First the facts:
1980 Corvette
New water pump
New thermostat
New hoses
Bypassed heater core
Flex fan with no clutch
Aux Elec fan wired to run constantly
Fan shroud is present and not broken
Most of the weatherstripping on top of the shroud is missing
New temp sending unit for temp guage

I called a radiator shop earlier today about having the radiator cleaned. I met a real live honest business man. We discussed the problem and he told me that the radiator was not the problem. I just wasn't getting the necessary airflow through the radiator.

It has only been in the 50s here when I'm driving the car, so I know this is only going to get worse when the temperature rises during the summer. The car runs 220 degrees once warmed up. Driving around it stays at almost exactly that temperature. Last night I went to the drive through at Sonic and while waiting in the slowest line ever, the temp started creeping up to around 240 before I could escape the drive through.

The radiator shop owner suggested that I check between the ac condenser and the radiator for debris. He also suggested that I measure the temp of the coolant compared to the reading of the guage.
Is there a way to test the sending unit?

So, what and where do you guys suggest I start looking for the solution to my cooling problem?

 

Try finding someone with a lazer thermometer to check your temps all under the hood. I was concerned about my gauge readings even after changing the stat. and rad. A buddy's lazer showed my gauge was reading about 20 degrees high. If it is in fact hot it could only be about three things: air flow, water flow and tuning. Incorrect timming usually makes the engine hot when it is under load. Good luck.

 

Check the blade positions of the fan. If your fan is bolted on backwards it will not draw or pull the air through the radiator as effective as it should. I bought a car with a rebuilt engine and the fan was installed with the blades in the opposite direction and had bad cooling problems, and a very rough running engine. After looking at a friends car I saw that the blades were wrong , replaced it and it ran perfect.

Just an additional opinion/story.

kdf

 

Ditto the elec fan, make sure they are not fighting each other too. Did you put a spacer on to move the flex fan into the shroud?

 

I did some digging and came up with an old picture of the engine. It is the best picture I have at the moment. I can take another when I get home tonight.



I have been curious if the elec fan is fighting the flex fan for a while. The flex fan should be pulling air through the radiator towards the engine, correct?

 

Yes the flex fan should be pulling air through the radiator.

 

That looks like it is on right with the spacer. Should be able to put your hand behind the elec fan when it is on and feel the wind, with eng off of course. It does look like you are missing some of the top edge of the shroud that is supposed to butt against the rad with a seal, air will pour through there really killing the mech fan effeciency.

 

I see what you mean about the radiator shroud. Tonight when I got home I started looking everything over real good. I know that my ac is not hooked up, so I removed the A/C condenser from the car which opens up all air flow to the radiator. Second, I started playing with the wiring for the elec. fan. I realized that it was not hooked up like I thought. I have the wiring run to the center console to put in a switch for the fan.

Now, about the radiator shroud. Originally that should have been covered by that big air intake box right? What options do I have to fill the gap at the top of the radiator?

 

I think I see your problem. Its looks to me like you have the electric fan sitting directly infront of the flex fan on the radiator. If this is true then you are killing the efficiency of the flex fan because its has the pull the air through that electric fan as well. If I am seeing things correctly it seems that you need to decide which fan to use, because both can't be performing the same job. Maybe I am seeing things wrong.

Sorry for the small image, everytime I upload pictures to my photobucket they become really small and I can't figure out why.

 

The aux. elec. fan was part of the air conditioning package. In '80, air conditioning became a standard feature, not just an option. It was designed only to work when the a/c put too much of a load on the car. My a/c is long gone, so I'm just gonna hook it to a switch.

Both the flex fan and the elec. fan are pulling air in the same direction.

 

My electric is running all the time when the key is on.......got to help.

Overheating....check t'stat, timing, air/fuel mixture (to lean will cause overheating....ask me how I know).

 

My in-dash gauge: 220+
Mechanical gauge mounted under-hood: 180

Gotta test the gauge!

D. Ocean
Miami, FLA

 

I agree about the laser temp sensor. My beater car is a 91 Tracer and I though I had all sorts of cooling problems. Turns out the sendor unit was lying. Get a raygun temp reader and see what the radiator really is. The outside (after cooling) should be about 150. In about 180-190.

Tuning is very important. After Lars timed and tuned my engine the temp dropped by 20 degrees and it was a lot quieter. Did I mention the gain in HP also. Check your timing and you may get a lot cooler. WOrst case you can change it back and it costs you nothing to try.

I put a post up about correct sending units as I need one also. The repalcements from the cheap auto shops read high by about 20 degrees.

Pete

 

lots of good tips already.
more on my homepage

 

Matt, I read your page on cooling. I'm so lost I don't know where to begin. If it wasn't already obvious, I'm a complete novice when it comes to this stuff. But, that's why I'm here, to learn.

I bent a piece of sheet metal to form a temporary upper shroud. I took the car out today and it just isn't doing any better. Turning the elec fan on results in an instant 5 degree rise in temp. After a closer examination, the foam that seals the gap between the radiator and the support is missing on the passenger side. It is also missing across the top where it seals to the hood. Is that enough opening to ruin the pulling effects of the fan?

I don't have the money for a laser temp guage, nor do I know anyone that has one.

74FLCONV - How did you mount up a mechanical guage under the hood. Based on things that I've read in the past, I have little doubt that the stock guage is giving an inaccurate guage. The sending unit is new, but is was a $9 unit from the local parts store.

 

I tried a "correct" elec. temp sender from Painless and my stock gauge still read high. Out of frustration, I purchased a manual gauge and installed the sender in the un-used hole in the opposite head. Coiled the tubing nicely and hose-clamped the gauge, face-up, on the passenger side fenderwall. I know you can't read this while driving, but if I hear/smell something out-of-the ordinary, I can pull over and check it. I check it every time I drive the car and it sits at 180/190.

D. Ocean
Miami, FLA

 

easy way to verify temp
drain/flush
fill w/ water
leave cap off it will boil over at 212 (at sea level)

 

Today I ordered the foam that seals the top of the radiator support to the hood and the foam that seals the radiator tanks to the side of the radiator support. Between that and the home made upper shroud, I'm hoping by the weekend I have my problems solved.

I also realized after reading Aflac's post that I forgot to put the spring in the lower radiator hose.

If after making the above changes, and the problem still persists, I'm going to install a mech. guage under the hood.

 

another way to check the gauge,
remove sensor.
boil a pot of water
bring it to the car
dip sensr in
ground
should be 200-212.

 

That's a pretty good idea. Just gonna have to do it after my wife goes to bed or I'm gonna get in trouble for taking a pan of water out to the garage.