Can some one tell me what the motor temp guage is reading?

Is it reading 90C or 100C or?

I've assumed it is 100C and being a 603 #14 head I've been generically worried about running too warm. For example drove accross the AZ /CA desert last week (HWY 10) and with the AC on and 94 to 100 F ambient temps with the needle floating around the mid line mark. Over a tad upgrade and lower down grades.

Thanks

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1986 300SDL 440,xxx

Looks like slightly less than 100 C to me, but due to parallax, the apparent reading may be incorrect. Can you get a photo with the front of the camera lens parallel to the plane of the gauge (as opposed to what you have here, which is at a slight angle)?

How long has it been since you replaced your thermostat? Are you sure you've got a stock 176F / 80C thermostat in there? Some of the ones that are available open at higher temperatures.

Are you using the proper coolant (Zerex G-05) or generic green?

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Lots of diesel W126s in the past
Current: 1991 Toyota 4Runner with an OM603

It's 100C. and the temp is not a concern considering your ambients.

If it climbs to 110C. you've got make some provisions to keep it there (shutting down a/c and opening the windows).

The head is only harmed if you lose the belt and/or water pump. Proactive replacement is strongly recommended.

The use of a 140 cap is also strongly recommended. The boiling point is raised to 109C. with that cap with plain water.

Of course you have a 50/50 mix of Zerex G-05 and distilled water in the system............right??

Thanks guys....I figured so

With the exception of a four year old radiator all the proper goods and maint practices in place. Citrus flushes to new pump, MB Coolant w/ redline, etc. Worked this cooling thing for seven or so years .

I really don't like to run on the "border" of 110. All winter long with ambient temps < 90*F it runs like a cool cucumber @ 80 - 85C.

I think it just getting older with almost 350k. I'm searching for a 70* "Tropical" thermostat for this summer's desert travel and there will be a lot...twice a month....and its just getting warm out there....and at typical 115 F ambient ya just can't roll down the window or ya overheat ones brain lol.

I think the stock set up just can't handle the extra heat x long distance 75 mph.

Wondering if there is an oversized radiator out there or a custom shop anybody knows. Have more room towards the fan for a deeper radiator. Going with a trans cooler too I think.

Thoughts?

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1986 300SDL 440,xxx

If it never gets above 100, why are you worried? 100 is a long way from 110. Make sure your fan is engaged the next time you reach 100. If it is stop worrying, if it isn't it is time for a new clutch.

You may want to try cleaning the condenser and the exterior of the radiator. If the heat isn't reaching the clutch the fan won't engage.

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1987 300TD 309, xxx 2.8.2014 10,000 mile OCI


Be careful of the toes you step on today, as they may be connected to the ass you have to kiss tomorrow. anonymous

“Be who you are and say what you feel, because those who mind don’t matter, and those who matter won’t mind.” Dr. Seuss

You ought to see the brain overheat that occurs when the vehicle stops and you're sitting on the side of the road at 115°F.

............makes the thought of rolling down the windows a positively euphoric experience............

These guys sure hit the nail on the head. I replaced my fan clutch in my 606, as well as a new 85c thermostat and MB coolant with distilled water (60/40 mix currently, I need to dump some and replace it with water to regain the 50/50 mix) and I reached about 95-97c pulling a 5% grade for what seemed like endless miles yesterday. The ambient temps were only about 75f, but I had the ac maxed out in order to test my system and ensure it'll handle the desert heat this summer. I was reading on Jim F.'s site, the Cool Harness guy, that he recommends a 40/60 mix in the summer if you're running a bit warm, but I think given your conditions all seems pretty well.

The simple answer is to permanently disconnect the transmission cooler hoses from the radiator.

Install an after-market trans cooler, and connect to it.

This removes roughly 1/3 of the thermal load from the cooling system.


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1985 300SD
1983 300D
2003 Volvo V70

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This is probably what I need to do.

I hope this isn't hijacking a thread, it's relevant after all.

I have recently finished installing my newly assembled 3.0 603 in my '91 350SD. The block's cooling passages are perfectly clean, as is the #22 head. I installed a new Laso water pump, new Behr radiator, correct MB coolant and a new MB 80deg. thermostat. I have driven the car about 500 miles, and the ambient temp has not been above 70deg F. The running temp of the car has consistantly been about 90, and one time off the highway it climbed to 100. Point is, I can't think of anything else I can do to lower the operating temp. Am I missing anything?

Thanks

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Chief

1991 350SD

x2

When the system looses pressure, the cooling isn't as effective. Look for leaks, and disappearing coolant. I'll bet it's your radiator/expansion tank cap.

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2013 Volkswagen Jetta Hybrid SEL Premium (Sparky)
http://badges.fuelly.com/images/smallsig-us/193500.png

It's a car not a science experiment! Open the throttle!

Kindly review the three posts that I have made in this thread (while trying to help you at no charge) and let me know what you find to be condescending.

Then help me understand how a fully actuated 75* thermostat promotes cooling any better than a fully actuated 80* thermostat. Presumably, both would allow for the exact same degree of coolant flow to the radiator above 94*. So, if the two thermostats perform exactly the same at the upper end, how is is a lower-rated thermostat going to reduce a 100* coolant temp any better than the higher rated one? 100* is outside the range of regulation for either thermostat.

What is your coolant/water ratio?

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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

I don't think tango was condescending, but Brian Carlton certainly seems to be at times.

That said, around here I think you have to take the good with the bad.

Some of the guys are crusty (and, in fact, are quite proud of it), but they know their stuff.

I think the crustiness must come from a lifetime of keeping old diesel Benzes running. It'll probably happen to me sooner or later.

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Lots of diesel W126s in the past
Current: 1991 Toyota 4Runner with an OM603

It is a well documented FACT that many vehicles benefit from an after-market transmission cooler.

Look at RV and 4x4 forums, not to mention special application vehicles such as Forrest service, ambulance, law enforcement, etc, etc...

Most of our vehicles are high mileage, the thermal load rises from stacked wear factors, and in some cases have exceeded any reasonable factory cooling capacity.

Many owners of RV, 4x4, and special application vehicles have learned why a separate transmission oil cooler is needed the hard way.
transmission oil cooler - Google Search
Transmission Temperature Gauge



For durability.
Removing the thermal load of the transmission from the engine cooling system is a win - win upgrade...
Your source for RV, heavy duty off-road and overdrive transmissions



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dedicated transmission cooler in 1995 E300D

Buying and Installing a Transmission Cooler W123

Buying and Installing a Transmission Cooler W123

Transmission Cooler


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I like the idea of an external cooler for my 95 E300, I'm sure the transmission would benefit quite a bit in my application as I drive through the mountains regularly in the dog days of summer. I'm hoping he'll be able to rig something up in that thread, or at least figure out a part number for the Mercedes unit. I am not really worried about my engine temps as I have to try really hard to exceed 100c, if I even can that is, but a cooler trans should help improve its life-span. Still, I wonder what my average trans temps are in stop-and-go and mountain driving in the summer, I imagine it can't be too far from 200*...or more.