Cool/Heat: Let's talk overheating

[JimC]

I posted on this some time back, but with new information, I thought I'd just kick off a new discussion.

The '63 overheats (or rides the "H" line) without much rhyme or reason. Initially I suspected maybe a bad ground, but I've been cleaning up dash wiring in recent days, and everything seems to be grounded just fine. I haven't checked the temp of the water with a meat/candy thermometer as was suggested last time yet, primarily because it's not something that manifests itself regularly enough that you can start the car and know it's going to happen.

Here's the weird part though. Whenever the car starts riding the redline on heat, if I open the heater core up and divert the flow through there, it cools down to normal reasonably quickly. Initially I would drive like that, with the heat slowly broiling me as I drove, but one day I was on a long drive on the Interstate and the car started heading towards overheating. I opened the slider, and closed it as the engine was just beginning to cool off. For whatever reason, the engine not only continued to cool to the normal zone, it stayed cool for the next 20 minutes on the interstate going 60 mph all the way to my destination. After that experience, any time it starts to overheat, I open the heat slider, slide it shut as soon at the temperature starts moving, and it's the same thing. It cools off, and stays cool.

My theory is that something of a significant size is blocking water flow, maybe at the return prior to getting pumped into the radiator, and getting caught somewhere due to suction pinning it in the channel. When I open the heater core, the change in water pressure eliminates the suction enough that the piece falls or moves or whatever, and the water can once again flow freely. Does that sound realistic? If so, where do I start looking for this blockage? Do I pop the block plugs out, or remove the water manifold, or where would I begin? Or am I totally off my rocker, and this is possibly something else entirely?

Any ideas appreciated. Thanks!

[PackardV8]

The first response to any overheating on a Stude is, "Knock out the core plugs and rod 'er out." Still good practice, but you've got some things to try first.

1. Disconnect the two heater hoses and connect up a garden hose and reverse flush the heater core.
2. Remove the heater valve and visually inspect the path and the shut off. Reinstall with the valve in the off position.
3. Reverse flush the radiator and engine. I made a tool; a 2" long 1/4" NPT nipple screwed into a male hose fitting. Remove the radiator draincock, screw in the fitting, connect up a garden hose, turn water pressure on full, start the engine and run water out the radiator fill cap until it runs clean.

jack vines

[JimC]

Sounds like I'll be wearing my swim trunks to the garage

Thanks for some direction, I'll see what comes up. Question: if something's blocking the channel, couldn't reverse flushing send it further back into the block, making it harder to get out? Also, this is probably a "well duh" question, but I'm assuming that I'll have to remove the thermostat for this?

Thanks again!

[Jackson]

First thing I would do is use an IR temp sensor to read the actual temp at the thermostat and compare that to the temp guage. Opening the heater valve provides additional cooling for the system so the overall coolant temp should drop.

[ROADRACELARK]

I use the 1/4" copper pipe, aprox. 2 ft. long from an ice maker for a refrigerator. Wear some throw away clothes and a face shield, it gets nasty. Knock out the freeze plugs and with maximum hose pressure, moving the copper pipe around, you will be amazed at how much crud comes out. Make sure your engine ground strap has good clean connections so the temp gauge will read accurately. Use a lighter mixture of antifreeze. Down here in Jawja, we don't need it to be lower than 0 degrees.(-34 degree mix just sells more antifreeze) That alone makes it run cooler. Hope this helps...It has worked on many I have done.

Dan Miller
Auburn, GA

[mmagic]

First thing I would do is use an IR temp sensor to read the actual temp at the thermostat and compare that to the temp guage.

Absolutely agree. One of the best $39 I've spent at HF. Quick read of radiator in and out temp, individual cylinder temps, tire temps etc. with an aim of the gun. Similar questions... turned out my gauge was right.

When I rodded the water jacket on the Champ, I followed with vinegar overnight to clean calcium buildup off of jacket walls. OMG did it get results! So I flushed and did it again. Flushed, sealed it up and it was soon overheating at idle! Lots of crud floating in radiator... so much that it had plugged the thermostat! Flushed, flushed and flushed... thought I'd never get all the crud out... almost regretted the vinegar treatment.... but, once it was purged I can hardly get it up to mid point on the gauge and IR sensor confirms about 30-40 degree temp drop inlet to outlet.

