so i have the all to common overheating problems with my 108

it hasn't gotten too bad until today it passed the 220 mark and about half way to the red. it was 100 degrees and i was using the AC, my drive is only 4.2 miles from home and i was ok until about the last half a mile from home, and every time i hit a red light it just jumped up to about half way to the red.

someone at work told me that i should tune the thermostat, basically drill a couple small holes into to let the coolant constantly flow through. has anyone tried this and had luck with it?

i am about to replace water pump, and thermostat because the ones currently on the car have been there for an unknown amount of time. the clutch fan is a little loose, when i spin it by hand it spins a little on it's on own but there is still resistance there (not sure if this is even worth changing out?)

i will send the radiator to get cleaned and resealed.

any other tips or tricks? thanks!

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W211 '03 E320 | W108 '72 280SEL 4.5

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Is your aux fan running? Even with an aged slipping clutch, my 4.5 never got close to overheating once I replaced the radiator with one I bought off the forums that had been boiled out. On the VERY rare occasions it got to 212°F the aux fan would kick in and that'd be it... of course that was probably max 90°F ambient, if that; you're probably dealing much higher. Drilling out the thermostat won't do any good to enhance cooling. Your system isn't dissipating enough heat, which means either not enough airflow across your radiator, or not enough coolant flow through the radiator - it's also possible your radiator's fins have 40 years of grime in them, blocking the airflow. It'd surprise you how often that's overlooked. Do a good engine flush if your coolant is anything but bright and new-looking. If none of that does the trick it's time to look into converting the clutch fan to an electric one, unless you want to buy a new clutch which would probably cost as much and is a real drag on the engine!

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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

Most of what you are planning makes sense. But drilling holes in thermostat on a Mercedes is generally not recommended. There is an explanation of how the system works in this link:

560 SL Overheating question--done the search, can't find the answer... - Page 2 - Mercedes-Benz Forum

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

Have the radiator boiled out. My 72' 220 was getting hot in a similar fashion, new water pump, new thermostat, new hoses, fresh coolant. Took a spare known good thermostat and drilled a hole in it. No improvement.

Took the radiator to a radiator shop, $38 later my car was running at the correct operating temp.

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68 280SL - 70 280SL - 70 300SEL 3.5 - 72 350SL - 72 280SEL 4.5 - 72 220 - 72 220D - 73 450SL - 84 230GE - 87 200TD - 90 190E 2.0 - 03 G500

Nissan GTR - Nissan Skyline GTS25T - Toyota GTFour - Rover Mini - Toyota Land Cruiser HJ60 - Cadillac Eldorado - BMW E30 - BMW 135i

so... coolant was low

the car was running hot as i said coming home, when i got home i parked it and popped the hood to take a look. i know the radiator has a very small leak from the top cap which is why i was already planning on taking it to get cleaned and re-sealed. the whole radiator was hissing and you could see the leak at the top cap, i left it. when i came back it had leaked a ton of fluid out, no idea how it came out. hoses are good. i filled it back up, took almost a whole gallon, and the radiator is def holding the fluid. turned it on and no leaks, this car does not have an overflow tank, just a tube that runs down the side of the radiator so maybe it got hot and boiled out?

it doesn't look like there is a gallon worth of fluid so it's hard to say how much was actually in there before.

as far as the other questions, aux fan does work. i'm sure low fluid had a lot with it getting this hot for the first time ever, but even on normal circumstances it gets hot, just not nearly as fast or as high as it did today.

Graham, i'll review the the link. maybe i'll just try changing out all these components before i start trying to mod the system.

Paul is a boil out the same as rot out? i was quoted something like $100 for a rot out and a re-sealing of my radiator.


the clutch fan barely has any free spin by hand or after i turn off the car, should i look at replacing this as well? i just figure since i am doing a whole cooling system over haul might as well do this if it's needed.

thanks for all the feedback fellas

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W211 '03 E320 | W108 '72 280SEL 4.5

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Perhaps 20 years ago (maybe more), a short article appeared in THE STAR about drilling a "bleed" hole in the thermostat to allow passage of small amounts of coolant before the thermostat warmed sufficiently to fully open. If I remember correctly, the 107 and 108 cars were particularly prone to very high temperature gauge readings immediately after starting and on short drives because of the extended time it took for the thermostat to open so as to allow full flow. The proposed solution was placement of a small hole in the thermostat flap to allow some coolant to flow and to allow any trapped air to pass even when the thermostat was fully closed. I've just tried a search of past THE STAR issues on the MBCA site, but quickly became frustrated by my inability to narrow the search limits to less than 15 pages. Does anyone else remember this article which may have been part of the "Driveway Mechanic" series? Does anyone know where it may now be found?

