It was 100F/36C here over the weekend.

100F+ 70%humidity+a/c max. = 100C engine temps
Welcome to Texas! Were having unseasonably warm temperatures right now.

Removing the thermostat will only cause it to take a little longer to get there but once you reach 100C you will have to wait till 7 a.m. for it to get much lower. (Been there, tried that)

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Sam

84 300SD 350K+ miles ( Blue Belle )

On some gasoline cars if you remove the thernostat the engine will overheat because the coolant circulates too fast. In the past I have dismantled faulty thermostats so it will slow down water flow but never shut when I have been too cheap to go buy a new one. I know I'm a cheap bastard!

Not a good idea. The thermostat DOES prevent cooling until the temperature reaches the setpoint (usually 75-85 deg. C.) and then over the next 10-15 degrees closes the cooling by-pass port and directs the coolant thru the radiator. When you remove the thermostat you allow cooling to commence immediately (so the engine may take a VERY long time to reach proper operating temperature - which increases engine wear and drops fuel efficiency) AND the bypass port is never closed - so only about half of the coolant ever passes thru the radiator - and that reduces the capacity of the radiator to about half what it would be with a properly operating thermostat. The thermostat doesn't impeed cooling once operating temp has been reached and inded in the case of a Mercedes diesel, increases the capacity of the system to dissipate heat.

Water Wetter will increase the cooling capacity of the cooling system (modestly when using the apporved anti-freeze/water mix - more when the anti-freeze concentration is lowered) but under most conditions the engine will still run at between 85-95 deg. C. because that's where the thermostat is designed to keep the temperature unless the engine is really loaded down.

Marshall

If your thermostat is working correctly removing it WILL NOT improve cooling and it could result in overcooling which will reduce your mileage slightly and cause increased engine wear.

If it is not working correctly spend the $5 or $10 for a new one.

By the way it sounds like your air conditioning needs to be recharged.

It's a mystery to me why some people think Goober down at the filling station knows better than the design staff in Stuttgart.

By the way if you remove the thermostat restriction and the car runs hotter it's not because the water is going "too fast". It's because it's barely moving at all. Removing back pressure on the water pump can cause cavitation very easily and in hot water easier than cold. So you need the restriction and the pressure cap. You also need antifreeze to raise the boiling temp of the coolant and to prevent corrosion.

Car designers figured all this out years ago.

Do a search on Doktor Bert and his experiences without a thermostat.

Here is the thread for you:

http://www.peachparts.com/shopforum/showthread.php?t=114673

Read it first, before you jump to a false conclusion.

He's hardly the "Goober down at the filling station".

He's got a lot of real world experience without a thermostat in a 617 and the experience differs from "the design staff in Stuttgart".

Dr Bert has chosen to maximize cooling (even when it's NOT needed) not by eliminating the thermostat structure, but by removing the temperature sensor and thermostatic action - VERY different from running without a thermostat (even one that been eviserated) in place.

What he has done will increase the time it takes the engine to reach optimal opearting temperature. With a thermostat hanging open (rather akin to what he's done), most of my OM60x engines will never even reach 65-70 deg. C in temperate weather (may not reach 55 deg. C. in COLD weather) and the cost is seriously increased wear, slow boiling off of water and volatile accumulates in the oil and considerably lower fuel economy. When temps reach zero (F) the output from the heater isn't really even teped and at 20 below it becomes darned cold (and the engien does NOT run well and even the coolant operated fuel hear doen't do it's job.

As to his suggestion about reducing combustion/exhaust temperatures, that's what an EGR does and BOY does that increase engine wear and lower turbo boost. Boost pressure is absolutely correlated with exhaust temp. There may a a really good reason to run some engines without a thermostat, but I haven't seen one on this forum.

A thermostat is a device that is designed to PREVENT cooling until the engine reaches it's intended operating range. Then it should become invisible - allowing maximal cooling. The Mercedes design does that perfectly when the system is in good working order and is properly maintained.

Marshall

I'm starting to feel pretty good! I can't get mine to go above 90 C no matter what I do to it. It runs at a constant 85 C with the AC off, and will run a little cooler with the AC on. Then it starts to creep up as Mother Nature tries to cook me & my beloved Kraut, but the highest it's ever been is 90 C. Don't get too jealous of me, though. I think my AC needs a little freon, and the fact that my coldest air is being used to cool the windshield (vacuum leak, ACC vacuum disconnected) probably isn't helping much. The car is only comfortable if the outside temp is under 85 F, and it the highs won't be that cool again until September or October .