[jackb]

..I'll bet if you start the car and leave the slider open to hot water your temps will again go the hot side and stay there without change. When you open the hot water (Slider) you simply introduce cold water (from the heater system) into the system with an immediate cooling of the hot water... I don't believe that the opening of the slider forever changes yopur temps..

[altair]

I posted on this some time back, but with new information, I thought I'd just kick off a new discussion.

The '63 overheats (or rides the "H" line) without much rhyme or reason. Initially I suspected maybe a bad ground, but I've been cleaning up dash wiring in recent days, and everything seems to be grounded just fine. I haven't checked the temp of the water with a meat/candy thermometer as was suggested last time yet, primarily because it's not something that manifests itself regularly enough that you can start the car and know it's going to happen.

Here's the weird part though. Whenever the car starts riding the redline on heat, if I open the heater core up and divert the flow through there, it cools down to normal reasonably quickly. Initially I would drive like that, with the heat slowly broiling me as I drove, but one day I was on a long drive on the Interstate and the car started heading towards overheating. I opened the slider, and closed it as the engine was just beginning to cool off. For whatever reason, the engine not only continued to cool to the normal zone, it stayed cool for the next 20 minutes on the interstate going 60 mph all the way to my destination. After that experience, any time it starts to overheat, I open the heat slider, slide it shut as soon at the temperature starts moving, and it's the same thing. It cools off, and stays cool.

My theory is that something of a significant size is blocking water flow, maybe at the return prior to getting pumped into the radiator, and getting caught somewhere due to suction pinning it in the channel. When I open the heater core, the change in water pressure eliminates the suction enough that the piece falls or moves or whatever, and the water can once again flow freely. Does that sound realistic? If so, where do I start looking for this blockage? Do I pop the block plugs out, or remove the water manifold, or where would I begin? Or am I totally off my rocker, and this is possibly something else entirely?

Any ideas appreciated. Thanks!

I would like to suggest a simple test, remove the lower rad hose and seal the opening with the drain cock closed, fill the radiator with water then drain into a container and measure the quantity. Find another clean radiator and compaire the quantity to be assured the full volume is available in your radiator. Blocks can be filled with muck coolant can be down a quart or two and the engine will still stay cool if the radiator is functuning at full volume. Also confirm your timing and the centrifugal advance system.

Opening your heater system for additional cooling is a standard trick when assending a substantial hill under heavy load. To have to use this method on a level road indicates a radiator volume problem. Dave

[RadioRoy]

The first thing I would do is check to see if it is actually overheating. Use an infrared thermometer, like previous posters said, or just buy a candy thermometer.

If it is overheating, you can start with the easy things, like thermostat, hoses and the like, before popping the freeze plugs.

If it is not overheating, you might suspect the temperature gauge sending unit. On a V-8 it is on the rear of one of the cylinder heads.

I had a problem with my 60 Lark ragtop. The car came to me without a thermostat, because when a thermostat was installed, the temperature gauge went crazy. After a new water pump, re-cored radiator, and a failed attempt to pop the freeze plugs, I changed the temp sender. That was the problem all along.

So the moral of the story is to figure out what is wrong before tearing everything apart.

[JimC]

Roy, thanks. I will try to manually check the temp at some point. The hardest part of that is that this never happens when stationary, only at speed, and usually when going 45mph or higher. I'll get an infrared thermometer and pull over next time.

I forgot to add that the water pump, thermostat, and both hoses are less than 6 months old. I verified that my thermostat worked by putting it in hot water before the install, as I originally suspected that the old one might be the culprit.

[SN-60]

If there's ANY chance that the radiator in Your car isn't up to par...........save Yourself a lot of time and heartache and replace it with a new one or recore it...EVERYTHING else is really just a band-aid.

[JimC]

I'll have to check the radiator. I know it was replaced a year or so before I took ownership, but with a used radiator, so you never know. Thanks!

[41 Frank]

That radiator you have was in my '63 Lark and never overheated for me. Only reason I took it out is that the other one I had was cosmetically better.

I'll have to check the radiator. I know it was replaced a year or so before I took ownership, but with a used radiator, so you never know. Thanks!

[Gunslinger]

If it only happens at speed, check your lower radiator hose. If the internal spring is rusted away, there's nothing to keep the lower hose from collapsing under vacuum. That restricts the coolant flow and at low speeds or sitting, the hose expands out and looks normal.

Check that hose...it could be as simple as that.

[StudeRich]

OR...the New lower Radiator hose had NO inside Spring! Some have been coming that way, I would check it.