Technical Water boiling

Hello everybody, I'v been ownin' a 1954 Chevy Bel-Air, over here in Italy for almost 40 years now.
Lately water/liquid started to boil. I checked the thermostat, but it was ok. I even tried without thermistat, but water kepr boling.
So, I was enough sure somethin' happened to the head gasket. I went to my local car repair shop: they checked the head..and the mechanical test said the head was ok. Anyway they rectified it and they're goin' to put a new gasket on, of course.
Now, do you think this boiling is caused by a failing water pump ? Or radiator ?...
Any idea ? I never had water boling problems at all. Thanks so much for your help. Alberto

 

By boiling do you mean it’s overflowing? What does the temperature gauge read?

could be as simple as a the radiator cap

when it’s hot feel different parts of the radiator, are there cold spots?

 

Yes, it's overflowing. Unluckily my temperature gaude doesn't work....so I don't know.
Now the radiator is apart...

 

I think I am goin' to redone the radiator core...what do you think about it ?

 

Did the shop remove the head? I don’t know of another way to check it for cracks other than removing it.

Do you have the car at home now? And have you removed the radiator? I ***ume that’s what you mean by “have the radiator apart”.

And it still boiled over with the thermostat removed? Okay, put the radiator back in, keep the thermostat out, fill with water and fire it up and let it run with the radiator cap off, see if any bubbles are forming through the fill hole.

Are any of the spark plugs noticeably cleaner that the others? If so, this would indicate that cylinder is getting water/coolant in it and “steam cleaning” the spark plugs

 

Yes, the head and radiator were (are) removed.
I am goin to check if the radiator is ok.
Will check the spark plugs.
Thanks for the advice.

 

Long as the radiator is out, pull the pump & make sure the impeller hasn't started to spin on the shaft. It happened to me once with a ''rebuilt" pump ...

 

While you have the radiator out take it to a radiator shop and have it flushed out to make sure it isn't clogged up. HRP

 

Do you have easy access to any of the core plugs in the side of the engine block? Removing a plug may tell you if the coolant p***ages in the block are plugged with rust or scale. Also check your ignition timing. If it's retarded too far it will make the engine temperature increase. Getting a working temp. gauge would also be a big help for troubleshooting.

 

Ok..thanks for the advice.

 

Yes, thanks. I just planned this. Thanks.

 

For that matter, is the belt properly tensioned?

 

Good golly, miss molly! Get the temperature gauge working! If it had been working you would have seen the coolant temperatures rising over time. The radiator is probably at least partially plugged. Since it is off, have it rodded out. Or a new core. Afterv40 years [ good for you ] a new one would not hurt.

Ben

 

Thanks. I am goin to check everythin I can. Thanks

 

Yes, I would say it is.

 

I know..you're right..
I am goin to have it working.

 

I bought a car once really cheap, because the owner said it overheated and would boil over. I put a new radiator cap on it and never had an issue after that.

 

How can it change so much, puttin a new radiator cap ?

 

The radiator cap has a spring in it to put pressure on the cooling system, that raises the boiling point of the water. There is also a rubber seal to seal off the opening under the cap.
If either the spring or the rubber seal are bad, a new radiator cap could fix your problem.

The radiator shop can test your cap as well as test your radiator. Both the cap and the radiator need to hold the pressure.

 

..... and this should have been the starting point to solve the problem. Easy and cheap things first.

My daughter's mechanic wanted to replace the EGR on her Toyota Prado because it was losing coolant but there was no sign of a leak. She was quoted a couple of grand to do the job. On my advice, she took it to my mechanic for a second opinion. New radiator cap, problem solved. Needless to say, my mechanic is now also her mechanic.

 

Lots of reasons.
Wrong cap is one. A lot of older cars require a deeper cap. Below is a comparison of a new vs older model. If you use the new cap on an old radiator, it will fit but inside the seal won't hit the throat in the radiator, so it won't build pressure. For every pound of pressure (over atmospheric pressure), the boiling point is increased by 3 degrees. So, a 4-pound cap makes the system 12 degrees cooler compared to running at ambient pressure (or a cap that has worn out seals). New cars have 17 pound caps or more, but they're radiators/heater cores/hoses and the like are designed for that kind of pressure. If you put a 17 pound cap on a flathead (for example), you will be replacing the radiator, the heater core, and likely the water pumps very soon.

 

I don't know how long you have owned the car but cars with top tank radiators have to have air space above the coolant for expansion or they will push coolant out the overflow. That is a common new guy to old style radiator mistake when adding coolant/water. you want about 1 inch = 25 mm of coolant above the top of the tubes cold and not more than that. Otherwise it will puke coolant out until it finds it's own level every time.