Jcu1287

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Jun 23, 2019
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1990 L98 C4 Coupe
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So I have a 1990 L98 and just had the intake done and everything fixed up. I know these cars run a little hot but is it normal in 111 degrees weather for the temp to basically pin at 260 for a few before it drops a bit? Mine did it just a little bit ago on the way home from work. I would love some advice or knowledge from the Vette world on ways to run it cooler without doing anything major. Thanks
 
Nope, 260 is too hot by a fair margin.

These cars tend to "clog up" the front of the radiator with road schmutz and it restricts the flow of air through the core.

The cure is often to pul the rad, spray cleaner over the front (assuming you don't find leaves, plastic bags, furry mat of fuzz, etc), let it sit for a while, then turn it over and flush it from the back with water from a garden hose. Low pressure only, high pressure can damage the cooling fins.

Of course, if your cooling system hasn't been changed in a while and/or your thermostat is old, you need to get those serviced as well.

Thermostats tend to "drift up" in thier base opening temperature as they get older.
 
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Just had a new thermostat and intake gasket all done with new coolant and everything. Gotta be the old radiator
Not saying this is the issue, but when a rad gets older, the bottom tubes in the core can often be blocked by crud and sediment (often wear materials and scale that builds up) that settles out of the coolant. Scale (ie:calcium and other metals) can also build up on the ends of the rad tubes (like your shower head) and even build up inside the tubes themselves.

This all, obviously, reduces the efficiency of your rad. You used to be able to get a rad shop to “rod” or “boil” your core and return it to near new effeciency. But with the advent of plastic tanks on aluminum cores, that practice has pretty much gone by the waysides at almost every shop.

Most will just recommend you replace the plastic tank rads.

Yet another symptom of our “ throw away” society....
 
Not saying this is the issue, but when a rad gets older, the bottom tubes in the core can often be blocked by crud and sediment (often wear materials and scale that builds up) that settles out of the coolant. Scale (ie:calcium and other metals) can also build up on the ends of the rad tubes (like your shower head) and even build up inside the tubes themselves.
So would having a shop do a RAD flush help it or would it just be more beneficial to replace the damned thing? I know it is the original radiator so it may be due. I don't care about cost as much as I do getting the Big Red Machine running smooth and cool as the other side of the pillow.
 
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So would having a shop do a RAD flush help it or would it just be more beneficial to replace the damned thing? I know it is the original radiator so it may be due. I don't care about cost as much as I do getting the Big Red Machine running smooth and cool as the other side of the pillow.
Hard to say.

depends on what services are available where you are and how much you would have to pay for a new rad.

Here in canada, a new rad can easily go 500 CAD. But in the states, I’ve seen guys commenting that an oem rad can be had for around 100 usd.

I would say price out a “flush” (assuming they intend to “rod” the corr) and how much a new replacement would cost.

then go with what makes the most sense.

keep in mind, I’m trying to diagnose your overheating issue over the internet. I could be completely wrong here.

Best bet is to take my info and make an informed choice based on what you see.

I would probably try cleaning the outside of the core first to see what it does. Costs nothing to pull the shroud, spray the core with some detergent and run a garden hose through it backwards. if that makes no difference, perhaps try and look in the rad to see if your tubes look like they’re covered in mineral deposits.

Vette’s do tend to run a little warm when sitting still. Nature of the beast with everything scrunched doen as low as it can go and packed tightly under that clamshell. but 210-220 should be where it lives most of the time.

i have an issue with mine as it seems to want to run right at 230, which is too high for me. It runs at 230 because thats where the main and aux fan kick in and hold it there. My cooling sustem needs a good going through. I’ve only had the car about 2 weeks and gawd knows when the last owner gave it some proper maintenance....
 
So would having a shop do a RAD flush help it or would it just be more beneficial to replace the damned thing? I know it is the original radiator so it may be due. I don't care about cost as much as I do getting the Big Red Machine running smooth and cool as the other side of the pillow.

Personally... I would replace the entire thing. How much fun are you having with your car now?
Better to be driving and enjoying yourself than playing around hoping you don’t overheat and wipe out your engine.
The thing is old and the cost while annoying is peanuts compared to the alternative. You will spend less and enjoy more imo.

D
 
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Yeah probably what I'm going to do. I just had the intake done and new alternator and fuel filter. It is so much fun to drive especially down the highway in Vegas except for that desert heat. Thanks man
 
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Keep in mind if you’re running around in + 100f ambient temps, it’s only going to get so cool.

You cooling system works soley dependant on “delta T”. That is, it only sheds a certain amount of heat based on the temperature difference between coolant and air.

Should your ambient temps be high, the rad may not be able to drop the engine temp as much as if you were scooting through lower temperature air....
 
Ahh yes the old hot running corvette story. I went through it and after many dollars spent due to an overheat, the simple cure was a new stock radiator. I did the work myself for less than $200.00. I haven't seen the temp past 1/2 ever since. I bet you can easily squander more than that friggin around with flushing and chasing odd items. Not withstanding you do need to check for crud in the space between the rad and the a/c coil.
Thats my 2 cents ,good luck.
 
Seems to be running a little better and I have refrained from driving it in the afternoon here in NV until the weather changes. With that it runs pretty cool a bit past middle and then it rises a bit at stops but she seems to be running sexy. Definitely will be doing the radiator sometime soon tho. Thanks friends I really love having a place and great people to ask and admire the C4
 
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