Overheating

[pch90265]

Hi,
Over the weekend I got stuck in really bad traffic and the temp gauge in my '71 280sl (auto-a/c) shot up to red.  The gauge would come down around 25mph or higher but would go back up as soon as I came to a stop.  Eventually I pulled over and waited for about one hour for the traffic to die down so that I could drive back home without any problems.

Any ideas on the possible culprit for overheating would be greatly appreciated.

[bpossel]

Hi pch90265,

What I have done over the past several years, since I have owned my 113, to reduce temp issues, is to:
1. replace the thermostat (75degree C)
2. replace the visco fan
3. replace the water pump
4. clean the thick crud/dirt off of the engine
5. have my radiator recored with add'l row
6. replace 100 degree & 17 degree switch
7. flush radiator fluid & install new fluid with mix of "water wetter", distilled water and regular radiator fluid.
8. ensure timing is set correctly

Now in Memphis, TN. summer traffic, my temp is 180 while driving (car moving) and slightly higher while in stop & go traffic.

The real test will be when I drive to Ohio next month for our meet at Joe's. Highway (many hours at high speed) and stop & go traffic...

Regards,
Bob


bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[J. Huber]

Hey PCH. It seems like every summer I end up telling this story -- but it is worth hearing, especially since it occurred in your neighborhood (I assume). Back in 1991 I was coming through LA on a Sunday afternoon. Destination: home in Santa Barb. It was summer and pretty warm -- and car started to overheat. When I saw the red needle going up, I stopped for water and to let things cool. I leapfrogged from gas station to gas station -- kept rising -- but nothing (Sun.) was open. Not wanting to leave my car on the 101, I just went for it. Big mistake. At the SB/Ventura Co. line the car just died. (or I should say went into a deep coma)... at the time 3500+ dollars got me a new upper engine rebuild. I now pay very close attention to that needle!

Moral for ALL of you -- please listen to your car when it cries for help!

Bob's list sounds very helpful. I have a H/E radiator in there now and am sure to keep things well-maintained. For years, the gauge stays very steady even on the warmest of days. However, not a whole lot of traffic jams since we re-settled here to Nevada County...

James
63 230SL

[pch90265]

Many thanks to Bob & James. I will look into all areas mentioned on the list. By the way, the problem occurred on PCH heading south toward the 10E between Malibu & Santa Monica. An area of heavy congestion on weekends, especially in the summer months.

Bert
'71 280sl

[ja17]

Hello,

Don't forget, you can turn the heater on full in case of emergency. This will add cooling capacity to the system and may prevent an oveheating situation. A little sweat now could save a lot of sweat later!

Joe Alexander
Blacklick, Ohio

[jeffc280sl]

In case you missed my comments on another thread here is a copy.

Sorry to hear the MB kit didn't work perform as hoped. For about a year I have been using a hose and 2 tee fittings to bypass the heater core. It is an inexpensive way to route hot water from the head back to the radiator without going through the heater core. The heater hose fittings in the head are larger than the outlet used by the MB kit effectively allowing more hot water to circulate out. Basically I have installed a tee fitting in the supply and return heater hose to the heater core. The fittings are connected by a new hose which goes over the head. I don't drive the car in the winter and when I need heat I use the heater levers as before and adequate heat is available in the cabin.

My only concern is that the operating temperature is too low at about 185 to 190F. I think optimal temp is arounr 200F. At idle in traffic the temp gauge rises very little.


Jeff C.
1970 280SL 4-speed

[athadani]

Had overheating issues in summer slow traffic despite have taken all known steps discussed in this form but without relief from the stress that this causes. But, NOW, a friend, neighbour and Pagoda owner advised that I have the radiator fluid changed and do not add any more anti-freeze fluid protection than for upto -20 degrees centigrade which is quite enough for Geneva, Switzerland winters. And, the needle just stays put at normal 80 c or 180 f regardless of the hot weather, today 30 C or traffic conditions, was stuck for 15 minutes at a time in slow traffic today.

Hope this helps.

Ashok

[bossanov]

"...and do not add any more anti-freeze fluid protection than for upto -20 degrees centigrade "

I am not sure what this means.  Please explain.

[mdsalemi]

"...and do not add any more anti-freeze fluid protection than for upto -20 degrees centigrade "

I am not sure what this means.  Please explain.

Water dissipates heat better than glycol antifreeze.  Therefore, cooling is better (in theory, at least) with a lower concentration of glycol than with higher.  You need to balance that equation however with practicality: pure water would be best,but with no anti-corrosion chemistry pure water would not be a good choice. Pure glycol isn't wise either.  So, the writer is suggesting a coolant balance to -20c. that would be -4 F.  That's actually not wise unless you live somewhere where it absolutely does not get down that low. My coolant is balanced at 50/50 which I think is providing protection to about -35F.  Most recommendations for northern climates vary between 50/50 and 60/40.