Water temp is a lot colder than normal

[beatshack]

Lately in the last few days, I've noticed my car warms up fine while idling, but soon as I start to drive at freeway speeds, the water temp actually drops! (even if i'm going WOT in 2nd and 3rd). It seems to be running colder in general, and water temp drops easily, and only seems to get up to normal temp (around 80 to 85 C) when I've sat at a few red lights.

I've double checked with my logger to make sure the gauge is just off, but the logger shows the same thing. Also, checked the water level and it slightly low but nothing major.

 

[vintagemuscle]

although you say your car warms up fine, maybe your thermostat is stuck open?

 

[eclipsh]

Sounds like a dead thermostat. I just fixed that problem in mine two days ago. It took longer to go buy the parts than to do it. Also, double check that you don't have any coolant leaks anywhere. If you do, you'll end up killing the new thermostat as soon as fluid levels drop too low.

Nice looking car by the way

 

[beatshack]

Thanks, I will do that.

 

[steve]

Over the years I've had three thermostats fail open on my DSM. Each time in the winter and I can tell it's happened becasue the car will warm up in the driveway and then go cold as soon as air starts flowing through the radiator and overcooling the engine. Normally the thermostat would close to regulate the temp.

Steve

 

[beatshack]

Steve, thanks

I don't know if it failed or just stuck open for a few days.. tonight on my drive home it ran at normal temp... but it is below 0*C outside, theres a chance it may have closed and got stuck closed again. Any how I'm going to replace it.

 

[toybreaker]

I, too am a member of the stuck stat club...

A few lessons I leaned the hard way...

Buy the new thermostat at the dealer. The oe piece is waaaay better than most of the aftermarket stuff.

Try to keep the cooling system full at all times. The t-stat lives pretty high up in the cooling system, and it'll run dry pretty fast if the coolant level drops much. And low coolant will kill a stat pretty quick...

Try and keep all the coolant hoses up to snuff. There's so many little coolant transfer hoses on these cars that it can be a full time job. However, the penalty for losing a hose can be an overheated and toasted motor. The hoses into and out of the heat exchanger at the oil filter seem particularly troublesome for me. Oil kills the bottom hose, and turbo heatsoak drys out the vertical one. If'n you spring a leak in one of the small hoses, you could quite easily run out of coolant and damage things...ask me how I know....

Apon t-stat repacement, make sure you get all the air out of the system. And set the coolant level in the overflow tank with the engine warm and check it often....