Yes, and the upper hose and cap too. Stick the garden hose in where the upper radiator hose went and blast it with water while you look at what's coming out the bottom outlet. Shut the water off, then repeat but this time through the bottom hose outlet, then hit the drain hole too. Keep doing it back and forth it till the water comes out clean and flows out as fast as you're dumping it in.

It drains out the outlet opening on the water pump, where the other end of the lower radiator hose connects.

So remove the t-stat and reinstall the housing back on with no t-stat inside. Remove the lower radiator hose completely, from both the water pump end and radiator end. Attach the upper radiator hose to the thermostat housing with clamp to use as a guide to keep from making a big mess on the top of the motor. Stick the end of the garden hose into the open radiator side of the upper hose, and force water down through the t-stat opening at full blast. Water will now circulate through the engine and come out of the water pump outlet where the hose was. Again, blast it till it comes out completely clean, and flows out at about the same rate that you are putting it in. I like using a gun on the hose. It makes it a one man job.

Once done, reinstall t-stat and hoses. Refill with a clean new 50/50 mixture of water/antifreeze. Start the car and note the temps.

Here's a tip. After getting the hoses on, fill the engine block with coolant using a funnel through the t-stat hole directly before you install the t-stat. Once engine block is full up to just below the t-stat mounting surface, install t-stat and housing. Use sealant and new gasket. Then top of radiator. This method get's the entire cooling system almost 100% full, reducing the amount of times you need to "burp" air bubbles from the system. With this method, you'll only need to add a little more coolant the next few days maybe once or twice.

 

ok, I will keep you updated on whether this solved the problem, thanks for the info.

 

Very interesting, I'll have to keep this one in mind for future reference.

But before all of that, wouldn't you check to see if the coolant EVER flowed?? That would be my first item on the checklist.......pull the radiator cap and check to see if there is water flowing at all. Then I'd go from there.

 

ok, so I did the water trick and flushed the radiator and the motor. I started it and it ran good for a while, got up in temp and then would drop back down 3 degrees, so I thought it was fixed.

Then it stopped and just started to rise again, got to 260 and turned it off.

Now the radiator is getting hot, but its building pressure, when you turn the car off you can hear it bubbling into the overflow and start dripping antifreeze out. If you start to turn the cap you can hear it releasing the pressure.

Should I take the brand new thermostat out or is that my problem?

 

That is normal operation. That's the way the system is supposed to work. But it still should not be reaching 260 with fan running and coolant now circulating. Your fan should be kicking on at about 230 and temps begin to drop. When is the fan coming on? Fan should keep the temps from going up that high. Are you sure the radiator is clear of obstructions? Let the car cool, top off radiator, and take it for a drive and see what the temps do with air coming in through the front. What temp is your thermostat?

Did you flush a lot of junk out of the radiator and motor? How was the water flow when you where done?

 

the fan comes on immediatly soon as you start the car and stays on, I don't know why because it use to not do this before.

The thermostat I put in was a 180 degree. I flushed all the openings till water was pouring out the openings. not really alot of stuff came out, but I did it for a good while.

I did take it for a drive up the street and back thats when it reached the highest reading. Sitting in the driveway I got up to 245 and that was it.

It just seems like the damn overflow tank is fixing to explode from pressure, its got coolant seeping out the cap.

 

The overflow cap is vented. Did you have too much in there when you started?

Here is how I fixed this on my '86. I drilled 1 small hole in the thermostat (a 170). This hole allows some coolant to circulate at all times and helps with burping air bubbles. This reduces temperature spikes when you stop at a light and such, yet still not cause the car to take forever to warm up (if you do too many holes, that will happen, car will run too cool, that's why I said 1 small hole).

Then I installed a low temp fan switch. This one:

Instead of my fan turning on at the factory 230 degrees, it turns on at 200 and back off at 195. With the fan switch, and the hole in the t-stat, my car stays in the 190 range even in the hottest days, and the fan is not constantly tuning on either.

Does your car have 1 or 2 fans?

http://www.mamotorworks.com/corvette?frame=3.944


Go through the steps given here again:

http://temp.corvetteforum.net/c4/vad...erheating.html

 

ok, I think I fixed it. I went back out there and found it low on coolant, it sucked all the coolant out of the overflow. So I took the cap off started the car and added coolant so it get burp itself.

Took it for a drive and it never went over 222. At park it gets up to 235 and then drops.

 

where do you drill the hole at on the thermostat? I guess my fan is always on because the a/c is running???

And the low fan switch is only $25? That's worth it. I only have 1 fan.

 

That's the way the overflow system works. 1 gallon of cold coolant takes up less space than 1 gallon of hot coolant. So the overflow allows for this extra expansion, and suck it back when the car cools down.

For the next few days, let the car idle and periodicaly squeeze the upper hose with a rag around your hand. When you feel that the hose is not hard (stat open), slowly remove the radiator cap. Have somebody raise the idle to 1500-2000. This drops the water level in the radiator. Add more coolant with idle raised and put the cap on before letting the idle back down. This "packs" the radiator good. The hole is drilled on the flat "frisbee" surface of the stat. But I would not bother with it now that your temps are in check. The temps you reported are very normal for stock. Just keep toping the radiator off for the next several days. Level should hold steady after a few times. I guess that flush really helped. You just had pockets of air after the first drive.

The low temp fan is worth every penny. It goes where that pipe plug (on single fan cars) is on the head between #1 and #3 spark plugs, on drivers side. You have to make your own tool to fit the squared hole, and put a breaker bar on it to remove it. Yes, the fan should run when the AC is on.

 

With the inconsistencies....I believe the pump is on it's way out...

did you ever run the car with the radiator cap off to view the coolant flowing??

 

Yes I could see the coolant in the radiator moving around with the car running with the cap off.