My 1970 300SEL 2.8 with the 6 cylinder M130 engine would run hot constantly and nothing I did to resolve the problem helped.

Had the radiator re-cored with a heavy duty three row core, flushed the engine block, new thermostat, new water pump, new fan clutch and still the car would run hot and overheat. And forget about having the A/C on.

Finally I was talking to Tom Hanson at the Mercedes Benz classic center and he told me that many aftermarket non MB water pumps do not have the correct impeller to water pump housing clearance. This in turn causes not enough water flow, causing a run hot situation. So I bought a genuine MB rebuilt water pump, which wasn't cheap. Since installing the MB water pump my car hasn't run hot since! I can be idling on a 90+ degree day with the A/C on full blast and the temperature gauge never goes above the half way mark.

Just because the aftermarket water pump was brand new, I shouldn't have assumed it was operating at the specs the MB engineers had originally called for. Lesson learned! And that holds true for all aftermarket parts.

John

who manufactures the OE water pump?

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W211 '03 E320 | W108 '72 280SEL 4.5

http://i66.photobucket.com/albums/h2...ps9b542eaa.jpg http://i66.photobucket.com/albums/h2...ps5723c50f.jpg

I have two reprints of tehnical articles from The Star. These were compiled by Frank King in 1988/1989. Nothing in there. So possibly the article would later than that. Someone like George Murphy may have a way to locate the article.

One thing that comes to mind, is that early M117s used a lower temperature tstat. Important to use the right one. Ones from even slightly later MB V-8s are higher temp. The tstats do have an air vent and it should be at top when installing.

My 72 warms up normally and doesn't overheat. Original rad, fan etc At one time I did have overheating - Advancing timing eliminated that (25-30BTDC at 3000rpm)

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

I think it was rock auto but they offer thermostats rated for lower temps, I think there was 3 different ones offered with a 2° difference. However, with how hot the car gets I figured that 2° lower thermostat wouldn't really do much.

"Tuning" the thermostat is what all the old school people have been telling me to do though.

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W211 '03 E320 | W108 '72 280SEL 4.5

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The proper tstat is the 75C one. Late model M117s use an 84C. Apparently some aftermarket units have been found to be faulty, so best to test before installing or buy an OE type ( Behr or Wahler - Did ROCK have one of those?)

OE Pump is very expensive. I bought a Laso which may be OE supplier. Graf apparently also ok. Most others not recommended.

IMO, Drilling holes is a last ditch hack that doesnt address whatever the cause of the overheating is. It will also affect engine warmup in cold weather. This discussion is about diesels, but principles are same. When the bypass is closed and most of coolant passes through the rad, the tstat is wide open. The drilled holes will add just a slight increase in flow area - hard to see that it could help on this type of cooling system

Thermostat holes?

If rad/block has been cleaned and pump good, I would at least set timing up as suggested earlier (which is quite a bit more advanced than original spec) Easy to try and engine will run cooler.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

Both my cars have drilled thermostats for summer driving.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

did it make a noticeable difference?


there is a thermostat for 160º F which is 7 degrees less than OE. i looked but couldn't find an OE water pump online where would i buy something this? dealer? (scary thought)

i was looking at using a graf pump from autohau$, they also offer a meyle but i thought graf was the OE manufacturer.

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W211 '03 E320 | W108 '72 280SEL 4.5

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I'm not sure who originally made the OE pumps for MB. MB no longer sells new pumps for the most of the older cars and the only option was to buy a rebuilt pump from MB. Of course MB wants a good used original pump back as a core or else you'll have to pay a core charge.

The rebuilt water pump i got from MB was substantially beefier and much more heavy duty looking compared to the aftermarket pump i got from ********az. The rebuilt pump had a bigger heavier pump housing, bigger bearings, and a nicely cast and machined impeller. Some may have good luck with aftermarket pumps, that unfortunately wasn't the case with my car.

John

how much did the remanufactured water pump cost you?

__________________
W211 '03 E320 | W108 '72 280SEL 4.5

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