Overheating

[mountain33]

Have a strange overheating issue. 1971 383 stock roadrunner. No modifications at all. It started around November of last year. When I would drive to our local car show. Which is 15 miles away. The car would overheat. Not on the way there but on the way home. As soon as I back it up the hill of my driveway. Car would overheat puking green fluid down the driveway. I replaced the thermostat in November ran car no issues. I took car out last weekend to the show. No problems. 3 hours later returning home. Back it into driveway car overheats and antifreeze flowing down the driveway. I'm going to replace the hoses just because, like I said original. Would water pump cause this? It's original as well. Car doesn't overheat for some reason until I back into the driveway. It does take me a few tries to maneuver around my other vehicles . Could that be the issue? To much load backing up and down trying to get it into place? Been driving car since 2019 with no issues. The radiator had a small crack repaired 2 years ago at which time it was serviced at a shop. Sorry for long post

 

[tonysrt]

Have you looked into the radiator to see if the tubes are clear? Calcium builds up in the tubes when using tap water which is why we should use distilled water. If tubes are clogged take it to a radiator shop to have it cleaned out or recored if necessary. You could try OTC radiator cleaner, but depends on how bad tubes are clogged. Unless hoses are sucking closed may be useless changing them.

 

[3sloppydogs]

Is your fan mechanical or clutch driven? Maybe a bad clutch if you have one. Also using a thermometer (Lazer type is fine) check your radiator for good flow and cooling. Might be a clogged radiator.

 

[1967coronet]

Are you leaving room for coolant to expand ? You need your level at aprox 1 inch down when cold.
Also like posted above check the actual temp with a lazer temp gauge.
Possible sticky thermostat ?

 

[twecomm]

You may want to pull the radiator, take to a reputable radiator shop and have it "boiled out", after years passages can get blocked by deposits. Also a Flowkooler water pump w/ hi flow thermostat will make a big difference.

 

[mountain33]

Wouldn't they have boiled it out when I had the crack repaired two years ago or would that been an add on?

 

[mountain33]

Is your fan mechanical or clutch driven? Maybe a bad clutch if you have one. Also using a thermometer (Lazer type is fine) check your radiator for good flow and cooling. Might be a clogged radiator.

Mechanical

 

[mountain33]

Are you leaving room for coolant to expand ? You need your level at aprox 1 inch down when cold.
Also like posted above check the actual temp with a lazer temp gauge.
Possible sticky thermostat ?

Yes. Left room for expansion

 

[mountain33]

Have you looked into the radiator to see if the tubes are clear? Calcium builds up in the tubes when using tap water which is why we should use distilled water. If tubes are clogged take it to a radiator shop to have it cleaned out or recored if necessary. You could try OTC radiator cleaner, but depends on how bad tubes are clogged. Unless hoses are sucking closed may be useless changing them.

I did use tap water. Will try the OTC cleaner and see what happens.

 

[mountain33]

When I get the laser thermometer. Where should I point it to get temp readings? Am I taking reading off the radiator by the cap or taking readings from different locations on the radiator to compare and see different temperatures? Thanks again for all the replies. Much appreciated

 

[mountain33]

The really crazy thing is it only does it when I come home.

 

[68BabyBlue]

I had a nearly identical problem with my '69 GTX two years ago, stock 440 factory A/C car. Problem turned out to be two fold, radiator was partially clogged, and once the engine ran at full temperature, the lower hose would collapse. The car would return to normal operating temperature at idle, got hot after running highway speeds. I figured this out when I drove it to Carlisle that summer. On trips to local shows, it wouldn't overheat until I was nearly home.

Got the original radiator re-cored, and replaced the lower hose with one containing an internal reinforcing spring. Problem solved. Drove to Carlisle last summer with no issues in 95 degree heat. Car had been restored 20 years ago, and driven only 1000 miles since. Pretty sure the system didn't get flushed during that time.

 

[Ron H]

Usually a failing water pump gives some signals: Leakage from the weep hole, fore-aft play with the fan, sporadic ticking or rattling noise. Can also observe the flow of coolant from the rad-cap opening once the thermostat has opened up; something I’ve done when refilling the system to bleed out air pockets. I press in a clear-plastic wide mouth water or soda bottle with the bottom cut off that will stay put in the opening, otherwise coolant may overflow creating a mess. Part of the process is slightly revving the engine.

As mentioned, only use distilled water or just get the pre-mixed 50/50 stuff. I run about a 70/30 mix (70%) water as my car is only driven in warmer months and sits in a heated garage. Given your descriptions, such as old hoses, does sound like your system should be cleaned-flushed, including the block, new hoses, t-stat. Also check the cap, they can fail or even, as happened to me-grr, a brand new one that was for crap. There’s a bunch of possible gremlins to look for…I’ve had a few occasions to hunt those down over the decades...related to engine builds and tuning.

 

[pnora]

Have a strange overheating issue. 1971 383 stock roadrunner. No modifications at all. It started around November of last year. When I would drive to our local car show. Which is 15 miles away. The car would overheat. Not on the way there but on the way home. As soon as I back it up the hill of my driveway. Car would overheat puking green fluid down the driveway. I replaced the thermostat in November ran car no issues. I took car out last weekend to the show. No problems. 3 hours later returning home. Back it into driveway car overheats and antifreeze flowing down the driveway. I'm going to replace the hoses just because, like I said original. Would water pump cause this? It's original as well. Car doesn't overheat for some reason until I back into the driveway. It does take me a few tries to maneuver around my other vehicles . Could that be the issue? To much load backing up and down trying to get it into place? Been driving car since 2019 with no issues. The radiator had a small crack repaired 2 years ago at which time it was serviced at a shop. Sorry for long post

What makes you think its overheating? How hot is it running? To me you claim it only does it when backing up an incline. That tells me the coolant has expanded as well as filling the top tank while on the incline. Sounds to me like the cap is not sealing.

 

[Rusty knuckles]

I agree with pnora. I think your cap isn't holding any pressure.

 

[WileE]

The really crazy thing is it only does it when I come home.

Then drive it over to my house and leave it here. I'll take good care of it. I'll even give you a lift back to your place.

 

[1967coronet]

As far as the lazer, test at thermostat housing. Also the top or inlet of radiator and the bottom or outlet.
If your radiator is cooling , fan draw ok ect. You should see aprox 30 to 40 degree drop in temps between the inlet and outlet.

 

[mountain33]

What makes you think its overheating? How hot is it running? To me you claim it only does it when backing up an incline. That tells me the coolant has expanded as well as filling the top tank while on the incline. Sounds to me like the cap is not sealing.

Im going with the fact that you can hear the coolant percolating out like an old coffee pot. Next time probably this weekend. If its not raining. I will take pictures of the gauge before going up driveway and after. Will also record the percolating sound. Will also check to see if it does it pulling straight in.

 

[mountain33]

As far as the lazer, test at thermostat housing. Also the top or inlet of radiator and the bottom or outlet.
If your radiator is cooling , fan draw ok ect. You should see aprox 30 to 40 degree drop in temps between the inlet and outlet.

thanks for info. figured it would be something like that but wasn't sure

 

[mountain33]

Then drive it over to my house and leave it here. I'll take good care of it. I'll even give you a lift back to your place.

But what happens if it overheats on the way to your place? Will be looking for a good home for it eventually. Bones are aching.