Engine overheats

Thanks,

I will do that and let you know if the problem goes away. Do you have any concerns about aftermarket thermostats? The new one looked somewhat different than the old one - less material to it and obviously less expensive.

Mike

Well, I have replaced the temperature sensor and also replaced the thermostat with a new OEM one. Put everything back together and bled system and the problem is still there in fact worse. Maybe it is worse because I just did it today but I have run it through 3 hot/cool cycles and rebled the 2 bleed screws near the thermostat. It never boils over. The temp guage went up and down as it got warmed up but eventually worked its way to pinning the needle at hot. It seems hotest when the vehicle is idling. If I am traveling at medium to higher speeds and have the heater on hi it comes down somewhat. It is winter here so it is maybe 10 degrees outside which might be helping me a little. The radiator fan is in good condition with all blades looking normal and it spins all the time the car is running. The front of the radiator does not feel very warm and the hoses to and from it are not very hot either. The last thing I want to hear is the water pump - I changed the timing belt last year and that was a he** of a job and the water pump is underneath that yet. Any ideas?
Thanks
Mike

I checked the temp on the metal casting right where the sensor is with an infrared heat gun and when the needle was at very hot, the highest reading I got was 195. It was about 5 degrees outside so my guess is the thermostat was operating normally and the radiator was barely warm, maybe 80 degrees where the coolant comes back out. The engine is running perfectly and I really don't think this is an engine problem. I would suspect the guage too but there are many times when the temp reading is normal and I would think the guage either works or it doesn't. I have read some other posts that show a similar problem along with irratic readings from the fuel guage and this was attributed to the electrical board that governs the dash. I have had no issues with the fuel guage so far.

Hi all,

My '01 Montero is haviung the same exact problem. As of now I've replaced the thermostat, radiator cap, 2 coolant sensors ( I think one was called a "switch" - for the fan?). The belts and water pump, pulley and timing belt are all within 1 to 2 years old. I also cleaned and reseated the instrument cluster.

Car runs fine - just erracitally reads hot.

On this question, did you guys ever determine if the gauge was misreading or it was something else?

I am pretty sure my guage is misreading but the question is why. The sensor has been changed, It's possible that the guage is bad but I doubt that because there are so many times that the guage reads normal. There is an elecronic board that is involved with these functions and I am thinking along those lines. Does anyone know if the dealer can check for this or is it just a "replace the board and see if it goes away".

What part are you referring to when you say controller?

Thanks
Mike

Still working on this problem and I just realized that when I changed the temp sensor, I changed the one that has 2 contacts and I believe communicates with the computer. I did not change the smaller one behind it that I am sure is the sending sensor for the gauge. I am trying to find that part number but I keep getting the number of the one I replaced. Now I am pretty sure this sensor is the problem. I had been checking some other parts - the manual said to test the gauge, I pulled the cluster out and on the back of it I had 2 places to check for resistance. I was suposed to get 210 ohms and I got 246 which is probably in line. It also said to check the temp sensor with the ignition on and the wire attached and you are suppsed to get 9 or more volts - I got 2.4 volts. Pretty sure its the sensor. I didn't pull it out and put it in water and test.

Mike

I purchased a new gauge sensor and put it in today. I tested the old sensor and per the manual, in 150 degree water it should give 104 ohms of resistance. The old one gave about 230 ohms and the new one gave about 100. I put the new one in and now the guage goes even higher. It still starts off at cold and slowly moves up as the car warms up but continues up and now pretty much always stays at or above H. The other test the book talks about is to turn on the ignition and test for voltage on the tab of the sensor to ground and you should get at least 9V. I did that with the old and new sensor and I get about 2V. It goes on the say check the wiring harness and then replace the gauge. I can't think it is the wiring harness because I would expect either all or nothing. Do you know if the gauge is available anywhere other than a dealer? Any other thoughts?
Thanks
Mike

Your guage in the instrument cluster is faulty.

This is a very common problem in NM model Montero/Pajero's. Check with your local dealer about a replacement guage.

Did you ever find out the source of the problem? I've been dealing with the same problem. I have replaced the thermostat and sensor and did a complete flush and the gauge still reads hot.

Im having all the same problems as those listed above. Also having sparatic issues with after backing out from garage puttin into drive from reverse, theres like a pause or its in nuetral for 2seconds or so, then it will engage with loud clunk into gear and go. Yesterday I had only gone 1/4 mile if that and the service engine soon light came on and the car started acting sluggish sparaticallylike as if had clogged fuel filter. Was doing this shudder here there, wasnt nonstop consistant shudder vibration, butacted as if going to run outa gas. Went 3 miles and parked the temp guage in dash actually reading normal bit less than half the entire time but when parked engine totaly overheating with steam comin from under hood. Checked and topped off water after let cool abd went to autozone for them to check with diagnostic and came up with OSS sensor failed. Would that cause some of probs having?ReaDING OF THAT INSTRUMANT CLUSTER, HOW MUCH IS THAT?My daughter needs use of this vehicle when she goes to college but dont want her to break down. Thanks for any help
stacy

I have a 2001 Montero Sport with 365,000 miles. I experienced the same over heating problem as everyone else on this post. I did notice when I replaced the water pump that the fins where smaller on the after market pump than the original pump. I suspect that most after market pumps do a poor job of circulating the water.
If you tried everything else it might be time to buy an original pump from the dealer.

The fix is actually pretty easy for free. Or its a $200 part your choice. I've had a 2002 Montero Limited and Im currently driving a 2003 Montero Limited. Both had the same problem. This video on Youtube walks through the steps to fix it yourself. You'll need a soldering iron, or a heat gun with some flux to heat up all connections and let them re-melt and reconnect. the Resistor R10 on the inside of the white module, that is behind the speedometer the solder joints have cracked. Heating up the entire board worked for me on the 2002 montero, just dont touch the components after you have used the heat gun OR all the electronics will just shift and you'll be buying a new module. Also the module stores the mileage for the vehicle and it has to be re-programmed to the same value as your old one so that means a dealer trip. The EASIEST fix is go buy yourself a $20 soldering iron with a fine tip, some silver electronics solder from Radio Shack or then simply touch for a fraction of a second on the right and left side of the Resistor R10. It's a very small rectangular resistor. If you touch it for more than 1 second you can completely dislodge it and you're buying yourself a new Module. Also if you DONT do the last part from this video of clicking down the speedometer face AFTER you are replacing the module, the speedo will NOT work or it will seem stuck or not work at all. That fix is the last part of the video where you take off the clear plastic cover of the speedometer module, and press the face at three points, which then "clicks" into place on the Module which is mounted right behind the Speedo. The video is here: https://www.youtube.com/watch?v=JMI0_TezfwQ there is another way to fix on the cheap if you dont want to solder. it's buying a used speedo on ebay, pulling the speedo module out and replacing it in your cluster. dont forget to do the click the front face of the speedo -- as well or it will not work properly (the speed) it will be jerky or look stuck or just not work right. WHILE you're in there with a new / used cluster, test each of the bulbs and replace any burned out instrument cluster bulbs. Here is the second video on replacing the Speedo / Temperature gauge module https://www.youtube.com/watch?v=t4Jl06XOmqs Hope that helps everyone. John

Regarding purchasing a new module. If you decide to buy a used Speedo somewhere like ebay. I tried to find one that had mileage that was close to my mileage so I wouldn't have to pay a programming fee at the dealer. John