1973 280se 4.5 TEMPERATURE PROBLEM.

[randysue2]

Hello Again... Does Anyone Have Any Ideas On Why My Temperature Needle Seems To Rise When Sitting In Traffic, And Goes Back Down When Moving. It Rising All The Way To 275, Then Will Slowly Start Back Down When I Get To Moving. Any Help Greatly Appreciated. Randy Ray Caudle.

[JeffreyNMemphis]

Hello Randy,

I don't know specifically why you are running that hot... Most cars will run hotter in stop and go traffic because you won't have as much air circulating through the grill. Also, if you have issues with your cooling system, they will be magnified sitting in traffic.

I am not a mechanical expert, but I would say that driving the car with the temperature as high as 275 degrees will lead to expensive damage. I know that this forum is very active with 280SE/SEL 4.5 owners. You will surely get an intelligent answer here. Someone here can tell you from experience what happens when your engine gets that hot, and I bet it is not pretty.

[nhdoc]

Originally Posted by randysue2

Hello Again... Does Anyone Have Any Ideas On Why My Temperature Needle Seems To Rise When Sitting In Traffic, And Goes Back Down When Moving. It Rising All The Way To 275, Then Will Slowly Start Back Down When I Get To Moving. Any Help Greatly Appreciated. Randy Ray Caudle.

First of all that is bad. You may have one of several things wrong. Bad fan clutch, bad thermostat, bad aux fan sensor or bad water pump. Could also be a bad radiator. The bottom line is you will damage the engine if you let the temp rise that high so don't.

My money would be on the fan clutch and aux fan. Also, make sure the fan shroud is present and is a good fit around the fan.

[ADP]

If your aux fan is coming on - check out your thermostat. I've had them malfunction like that before in a GM car, the little spring became sluggish. Amazing how a fairly inexspensive part could cause so much damage.

Also, are your hoses squishy?

When I got Brunhilda she had the wrong thermostat and ran a little hotter than she should have. Not that hot though, thats not good at all.

Ann

[alabbasi]

I had the same problem with my 6.9 and the aux fan would not come on in traffic. The problem was the thermostat. The temp would rise all the way to the top in traffic, but the flow of air will lower it when driving.
When I removed the thermostat, I found foam on the top pipe. It looked like no water at all was getting to the top of the engine and as a result, the aux fan would never engage.

Try the thermostat first, it's cheap.

[xtreme barton]

id do a flush of the coolant system (if not done recently) and check for anything abnormal .. make sur eyou put the proper mixture back in.. you can take your thermostat out and check it in boiling water to see if it opens properly(thermometer is needed) id just go buy a new one as they are usually only 8 dollars or so .. next try and squeeze your radiator hoses (be careful not to grab it when its real hot) and see if the top is fairly hotter than the bottom .. also squeeze it closed and release it to see if you can feel the coolant flow through ..

when your engine gets hot you should shut the motor off and spin the cooling fan (not the electric one ) and see if its hard or very easy to spin .. this will tell you if its engaging or not.. when its cold it should spin freely and when its hot it should be hard to turn

have you tried turning the heater on full blast ? does it help at all ?

do you have any fluid draining from the bottom of the water pump ?

let us know the results ..

im leaning towards a new radiator

[MunichTaxi]

I'm located in Olympia,WA. Where are you?

Don't drive the car if the Temp is actually hitting 275 F. Could be a bad Temp Gauge. Could be not enough coolant, or an Air Bubble in the system.

Are you loosing coolant?