C5 Temp goes to 240*

[froggy47]

I also suspect a sticky stat, however, the holes in the condensor & radiator are so small that I think the radiator needs to come out to really give it a cleaning & also depending on water hardness, coolant maint etc, you could be getting some restriction in the radiator.

10 years old.

New stat, radiator & tune the fans to come on earlier will fix.

:)

[LLC5]

Originally Posted by c5havin

Thanks TG! That is what is on the agenda for the day. The thermostat and the fluid were changed along with the water pump, but parts wear out. I'm praying that no damage was done if the thermostat was the original problem.

And LL......This came on all at once. As I said, summertime here in the central valley of CA, the days get pretty warm. Usually triple digits for a few months. I notice at that time of year I need to blow the debris out of the condenser and radiator. Most always causes a 10-15 degree temp drop in the operating temp. Thank you for your replies TG and LL !!!!!!!!

If you start the vehicle cold and let it warm up with out driving it, does the temp come up slowly and normal, or very fast to 240*F? Do both radiator fans come on at about 228*F, and faster at around 235*F? If so, then you may still be looking at a restriction in your radiator or condensor. Keep in mind that a restriction in either one will affect cooling capacity, they BOTH have to be clear of debris and there are special tools designed to do a thorough job, blowing air with just an air gun will not clean out a lot of debris.

[c5havin]

Thanks Froggy. Well gang, I changed the stat, a/f, and so far so good. Never got above 212 at idle. Can anyone tell me what temp the low speed fan is supposed to come on? I thought it was at 212*.

[c5havin]

Originally Posted by LLC5

If you start the vehicle cold and let it warm up with out driving it, does the temp come up slowly and normal, or very fast to 240*F? Do both radiator fans come on at about 228*F, and faster at around 235*F? If so, then you may still be looking at a restriction in your radiator or condensor. Keep in mind that a restriction in either one will affect cooling capacity, they BOTH have to be clear of debris and there are special tools designed to do a thorough job, blowing air with just an air gun will not clean out a lot of debris.

Hello LL. After changing the stat and fluid, I let the car idle for nearly 1/2 hour. Never got above 212* according to the DIC. Temp came up real slow. The car never got hot enough to allow both fans to come on. I drove it for a bit, and temp went from 212, down to 206. I'm letting it sit for a bit, which prolly raise the temp, ck for leaks, and retest.

[froggy47]

Originally Posted by c5havin

Hello LL. After changing the stat and fluid, I let the car idle for nearly 1/2 hour. Never got above 212* according to the DIC. Temp came up real slow. The car never got hot enough to allow both fans to come on. I drove it for a bit, and temp went from 212, down to 206. I'm letting it sit for a bit, which prolly raise the temp, ck for leaks, and retest.

:)

I have had sticky stat in other vehicles, it lives in a pretty harsh environment.

[Fixvet]

Originally Posted by c5havin

Hello LL. After changing the stat and fluid, I let the car idle for nearly 1/2 hour. Never got above 212* according to the DIC. Temp came up real slow. The car never got hot enough to allow both fans to come on. I drove it for a bit, and temp went from 212, down to 206. I'm letting it sit for a bit, which prolly raise the temp, ck for leaks, and retest.

Be sure your dash temp reading and the DIC temp reading results are about the same. Normally if one of them is crazy, it can be a faulty water temp sensor in the drivers side head. However, sounds like you're git'in 'er done!! At idle, low speed fan should always come on w/ a/c turned on. W/o the a/c on it comes on around 220 normally, I believe without digging out my manuals. At speeds above about 40mph, neither fan will operate because of the airflow from outside on the road is high enough and the fans are not needed....unless you're plugged up.

[c5havin]

After testing again, all seems to be well. I really appreciate everyone's help and input. You guys are the best!

[c5havin]

Originally Posted by froggy47

:)

I have had sticky stat in other vehicles, it lives in a pretty harsh environment.

I reside in Bakersfield. We know what brutal heat is all about!

[LLC5]

Originally Posted by c5havin

Hello LL. After changing the stat and fluid, I let the car idle for nearly 1/2 hour. Never got above 212* according to the DIC. Temp came up real slow. The car never got hot enough to allow both fans to come on. I drove it for a bit, and temp went from 212, down to 206. I'm letting it sit for a bit, which prolly raise the temp, ck for leaks, and retest.

Sounds like you have it fixed which is great. The fan will come on around 228*F on your DIC, it wouldn't be a bad idea to let it idle and see when yours does come on. Remember to check the surge tank level when cold (preferably overnight) for at least 2-3 cold to hot cycles to make sure the coolant level remains correct.

[ToolGuy]

Sounds like you got it fixed, good job!