corvettesummer79

runs around 210 for first half hour but can creep over 220 with
stop and go driving. hosed off condenser and rad. missing middle top seal. antifreeze looks clean and debris free. cant see any flow to speak of with cap off. can squeeze both rad hoses all the way closed while running top one very hot. new thermostat installed recently.
Have the front spoiler wind foil in place. Is it ok as long as it stays under 230 ? Id rather replace top rad seal do a flush and fill and put some water wetter in than replace water pump. Thoughts appreciated

scrappy76

Was it running hot before you put the new thermostat in ? What temp rating is the new thermostat and what was the old one ?

Not really sure if a water pump can get weaker to where it doesnt cool as well. Usually what happens is it will start leaking, or the bearing will go bad and get loose, Or it breaks.

Ontario73

I would be concerned that your system isn't building any pressure. If you are actually running at a true (stock gauge is questionable) 220* you're already over the boiling point at atmospheric pressure. Check your rad cap and replace it for the low $s involved.

It is also possible you still have air in the system. Some people have had good luck purging these cars by drilling a small hole in the thermostat before installing. Some T-stats even come with this hole, so, these is something to the concept!

corvettesummer79

Thank You Scrappy and Ontario yes it was running hot before I put the stat in. It didn't even have a stat. the new one is a standard I bought from Advance or Oreillys probably a 190 stat. So no one thinks it has
anything to do with the water pump? just an airflow issue or air in the system? I burped it with the cap off but I will try to get a cap with pressure relief valve. thanks

corvettesummer79

The water ump doesn't leak at all

corvettesummer79

spring is in place on lower radiator hose

corvettesummer79

I replaced the sending unit but had to put a resistor in line because it was reading too high

DaveL82

I chased over heating on my 80 years ago. Found out that any leaks of air around the fan shroud to the rad, the rad to the core support will allow air to leak in from a round the rad not through it. Make sure the fan can only draw air though the rad if not it will get warm. even a small air leak makes a difference.

redvetracr

there is a tool you might be able to borrow that you twist onto your cap and pump up that checks how much pressure it holds, I believe a pressurized cap is worth 3 degrees per pound of pressure, same tool can check the cooling system for leaks, it might be as simple as needing a new cap and replacing that top seal....PS: Water Wetter did nothing for me, I consider it a high priced water pump lube as I run straight water

corvettesummer79

Thanks Dave I am going to try spraying the condenser and radiator with some kind of coil cleaner not sure what to use, they look clean but might be hidden crud in there.

corvettesummer79

Thank you redvetracer you saved me some cash

scrappy76

I assume your clutch fan setup is operating correctly ?
A water pump is exactly its name. It moves the water from the engine to the radiator. unless it has broken or missing fins, it will pump the water like its suppose to. The shaft however can break. Then you would overheat all the time. the pump can lockup if the bearing goes bad, again will overheat all the time. Lastly, it will start leaking, you will see that.

I wonder why it did not have a thermo in it originally, ongoing issue before you got it. So check you clutch fan, all your seals, your air dam, and yes make sure the rad and ac condencer fins are all clean. Also, make sure your timing is not too far advance, that could cause higher temps.

corvettesummer79

Thank you Scrappy clutch fan is working fine because I can see it. will haveto learn how to set the timing but its running great now
maybe a slight bit too rich but since put vacuum advance to the right port this quadrajet is very responsive. You know your stuff wish I had your experience and knowledge take care

scrappy76

Thanks for the compliment. I still have alot of learning to do. There are a ton of guys here that know more than I.

You mentioned about seeing your clutch fan working properly. You will have to actually spin it to test it. ! With the engine off !, see if you can spin the fan easily by hand. If so it could be bad. Or if it feels loose and you see it moving at the shaft, it could be going bad.
If you try to spin it and its really hard to do, then you should be ok.
As your engine warms up, its the clutch that starts locking up to make the fan blade move. But if the clutch is worn out the blade will look like its moving with the engine running, but wont be moving enough to keep cooling the radiator. If your clutch is fine, then again you either have issues with radiator seals, Air flow, dirty radiator and ac fins. Or timing advance.

corvettesummer79

cool will check it tonight when son gets home from school

OMF

How old is your rad? I'd say 90% of cooling problems with these cars are plugged up radiators......the other 10% are a mix many things.
A new rad can really do wonders.....you never know what has been dumped into the cooling system in the last 35 years.
Try getting it good and hot, and then open the hood and spray water on the front of the rad while the engine is running.....I bet it cools in a big hurry. Thats a good sign the rad isn't up to scratch anymore.

corvettesummer79

Thank you ssstocker its an original radiator as far as I know it has 70k miles. Scrappy helped me and I think the fan clutch may be bad or going out.

corvettesummer79

sprayed coil cleaner on both sides of rad and condenser installed new rad cap replaced hood rad seal installed new clutch fan probably dint need to but glad its done will see what it does now
what is an air dam?

redvetracr

aka...lower spoiler

TedH

When I was diagnosing heating concerns, I added a mech temp gauge under-hood to verify if my gauge was correct. I had to swap temp sender as my DART heads had different thread. So, to ensure that I had reliable reading after the DARTs and a different sender in cyl head, I installed a $20 mech gauge with sender in one of the available coolant ports on the intake. Gave me good peace-of-mind for $20.

As others have said, cap is cheap to replace, be sure you have the correct seals around radiator, correct shroud and the fan clutch working and fan blades have about 1/2" exposed out of the shroud on pump side.

As PO had removed the thermo, I suspect they had chased the issue also.

Radiator look unclogged from peering in from cap? right capacity radiator?