so much for that writeup man. im def going to do that once i blow up one more time lol. but for now i think im gonna flush out my trans and heater core and take out my Ac condensor so i can really give the rad a good clean. thanks a lot for all the help and suggestions.