well i have had a on/ off problem with the TT running warm about 1 notch past half sometimes. i replaced the rad temp sender, the "Blue" sensor, and the fan control module, i noticed a few hundred miles ago the antifreeze was low so I added some, now I went to drive it today and it was low again, I have never seen any leaks in the garage. I dont drive it very often in the winter due to the bad roads around here. and I know from a previous civic and cadillac Northstar if a head gasket is letting go the antifreeze will be burned. I have never smelled any antifreeze in the engine bay. I also know they ran a little warm but not in the red hot when the head gasket is letting go . the car has right at 100,00 miles. what do you guys think? any diy for a head gasket install I guess i will do the timing belt again even though it was done at 75~80 k by the previous owner, but about 3 years ago. any test you guys would suggest?

 

I would say its the water pump, its a known problem with the TT. Since the T belt was done 3 years ago i would say its time to do the T belt and water pump combo again.
A blown head gasket would have oil in the coolant, and coolant in the oil. Not to mention white smoke coming out the tail pipe and severe overheating.

 

Plus coolent in the cylinders where you could see it with the spark plugs removed. They must have replaced the old wp with a plastic one again instead of metal.

Also it was and is still running G12 and ONLY g12 right?

 

Mine does the same thing now actually. This happened after I switched to the metal impeller water pump. When I look at the hvac temp it always gets up to 102c (1 notch over the middle) and then bam something kicks in and back down to about 96c. When i'm moving along it stays one below the middle.I'm thinking we both might have a flaky thermostat.

 

yep i got the G12, how much coolant for a full system flush do you guys think i have 2 of the smaller bottles from ecs, i already have a water neck and thermostat i never got around to putting on, and im going to do the darm timing belt and waterpump i guess ,,,is ECS still the best place to get one? the diesel geek site was shut down , I guess i will pull the radiator and give it a good flushing. also.. . And all this $$$ could have went towards mods.

 

Does it actually ever overheat? Or just does it go one past the center? Any driving behavior affect it? Or does it do thaht all the time no matter what?

 

not all the time & it doesent stay at one notch past half.. it will be at half then got one more notch, for a minute or two then back down to half.. Doesnt seem to affect where needle is when i drive it harder. on the hvac it will go 103 C then back down to 99 then another ten minutes back up, then down. then i might drive it for 45 minutes it it will never go past half the whole trip. it is driving me insane

 

sounds like a classic failing thermostat. replace it and see what happens. they're cheap and easy to replace.

 

I've had the same poblem with my car.
New T-stat will be in this weekend hope it helps.