Differences in thermostats - Page 3 - PeachParts Mercedes-Benz Forum

stephenson · #31 01-08-2007, 07:55 PM

Tstat determines the MINIMUM termperature of the engine, given circumstances conducive (i.e. enough thermal transfer) - right?

Temp while at idle in traffic is determined by the ability of the thermal transfer system - coolant, two types of fans, radiator, etc - to deal with the extra heat - as they kick in the temp will never go back down below the set point. That said, I have had engines cool below the tstat set point on extremely long grades when the cooling effect was simply too great ... but, this was not excessive.

Maybe we should do a poll more formally, asking where everyone's needle points in normal operations - i.e. when tstat is determining minimum temp. Do it by specific engine type, and look for the most common position.

Both my previous 300CD and my current 350 SDL maintained temp so that needle pointed about one width above the 80C mark on the gauge.

t walgamuth · #32 01-08-2007, 08:54 PM

that is where mine run. i cant remember what my 124 bodies did, it has been a good while since i had them.

when i first got the 350sdl it ran around 60. that is not good. i think it contributed to the sludging of the engine.

tom w

anarchy · #33 01-09-2007, 01:32 AM

i am so confused on what thermostat to buy, at the moment my car doesnt have one, it hasn't had one for 4 months because the ones ive put in make the car over heat or run at 120

MarkM · #34 01-09-2007, 05:53 AM

Buy a Wahler from Auto Zone...it runs coolest...just above 80C

t walgamuth · #35 01-09-2007, 07:57 AM

Quote:

Originally Posted by anarchy

i am so confused on what thermostat to buy, at the moment my car doesnt have one, it hasn't had one for 4 months because the ones ive put in make the car over heat or run at 120

i bet you put them in backwards.

tom w

retx · #36 01-09-2007, 12:24 PM

well i just ordered one from dieselgiant. does anyone know off hand what the ones he sells are rated at? just curious.

also, other than the tstat working or not working correctly, not being the right temp rating for the right car, or having being modified....i have a 93 ford e150 van, it runs "hot" when on tour. but its really not. even when not loaded down and just using it as a daily driver...it reads hot. its because the temp sending unit is not accurate anymore. so even though the engine/tstat/coolant is correct and running cool and smooth, the gauge is showing hotter. the location of this sending unit, cost and the fact that its a van, being hard to work on, i have decided not to change it. have had it for four years, numerous tours across the states and have had no issues with it. just a thought.

tobybul · #37 01-09-2007, 02:05 PM

There are a lot of factors affecting the quality and performance of products including tsats as we all know.

In theory, it should work as designed... but thats in theory and may not always work as designed. Thats why not same products perform the same. Variables include workmanship, material, installation, other components in the cooling system, etc.

As said, Dieseldiant has a pictorial on drilling holes to help adjsut the temp. I believe that one big factor (covered in a discussion in this forum) affecting cooling performance is the oem radiator vs aftermarket. Based on the performance of my 84D (aftermarket rad) vs my 85D (oem rad), I beleive that the oem rad does not cool as well. The cooling performance of the rad has a direct bearing to the engine temp. I don't think this means that the oem rad is no good. Its just the the non-oem maybe more efficient (more surface area?).

Of course the stat is a key element. The oem stat is designed to work with the other oem components in the engine.

my 2 cents

Shorebilly · #38 01-09-2007, 03:06 PM

Quote:

Originally Posted by t walgamuth

i bet you put them in backwards.

tom w

Although I did not make the attempt, from what I saw when I changed my thermostat about 10 days ago......I don't think it can be inserted backwards.....do not think that the thermostat will clear the housing if inserted backwards.....

SB

BUT....don't forget the arrow....

tangofox007 · #39 01-09-2007, 03:06 PM

Quote:

Originally Posted by tobybul

As said, Dieseldiant has a pictorial on drilling holes to help adjsut the temp. I believe that one big factor (covered in a discussion in this forum) affecting cooling performance is the oem radiator vs aftermarket. Based on the performance of my 84D (aftermarket rad) vs my 85D (oem rad), I beleive that the oem rad does not cool as well.