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1982 300D, black w/ palomino leather, 203K
2001 E320, champagne, 105K (Mom's)
1999 Dodge Dakota, squeaky & battered, 142K

I notice your Doktor Bert lives in Visalia California where temps never go below freezing. Eliminating the thermostat is not recommended, but it is something you can get away with. You might not even notice the drop in mileage and the increase in wear, especially if you live in a hot climate. I see he makes the point about manufacturers using hot thermostats to increase mileage, and he knows that running an engine too cold will increase wear.

The other example he gives is industrial engines, which run at steady speeds for long periods and start from cold a lot less often than street driven engines. So eliminating the thermostats should do practically nothing.

I would ascribe the low cylinder wear to more modern rings and oils. Since 1980 car makers have been using low tension rings to reduce friction and increase mileage. Consequently these engines engines show little or no cylinder wear. Better oils have helped too.

By the way the only 317 cu in engine Ford ever made was the 1953 - 55 Lincoln engine. This engine was also used in Ford F8 trucks and as an industrial power plant. So if they were that old, no wonder they had the old 50's style rings and pistons, and showed cylinder wear typical of that era. And no wonder wear decreased when they were bored out and fitted with modern pistons and rings, and run on modern oil.

"I also inflate the tires on my vehicles with Nitrogen as opposed to air, because it allows tires to run cooler at sustained high speeds"

This is pure bull****. Nitrogen does nothing for keeping tires cool. It also does nothing to control expansion pressure, unless you have found some way to repeal Boyle's Law. The reason racers use nitrogen is because you can buy a cylinder of nitrogen @ 2000 PSI for $30 at any welding supply dealer, and it will take the place of an air compressor at the track. One cylinder will last a weekend racer a full season of inflating tires, cleaning parts, even running air tools. It's purely a matter of convenience.

Racers have been using compressed nitrogen cylinders at Bonneville since the 1930's and this is how the myth that nitrogen is better for tires got started. The reporters writing up the speed record attempts started it, or possibly the mechanics fed them a tall tale and they didn't know enough chemistry to see through it.

In other words, your Doktor Bert is a high grade Goober with a degree in bull****.

Since you are so knowledgeable about nitrogen, maybe you would like to explain why all jet airliners use pure nitrogen in their tires, as well? Tires that must achieve 200 mph on a daily basis.

I do agree that running cooler is not the reason.

Still think it's cheaper than compressed air to fill ten of those babies?

"Since you are so knowledgeable about nitrogen, maybe you would like to explain why all jet airliners use pure nitrogen in their tires, as well? Tires that must achieve 200 mph on a daily basis.

I do agree that running cooler is not the reason.

Still think it's cheaper than compressed air to fill ten of those babies?"

I don't have to explain it. I never said they did, and I don't know what they fill them with. I just finished explaining that in a situation where you are away from the shop and away from your air compressor, nitrogen cylinders are a cheap, convenient, clean and quiet alternative to a gas powered portable compressor. Perhaps the explanation is that it is more convenient to inflate the tires from a service truck than to tow the aircraft back to the hanger when the tires are low.

In fact it is a lot cheaper and more convenient when you add up the cost of a gas powered air compressor, the fuel to run it, and the time and expense of servicing it. That's why racers started using it 70 years ago.

My w126 300SD (the 617 turbo) has and will run at 120C all day if the outdoor heat, driving conditions, and AC status warrent it.
With the AC on, sitting at idle in my driveway in about 80 degree weather...the temp will climb right up to 120 then the AUX fan will kick on and keep things between 110 and 120.

With the AC off, sitting at idle, same conditions, 100C is common with no AUX fan operation.

AC on or off, crusing temps vary from 90-110C depending on outside conditions and AC operation...nothing fantastic.

Keep your 617 turbo out of the red and you are fine. Period.

P.S. Just make sure your cooling system compoents are up to snuff!

Wow...........how's it feel to be the hottest guy on the board????

dont remove your mb thermostat.

larry is right on.

mb's have a bypass thermostat not the more common type which just blocks all flow until it reaches temp. the bypass flows from the pump back to the block until warm thereby allowing no hot spots. after that it will flow all of the water to the radiator... if you take it out you will lose the full force of the cooling system when it is needed by splitting your flow betweent the block and the radiatior instead of flowing all of it to the radiator.

the only time to take one out is if it is stuck and no replacement is available and then only til you can put one in.

as far as the hotness under the hood... i always think of the heat sink effect on all those hoses and wires when the engine is really hot...like it would be in texas... when that happens when i am on a trip and have to stop and shut down i always pop the hood and leave it up a couple of feet to cool down. if i stop at a rest area or such i wil also do this with it running.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

My right foot feels a little heavy

Again the aircooled VW reference...if you haven't experienced overheading VW heat...you haven't experienced engine heat