300SDL Shakeout Run - Page 2 - PeachParts Mercedes-Benz Forum

diesel dave · #16 06-21-2009, 11:26 PM

it is hard to accept but i had a bad over heat problem with my 86 300SDL and after nothing else worked i changed the radiator. afterwards i opended up the old rad and the channels were so stopped up i was amazed anything got thru. it looked like a calcium build up. there was no evidence of mineral build up on anything else like the thermostat or other metal or plastic parts. that liquid is reacting with that metal even when you are not driving the car. it may only have X number of miles but that rad has been under water since 1986. sadly this is an expensive experiment but i believe you are headed in that direction. it cost me over $300. i installed it my self because i love to work on the machine. the car temp is now solid at the right temp with no fluctuation. cool as a new. you gotta act soon to protect that aluminum head. if/when you do it, pry open the plastic tanks of the old rad and check out the channel's clearance. then recycle the aluminum rad. good luck.

mplafleur · #17 06-22-2009, 12:35 PM

I don't have an overheating issue (except when the hose came loose and I lost coolant) as I run rock solid at 82*C.

I did notice that my fan clutch does not engage at high temp. My fan was stored flat on a table for 6 years. I'm sure I have no fluid in the clutch. I bought the oil to refurbish the fan clutch, but have not completed the procedure yet.

In testing the cooling system, I compared coolant flow on my '85 SD to my '86 SDL. They both were pretty similar, as they both wouldn't even get the flow indicator to move, even at several thousand RPM. But, they both flowed relatively the same in the amount of coolant flowing by visual inspection. My '85 SD never rises above the 85*C mark.

compu_85 · #18 06-22-2009, 02:15 PM

Michael,

Be careful driving with a dead fan. I found that my SDL would overheat on the highway if it was hot outside and the AC was on when the fan was dead.

You might consider installing the plastic 606 fan, I hear a complete assembly is like $100.

-Jason

amosfella · #19 06-23-2009, 12:41 AM

AC is probably a bad Klima relay..... Overheating was probably air in the system that slowly bled out....

mplafleur · #20 06-23-2009, 10:14 AM

My overheating was definitely the hose to the expansion tank. I could see the steam of water coming out of it and it came off in my hand. I could see the trail of coolant I was leaving on the road.

Now it's steady at 82*C.

AC works fine. Nice to have a car with AC again.

I will fix the fan clutch though. I need more air flow in stop and go traffic.