High coolant temp

[secondchance]

I replaced my radiator (OEM) about 5 years ago and installed Marc's chip about a year ago and she had been running at around 213 - 215.
Last week in 90 degree weather in rush hour traffic I noticed temp gauge hitting 230. So, I turned off the AC and temp came down to 213 and as I drove home.
Yesterday (90 degree day), driving back from the body shop (yes, I got her back and she looks perfect!), driving 65 mph, temp was a 225. Normally, 65 in 6th gear use to be around 213 and a little cooler in 5th (better coolant flow I figured).
I will check for any debris on the front of the radiator and fans (been busy).
Anyone had a similar experience?

[HIZNHRZ]

Yun, with time and mileage (depnding on driving conditions) the conditions you are describing are what I experienced with my Red/Gray 91 fair weather daily driver. At the time the car was about 10 years old and had ~15K (very short commute to work) miles. I pulled the radiator and cleaned it and the car again ran cool again. If you saw what I cleaned out of the radiator fins you would have thought I drove the car at the beach. It was a very fine sand like material. It was almost more like dust than sand but the radiator was packed with it; especially towards the bottom. After cleaning it out, it was only about another year before the running unusaully hot conditions returned.

I pull the radiator again. Mileage was only another ~8K miles but the radiator was as loaded with sand/dust like material again that was very hard to see when crawling under the car or when looking from the top. This time I replaced the radiator with a Fluidyne radiator and thermostat. The car ran cooler than it ever had. It's only a guess but I'm thinking the stuff that loads up the radiator has something to do with the crap thrown on the streets in the winter.

I sold the car soon after. I do talk to the new owner. The car now has over 30K miles and the new owner has never brought up and cooling issues. The only other thing I can say is the stuff was very hard to clean out. I'm thinking as the open area aperture becomes restricted and it not only impedes air flow and cooling but it also loads back up again much quicker. I don't think it's your problem but I also have a 160 degree thermostate you are welcome to if you wanted to try it.

[secondchance]

Hate to admit it but I think you are right.
I drove this car after snow and all that stuff they sprinkled on the road.
I just checked Fluidyne but seems they no longer have one for corvette. Is fluidyne the wider one (racing application)? I hear Dewitt no longer offer one for C4.
Any recommendations - a good direct fit aluminum for street application?

thanks for the offer Scott. If I decide to try 160, I will call.

[pantera1683]

Originally Posted by secondchance

Hate to admit it but I think you are right.
I drove this car after snow and all that stuff they sprinkled on the road.
I just checked Fluidyne but seems they no longer have one for corvette. Is fluidyne the wider one (racing application)? I hear Dewitt no longer offer one for C4.
Any recommendations - a good direct fit aluminum for street application?

thanks for the offer Scott. If I decide to try 160, I will call.

There are plenty of replacement rads on ebay (china?), corvetterecycling (NOS great price), dewitts (they still make c4 rads), and others.

[Aurora40]

FYI, if it was while cruising in 6th, try downshifting to 5th. If that brings the temp down quickly, it is caused by the low coolant flow at low RPM. It's a common issue that doesn't really have a solution (other than to downshift or drive faster).

[secondchance]

Originally Posted by Aurora40

FYI, if it was while cruising in 6th, try downshifting to 5th. If that brings the temp down quickly, it is caused by the low coolant flow at low RPM. It's a common issue that doesn't really have a solution (other than to downshift or drive faster).

I know. She was running 220 in 5th. Normally, in 6th would run 213 and 207 or so in 5th.

[secondchance]

Those who are using Dewitt - are they better cooling relative to OEM? I remember reading fans have a bit of difficulty pushing air through - true?

[GOLDCYLON]

Originally Posted by secondchance

Those who are using Dewitt - are they better cooling relative to OEM? I remember reading fans have a bit of difficulty pushing air through - true?

True thicker rad core


mine always runs cooler in 6th with a stock rad

[secondchance]

Mystery solved!
Rather than speculating I went for a test drive, noted it was doing the same thing - temp climbing even while cruising at 55 - 60.
Came back home, got on my back with a flashlight. It turns out that a plastic flap that is hung at the top of the radiator has to come down, tuck over the bottom of the front bumper and this is held in place w/ a plastic tab. It seems this piece has come loose and at speed this piece is piece is pushed back to the radiator. With both fans running, this piece get sucked towards the radiator further worsening the problem.
Hah! I don't have to spend a whole day wrestling with a radiator!

[Kb7tif]

Has anybody tried to restict the flow in the coolant bypass line? Without blowing out the rad (ha). I read writings from people who had MH do this as a last resort type of thing that fixed high temps once and for all.
Saw pics of somwone who actult put in a shut off valve so he could set it for best results, Traffic, high revs ect.