Over Hearting issue with 2000 Jeep Cherokee

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Bacci

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Good day All,


These last couple of weeks, i have been fortunate enough to have my Fathers Cherokee while my BMW is under the knife, but ive been experiencing some issues with the radiator and heating system.

While driving, a hear a loud "whistle" type noise when i release the gas pedal and only cold air comes out of the fan. The temp gauge climbs and descends very little but enough to say its not steady... 2-3 mins of highway driving, then BAM... Check Gauges - Temp overheating. So, i pull over... wait 2 min and start it up and everything works fine... :dunno:

I noticed it deosnt do it all the time & only when i have the Windshield defrost on. There is a sufficient amount or prestone in the truck, so i figure thats not the problem.

Anyone have a suggestions as to what it can be?
I seek the advice of the wise on this one.

Thanks in advance,
Bacci
 
Well it really sounds like a problem in the cooling system to me. When was the last time the thermostat was replaced? it doesnt burn any prestone?
 
Well it really sounds like a problem in the cooling system to me. When was the last time the thermostat was replaced? it doesnt burn any prestone?

Well, the truck is a 2000 with 242,000 KM on it so its done alot of road. I am not suprised to see afew things start going on the fritz here and there (suspension, coolant system, brakes, etc)

Honestly, i wouldnt know when it was changed - i know the truck had a similar problem with the radiator 2 months back, but i dont know the extent of what was changed.

I would i know if the thermostat is deffective? :dunno:

Thanks again M85Iroc-Z.
 
its possible the thermostat is staying closed, or not opening fully. You can always test the termostat to see if it is opening, or you can simply change it (6-7$ part)
 
1) Could be air in the cooling system resulting from a coolant leak. This can cause the no heat inside and engine overheating that you mentioned. With that kind of mileage the possible sources for leaks are numerous including heater core, hoses, rad cap, water pump....etc.
Have you ever noticed any leaks on the ground after it's been parked for some time?

2) You may have too much water (and not enough antifreeze), which will of course freeze causing overheating and worse yet a blown head gasket or cracked engine block.

3) Two ways to check the thermostat;
- Crude way; Feel (squeeze) the upper rad hose as the engine is warming up. Once the thermostat opens you will be able to tell that the coolant is flowing through the hose. Note that it will only open once close to 200 deg F, temp rating is stamped on thermostat.

- Remove thermostat and hang in a pot of boiling water with a wire. Use a thermometer to follow temp of water, thermostat should open once temp setting is reached.

If you're not comfortable doing these verifications, then simply bring it to a garage for a cooling system pressure test, test strength (mixture) of coolant, and a leak check with dye if no obvious external leaks are found.
 
1) Could be air in the cooling system resulting from a coolant leak. This can cause the no heat inside and engine overheating that you mentioned. With that kind of mileage the possible sources for leaks are numerous including heater core, hoses, rad cap, water pump....etc.
Have you ever noticed any leaks on the ground after it's been parked for some time?

I have checked for leaks at the heater core, rad cap, water pump & hoses and did not find any type of leaking on them. :dunno:

2) You may have too much water (and not enough antifreeze), which will of course freeze causing overheating and worse yet a blown head gasket or cracked engine block.

The cooling system was flushed out & refilled no more than 3 months ago and was replaced. However - i did noticed that the coolant was a very pale white - and not the usual "toxic" green... Should this be flushed out again?

3) Two ways to check the thermostat;
- Crude way; Feel (squeeze) the upper rad hose as the engine is warming up. Once the thermostat opens you will be able to tell that the coolant is flowing through the hose. Note that it will only open once close to 200 deg F, temp rating is stamped on thermostat.

Ill take the time to test the thermostat as i fear this may be the root of the problem. Given that the problem is intermittent - i think its not kicking in right.

If you're not comfortable doing these verifications, then simply bring it to a garage for a cooling system pressure test, test strength (mixture) of coolant, and a leak check with dye if no obvious external leaks are found.

I havnt lost all hope yet! ;)

Thanks for the advice - I'll start from there.
Chris
 
I have checked for leaks at the heater core, rad cap, water pump & hoses and did not find any type of leaking on them. :dunno:

You should also crawl underneath and have a look just behind the water pump pulley to see if there is any staining around the weep hole.

The cooling system was flushed out & refilled no more than 3 months ago and was replaced. However - i did noticed that the coolant was a very pale white - and not the usual "toxic" green... Should this be flushed out again?

I would test it's strength first. You can pick up an inexpensive tester at Cdn tire or Walmart for less than $10. Then you will know if you need to add water or coolant or dump everything.

Ill take the time to test the thermostat as i fear this may be the root of the problem. Given that the problem is intermittent - i think its not kicking in right.

Could be, it's the cheapest part to replace so why not. Do yourself a BIG favor and DO NOT BUY the Cdn tire "fail safe" thermostat, they always tend to fail and by default lock in the open position. Better of spending a few more bucks and getting one from the dealer or auto parts.

Let us know what you find
 
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