Do I have a stuck thermostat?
 

I have a new "to me" 85 300tdt Euro model. I am planning on converting it to WVO. I took it on a long highway drive, 130 km/h, with the outside temperature around 0 celcius/32f. The best I could get on the temp guage was 60-65C. I live in Canada and if I'm going to drive this on WVO I need more heat than that. I appreciate the help

Peter

Yep...When you install the new one, the arrow goes up (if there is one), not a diffacult job.

Does that mean that his thermostat is stuck open or stuck closed?

thermostat
 

peter my experience with under heating has been the thermostat,what really happens is not sticking but the spring gets weak and the lower temp causes the thermostat to switch from block circulate to radiator circulate too early.
hope this helps

Thanks for the replies

I bought a jack and jackstands today and I will order a new t-stat. I have ordered a few parts throught my local Benz dealer, I can find them online a bit cheaper but when you figure in shipping to Canada then brokerage fees , I think the dealer is compareable. It's a lot easier as well and pretty close.

Peter

huh, imagine that, I just got in 5 minutes ago from replacing my t-stat because of the same problem. Temp is perfect now.

That would mean Its stuck open which is what usually happens when they go bad. If you put one in water with a thermometer and put it on the stove, you can see at what temp it opens.

It sounds as if you have a thermostat that is stuck open.

When you install the thermostat in put the large end of the unit towards the engine, i.e., the flat part should be facing our towards the top radiator hose. The bulb on the dack of the stat contains a liquid that expands when it get hot. As the liquid expands it pushes the center of the stat open and allows the hot water from the engine into the top of the radiator. If you watch your temp gauge as the engine heats up you will see it go past the normal temp and then fall back to the normal range. The falling back is an indication that the stat is working.

As was said you can check this out by putting the stat in a pan of boiling water. If you have a thermometer with a 250 deg. range you can tell at what temp the stat opens.