60°C Thermostat: - PeachParts Mercedes-Benz Forum

Doktor Bert · #1 04-13-2009, 01:56 PM

I have always used the 60°C thermostat, but can't seem to find one now. Any sources???...Robert

JonL · #2 04-13-2009, 01:57 PM

Why such a cold T-stat? IMO, your engine will be happier at 80 - 86C.

oldsinner111 · #3 04-13-2009, 01:58 PM

I know Stant makes a 70c.Most people will tell you 85c is the best.Cummins,and Powerstrokes add a 205 f degree.
My Dad when alive lived in Clovis.

Doktor Bert · #4 04-13-2009, 02:20 PM

I have always used the low temp thermostats in everything. When we were racing, (even fast street cars) I ran no thermostat and guys would always talk about horsepower and how engines run better, more efficiently with higher coolant temps. I used to keep the dyno sheet from my 500+ HP 1966 Ford fairlaine in the glovebox, just to show guys how you could make that much power with 170°-180° F coolant temperatures.

I put 7 years of street driving on that car with no adverse wear or sludge buildup.

You may indeed get lower tailpipe emissions with higher coolanty temperatures, but we made more horsepower and torque on the dyno (and faster lap times) with lower coolant temps. What the dyno tests will NOT tell you is how much HP and TQ you can make with HOT underhood air going into the intake through that hot radiator.

I prefer the lower temperature thermostats because of our + 100°F summer temperatures...Robert

JonL · #5 04-13-2009, 02:33 PM

Cooler temperatures might indeed give you higher HP, especially if the intake and cylinder head are kept cool. Better volumetric efficiency, higher air density. However, in a street car the only time that would matter is when your accelerator is on the floor.

You may not have noticeable wear or sludge buildup, but you still may be raising the risk of corrosion related wear and depleting the oil additives more rapidly.

If your cooling system is working correctly, a 60C thermostat will not keep you from overheating any more than an 85C thermostat, no matter what the ambient temperature. For a street car I guess I don't see the benefit of the cold t'stat.

Doktor Bert · #6 04-13-2009, 03:22 PM

I won't bore you with results of oil analysis, tec., but I can tell you, there were no adverse effects/measureable wear/sludge after 7 years of street driving without a thermostat.

In racing, we used to have a saying; "Results trump theory everytime...."

If running a 60°C thermostat is detrimental, why would MBZ sell them??? I bought my last one at MBZ of Fresno by application...Robert

JonL · #7 04-13-2009, 03:42 PM

OK, you have the data to back up your use of the cold t'stat, so I won't argue. I would still say though that what is appropriate for racing is not always appropriate for a daily driver.

I don't know why MBZ sell a 60 degree t'stat for automotive use. It would make sense for marine use. In marine engines with salt water heat exchangers, if the heat exchanger runs too hot the salt will precipitate out and clog the HX tubes. Cooler than normal engine coolant is used to prevent that from happening. Might also make sense for very high altitude use to give additional margin for boiling and water pump cavitation. I'd be interested to know where MB recommends its use if you ever find out,.

pawoSD · #8 04-13-2009, 03:44 PM

I'd imagine (especially on a diesel) that 60C isn't a good idea....if MB recommends 85C...use 85C! They spent a lot of $$ researching that!

winmutt · #9 04-13-2009, 03:48 PM

I would say that neither matters and that 85' is for cold weather climates.

[edit]
20-005 has some very interesting reading. 85' is NOT what is listed, 80' is. Tstat is actually a TWO stage valve. The bypass valve opens at 80' and flows to pump bypassing the radiator. At ~ 94 the main opens and bypass is open. Above 94' the bypass valve is closed and main remains open.

My car always stays just under 100 so I wonder if my bypass valve is faulty. Only once has it ever stayed at 85 as one would expect, it was a rare 90mph sustained over 10miles. The perplexing issue is that of course this is the same result on 2 different engines, radiators, tstats.

Doktor Bert · #10 04-13-2009, 03:57 PM

Quote:

Originally Posted by JonL

"OK, you have the data to back up your use of the cold t'stat, so I won't argue. I would still say though that what is appropriate for racing is not always appropriate for a daily driver..."

Jon,

I would never advocate the elimination of a thermostat in a street car. We did drive my car everyday for 7 years without one and raced it on the weekends too. We never saw any problems from the lack of a thermostat, but in my area, winters are rarely, if ever, under 32°F.

When I bought my last 60°C thermostat, I got it from the dealer in Fresno, so I would have to assume the factory intended them for summertime use???...Robert

JonL · #11 04-13-2009, 04:04 PM

I guess it could be recommended for summer use, but I just don't understand why. 60C is very, very cool... it's only 140F. I've never seen a recommendation for such a low temp t'stat, but I haven't seen everything!

KarTek · #12 04-13-2009, 04:07 PM

A Diesel engine runs much more effeciently at a hotter temp. A common performance/economy mod on the powerstrokes is to run a 203* 'stat - up from 195*.

In my OM606, I stepped up from the stock 80*c to an 85*c and so far I'm seeing about 1 MPG better after 2 tank fulls. This, of course, is not enough for a truly scientific conclusion but it's encouraging.

280EZRider · #13 04-13-2009, 04:08 PM

It has always been my understanding that with no thermostat, pressurization is less, which would cause a lower boiling temp. In addition, with less pressure, the water pump would have less mass to push (sort of cavitating) and hence allowing the possibility of head warping. Mating of surfaces also seems better at 85 as opposed to 60c. For example, I've seen all kinds of strange leaks occur during a cold winter and by spring, they fix themselves.

By the way, spent a lot of time in Visalia during the mid 80s. It's is great little town, except for the 100f weather in summer.

pawoSD · #14 04-13-2009, 04:12 PM

I can't imagine using a 60C t-stat in MI.....you'd get essentially no heat in the car!

Doktor Bert · #15 04-13-2009, 04:19 PM

I always use a 160°F in my 1975 Pontiac Firebird and have good heater performance. Almost all of your chip upgrades, for gasoline vehicles, come with a low temperature thermostat....Robert