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overheating aftert T-stat change
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Author:  TJ2 [ Fri Jul 30, 2010 7:19 pm ]
Post subject:  overheating aftert T-stat change
I put a new t-stat in yesterday, then drove around a little to check coolant level and get rid of air.

All was well until I went over 'the pass.' It's an 1800 ft elevation rise in about two miles on either side. It's a trip I make about ten times a week.

The coolant gauge topped out before I hit the top of a two mile climb. Ambient air temp was about 93 F. I couldn't see the fan in the bright sun, but looked at it with flashlight after dark. I looks just like a radiator fan doing its thing. The coolant gauge sits right in the middle when driving on the flats. . . with the ac on or off.

The FSM says the air pockets should be gone within a hundred miles or so. Also, my coolant level is still a little high. I'll correct that after things get ironed out.

Any ideas?
Author:  kapalczynski [ Fri Jul 30, 2010 8:15 pm ]
Post subject:  Re: overheating aftert T-stat change
Check your fan clutch, sounds like it may not be working. The little electric pusher fan should have kicked on as well, but it doesn't do much. 90% of the time our jeeps don't even need the main fan. The thing is hardly used, but going up a long hill with torque converter locked or towing it is definately needed. Many CRD's remove the main fan for fuel economy, but I don't like that idea for the simple reason you may need it going up a long hill, etc. It is quite possible it has gone out and has been out for awhile and you never noticed. This was the story with mine, only 2 times did temp ever go above half, both times I did not hear the fan clutch engage. I completed this simple test and found mine had gone out.

Procedures to check your fan clutch:

Insert cardboard right in front of radiator (behind grill to block off air flow through radiator) and hold engine at 2400 RPM's.
Listen for the fan engagement. You should hear a SIGNIFICANT ammount of air flow change when the fan clutch engages. It is loud and obvious.
Use a scangauge or keep an eye on the coolant gauge and don't go over 225* F (exactly 5/8 mark on the gauge) for the test!!! Should lock up at 195*-205* F, and unlock at 145*-185* F (Per the OEM Jeep Liberty 2.8L Turbo diesel manual).


Oh, and if your fan clutch is bad, look into the "FFF Mod" as it is SIGNIFICANTLY better cooling than the OEM fan clutch and the setup is cheaper than a new OEM fan clutch alone. I towed a 6500lb truck with the jeep and with a higher than factory temp thermostat for about 40 miles adn temp didn't budge over the operating temp.

FFF thread link: http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=51618

FFF Pics:

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Part numbers and prices to complete the kit:

Flex Fan - Imperial Part number 223619 - 19" reverse direction High flow flex fan(Advanced auto - free shipping from local store - $28.99):
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Adapter - Flex-a-lite part number 851 - 30 mm x 1.5 pitch flex fan adapter (Amazon.com - $43.07 - free shipping):
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Washers (used as spacer to allow clearance between engine accessories) - McMaster-Carr part number 93849A112 - (2 needed) (mcmastercarr.com - $4.58 each-2 needed plus shipping cost):
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You will also need 4 bolts and 4 lock washers to fit the adapter found at any hardware or auto store.

Total cost about $100. Cheaper than a fan clutch alone. :D

Good luck!

- Mark
Author:  TJ2 [ Sat Jul 31, 2010 1:46 am ]
Post subject:  Re: overheating aftert T-stat change
Thanks Mark, that was all good info. The thing is. . . it was not overheating with the stat stuck open. Getting too hot only started after I replaced the t-stat.

I'm looking at the coolant level in the expansion tank. I put too much in it at the first refill. Tonight, I let some out and it's about down to the 'cold full' line, but I don't see any expanding when it heats up. Doesn't the fluid level go up in the tank when it gets hot?

I'll check the fan clutch with your method tomorrow. It looks like the cardboard has to come up from the bottom to sandwich in between the radiator and intercooler?
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