Coolling

i constantly struggle with keeping the heat down on the jeep.

i just had my water pump gasket blow changed it out and everything back together an i still can't keep it cool. it seems like there is always a air bubble in the upper hose. am i doing some thing wrong? is there any tricks or mods i can do to bleed the system of air?

second thing is the previous owner ran water in the thing and i don't think he ever changed it, every time i flush it and refill the next day the fluid is rusty in color again. this is probably the cause of most my problems. i have flushed the engine rad and heater core for hours till its clear coming out. when i had the water pump off inside of the engine looks clean. is there a product i can run to clear the rust?

and where could the rust be coming from?

any help would be great

Re: cooling

Trying to think of a humorous way to say that you should provide the readers of your thread the BARE minimum of information about your XJ, seeing as how they were produced for 17 years, 8 different engines, different transmissions, with or without a/c, those kind of things.

8? 4.0, 2.5, 2.8, 2.1.. which ones am I missing? Or are you counting the various iterations of the 4.0?

my bad i though i had that in my sig

99 sport 4.0 MT with ac

RedChuck said:

my bad i though i had that in my sig

99 sport 4.0 MT with ac

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Yeah, no sig on unless you go "RED".

Ok, the bad news is that running water (a**uming TAP water) is really bad for a cooling system.

Here is what I would do:

1. Buy a commercial flush, not the 15 minute kind but the one you leave in the system for 500 miles. Follow the directions.

2. After you have drained and neutralized the flush agent, install a Stant SuperStat Premium 195 degree thermostat. It has built in features for stabilizing engine temperatures.

3. Fill the cooling system with 50/50 mix distilled water and coolant, and don't forget to fill the recovery bottle to the "cold" line. Install a new radiator cap--no flappers, just get a standard cap of the correct pressure. Go for a short drive and then park it with the nose up with the radiator cap at the highest corner. Then let is sit and cool down for 30-minutes or more. That should get most of the air out of the system.

RedChuck said:

i constantly struggle with keeping the heat down on the jeep.

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When ???

Normal driving ?
Hot weather ?
Towing ?
Offroad ?

All of the cooling components need to be kept in known good condition.

RedChuck said:

i just had my water pump gasket blow changed it out and everything back together an i still can't keep it cool.

Click to expand...

Replaced water pump as well as gasket ? .... If not .....
Was the impellor housing corroded out ?
Were the impellor fins in good condition ?

RedChuck said:

it seems like there is always a air bubble in the upper hose. am i doing some thing wrong? is there any tricks or mods i can do to bleed the system of air?

Click to expand...

Take your time filling the system ... Pouring it in, in a rush instead of letting it slowly fill, will in most cases cause an air pocket.

Park nose up, remove the thermostat temp sensor during filling and a bunch of others info like from joe_peters on the forum will help with the "air pocket" issue.

RedChuck said:

second thing is the previous owner ran water in the thing and i don't think he ever changed it, every time i flush it and refill the next day the fluid is rusty in color again. this is probably the cause of most my problems. i have flushed the engine rad and heater core for hours till its clear coming out. when i had the water pump off inside of the engine looks clean. is there a product i can run to clear the rust?

and where could the rust be coming from?

any help would be great

Click to expand...

Clean water wont hurt in the cooling system ... but there is rust issues if its not changed out regularly. The anti-freeze additive needs to be used according to YOUR weather conditions.

The 50/50 mix is a factory average anti-freeze/water spec

68% recommended for max protection against freezing conditions ... however that same concentration - in a warmer climate / summer - will cause overheating issues ... as can the 50/50 mix.

44% is the recommended minimum mix ... However I use even less anti-freeze for my vehicle ... but just enough to ensure some lubrication/corrosion protection ... It also gets flushed/changed regularly, rather than being forgotten about because the supplier claims some gazillion mile life expectancy of the product

Thermostats are fun things :laugh:

IF all your cooling system is in good condition ... and set up for YOUR operating area ... and its still running warmer/hotter than you would like ... experiment with some thermostats.

Get the operating specs from the manufacturer of the thermostats and try lower temp units ... or even 195'f temp thermostats with faster opening / better flow characteristics than the factory, chrysler thermostat.

Anything lower than 180'f is IMHO totally unnescessary/waste of time ... but there are a number of brands with half a dozen different temp ratings in the 180-195 range.

A thermostat change is not a fix for a dodgy radiator or waterpump or whatever tho ...

:cheers:

One of the disadvantages of 180 or 185 Stats is that the engine expects to run at 190 min. The ECU may go in to cold/start mode below the 190 level causing fuel enrichment to warm up the engine to the required 190 min, which it will never reach or it will cycle excessively. On later models it may set of the CEL

sjx40250 said:

One of the disadvantages of 180 or 185 Stats is that the engine expects to run at 190 min.

