1965 hot idle temp

[Timotbird]

Apparently big block motors can be prone to overheating after prolonged periods at idle, especially on warm days.
I’ve had issues with my 390 block and have tried the following.
After first purchasing the car, I removed the radiator and had it cleaned at a radiator shop. They do classic vehicle work and mentioned that I had a four core radiator, so that was a plus.
They also mention these motors need to pull a minimum of 2200 cfm at idle to keep from overheating.
I noticed a previous owned had likely had an electric fan on the radiator since there was wiring at the radiator running to the temp temp sensor area.
I’ve also read a few degrees of engine timing differential can have an influence on engine temp.
The engine temp idles fine for reasonably reasonably long periods on days when it’s in the 70-80’s but any warmer than that, it’ll start pegging the temp gauge after 4-5 min.
Any comments for consideration other than hanging an electric fan back on? BTW, I have a 7 bladed fan under the shroud with an a/c size pully driving it…
Thanks
Tim

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[74 Harley]

You really need to get an accurate temperature measurement with either a mechanical gauge or one of the infrared thermometers.

 

[Timotbird]

Ok, thanks.
As I had previously mentioned, this is more of an issue in warm to hot weather. Since we’re still in winter, I’ll investigate more throughly as the weather warms.
Additionally, I had replaced the water pump since it was weeping at the vent with the heavy duty option. I can’t quite remember if I put the 180 or 160 thermostat back in.
I’ll read the engine temp with a heat gun and gauge.
Seems like most newer big block customizations across all OEM’s though, run electric fans.
I’d be curious how owners in high heat area’s ( ie Arizona, etc) have addressed the problem if they experienced one and/or what percentage of owners have added switchable electric fans on the radiator, for use as necessary.

 

[Frankie the Fink]

I've dealt with this a lot on my classic cars, engine overheating at idle is almost always an air movement problem, at speed its a water movement problem.

I'm not specifically a T-Bird guy but some generic things to check:, is the fan properly situated in the shroud (usually 1/2 way in), is moving air directed through the radiator (e.g. no gaps in the shroud or missing shroud parts), if there is a fan clutch, is it working, are all the pulleys the right size, is the fan belt tight....has the engine been excessively 'bored out' (say over .040), is the vacuum advance working properly, if there is a spring in the bottom radiator hose is it weak or collapsed, is the T-stat the proper temp and working... Finally, vintage temp gauges are sometimes notoriously inaccurate, 20 degrees off in some Chevy products. As noted above confirm you actually have a problem.

Not a big fan of electric SPAL fans...they require significant mods around the radiator and are significant current draws, almost always requiring circuit breaker additions, sometimes temperature switches and alternator upgrades. These motors in original trim operated fine 'back in the day' even with A/C running and idling in traffic jams on hot days, they should still be able to do so.

 

[kbuhagiar]

These motors in original trim operated fine 'back in the day' even with A/C running and idling in traffic jams on hot days, they should still be able to do so.

^^^This^^^

This in not a swipe at the OP, but I can never understand the rush to install an electric fan on an overheating FE engine, when these cars left the factory perfectly able to maintain a normal operating temperature under the harshest of conditions.

(Exception: If the engine in question has been in some way modified, i.e. bored out or otherwise souped-up, all bets are off.)

But a factory stock engine should be fine with a factory cooling system.

Hot weather is nothing new, it got up into the 110s in Arizona (and elsewhere) in 1965, too.

DISCLAIMER: My 62 Tbird also exhibited the same tendency to overheat at idle on a very hot day. I replaced the radiator; problem solved.
I didn't try to have my old radiator cleaned because, frankly, I didn't trust any of the local radiator shops.

 

[Timotbird]

Great commentary. Thank you all very much.
Getting an accurate coolant temp reading seems the first and foremost thing on the checklist.
I’ll be running down the other items to take a look as well.
The fan shroud is in tac with proper spacing in relation to the fan.
Having this form is invaluable for do it yourselfer’s like me.

 

[Frankie the Fink]

Yeah - "old school" radiator shops are few and far between now, if they don't do the correct procedures to remove scale and slime from the core and do a half-baked job then its not good. Not saying that happened here of course.
Sometimes 'burping' the system helps. I AM TOLD, I've NEVER done it ever, but fellow hobbyists tell me it eliminates air bubbles in the system. However, this should occur naturally as the system and motor are run.

 

[Timotbird]

One more thought.
Given the engine block is 60 years old this year, I wonder how much scale/rust may have built up around the interior cylinder walls etc.
Short of removing a few of the freeze plugs to clean and check, probably not much to be done about that…

 

[Timotbird]

And…
As I think of it, I grew up in the 60’s in the San Francisco Bay Area.
A popular summer trip was a drive to the Santa Cruz area on the coast. On a nice day the roads were bumper to bumper with cars going over the coastal hills. A normal 45 min drive could take an hour and a half.
There were a noticeable number of relativity new mid sixties auto’s pulled over to the side of the road with steam venting from under the hood from inching along the upgrade on the way to the beach.
So I’m inclined to believe air flow through the radiatior, even with the then current engine design and capable of being fully funtional in higher heat area’s of the country, could still present engine overheating and vapor lock in the right conditions.

 

[Frankie the Fink]

I was a used car dealer in the 60s and the abysmally poor maintenance many received was more the cause of overheating than lack of design or capacity from the factory. And 'pegging' the gauge after idling 4 minutes is not normal - period. Even a marginal factory cooling system would go far longer than that... You have something wrong somewhere.

There are flush kits for cooling systems and engine blocks that you could try IF you can keep the car running long enough..

 

[Timotbird]

Good Idea.
Back flushing the block through a tee in the heater hose would be an easy procedure.
As I had previously mentioned, the car will idle with a normal coolant temperature indefinitely provided it’s not to hot out.
It’s just the hot day’s, with 90 plus degree air drawing through the radiator, that causes an issue with prolonged idling.

 

[doug7740]

One more thought.
Given the engine block is 60 years old this year, I wonder how much scale/rust may have built up around the interior cylinder walls etc.
Short of removing a few of the freeze plugs to clean and check, probably not much to be done about that…

A major contributor to overheating conditions can be caused by neglecting the cooling system. It is recommended that the cooling system be drained and flushed every two years. Proper cooling system maintenance prevents rust and sludge buildup around the cylinder wall cooling jackets. The attached photos show what can happen when a cooling system is not properly maintained.





Removal can be accomplished by removing as much rust as possible by digging and probing with a coat hanger or similar object. Pressure wash until all the rust is flushed from the block allowing coolant to flow freely around the external cylinder walls inside the engine block. Replace the core plugs with brass plugs.

When servicing the cooling system use a 50/50 mix of anti-freeze/coolant and water. Coolant rust inhibitors start to break down in a couple of years requiring the system to be drained and the coolant replaced. A clean cooling system promotes a cool running engine.

doug7740
1955 Thunderbird Blue

 

[Timotbird]

Great pictures.
The last time I replaced the water pump, it did’nt appear to have to much buildup in the jacket’s behind the pump.
That might not reflect what build up may have occured in the rest of the block but would certainly be an indicator if there were any noticable amount present…

 

[Frankie the Fink]

I would also say that off shore reproduction water pumps often have thicker castings with narrower water passages and less cooling capacity. - I've come across that working on vintage Chevys...