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2001 Mitsubishi Montero over heating

Tiny
EDDIE FORTNER
  • MEMBER
  • 2001 MITSUBISHI MONTERO
  • 6 CYL
  • AWD
  • AUTOMATIC
  • 122,000 MILES
2001 montero starting over heating. I replaced the thermostat but got same result. I removed the thermostat and it quit running hot for a couple months. Now when I crank up and run it will register on the temp guage half way to just above half hot. The guage will sometimes bounce up to 3/4's and back to half. Whenever I stop with the engine running the temp doesn't rise or fall. Whenever I shut the engine off and turn the engine back on in 1 to 20 minutes the guage is pegged out hot. After it runs for approx 3 to 5 minutes the temp guage comes back down to half way.
I put another thermostat in and within 5 minutes of running it pegged out hot. I could here the water boiling and tell by the tightness in the hoses that it was very hot. I unscrewed the vent bolts above the therm and on the top hose side it released lots of pressure but no water. I was able to remove the radiator cap and it boiled over. When I removed the therm it was still open so it was working correctly.
Any ideas?
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Saturday, July 18th, 2009 AT 1:09 PM

7 Replies

Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Hi Eddie,

The engine is definitely overheating and seems there are air in the system. Did you bleed the system after replacement of the thermostat?

When engine is cold, remove the radiator cap and check the coolant level. If it is low, loosesn the bleeder bolt on top of thermostat housing and fill coolant till no bubbles overflows. Tighten bolt and top up at radiator cap. Turn on heater to maximum and start engine without the radiator cap.
When coolant level drops, top it up and continue running till the level stays constant.

If the coolant in radiator is not moving when thermostat has opened, the problem could be a faulty water pump.

If the level maintains after some time and you keep getting air bubbles, the most likely problem would be a bad head gasket.

If level remains constant and no bubbles are noted, close radiator cap and restest. Top up reserve tank if necessary. If it is overflowing most of the time, either the head gasket or radiator cap is bad.
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Sunday, July 19th, 2009 AT 1:33 AM
Tiny
ANTUF
  • MEMBER
  • 3 POSTS
Hello Eddie, I have the same problem and would like to know if you solved it. Please reply. Thanks
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Saturday, January 29th, 2011 AT 7:23 AM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Antuf,

Have you done all those that I have advised?
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Thursday, February 3rd, 2011 AT 12:37 PM
Tiny
ANTUF
  • MEMBER
  • 3 POSTS
Hi, thanks for the reply. The car is in the garage at the moment fitting new nozzles. I shall try out your suggestions and get back to you asap. They are having a problem at the moment. The computer is reporting a faulty "main sensor" on the injector pump and it is causing high revs. Dunno what that is but this is Kenya and we have to live with our mechanics who do not possess the required training. It was okay when I bought it there.
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Saturday, February 5th, 2011 AT 6:15 AM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
If the Check Engine Light is indicating, get the trouble codes and let me know what it is.

High revs could be due to a faulty or stuck Idle Solenpoid Control Valve or lack of coolant in system.
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Sunday, February 6th, 2011 AT 6:05 PM
Tiny
ANTUF
  • MEMBER
  • 3 POSTS
Hi, Got the car back from the garage after replacing the the nozzles and serviced the injector pump. It is running really fine now but still have the problem of the resovoir filling up.I removed the thermostat which gave me better results but the car heats up as soon as I switch off the engine. There is absolutly no smoke and no moisture in the exhaust pipe, no bubbles or oil in the Rad. The garage mechanics came up with the conclusion that it might be the cylinder head gasket. Please HELP.
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Friday, February 11th, 2011 AT 10:13 AM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
If you have not replaced the radiator cap, replace it and retest.

If pressure still builds up, you have a possible fault with the head gasket.
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Friday, February 11th, 2011 AT 1:47 PM

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