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For some reason ... that is the general presumption :dunno:

sjx40250 said:

The ECU may go in to cold/start mode below the 190 level causing fuel enrichment to warm up the engine to the required 190 min,

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And yet anybody with an OBDII XJ can buy a cheap computer reader and watch the open/close loop function occur within minutes of start up and at about 68'f from a cold start.

On this forum there is information on renix testing by a member that indicates that system also doesnt need to be anywhere near 190' for loop changes to occur.

Information that is lacking is that for the OBDI XJs ..... However a factory option 180'f thermostat would certainly appear to reduce the credibility of the need for a 195' thermostat only.

sjx40250 said:

to warm up the engine to the required 190 min, which it will never reach or it will cycle excessively.

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required ????
never reach ???
cycle excessively ???

All the above are totally dependant on ambient weather conditions and driving conditions/vehicle cooling system quality ... which requires the veh dvr to make the correct decision about which thermostat best meets thier driving requirements.

sjx40250 said:

On later models it may set of the CEL

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A CEL should occur on both OBDI & OBDII vehicles ...... mil code 17 and P0125 which according to the factory manual needs a condition of .....



I find it all rather peculiar that the only specific temps mentioned in the FSM are

The vehicle is fitted with a 195'f thermostat ... yet doesnt specify it has to be .... in fact the only warning is "not to run without a thermostat" ... and
20'f - as in the DTC list.

Just where did this "must have" 195'f thermostat & open/close loop stuff come from ???

And why do so many apply it to all XJs ????

well put in a new water pump new stock thermo new coolant 50/50 mix new gaskets no leaks pressure tested.

jacked the cap side ran it for a 1/2 hour with the cap off topped it off now its time to try and over heat it ac on and hills but its 77 and humid so i don't know if it will. be hot enough to tell.

it boiled over the other day when it was 90 with ac on flat ground i let it cool and ran the heater till i got home parked it and drove Tj hopfully it will not over heat cause i want the ac. ill update if it is still

i think im going to flush it again in a couple of weeks with the commercial flush and hopefully clear the crap out. oh and get a new rad cap.

i need to come up with an easier way to bleed the system. i had the beast up on a loading dock ramp and let it run for 30 mins and still felt like there was air in it. it seams to be running good now but what a pain in the arse.

I am a firm believer in this mod on RENIX motors. It's a t-stat housing out of a junked 94. Remove the temp sensor, insert petcock valve. Fill at upper radiator hose, then pressure bottle until no bubbles come out, just coolant. Run, repeat, etc.

I had issues untill I got an OEM Thermostat

JJacobs said:

8? 4.0, 2.5, 2.8, 2.1.. which ones am I missing? Or are you counting the various iterations of the 4.0?

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2.5L CARB, 84-85
2.5L TBI, 87-90
2.5L MPI, 91-00
2.8L GM, 84-86
2.1L Renault turbo diesel, 85-87
2.5L Italian VM turbo diesel, overseas XJs
4.0L EFI, 87-90
4.0L MPI, 91-95/updated 96-99/distributorless ignition 00-01

Do you have the correct rotation pump installed?

urbanXJ said:

I had issues untill I got an OEM Thermostat

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That's right. A cooler t-stat will NEVER control maximum temperatures

ParadiseXJ said:

That's right. A cooler t-stat will NEVER control maximum temperatures

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Aahhhhh .... someone who understands thermostats ... :thumbup:


In fact NO thermostat can control maximum temperatures. They are a minimum temperature control device.

It is only a valve that keep liquids in the engine until it gets to the approx temp, set by the thermostat.

After that it opens & closes by varying amounts in an attempt to keep the engine temp at the approx temp setting of the thermostat.

If the cooling system (rad, pump & fans) is not providing liquid of a sufficiently cold temperature and at the correct quantities, for the thermostat to use to mix with the engine heated liquid ... then the temp of the cooling system and the engine keep rising until - :explosion

How can one improve the provision of cooler liquid from the cooling system to the engine ??? ....

a). by fitting a lower temp thermostat which allows more flow ... sooner
b). by fitting a high flow version of the original thermostat.
c). improving the cooling system.

The benefit of doing this is of course totally dependant, on taking into consideration the other things that control ... and cause vehicle temp fluctuations.

Some things that control maximum temps are ....

Design and size of the cooling system,
Windchill factor on the radiator,
Driver imposed load on the engine,


Some causes of high temps are ....

Dodgy cooling components,
High temp setting thermostat with a late fully open status,
Design and size of the cooling system,
Windchill factor on the radiator,
Driver imposed load on the engine,

:cheers: