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Unread 05-05-2011, 10:17 AM   #1
jeep crazy
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Replaced tstat, and still overheating In need of a new radiator/water pump?

I have a '99 xj sport, and recently I've been having some overheating trouble. When I drive it, the temp slowly creeps up till about 230. Even if I have the heat on full blast it will sit around 215-220. It gets up to 230 even on short 15 min drives.

Backstory:

I replaced my thermostat about 6 months ago, after I noticed my Jeep had been running a little warmer than usual (Instead of 195, it was about 210). Then, a few months ago I was a on a road trip and my heater hose burst on the freeway and I lost all my coolant. Luckily, I was able to get it off the road, and avoided a blown head gasket.

I replaced the hose and did a coolant flush, but the Jeep was still running too warm. I noticed some sludge at the bottom of my overflow tank, but after a thorough flushing I thought I got it all out. I also bought another new tstat, since the first new one didn't seem to help.

So after all that, I've been driving with my heat on full blast constantly for the last few months, and I want to get to the bottom of this. I'm thinking of getting a new radiator and water pump, just to eliminate variables.

Any insight would be great. I'm stumped.

Thanks in advance.



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Unread 05-05-2011, 10:26 AM   #2
jeep crazy
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P.s. It has 140,000 miles.
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Unread 05-05-2011, 10:40 AM   #3
CJ7-Tim
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210 indicated on the dashboard temperature gauge is the normal operating temp.


Overheating cooling system

The cooling system is a group of related parts that depend on proper function from each of its component parts to keep the engine cool. Service the cooling system and replace any under-performing or suspected weak parts. Any component part of the cooling system that is not fully doing its job will stress the others and your cooling system will overheat. The most important maintenance item is to flush and refill the coolant periodically. Anti-freeze has a number of additives that are designed to prevent corrosion in the cooling system, but they have a limited life span. The corrosion causes scale that eventually builds up and begins to clog the thin flat tubes in the radiator and heater core, causing the engine to eventually overheat. Coolant should be replaced every 36,000 miles or every three years.



-Use a flushing/cleaning solution and then drain and fill the radiator with a fresh 50/50 coolant and water mix. With a neglected cooling system you may have to flush several times.
-Inspect the radiator for mud/bugs/grass clogging the outside and mineral deposits clogging the inside. Clean or replace as needed.
-Replace the thermostat with a STANT or Robertshaw 195* thermostat. Cheap thermostats are cheap for a reason.
-Replace the radiator cap if your Jeep has one. An old worn out cap will allow boil overs and/or allow the coolant flash over into to steam. You will see the coolant temps suddenly jump from 210* to the Red Zone and back to 210* if your radiator cap is weak.
-Inspect/test or replace the mechanical fan clutch. A worn fan clutch will allow temperature creep at stoplights, in heavy traffic, and on the 4x4 trails. A fan clutch that “looks” OK is not the same as working OK. Consider installing a Heavy Duty fan clutch such as the NAPA #272310.
-Inspect the electric cooling fan and the fan relay. Apply 12 volts and make sure the fan runs. Exchange the cooling fan relay with one of the others similar relays. Confirm that the e-fan starts when engine temps reach 215-218*. Repair or replace the fan or relay as needed.
-Inspect/test or replace the coolant temperature sensor that activates the e-fan.
-Replace the water pump. The pumping fins can deteriorate over time and the pump will not flow enough coolant to keep the temps under control.
-Inspect/replace the radiator hoses. Make sure the coiled wire is installed in the lower hose.

If you have covered all the points listed above and still have overheating issues, inspect the head for cracks and head gasket for leaks. Exhaust gasses entering the coolant can raise the temperature of the coolant or cause steam pockets in the coolant that will temporarily block the flow of coolant

Read more about cooling systems here –

www.offroaders.com/tech/engine-overheating.htm

www.familycar.com/classroom/coolingsystem.htm
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Unread 05-05-2011, 06:37 PM   #4
keepishop
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Take a pressure washer to your radiator and clean all the dirt out of the fins. Probably will help a lot.
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Unread 05-05-2011, 08:12 PM   #5
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If all this is happening after your replaced your t-stat, I would replace it. It could be bad, sticking, and causing your overheating issues. Listen to Tim--go with Stant.
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Unread 05-05-2011, 08:21 PM   #6
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Originally Posted by jeep crazy View Post
..........I'm thinking of getting a new........., just to eliminate variables.........
When the variables are eliminated, the list gets really short.....probably disappears.
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Unread 05-05-2011, 09:52 PM   #7
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As CJ7-Tim said ... the cooling system is bunch of components that ALL need to be in good condition.

The thermostat is a heating device inserted into the "cooling system" .... Unless its faulty and sticking in closed/partly closed positions - it has no real relevance to running temps over what its rated at.

Since you're on your second thermostat ... its probably time to start inspecting/cleaning/replacing cooling system components.
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Unread 05-06-2011, 04:39 AM   #8
tjwalker
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Quote:
Originally Posted by jeep crazy View Post
So after all that, I've been driving with my heat on full blast constantly for the last few months, and I want to get to the bottom of this. I'm thinking of getting a new radiator and water pump, just to eliminate variables.
This.

You've already installed two stats, so it is unlikely to be related to this. However, stay away from cheap thermostats like the plague!

A new radiator AND water pump aren't particularly expensive, nor are they hard to install. Don't forget a new 16 pound cap (without a release lever)

If this were my XJ, it would get both of these parts installed. And quickly before a damaging overheat occurs.

I like all metal radiators and always buy a high quality NEW water pump. Never a rebuilt one.

And unless they have been replaced somewhat recently, a new fan clutch and all new hoses. These things are often overlooked and are nice to install when you are doing things like the radiator and water pump.

Dollar for dollar, there is no money spent for a better cause than with cooling system maintenance!
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