Old Radiator vs New Radiator

[CatMan1]

How do I know by staring at the car (28 Sport Coupe) if I have an old or new radiator? I've had the car for nearly a year and it's always spitting water out of the radiator cap. The last owner restored this car, but I suppose without knowing what he did I can't know the condition of the radiator. Yesterday it was not quite 70 out and I took it for a 28 mile highway round trip. Naturally it was loosing coolant. Some of it out of the overflow. It also was running rough when I got back home, but that could be the gas/Stabil I put in last Christmas? What would be the signs of an overheating engine?

[nkaminar]

An old radiator will show signs of the fins detaching from the tubes. The modern radiators have tubes that are oblong in shape. They also have 12 fins per inch. But a new radiator can be built differently. A radiator shop will be able to help.

It is normal for the radiator to spit out excessive coolant. There should be a deflector inside the top of the radiator to keep the coolant from spitting up towards the cap. The cap can be sealed with new or multiple gaskets. Some people use an O ring. I have an oversized O ring. The normal coolant level is down quite a bit from the top.

Most people install a temperature gauge at the outlet neck at the front of the head. A Motometer will give an indication but usually just when the coolant gets really hot.

Fix the gasket at the cap and then drive the car. The coolant will find it's correct level by spitting out excessive coolant out the overflow pipe. If the car overheats you will get lots of steam at the overflow and probably the cap too. If it does not boil over then you are OK. If it does boil over, let it cool down before removing the cap and adding more coolant.

An IR thermometer, available at hardware stores, can be used to measure the temperature at the head and outlet neck and at the radiator too. It is a handy tool to have to analyze problems, such as brake problems. The head should be at about 160 degrees after a drive. The temperature will rise slightly after you stop the car. Too hot would be 200 degrees or greater. If the car is running hot it may boil over after you have stopped.

You are right that the rough running may be unrelated. Look at the plugs. If the car is running hot the plugs will be white and show signs of over heating. There are lots of things to check to find the source of rough running and would be the subject of another thread.

[CatMan1]

Originally Posted by nkaminar

An old radiator will show signs of the fins detaching from the tubes. The modern radiators have tubes that are oblong in shape. They also have 12 fins per inch. But a new radiator can be built differently. A radiator shop will be able to help.

It is normal for the radiator to spit out excessive coolant. There should be a deflector inside the top of the radiator to keep the coolant from spitting up towards the cap. The cap can be sealed with new or multiple gaskets. Some people use an O ring. I have an oversized O ring. The normal coolant level is down quite a bit from the top.

Most people install a temperature gauge at the outlet neck at the front of the head. A Motometer will give an indication but usually just when the coolant gets really hot.

Fix the gasket at the cap and then drive the car. The coolant will find it's correct level by spitting out excessive coolant out the overflow pipe. If the car overheats you will get lots of steam at the overflow and probably the cap too. If it does not boil over then you are OK. If it does boil over, let it cool down before removing the cap and adding more coolant.

An IR thermometer, available at hardware stores, can be used to measure the temperature at the head and outlet neck and at the radiator too. It is a handy tool to have to analyze problems, such as brake problems. The head should be at about 160 degrees after a drive. The temperature will rise slightly after you stop the car. Too hot would be 200 degrees or greater. If the car is running hot it may boil over after you have stopped.

You are right that the rough running may be unrelated. Look at the plugs. If the car is running hot the plugs will be white and show signs of over heating. There are lots of things to check to find the source of rough running and would be the subject of another thread.

Gasket in the cap? Mine doesn't have one. Should it, then? That might help? I've never seen steam with this car. The last time I checked the radiator temp with a thermometer after a highway drive it was as high as 190. I'll be getting an IF Thermometer.

[CatMan1]

My coolant level appears to be about 1/2" below the baffle.

[gdmn852]

Hello, as mentioned,there should be a gasket between the radiator cap radiator. I had a 30 coupe that would do similar to yours , had the radiator cleaned out an that took care of it.It’s hard to find a radiator shop around here that does that kind of work anymore, they just change rather than repair.

[1crosscut]

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As long as there is coolant over the top of the tubes in the radiator you should be fine. Keep an eye on the coolant level and don't add any unless the tubes will not be covered.
There is a good chance that you are not overheating but it only looks like it due to too much coolant and no gasket in your cap.
Pick up a dial meat thermometer, pull the cap and place it directly into the coolant to check the temperature. Do this often until you learn what your temperature is actually doing. You can leave the cap off and drive with the thermometer in place if your coolant level isn't overly high.

Your coolant level will increase with higher temperatures so you need to leave room for that to happen.

One other thing. Have you checked the torque of the head studs? It is possible that you have combustion gasses pushing into the coolant under load while driving. Could be a source of your rough running too.

[Ed in Maine]

I had a radiator that was original and the fins looked wonderful but it over heated. I hated to replace it. Look at the sheet metal frame work. Is that original construction? If it is look at the core. Are the fins straight or are they fluted. The original cores were stamped with a decorative fin. If the fins are just straight then it was re-cored at some point. As I said, I hated to have a shop butcher up my nice original radiator so I removed the top tank. Anyone can do this if you are patient. I filled the radiator almost up to the core with water to protect it from the heat, used a propane torch, heated and blew off the solder with a air compressor nozzel. Pick a nice warm day, over 80 F. I used a brass welding rod and bent with a small "L" at the tip to fit into the tubes. I used spray Gunk down each tube and carefully pushed the accumulated grease and dirt into the bottom tank and then flushed everything out. When I got everything back together, the car ran at 155 F with no leaks. Good luck with yours, Ed

[CatMan1]

Originally Posted by 1crosscut

As long as there is coolant over the top of the tubes in the radiator you should be fine. Keep an eye on the coolant level and don't add any unless the tubes will not be covered.
There is a good chance that you are not overheating but it only looks like it due to too much coolant and no gasket in your cap.
Pick up a dial meat thermometer, pull the cap and place it directly into the coolant to check the temperature. Do this often until you learn what your temperature is actually doing. You can leave the cap off and drive with the thermometer in place if your coolant level isn't overly high.

Your coolant level will increase with higher temperatures so you need to leave room for that to happen.

One other thing. Have you checked the torque of the head studs? It is possible that you have combustion gasses pushing into the coolant under load while driving. Could be a source of your rough running too.

I haven't checked the head studs. I'll try that, too.

I had a long thermometer that was perfect for this, but I have no idea where I put it......