TEMPERATURE NEEDLE RISES BEYOND 55-60 Mph
 

The fan kicks in and coolant liquid is at the proper level. But the needle rises ONLY when driving up hill at 55 MPH and over. This doesn't happen when driving on surface, stop and go streets.

Recommendations to resolve this problem are very appreciated.

Re: TEMPERATURE NEEDLE RISES BEYOND 55-60 Mph
 

First, I'd try something simple like a new thermostat, maybe the current one does not open like it should.
How many miles on it. Has it always had the recommended coolant mix ?
If a lotta miles / bad coolant mix then perhaps a clogged radiator ?
Maybe also a tired water pump ?

Re: TEMPERATURE NEEDLE RISES BEYOND 55-60 Mph
 

You need to be more specific on what you consider "rises". Most Crossfires run just under the half way mark. When being aggressive or running hard, it is normal to be just above the half mark.

James

Re: TEMPERATURE NEEDLE RISES BEYOND 55-60 Mph
 

James - Mine has always driven just above the half mark when warmed up. By "rises" I'm referring to the needle moving from just above the half mark to just below the red in a matter of seconds. That is because I let go of the accelerator. This happens at 55 mph and above. Or also If I drive up hill at lower speeds.

Re: TEMPERATURE NEEDLE RISES BEYOND 55-60 Mph
 

ala-xfire -- Thanks for your recommendations!


I just broke the 160,000 mile. I've always made sure the coolant is at the proper level but have not flushed it once. Clogged radiator and tired water pump are a possibility.


Where would you go to buy a thermostat? and what is the recommended coolant mix?

Re: TEMPERATURE NEEDLE RISES BEYOND 55-60 Mph
 

Google/Rockauto a thermostat/water pump for a 2004 MB slk320.
Proper mix is 50/50 distilled water / Zerex G05 undiluted.

As a note, my gauge reads just below middle while at 55-60 MPH with no A/C, which is 186 degrees.
When I idle in traffic with A/C on, I have seen 208 degrees which is slightly above middle on the needle.
Mine quickly cools off when I am up to speed again.
186 without A/C, 193 with A/C
( I have an UltraGauge which displays temperature )

Re: TEMPERATURE NEEDLE RISES BEYOND 55-60 Mph
 

ala-xfire - Thanks again for your help!


What do you think are the chances that the car is not actually over heating, that it may be only the temperature sensor what's causing the problem?


I'm only saying this because the first time the needle went up to the red I immediately pulled over and opened the hood and surprisingly it didn't seem that over heated. It wasn't hissing and when unscrewing the cap of the coolant reservoir, it didn't have excessive pressure.

Re: TEMPERATURE NEEDLE RISES BEYOND 55-60 Mph
 

Update -- Just thought to follow up on repair. I replaced thermostat and flushed the coolant. Problem solved.

Thank y'all for your recommendations!

Re: TEMPERATURE NEEDLE RISES BEYOND 55-60 Mph
 

Thanks for the follow up !
Glad I could help.