I heard a rumor that a new, clean radiator transfers heat better than an old, gunked-up radiator.

nhdoc · #40 02-01-2007, 02:26 PM

Well, after watching the temp gauge on my newly acquired 300CD wander around after replacing the thermostat with a brand new MB one I decided to replace the temp sender.

Same thing happened with the new sender...first start of the day the car would run warmer than I like - going up as high as 100C before dropping down, then when I would pull up to a light the temp would drop below 80C...so I went to NAPA and bought a WAHLER thermostat and replaced the MB one...now the temp seems to be rock steady at just above 80C on the gauge

I have concluded that the MB T-Stat was defective...I call these "lazy" thermostats because they open late and close too slowly...anywho...it seems that I will be going back to the MB parts desk with this one and getting a refund as this Wahler is working fine.

#41 02-01-2007, 03:37 PM

Wow, lots of people chasing a problem that is not really a problem.

#1: I don't believe the temp gauge is really precise. As long as mine reads somewhere in between 85 and 105 C I do not worry about it.

#2: I cannot think of anything wrong with the car running at 95C all the time. In fact that is a good operating temp. It's not good to consistently run the motor cool, and it's obviously bad to run it hot.

nhdoc · #42 02-01-2007, 04:25 PM

Quote:

Originally Posted by mrhills0146

Wow, lots of people chasing a problem that is not really a problem.

#1: I don't believe the temp gauge is really precise. As long as mine reads somewhere in between 85 and 105 C I do not worry about it.

#2: I cannot think of anything wrong with the car running at 95C all the time. In fact that is a good operating temp. It's not good to consistently run the motor cool, and it's obviously bad to run it hot.

A properly operating thermostat will keep the operating temperature relatively steady. I've had many cars, any many Mercedes and when you see the temp gauge moving around under normal operating conditions something isn't right. The only time the temperature should fall below normal is if you happen to switch the heat on while the car is at or near idle...otherwise it really should operate within a couple of degrees of the design temp.

The MB stat I removed would spike over 100C and drop to under 80 during routine running...that's just wrong. The new Wahler behaves normally, the car warms up and the temp stays steady. These gauges are pretty accurate if they're working right, and this one is.

A car which runs at 90C+ is above its design temp. When new, these cars ran at just above 80C...a car running at 95C-105C means either the gauge is wrong or the engine is running warm. 80-85C is not cool...it's normal for these.

#43 02-01-2007, 04:33 PM

Quote:

Originally Posted by nhdoc

A car which runs at 90C+ is above its design temp. When new, these cars ran at just above 80C...95C means either the gauge is wrong or the engine is running a little hot. 80-85C is not cool...it's normal for these.

Very true. I just often don't believe that the car is running at the temperature displayed on the gauge. My car is 25 years old and has a quarter of a million miles on it. There is a long list of things that are no longer within design specs. When mine says 90C, it might truly be running at 80, or 85, or 95. The only way to tell for sure is to use an infrared heat gun. I find that it's splitting hairs for me to worry about the gauge reading as long as it's relatively normal (i.e. not 60C and not 115C.)

As far as your wild fluctuations in temperature, agreed, that was most definitely not normal!

toomany MBZ · #44 02-01-2007, 05:00 PM

Nothing offical, I've heard the 80 C stats keep 90 degrees C. I have replaced two 80 Behr's both read 90 at gauge. For all it's worth.

t walgamuth · #45 02-01-2007, 08:07 PM

Quote:

Originally Posted by Shorebilly

Although I did not make the attempt, from what I saw when I changed my thermostat about 10 days ago......I don't think it can be inserted backwards.....do not think that the thermostat will clear the housing if inserted backwards.....

SB

BUT....don't forget the arrow....

oh yes they can be put in backwards!!!!

don't ask how i know!

tom w