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Mercedes 300E 1991
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126 Posts
Discussion Starter · #1 ·
Hi there everyone,
just moved to Los Angeles from London (where I left my 300E Hammer Replica:( and I have a few questions;

Oil grade for the m103 engine? I have read and asked several people and they say 20w 50. But there is no Mobil 1 of this grade. So I used Valvoline High mileage (or something like that, its red bottle). I found this to cause the hydraulic tappets to make the dredded noise only on startup in the mornings. The car also felt sluggish, but I;'ll come to that later...
So I changed the oil to 10w 40 like I use in London and I also let out some of the transmission fluid as it was about 700-900 mil overfilled. I checked it at operating temp on level ground several times to be sure. Car just had a rebuilt transmission and I believe the mechanic who filled it up didnt know how to check the level and just filled it too much.
So now the car feels smoother, no sluggish feeling, kickdown works right, gear changes are fine and drop-shifts are fine too.

BUT it seems to be RUNNING VERY HOT. I mean standing in traffic and it goes above the 100 degrees celcius mark. in fact it goes between the 100 and 120 marks. This has got to be wrong????
I flushed the coolant system and put in new antifreeze (Prestone Yellow bottle) and filled water. It has about a 40% antiF and 60% water mix. It has also had a recent new radiator and water pump within last 18 months.

Now what is the problem here?

- oil grade not thick enough to handle the heat in engine?
or
-thermostat not working (the gold pin thing..)
or
-fan not reaching a higher/faster stage when required?

The fan does work, although I think it is intermittent. SOMETIMES IT DOESNT WORK AND the engine is flaming hot. So I put the heater on full blast, max heat to relieve engine temp.

I am not sure if it is or isnt related but the air intake hose is missing from the air intake. So when at idle the engine is taking all the hot air in, but on freeway the cooler air gets rammed in there so no overheating. I have ordered the part off ebay just awaiting delivery.
In any case shouldnt the car cool itself down when it reaches these temps? Or is it a stretch too far when the air intake hose is missing?

What do you guys think.

By the way many people recommend Mobil 1, tell me your opinion and what grade. I say this because I have always used the more premium 9not the cheapest one) valvoline oils in all my cars in london and here as well.

Look forward to hearing from you,

By the way I want to attend your famous SoCal meets! I have always wanted to come see like-minded enthusiasts' cars but I was in London. Now Im here so i wanna be there!

Sam
 

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Premium Member
Black on Black S124 Estate and White A124 Cabriolet
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1,719 Posts
K6JRF Auto Page

The "cool harness" mentioned here has been recommended by some experienced posters. Just a thought...
 

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Premium Member
Mercedes/BMW/Ferrari
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192 Posts
I like Mobil 1 15w50..
on the temp...I have seen them running that high with everything perfectly in order,but be sure to check the mechanicl fan clutch-they fail and don't flow enough...the radiators due get deposits that restrict proper flow on cooling especially on cars that have suffered through being filled with incorrect coolant...
Good luck welcome to SoCAL-now my second home
 

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93 300E 2.8, 79 450 SLC
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539 Posts
I am in SoCal too. Normally my car runs slightly higher than 80 mark. But I was driving up a mountain last weekend with AC on and my temp went up to 110C. Then, the aux fan kicked in and the temp settled around 100C. This car does run hot. I search this forum and notice this is normal for 300e. I am going to try Redline water wetter next time when I flush the coolant. See if it helps.
 

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1976 BMW 2002. 1991 250TD. 1995 E320. 2018 Honda Africa Twin
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2,687 Posts
i live in sunny southern california and run 100% water with some coolant for winter. in summer i just use water. it has better heat dissipation capabilities/ properties than coolant.
 

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Mercedes 300E 1991
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126 Posts
Discussion Starter · #6 ·
Thanks for all the replies guys,

Im just curious, I always use the genuine MB coolant in UK as its definately worth it with the cold weather etc. However in my car in LA I have used Prestone coolant (yellow bottle). Do you think this will have an adverse effect on the engine internals and cooling system. Also I believe the car never had much coolant in it to begin with before I flushed out and it WASNT getting so hot. Could this be because I have added 40% coolant or could it be because Im using 10w 40 oil as opposed to the generally accepted 20w 50 for hot climates?

Thanks a bunch for your advice. By the way if in anyone in the Valley area have a good deal on the rear tail lights? Preferably smoked or the red and clear as my car is anthracite grey (or gray, US spelling). Also looking for headlights because these ones on my 91 are very dorky looking. In London we have the normal flat face ones, much better. Looking for a bargain so please dont offer expensive things as I can just get it off ebay...In my house in London Ive got two extra sets for the rear and left/rights headlights as spare too. Witht the BOsch Xenon kit as spare also. So Im just wandering maybe someone out here is a bit excessive like me!!

Thank you,
 

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1976 BMW 2002. 1991 250TD. 1995 E320. 2018 Honda Africa Twin
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2,687 Posts
prestone is the wrong coolant. if its zerex g06 then its the right one.

i believe the oil viscosity has very little to do with the temperature problems you are having.
 
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