78 450sl Running Hot?
 

Does anyone know what is the normal operating temperature should be? Mine operates between the next dash after the 175 line (which I assume to be 200?) and the 250 degree "hot line." Don't have the owners manual to confirm. Mechanic checked it out and replaced electric fan and said it was fine. However these temps just seem too hot. Live in Las Vegas, so all operating temperatures are hot. Any suggestions? Thanks.

My '79 450SL runs about 180 degrees. On hot days it might move up to 200. Try some Water Wetter, it works, might reduce your temp by 5 or 10 degrees. How many miles on your SL? Maybe time to rod and re-core the radiator or a new one, $$$, yikes.

sbr

My '79 also runs at temps similiar to sbr's. However it is very sensitive to hot ambient temperatures. I also run Water wetter in mine and it does seem to make a difference. The prior owner had the radiator taken out and cleaned throughly.

78 450sl has 126K. Bought Water Wetter today to put in tonight. Hopefully it will help, and not have to deal with the radiator scenario. (New, $750 Performance Products, but may be able to find it cheaper/rebuilt/recored elsewhere). Thanks.

My 74 450SL also tends to run a little on the hot side too.

I am using the Water Wetter and I think it does help.

The 450SL does seem to run hot. I have always heard that.

Mike

My 1980 450 doesn't usually run hot. On a 600 mile trip from Delaware to Kentucky in April, I noticed that it ran extremely hot when going up some of those mountains in West Virginia and western Maryland. Have had no problems since, but this is only a weekender car, and it has not been real hot here yet. Previous owner mentioned the same type of problem on a long trip. Best of luck Bob M