68coupe

The underlying problem with my 1968 corvette is that it runs relatively hot.

Overall problem: In the current cool new England weather, about 60-70 degrees, at idle, the car will warm-up slowly, taking about 8 to12 minutes to fully warm-up. Once the car hits the thermostat, which is at 160 degrees, the temperature plateaus at 160 for approximately 2 minutes then steadily increases to 210 degrees.

When I am driving the car, the temp gauge reads 160 degrees. At a stop light, the temperature gauge increases to 210 in about 2 minutes.

History: Before this problem, I was having even more problems with the stock cooling system. The car would constantly run at 210 and when at a stop light would increase to 230 degrees in less than one minute. When I rebuilt the engine in the winter of 2004, I put in a new cooling system.

New cooling system components:

Be Cool Custom-fit Aluminum Radiator
Perma-Cool electric fan with adjustable fan relay harness
Weiand High Flow mechanical waterpump
160 degree thermostat and new thermostat housing
All new hoses
New stock heater cool

Stock equipment left in the system:
Stock expansion tank

Problems with new system:
I checked the radiator when cool and it looked like it was empty. I looked down into the radiator and could see no fluid. When I started to fill the radiator with fluid, the radiator remained empty, but the expansion tank began to fill up. I was pouring the coolant into the radiator, but the expansion tank level was increasing. I know this sounds a little funny, but it is true.

Another problem is that the new Be Cool radiator, which is supposed to be a direct fit is not really. It fits in the car well, but the top outlet, which the top radiator hose goes on, comes out of the radiator and then hooks to the left, making it impossible to use the stock hose. Instead, a flex hose was used. This is a potential problem area because, as I have read on this forum, if the radiator hose is higher than the radiator cap, it which will create air pockets.

Another more recent problem is the gauge has been acting up. After allowing the car to heat up, if I turn the car off, the needle on the gauge spins all the way to the right, going down to the 6 o’clock position. IF I turn the car back on, after only being off for seconds, the gauge goes back to 160degrees and then increases to 200 degrees after one minute.

I am not sure if I have a broken gauge, Air pockets, low radiator fluid, faulty components. There are just so many variables, and I am looking to narrow down the diagnosis, so I can have a procedure to fix this problem with a correct and logical starting point. For example, fill radiator, then change hoses, etc…

All suggestions are greatly appreciated.

Fevre

First thing I would do it take it to a rad shop and have them shoot it with a pyrometer to give you an accurate temp reading so you can tell if there really is a problem.

68coupe

What is a pyrometer???

Fevre

It is a infrared heat reading gun.

jerome french guy

Brettmc

Your gauge might be off...but even if it's not, a peak of 210 aint that bad. My 94 Surburban runs at that temp.

Brett

68coupe

I agree that 210 isn't that bad, but the thermostat is 160 and the outside temp is 60 degrees, so on a hot day, the temp will go up. In the summer, the temp was close to 230 at a stop light, which in turn, makes the car hard to start when it is hot.

I think the radiator hose is the issue. I think it may be creating air pockets, but it still doesn't expalin why when i fill up the radiator, the expansion tank fills up. I just do not understand that.
HELP.

Thanks

markdtn

You want to be sure your fans are coming on. Maybe 1 doesn't work. You want to be sure that you are pulling all the air through the radiator and that the radiator (and hood) is sealed to the core support. How are the fans controlled? Together or separate? Temp switch(es) in the head? In the intake? Bulb(s) tie-wrapped to a radiator hose? Sounds like an airflow issue, but have you checked timing? Could be advanced too far.

If you have a big inlet on the radiator, you may want to remove the expansion tank and add an overflow bottle. You don't really need both. You may be trapping air in 2 places instead of 1. May want to jack the car up or park uphill to fill the system if it is that close.

My TPI 69 with Griffin Radiator from DeWitts and dual C4 fans never gets over 200 with a 195 t-stat. My fans are controlled separately and the second one has never come on that I can tell. It is controlled by a switch in the head to come on at 208 I think and off at 185. The primary fan is controlled by the ECM. It cools fine in traffic with the A/C on in mid-90s and high humidity.

Summerfun

Check that foolish gauge and its connections too.
It may be shorting out somewhere or old cracked wires may react to electromagnetic waves in the engine perhaps?

The electrical gurus will probably TAO over that comment!!

Vetterodder

You didn't mention your timing specs so I wouldn't rule that out as the problem. Too little timing at idle can cause higher temps. Once rpm are increased and timing advances, problem goes away just as in your symptoms.

zwede

Why doesn't your stock upper hose fit? I have a Be-Cool radiator and have no problem using the stock upper hose. Maybe your radiator is defective.

As for your cooling problem, I agree it sounds like an air pocket.

Brettmc

I think I read on the forum once that you can drill 3-4 small holes in the perimeter of the stat to prevent the dreaded air pocket.

Brett

68coupe

total timing is at 36 degrees
18 degrees advanced and 18 initial.

I am not sure why the stock radiator hose didn't fit, maybe it was not the stock hose??

I can get one and give it a shot, a person I work with suggested the same thing.

But would an air pocket cause the expansion tank to increase when I put antifreeze in the radiator?

Thanks

68coupe

Also, there is only one perma cool fan, that comes on around 170 degrees. The fan is 16 inches in diameter and pulls 2950 cfm.

68coupe

Also, the temp sender is in the intake manifold and the fan sensor is in the water pump.

68coupe

Mark,
You suggested that I remove the expansion tank, but here is the problem, the expansion tank has and inlet and outlet. It is in between the heater core and the radiator, so if I remove it, I can run the hose coming from the radiator to a collection device, but what do I do with the hose that goes to the heater core? Won't that cause problems in the system. And I still do not understand the system all together. I thought the expanision tank was a critical component. I do not understand how the coolant would still flow if you removed it. Lastly, I still am confused why the level in the expansion tank increases when I add coolant to the radiator, isn't the radiator higher than the exapansion tank? Still really confused.

Thanks for all of your input.

Larry B.

Scroll down to the temerature senders. http://www.lectriclimited.com/mainpage.htm .common problem

page62

That fan could be an issue -- it simply not be up to the task, despite the rated cfm. Most folks around here are running dual Spal fans, which have some serious suction!

soggybottomboy

page62,
Where is the best place to get the dual spals?

soggybottomboy

I thought the hose to the expansion tank picks off before the cap seal? If that's the case then in order for the tank to fill and not the radiator doesn't this require that something is blocking the inlet under the cap?