- This topic has 19 replies, 10 voices, and was last updated 12 years, 7 months ago by
.
-
Topic
-
I’m working on a 1989 jeep cherokee the temperature gauge will register overheating did the car never acts like it overheats and it’s a closed system so there’s no radiator cap but the antifreeze seems to evaporate where is it doesn’t act like a blown head gasket I put in a new thermostat and a new sensor as well as a new instrument cluster in the same identical problem happens. could it be the radiator? any help would be greatly appreciated
-
Replies
-
Quoted From guitarranger11:
I’m working on a 1989 jeep cherokee the temperature gauge will register overheating did the car never acts like it overheats and it’s a closed system so there’s no radiator cap but the antifreeze seems to evaporate where is it doesn’t act like a blown head gasket I put in a new thermostat and a new sensor as well as a new instrument cluster in the same identical problem happens. could it be the radiator? any help would be greatly appreciated
Throwing money at a problem usually might eventually solve it. But testing before spending will save you money and allow you to purchase some nice tools with what you saved by analysis and testing. Save those parts you replaced they’re probably good.
I checked the oil and It’s a nice caramel color still (did oil change about 50 miles ago). I’m gonna try the air in the system and then I will post my results
I had that same problem on my 1974 Pontiac Firebird once and replaced the radiator and the problem went away.
But are you sure that you didn’t blow the head gasket? Pull out the oil dip stick and see how the oil looks like! If you see colors like white or coffee whit cream , then you blew the head gasket….you need to check the coolant level. if there is no radiator cap. then follow the small hose to the over flow tank.
look inside there. there should be marks min-max the level should be at max when the vehicle is cold.
as suggested above check the oil for a milky color. do you see any unusual white smoke out the tail pipe?
seeing you just changed the t-stat you maybe air bound. you will need to bleed the air out. heres a video to
help you do that. you will have to run yours with the over flow cap off. good luck and keep us postedC8-)Here is also another useful video if the bleeding does not help by Eric –
http://www.youtube.com/watch?v=hUzOTnsWImI
The coolant pressure tester and block testers can be rented from your local parts store.
Quoted From guitarranger11:
I checked the oil and It’s a nice caramel color still (did oil change about 50 miles ago). I’m gonna try the air in the system and then I will post my results
What is the condition of the water pump and its drive belt? A loose belt may not drive the pump or the pump may be weeping coolant. This could cause an overheating problem also. How much coolant is lost over what period of time? You may be able to get a loaner tool (with a required refundable deposit ) from your local parts store. If they have a coolant pressure check tool I would suggest borrowing it to test your cooling system. It may tell you where the coolant is going. If you put in a new radiator remember that most require a 50/50 mix of coolant and distilled water be used to validate warranty. I use water from my basement dehumidifier as it is close to distilled, no chemicals as in tap water
My bad I forgot to mention that I replaced the water pump as well it sprung a leak so I did replace it. I bled the system and same problem so now onto the radiator. I have to say I am starting to feel stupid and I am wondering if my customers think I am because I have moments of not diagnosing right the first time.
Quoted From guitarranger11:
My bad I forgot to mention that I replaced the water pump as well it sprung a leak so I did replace it. I bled the system and same problem so now onto the radiator. I have to say I am starting to feel stupid and I am wondering if my customers think I am because I have moments of not diagnosing right the first time.
A good $300 scan tool would tell you how hot the coolant temperature gets before the fan kicks in, how hot it is when the fan stops and a whole lot more. I don’t remember, did you check that the fan is coming on and that it is installed so that it is pulling air through the radiator not trying to blow it against the air that comes through when driving. My son installed his radiator so that it would blow against the air coming into the radiator when driving. No wonder he was running HOT.
Instead of using a scan tool, you can check the ECT with a DVOM on the ohm scale. The resistance of the ECT should increase or decrease (depending on if the ECT is a NCT or PCT thermistor). You would need to find a conversion chart to see what temperature would reflect the ohms.
Analog gauges are not very accurate.
Let’s back up a bit. You say the truck isn’t acting like it’s overheating. Cars won’t really ACT like they’re overheating until the condition causes a major issue, such as engine failure if you aren’t paying attention, or the rad/overflow tank spewing coolant. Let’s go over what you have done. You replaced the waterpump, and bled the system. Did you check the thermostat? If it’s stuck closed, overheats will occur, and t-stats are cheap. You can test a t-stat by pulling it, putting it in a pan of boiling water and watching for it to open at the temperature rating that is probably scribed on the t-stat itself (using a thermometer). Overall, you really need to watch the video posted by Dreamer, and run those tests. I’ll post it again, so you don’t have to scroll up:
http://www.youtube.com/watch?v=hUzOTnsWImI
Good luck.
Yea lets not replace anymore parts. You say you bled the system and that would be the first step, it can be a little different with an expansion tank but you do everything the same as in the video that was posted except you use the expansion tank as the ‘funnel’, you MUST turn the heater controls to hot so make sure you did that.
The next step would be to make sure the gauge is reading correctly and for that the suggestions above will work, keep in mind there is probably a separate sensor for the gauge on the dash than there would be for the computer, most systems work this way and to be honest I’m not sure of the set up on that vehicle. If you find the gauge to be working correctly but you still see an overheat be sure there isn’t a restriction of airflow through the radiator, sometimes leaves and debris can get trapped between the radiator and the condenser causing a restriction in airflow. Also make sure your cooling fan is working correctly and if you notice that the upper hose is somewhat cool to the touch after the engine warms up it’s possible you have an issue with the thermostat. Note that the lower hose will always be cool because it is the return from the radiator and it SHOULD be cool.
Quoted From EricTheCarGuy:
Yea lets not replace anymore parts. You say you bled the system and that would be the first step, it can be a little different with an expansion tank but you do everything the same as in the video that was posted except you use the expansion tank as the ‘funnel’, you MUST turn the heater controls to hot so make sure you did that.
The next step would be to make sure the gauge is reading correctly and for that the suggestions above will work, keep in mind there is probably a separate sensor for the gauge on the dash than there would be for the computer, most systems work this way and to be honest I’m not sure of the set up on that vehicle. If you find the gauge to be working correctly but you still see an overheat be sure there isn’t a restriction of airflow through the radiator, sometimes leaves and debris can get trapped between the radiator and the condenser causing a restriction in airflow. Also make sure your cooling fan is working correctly and if you notice that the upper hose is somewhat cool to the touch after the engine warms up it’s possible you have an issue with the thermostat. Note that the lower hose will always be cool because it is the return from the radiator and it SHOULD be cool.
You’re the man Eric, a good scientific explanation. I learned some thing today.
- You must be logged in to reply to this topic.