1966 427 425HP overheating

[Joe T.]

Car is overheating. Installed new 160 degree thermostat. Original Harrison radiator from 66. Should I replace radiator now to resolve overheating problem? Not sure what was done with radiator in the past.

[Keith B.]

Re: 1966 427 425HP overheating

read this

http://www.camaros.org/pdf/corv_cooling2.pdf

Also swapping thermostats are a waist of time unless the one is failed.

[Michael J.]

Re: 1966 427 425HP overheating

Did it just start overheating, and wasn't for a long time before this? Or did you just get the car? There are also timing and distributor/VAC issues that could be causing this. Maybe Duke will chime in and give his sage advice on the electrical system too.

[Leif A.]

Re: 1966 427 425HP overheating

Joe,
Cooling and electrical gremlins can be some of the most vexing to solve. Read the article that Keith posted. Then, read it again. If necessary, read it a third time. Then, most importantly, follow the advice that John gives in the article. I have yet to hear of an overheating issue that can't be resolved by following the information given. If your radiator is the original, it most likely is contributing to your overheating issues but it may not be the only issue. Stick with it, work through it and you will get results. Keep us informed.

[Loren L.]

Re: 1966 427 425HP overheating

Especially the paragraph that starts "Be sure you have a problem...."

[Patrick H.]

Re: 1966 427 425HP overheating

Car is overheating.

First of all, describe what you mean.
Is coolant boiling over? Is the temperature gauge elevated?
What other symptoms have you noted?
When did it start, and what was changed just prior to this?

We really don't have enough information to give you an adequate answer.

[Joe T.]

Re: 1966 427 425HP overheating

The car sat for three years before i got it. It is boiling over. The temperature gauge is elevated approximately 230 idling before I shut the car off. I just ran the car for the first time and it over heated. I also had a new k66 ignition, distributor and coil installed prior to delivery to me. It starts and runs fine with no misses.

[Keith B.]

Re: 1966 427 425HP overheating

find a old time radiator shop and get the tanks boiled out and re-cored. then flush the entire cooling system and re-fill with 50/50 coolant with new hoses

[Guest]

Re: 1966 427 425HP overheating

Check the cooling and top up , let it run with cap off check the temp. gauge and see what happans you may have air in system or a bad cap, let the thermostat open and see if cooling is circulating and check with heat gun , i would start with that first

[Glenn B.]

Re: 1966 427 425HP overheating

I finally traced my long time overheat at idle on my L36 to faulty ingnition wires (including the coil wire). The graphite seems to break down and the lines become higher impedance. Check that, and check your fan clutch, and check your timing - those are three likely culprits

[Duke W.]

Re: 1966 427 425HP overheating

The car sat for three years before i got it. It is boiling over. The temperature gauge is elevated approximately 230 idling before I shut the car off. I just ran the car for the first time and it over heated. I also had a new k66 ignition, distributor and coil installed prior to delivery to me. It starts and runs fine with no misses.

Did you actually drive the car or just let it idle. Please be more specific. Does it "overheat" in city traffic driving? Freeway driving, or just after idling for a long time? How long?

It may be time to rod out or replace the radiator core, and you should also convert the ported vacuum advance to full time. If the OE 360 12 VAC is functional, it's okay to use. If not replace it with a B26 VAC, assumlng it has the OE cam, but don't assume anything. Measure and report vacuum @ idle speed. Test the cap for 15 psi pressure holding. Most auto parts stores have pressure testers at the counter.

"Overheating" issues cannot be solved without a detailed description of the specific driving conditions and running some simple tests.

Duke

[Joe T.]

Re: 1966 427 425HP overheating

Well, just pulled the radiator. It is most defiantly original to the car and has been painted a few times. Also the core vents have seen their days. Many are bent in. I think here lies the problem. The car recently was timed and tuned when a complete ignition system was installed. K66, coil, distributer, alternator and voltage regulator. The fan clutch works fine. If need be, I will check the ignition wires. Thank all of you for your input.

[Harry S.]

Re: 1966 427 425HP overheating

Just a thought, try https://www.evanscoolant.com/product...mance-coolant/

My buddy has it in his 65 396. He can sit and let it idle in the middle of the summer and nothing happens. You need a complete flush/clean-out of the old fluid. The boiling point is 375+.

[William F.]

Re: 1966 427 425HP overheating

Thought some previous threads said this "waterless coolant" had some disadvantages??

[Darryl D.]

Re: 1966 427 425HP overheating

Well, just pulled the radiator. It is most defiantly original to the car and has been painted a few times. Also the core vents have seen their days. Many are bent in. I think here lies the problem. The car recently was timed and tuned when a complete ignition system was installed. K66, coil, distributer, alternator and voltage regulator. The fan clutch works fine. If need be, I will check the ignition wires. Thank all of you for your input.

You can buy a core fin "comb" to straighten them out. Yes, you may need to re-core the radiator but I would explain to the radiator shop that you would rather flush and repair the original core at all cost in order to maintain originality if possible.