behr vs. wahler thermostat opinions
 

i recently changed my thermostat when i decided that engine temperature as indicated on the gauge was fluctuating too much. it would dip down below 80C in easy driving then stay at it's customary 85C in normal conditions, occasionally rising to 95 - 97C in traffic where it's stopped by my resistive cooling mod. i concluded that my thermostat had started sticking and was slow in opening and closing.

upon reading Arthur Dalton's observations about the Wahler and Behr thermostat i went ahead and installed the Behr, noting that my old one was a Wahler. i also noted that the temp stamped on the new thermostat was 87C. anyhow, my temps don't fluctuate that much anymore but now it sits more in the 90 - 95C region, rising to 97C in traffic but still controlled by the cooling mod. it is somewhat different from my old setup where cruising would drop my temps to around 85C or a hair less. now cruising produces 90C - never less, and it doesn't matter if the AC is on or not.

i understand that these M104 engines run hot. i'm tempted to try a new Wahler thermostat to see if temps will go down a bit. also wanted to see what you folks have to say on this. (Arthur are you there?)

Behr vs. Wahler
 

I had the same problem with my '88 260E last year. In hot weather or stop and go traffic, the temp would start climbing into the 90's and make me nervous. I replaced the original Behr stat with a Wahler (don't remember the temp but it was the same as the original) and the gauge now holds steady.

I also changed the coolant same time as the stat and found that the old stuff was way too concentrated. It pegged my tester at -60. That also could have been what was causing my cooling problem, but overall I'm happy with the Wahler thermostat and have always used them in my Volvo's too.

<<i understand that these M104 engines run hot. i'm tempted to try a new Wahler thermostat to see if temps will go down a bit. also wanted to see what you folks have to say on this. (Arthur are you there?)
>>

You now have perfect running temps for a 104 HFM-SFI engine.
The thermo is designed to START to open at 87C and a steady 90/95 is perfect for optimum engine management design.

Behr!! many of the Wahler t-stats fail where the pin goes into the bridge at the top.

I recently received a Wahler from this sites Parts Shop as part of a t-stat housing "kit". The quality of construction of the Wahler is very poor compared to a dealer-provided Behr.

When I'm ready to do the intended job, I'll go get a real t-stat from the MB dealer.

I sure do wish I knew about this when I changed out my thermostat the othe day with a Wahler (which has done nothing to change my high operating temp-although I think it may be my radiator);)

Alan

Thanks Arthur, I'll print this out to read over and over to reprogram my thinking as to what "normal temps" are. This paranoia just started up the other night when I started experiencing phantom coolant level warnings. I just managed to unplug the sensor which was heavily encrusted and the light went out so now it's either clean it or replace it...

Your statement is exactly the same as my experience in my M104 engine. Before my water pump / thermostat replacement, my temp gauge was pegged at 85 C, or so. It rarely, if ever, moved. With the new water pump and Behr thermostat, I'm running 90-92ish, and runnin about 100 +- 2 degrees in hot weather in traffic. One day after pulling in my garage, I let the car idle to see what the temp gauge would do. It slowly rose untill it hit about 105-107 ish, and then a high speed fan came on, and ran untill the gauge got down to about 100 C, and then the high speed fan shut off. It then stayed more or less at 100.

I liked the temp it ran at before, even though I understand that now it's running how MB engineered it.

Go figure.

Did you ever consider the cooling mod? I like it because when it's just about at 100C, the high speed fans go on and blow down the temps to around 90C then shuts off. I know that if I take it off it will behave the way yours does...

That's your aux fan that kicks in when your engine is running closer to HOT! Have you checked to make sure that all of your hose connections, cap,etc are secure to maintain correct pressure? Also, feel your radiator for cool spots to see if there may be some clogging/circulation issues... I'm dealing with cooling circulation as we speak!;)

I think I'm going to leave my engine the way it is.

Even on the Las Vegas strip in temps above 100 degrees, the engine ran just above 100, and quickly went down to 92-95 when I was moving above 45 mph or so.

I really don't think running at 107 is condsidered hot. If you look at your gauge, even 120 degrees is not colored red. Engineers from MB have said that your engine can get as hot as 120 degrees everyday, and no damage will result. 130 degrees, though, is in the red, therefore overheating.

My engine hit 107 that one time only, and the fan immediately kicked in and cooled it down to 100 in less than a minute.

i guess paul has to qualify what he meant by "pulled into the garage and let it idle". if i've only been driving around town, my temps probably won't go up that high just idling. if i'd been on the highway then let it idle (even driving local for a bit), then yes, definitely the temps would rise over 100C too without the cooling mod...

Yes, that's exactly what I meant. After cruising at 75 mph for 25 minutes, I pulled into the garage and let it idle, when it promptly went to 107 when the high speed fan kicked on.

Generally speaking, if I just let the car idle, it stays in a normal (for Merecedes) operating zone in the middle nineties.

After having the dealer replace the radiator and one of the auxiliary fans, my 300TE still ran hot, all the way up to the red zone. After replacing the tstat with a 82 degree unit (Go-Rad German made) the car now runs back in the 82-85 range in 91 degree weather with the a/c cranked. Might as well replace the tstat first before doing any unnecessary repairs.

Chazmo

ok, i'll bite. where does one get this "Go-Rad" thermostat?