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300sd 83'
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489 Posts
Discussion Starter #1
I noticed that my temp gauge likes to hover around 100% when crusing on the highway at 80mph is this normal if not what should i do? The fans seem to kick in at around that temp to keep it from going above.
 

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2005 W220 S500 4Matic / 2008 W211 E350 4Matic
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997 Posts
Do you mean 100% of the range of travel, or 100 degrees, as in the "100" mark on the gauge? 100 degrees is a bit hot for a gasser, not sure about a diesel, but 100% would melt your engine like so much butter after not much time. If it is at 100%, TOW it, don't drive it, to a MB shop and pray you didn't kill the car!
 

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300sd 83'
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489 Posts
Discussion Starter #3
100 Degrees sorry for the confusion.

P.S. really like your quotes espessialy this one

"If you would not be forgotten as soon as you are dead and rotten, either write something worth reading or do things worth the writing." - Benjamin Franklin
 

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2005 W220 S500 4Matic / 2008 W211 E350 4Matic
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997 Posts
Thanks for clearing that up - and for the compliment!

I had issues for a while with hot running, and I think they all related to the previous owner using "radiator leak-stopper," which could easily double as marine epoxy in my experience. I ended up flushing the coolant, replacing the radiator after one semi-successful unclogging attempt, replacing the thermostat and drilling a 1/8" hole in it, and replacing the thermo housing. I also cleaned the monovalve assembly throughly. If I were you, I'd try the free stuff first, followed by the cheap stuff. Flush and fill is easy, as is the monovalve claning. Thermostats and housings aren't too pricey either. The clogged radiator is easy to replace, but hardly cheap. I was able to get a bunch of crap out of mine, but it never fully cured the issue, and the new radiator was well worth the trouble - it took all of ten minutes to remove the old and install the new, no kidding. It's worth replacing your hoses with the radiator out, and the belt/s are FAR easier to access with the radiator out as well. Good luck, and whatever you do, NEVER USE "RADIATOR LEAK STOPPER!"
 

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300sd 83'
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489 Posts
Discussion Starter #5
I'll give that a shot thanks alot. Should i drain the fluid and then just flush the radiator with a hose?
 

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2005 W220 S500 4Matic / 2008 W211 E350 4Matic
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997 Posts
Nope! Distilled water is the only way to go. Open the drain on the engine and on the radiator if you have one, let it all out, then top up with distilled water. Keep your heater on, set to max heat, no A/C. Run the engine for a minute or two, then reapeat a few times. Fill it up with Zerex G05 diluted to 30% with distilled water - at least that ratio and fluid works for gassers - again, not a diesel guy, so don't quote me! You will need to bleed air out through the bleed valves on the block and/or thermostat housing. The distilled water, by the way, is cheap, and any generic supermarket will carry it for around a buck per gallon. Resist the urge to insert Evian or some other yuppie mineral water! The minerals will corrode your engine! (Kidding, but seriously, don't do it. Only distilled water will do.)

By the way, the simple way to mix the coolant is to use an empty jug of distilled water - fill to 30% with Zerex, then top up with more distilled water. Kinda like that scene in Die Hard 3.
 

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300sd 83'
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489 Posts
Discussion Starter #7
Thanks Zeus I liked that movie I'll give it a shot over the weekend. Is there a radiator flush product that i can use also.
 

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300sd 83'
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489 Posts
Discussion Starter #8
do you know of a place where i can buy cheap bilstein shocks?
 

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2005 W220 S500 4Matic / 2008 W211 E350 4Matic
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There are citric acid flush formulas available, but it is best just to use distilled water if you are doing it yourself. If in the future, should you get your engine thoroughly taken apart, as in for head/valve work, that would be the time to worry about cleaning the internals of the cooling system. Distilled water will do wonders - just make sure you flush a few times, until the only thing coming out of the engine drain is pure distilled water - don't be afraid to snag some in a cup and look closely and smell it to be sure. As for shocks, I got my Comforts on eBay - I was in a hurry, and may have been able to find cheaper ones, but I just needed to get them ASAP for the trip I just took. They are not much more expensive than the lesser alternatives, and worth the extra cost. An easy DIY too, IF you buy the correct 12-point short socket or articulated wrench for getting the special bolts in and out on the bottom end of the fronts.

Speaking of Die Hard 3, remember how admirably that W126 held up to Bruce's stunt driving?
 

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2000 E55 AMG
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126 Posts
is it at 100 and over and under a bit? I had to do some conversions... 100*C is 212* F. witch still is not to hot, but something to look into. A gasser is average about 90*c. I second flushing the radiator.
 

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1989 560SEC, 1983 300SD
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89 Posts
Mine runs consistently at 100 degrees also. The fan is suppose to come on at 105 degrees according to my mechanic when I asked him your question. I'll be interested in seeing what others say for verification of this.
 

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300sd 83'
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Discussion Starter #12
It hovers around 100 it never really past it.

Was that a 560 or a 420 i think it was a 420 who needs a mack truck when you have a Benz 126 at least Thanks for the flash back Zues, good times good times.
 

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1991 300 SE
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18,534 Posts
There’s some counter-intuition when it comes to diesels: the faster they go – and the faster the car goes – the HIGHER the temp, they cool down in slower stop-and-go driving, the opposite of a gasser. At a sustained 75 mph my diesel will get just shy of 100 C. When I’m off the highway on surface streets it cools down to just over 80 C.

There may not be anything wrong with your cooling system, as long as it does not exceed 100 C; but if it’s been a while since or you don’t know when the last coolant change was, go ahead and do it now following the correct procedure noted above.

As an aside, these high temps are good for the 617s as it keeps them clean of carbon buildup and they are at their most fuel efficient as the hot engine burns almost all the fuel. It’s a very good idea to get your diesel nice and hot for a sustained period of time.
 

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300SD
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11,191 Posts
I have an '83 300SD with 106K miles and it is running at proper temperature. Steady 85 degrees C, never varies. The car's radiator may have been replaced shortly before I got it. I replaced the thermostat, water pump, fan clutch, gauge temperature sending unit, and the water bypass line.

Currently I am struggling a little with my '85 300D, which has an identical engine, but it running 10 degrees C hotter (around 95 deg C). I already have a new radiator and new water pump for it - will install in a few days and report back.
 

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1982 380SE AMG euro(parted out),1983 300SD "Good Girl", 1984 500SEL AMG euro "Bad Girl"
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3,256 Posts
My 83 300sd runs 85c light driving in cool weather to right at 100c when the AC is on in warm weather. I don't think you're too out of line. Might also try pulling the radiator and cleaning out the debris from the cooling fins from the back with compressed air or being careful with some high pressure water. You'd be surprised at the amounts of bug corpses, light sand, and grass seed you'll retrieve from 24 years on the road. I sat a radiator down flat and dropped it several times from 1-2 inches and got several Tbs of junk.
 
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