Engine Temperature - PeachParts Mercedes-Benz Forum

Stevo · #1 11-04-2012, 05:25 PM

Quote:

Originally Posted by Jareb

Yeah, I called the tech and asked him about it and he said the 95 was normal and dont worry unless it gets above 100. I guess the fact that its only 5 degrees more until a problem is what had me a little concerned. When the car ran at 85...it didnt bother me. He also said, that the new Behr's are opening a little higher than the labeled 80 degrees. {Several posts on this forum confirm that}. I guess my original question was:
Do thermostats "wear out" over time like the one I had in the car? In other words does the opening temperature decrease a little over time just from the multiple opening and closings on the thermostat "valve"?. Does the valve get weaker?
Is the Wahler considered a better and more calibrated thermostat than the Behr?

Well I sure dont feel qualified to argue with a professional MB mechanic but I think 95 is about 5 degrees over what most folks consider normal operating temp.

rscurtis · #2 11-04-2012, 05:39 PM

There are two more things you can check. One is the bleed tube between the water pump housing and the block to make sure it's open. Next, try a different sender. I had to try three in my signature car before I found one that was accurate. I set up a portable stove with a pot of water, and immersed a thermostat, the sender, and a mercury thermometer and hooked the sender to the car with jumper wires. I had one sender that was indicating almost 100* just when the thermostat was opening and the thermometer showed the water was about 185*.

Jareb · #3 11-04-2012, 06:02 PM

It cant be the sender because we are comparing the temp before a coolant and thermostat change and after the change. The sender is a non issue. The temp before was 85 and after was higher. Even if the sender/gauge is inaccurate at 85; the temperature was higher after the service.
I took the car for a spin to double check what I am seeing on the gauge. There is a mark at 80 and one at 100 on the gauge so I assume that exactly halfway between is 90 degrees and 3/4 the way is 95 degrees. Looking at it closely; it seems to be probably about 92-93 on the gauge so thats a little better than my initial readings.
I'm nitpicking here and dont mean to imply that anything is wrong with the cooling system. It just seems that the new thermostat is probably beginning to open at a temperature higher than the indicated 80 degrees and is fully opening around 92-93. The old thermostat was fully open at 85 degrees.
Again, no biggy.....just wondering if this is common with a new Behr thermostat and if the Wahler's are more accurately calibrated; therefore better than the Behr's?
I guess the only way to find out is change to a Wahler and see the results.

t walgamuth · #4 11-04-2012, 06:14 PM

It may be self bleeding (though this is news to me) but if it has an air pocket it will still need to be filled when the pocket is bled out.

Stevo · #5 11-07-2012, 09:18 AM

Did you figure out whats going on with the higher engine temps? My 85 240 would appear to over heat after being on the road a while but it was the gauge which was verified with the infra red temp gun. A smack on the dash above the instrument cluster would drop the temp.

Jareb · #6 11-07-2012, 09:23 AM

Quote:

Originally Posted by Stevo

Did you figure out whats going on with the higher engine temps? My 85 240 would appear to over heat after being on the road a while but it was the gauge which was verified with the infra red temp gun. A smack on the dash above the instrument cluster would drop the temp.

My best guess is that the new Behr thermostat starts to open closer to 85 than the labeled 80 degrees and isn't full open until about 93-94 degrees. I have burped the system and done everything I can to ensure there is no air bubble, including driving the car 300+ miles. I may try a Wahler thermostat to see if it might be calibrated closer to the 80 degrees than the Behr?
Not too worried about it because the car is not overheating.

Stevo · #7 11-07-2012, 11:12 AM

Quote:

Originally Posted by Jareb

My best guess is that the new Behr thermostat starts to open closer to 85 than the labeled 80 degrees and isn't full open until about 93-94 degrees. I have burped the system and done everything I can to ensure there is no air bubble, including driving the car 300+ miles. I may try a Wahler thermostat to see if it might be calibrated closer to the 80 degrees than the Behr?
Not too worried about it because the car is not overheating.

I haven't heard of any problem with Behr T stats, their both OEM but if your temps are truly running much over 90 your right on the edge of where you should suspect something is not right. I think its better to run a diesel a little on the hot side rather than the cold side, as long as she doesn't hit the red.

Jim H · #8 11-07-2012, 11:23 AM

Quote:

Originally Posted by Jareb

...I have burped the system and done everything I can to ensure there is no air bubble ...Not too worried about it because the car is not overheating.

The Good News is that there is no hurry to change anything, eh? It sounds like it is working OK, leaving you time to drive it where you need to go and 'play' with it' later if you wish.

Me, I'd drive it a lot and see if anything changed, since I have far more projects that require my limited time and even more limited brainpower!

qwerty · #9 11-07-2012, 12:17 PM

Quote:

Originally Posted by Jareb

My best guess is that the new Behr thermostat starts to open closer to 85 than the labeled 80 degrees and isn't full open until about 93-94 degrees.

Fully open at 94 is precisely what is specified in the 617.95 Engine Manual.

If you are maintaining a fairly constant temp given changing engine load, it's likely that your thermostat is not operating at the end of its spectrum.

Quote:

Originally Posted by Jareb

The old thermostat was fully open at 85 degrees.

How did you arrive at that conclusion?