Hi

1993 240 wagon, NA.

The car is running quite cold. Granted, it is very cold here (WI, 5deg F +/-) but the temp indicator gauge never goes above 25% up, even after 30 minutes of driving or so. I'm pretty sure the gauge works (it is not stuck at the bottom at least), but I cannot tell what is going on.

Also, heater is blowing cooler than usual (i.e. not burning my leg when I crank it).

Coolant level looks fine, and coolant is pretty much same color as new.

I have tried squeezing the coolant tubes going from radiator to engine to overflow reservoir, the top tube is quite hot, the lower tube is quite cool. Is this normal? Squeezing either one causes the fluid to squirt in the overflow res from below.

Can an air bubble work into the cooling system and prevent normal flow? Is there a pump that moves the coolant, or is it just convective? Idiot engine light is illuminated, and engine is throwing codes 121 and 231, but I'm pretty sure that is unrelated (just another dying AMM).

No idea where to start on this one, so any suggestions would be welcome.

Happy new year!

Thank you all for the advice!

I will order a new thermostat, looks like IPD has them in stock.

Now at least I know where to start.

Best regards

I just replaced my thermostat with one from NAPA. Works great, and a whole lot quicker than waiting for IPD.

Mark

Usually thermostat as others said but I had this a couple of months ago and it was a bad thermostat gasket - the ring inside. Coolant leaking past.

I put cardboard in front of the radiator until I could get to it. My gauge was ~ 25% and w/ a new gasket it's just under 1/2 which is what I expect.
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240s: 2 drivers and some parts cars

Classic thermostat failure symptoms. The fact that your heater is blowing cold seals the deal. No matter how cold it is, your engine should always warm up to approx. the same temp: it will just take longer. I had an '83 in Minneapolis for 5 years and it never took more than 10min of city driving to warm up.

Just replace it. It's easy to do and costs about $10. Have some 50/50 on hand 'cause you will lose some coolant in the process. Your car will run better, too. It could explain the codes, but I'm not familiar with them. I'm more of a pre-'86 guy (no OBD)

Charlie
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1985 244DL B230 M46 170k

The upper radiator hose is hot. Good, that's coming from the engine. The lower hose is cool.. Good the radiator is doing it's job.

Maybe the Hot upper is , in reality, not as hot as it should be because the T'Stat is stuck open a bit.


OR you have a combination of a bad Compensation board combined with it just being really cold.

Is there plenty of coolant in the reservoir? There should be some in there even when the engine is cold.

Otherwise, check the T-stat.

-Ryan
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Athens, Ohio
1987 245 DL 314k, Dog-mobile
1990 245 DL 134k M47, E-codes, GT Sway Bars, GT Braces, Draco Wheels
1991 745 GL 300k, Regina, 23/21mm Turbo Sway Bars

" Is there a pump that moves the coolant, or is it just convective?" Ofcourse the lower rad feeds it coolant from the radiator, it is called water pump. How about idling, did you try to idle for 10-20 minutes. I guess it is just too cold.

Another thing is check your thermostat ? is it there or if it is stuck open , if so then it will take a looong time to heat the car.

You can also replace the thermostat with hottest 92 deg thermostat.
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DD-1990 240 DL SW M47II FI 3.1 234 K miles

Thermostat? air bubbles will work there way to expansion tank.