1965 overheating

[Joe D.]

my 65 over heats in traffic or at an idle,everything is new with no corners cut. on the highway temp runs around 200. the motor is a 327-365 bored .030. i have tried different thermostats,evans racing coolant (boy that was a joke) and a 7 blade fan. if you start the car cold and let it idle it takes about 20 minutes before it boiles.i have won 3 top flite awards and would like to pv the car but with this problem thats impossible.can anyone help!!!

[Joe L.]

Re: 1965 overheating

my 65 over heats in traffic or at an idle,everything is new with no corners cut. on the highway temp runs around 200. the motor is a 327-365 bored .030. i have tried different thermostats,evans racing coolant (boy that was a joke) and a 7 blade fan. if you start the car cold and let it idle it takes about 20 minutes before it boiles.i have won 3 top flite awards and would like to pv the car but with this problem thats impossible.can anyone help!!!

Joe-----


Overheating can have many root causes. Based upon your symptoms as-described, it sounds like the car runs fairly normal temps at cruise, although possibly a bit on the high end.

With problems like you describe, a thermostat temperature change is going to do you no good, at all. If one new replacement thermostat doesn't help, then forget further thermostat changes.

Idle and slow speed cooling problems are often attributable to a poorly performing fan clutch. Do you have a KNOWN-GOOD fan clutch or are you using a new, high quality, OEM-type fan clutch (i.e. GM #3916141)? If not, that's the first thing I'd go for.

Second, what sort of radiator do you have in the car? Is it an original GM aluminum unit dated for the car? If so, it's 43 years old and might be "weak" for a variety of reasons (even if it doesn't leak).

Do you have a copper/brass replacement for the original aluminum radiator (i.e. has side tanks rather than tankless construction, as original). If so, these replacement radiators provide about 30% less cooling capacity. I would not use one.

Next, I'd do a "block test" on the cooling system to see if there are exhaust gases present in the coolant. If so, you have a cracked block, head, or leaking head gasket. Kits for this test are available but you might be bettre off to take it to a radiator shop that already has the equipment and expertise to do this test. Exhaust gases in the coolant will quickly overheat the coolant beyond the capability of even a perfect cooling system to remove it.

[Louis T.]

Re: 1965 overheating

Hi Joe,

I agree with everything Joe Lucia said.

I'll take from your Top Flight mention as a given that everything is factory stock or restored as such, including engine timing settings. Also, you shouldn't need nor should you use a fan blade with more or differently angled blades. The engineering combination of radiator, shroud, fan, fan clutch, and water pump developed by Chevrolet were optimum for each engine configuration.

If your radiator is an original or an older repro, I'd check the temperature when the car is fully warmed up at a variety of points with an infrared temperature gun to make sure that all of the passages are clear.







Good luck!

Louis

[Wes S.]

Re: 1965 overheating

What do you have your timing set at? Is the vacuum advance work? How about your weights, do you have the right springs and Weights?

[Dave S.]

Re: 1965 overheating

I agree with Wesley. Many overheating problems like what you describe are often the result of hidden timing issues (mostly too retarded). Try an experiment and move the timing 10 degrees earlier (before TDC) and see if this makes your problem better. (it might run poorly at cruise, but see if this is a source of your problem). If so, then you can drill down into the MANY causes of timing related issues (including fuel ratio/quality/compression) ones.

Dave

[Michael W.]

Re: 1965 overheating

Great post!

I am still facing the same issue on my 65. My enige is a perfect rebuild, but till now did not check the fan clutch. I have a brass NOM radiator, so I start the think that this might be the issue.

Thanks

[Mike M.]

Re: 1965 overheating

Is it boiling over or is the gauge just showing high temp.

[Bill T.]

Re: 1965 overheating

Just moving the coil on the fan clutch back a notch changed my temp from 200+ to around 170. I no longer overheat in traffic or when idling...

[Jack W.]

Re: 1965 overheating

Great post!

I am still facing the same issue on my 65. My enige is a perfect rebuild, but till now did not check the fan clutch. I have a brass NOM radiator, so I start the think that this might be the issue.

Thanks

well, you can start with the less expensive stuff and move your way up, and surely an operational fan clutch is a must; but in all likelihood, your copper-brass rad simply cannot keep up [based on personal experience chasing my own run-hot issue a few years ago with my 65 SB]. I'd say it's time for a proper stacked plate aluminum rad from Dewitts.

[Martin M.]

Re: 1965 overheating

When I lived in the Boston, MA area my '63 Cvt with a Brass Radiator always ran @ 180 until the year before we left to move to Nevada. Then it would slowly climb to about 210 on the highway. Local was OK.

I figured that some service would be required to deal with the Las Vegas heat. Being somewhat conservative I decided to change the thermostat first. I put in a RobertShaw 330-180 thermostat, and the car immediately went back to the 180 it displayed in MA. We drove this car out here for 5 years with no other changes concerning.

All the posts I read say a brass radiator will not work well. Well it was fine on those LVCA weekend jaunts on I-15 at 80mph, showing always 180.

I guess just lucky in Las Vegas
Marty

[Joe D.]

Re: 1965 overheating

Hey Louis,
I Appreciate Your Response!
You Asked For More History On The Car.
I Have Owned The Car For 17 Years And As Soon As I Bought The Car I Totally Disassembled It; Hence Started The Restoration Process. I Finished About 3 Years Ago.
But Evertime You Get Your Car Judged It Starts All Over Again.
The Radiator Was A New Aluminum About 10 Years Ago. Water Pump Was Rebuilt And Block Was Flushed.this Is My Second Over Flow Because The First One Rotted Out.i Contributed That To The Chemicals In Our Water.the Car Has Had The Heating Problem From The Start.
I Have Not Had Time To Check The Fan Clutch Yet Or Do A Block Test.the Fan Clutch Was Refurbished Several Years Ago.
Thanks For Your Input
Joe Dean