#21  
Old 03-20-2021, 06:44 AM
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Ya I'm thinking this is pretty strange. 50/50 mix for me also. Only thing that comes to mind for me is you have the coolant filled completely to the top of the radiator. No room for expansion. Coolant level should be about 1" from opening.
Any updates?

Charles

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Old 03-21-2021, 05:24 AM
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Hi All,
Here is the latest.

I took the cap off (slowly) and released the pressure. I let the car sit overnight without the cap on. I did not start the car at all.
The next morning I put the cap back on. The next day I went to take the cap off and it had built up pressure, without even having started the car.

Next step.
My mechanic went to tighten the head bolts down (just a theory that it might be the problem) and had to stop as he found tiny broken springs in the top of the cylinder heads. They are the valve stem seal springs disintergrating. I have had the car towed back to the shop who overhauled the motor and they are in the process of replacing the valve stem seals and then will investigate the system holding pressure. By the way, it isn't just a small amount of pressure it is holding. If I removed the cap quickly or not carefully, it would spray all out over the fender.

  #23  
Old 03-21-2021, 09:08 AM
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Have you tested the coolant with a multimeter for electrical current?

  #24  
Old 03-21-2021, 10:38 AM
shermanator2 shermanator2 is offline
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Quote:
Originally Posted by fbd73 View Post
Hi All,
I took the cap off (slowly) and released the pressure. I let the car sit overnight without the cap on. I did not start the car at all.
The next morning I put the cap back on. The next day I went to take the cap off and it had built up pressure, without even having started the car.
.
This is very interesting. We are now getting somewhere. Was the battery connected or disconnected when it built up pressure on its own? If it was connected, then once you get it back and the issue is still there, then try it with the battery disconnected.

I am not surprised that it had full pressure in it just like it was running and hot. You seen th have electrolysis or something else chemical going on here that is giving off a gas and pressures the system until the cap bleeds off just like when it is running.

  #25  
Old 03-28-2021, 05:56 PM
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Hi All.
An update.
The engine rebuilders replaced the valve stem seals with a better type so that will fix that problem.
While the car was there, I took a snapshot of the last suggestion about disconnecting the battery and gave it to the mechanic. He tried it and guess what, no pressure build up.
I got the car back on the weekend and tried it myself. I parked the car and let it sit for about 2 hours and then disconnected both battery terminals (I didn't think to do it immediately after parking it) and let the car sit for another couple of hours. There was still pressure there when I went to remove the cap but not a lot. I then checked it another couple of hours later and no pressure. I checked it this morning before I left for work and still no pressure build up.

So, if it is electrolysis, what can I do so that I don't have to disconnect the battery all the time?

Any thoughts?

  #26  
Old 03-28-2021, 07:54 PM
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Just an FYI...not a bad idea to disconnect the neg. terminal when the car is parked. I do this and run a battery tender.

  #27  
Old 03-29-2021, 11:31 AM
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Quote:
Originally Posted by fbd73 View Post
So, if it is electrolysis, what can I do so that I don't have to disconnect the battery all the time?

Any thoughts?
It looks like you have an electric fan mounted to the radiator. If there is some electrical leakage from the positive side through the fan or fan thermostat into the radiator, and the radiator is not electrically bonded to the engine, then I could see this happening. Is the radiator in rubber mounts that electrically insulate it from the chassis? What is the electrical path from the fan and thermostat and whatever other fan controls you have back to ground? Do you have the ground straps from the engine to body installed?

You are looking for something in contact with the coolant that is at a different voltage than something else in contact with the coolant. If you have a multimeter, measure the DC voltage from the radiator to the engine block with the battery connected. It needs to be very close to zero.

A wire from the radiator to the engine may solve it, but if there is leakage current from the fan system, your battery may run down while the car is sitting.

  #28  
Old 03-29-2021, 02:42 PM
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Quote:
Originally Posted by fbd73 View Post

Next step.
My mechanic went to tighten the head bolts down (just a theory that it might be the problem)
I would think that this would have ruined the head gasket, too - if this was the problem.

Also - I'm not following the logic that bad valve seals could cause extra pressure in the cooling system.

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  #29  
Old 03-29-2021, 04:01 PM
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Quote:
Originally Posted by Chris65LeMans View Post
I would think that this would have ruined the head gasket, too - if this was the problem.

Also - I'm not following the logic that bad valve seals could cause extra pressure in the cooling system.
I think that he was saying that the valve seal problem was a separate problem discovered when his mechanic was re-torquing the head bolts. The head bolts nor the valve seals can have anything to do with the cooling system pressurization issue.

  #30  
Old 03-30-2021, 08:09 PM
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That is correct Sherminator. My mechanic found the broken valve stem seal springs when he went to tighten down the head bolts.

Here is the latest.
For the last few days I have had the battery terminals off and on and checked the radiator cap. There is still no pressure build up. I haven't started the car though. I will do that in the next hour or so and run it up to temperature and then do the whole process again to see if it builds up or retains pressure in the cooling system.

  #31  
Old 03-31-2021, 01:50 AM
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If it's electrolysis no starting would be necessary. Pressure building when the battery is hooked up, and no pressure when the battery is disconnected would point directly to an electrolysis issue.

I'd want to know that for sure before adding the variable of running the engine. That way you could mark electrolysis off the list and forget about that possibility and move on to something else.

Can't wait to hear what the solution ends up being.

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Old 04-02-2021, 06:40 PM
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The latest.
2 days ago, I took the car for a drive to warm it up. When I got home I immediately disconnected the battery. The next morning I released the radiator cap and ..... no pressure.
So, yesterday I took the car for another drive. (I know, I hated every minute of it. LOL). This time, I did nothing i.e. left the battery connected. I have just gone out and released the radiator cap and .... Heaps of pressure.
I will leave it for today (with the battery connected) and see what happens this afternoon.

So thankful for you shermanator2 for your theory on this and leading me to a possible answer.

  #33  
Old 04-02-2021, 07:17 PM
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It's got to be something electrical that is submerged in the coolant, but isolated from the block, and something that is energized all the time.

Can't be something that would present a large surface area, that would kill the battery in no time. So something small, I keep thinking a temp sending unit wired up strangely, normally that would not be energized with the key off.

There isn't an electrical lug on the alternator touching anything on the temp sending unit is there?

  #34  
Old 04-08-2021, 11:03 PM
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Update.
I took the car for a drive to warm it up and when I parked it back in the garage, I disconnected the wire from the back of the alternator, but left the battery connected.
The next morning I released the radiator cap and there was a bit of pressure (also a bit of gurgling back into the overflow bottle), but not as much pressure as in the past.
I checked the wiring around the alternator and the nearby temp sender unit (for the electric fans) and can't see any wiring touching anywhere.

My next step is to take it for another drive over the weekend (how I hate that, LOL), and then disconnect the temp sender wiring and see if there is any pressure build-up or retention.

  #35  
Old 04-09-2021, 02:13 AM
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Sounds like you are getting closer.

The problem should have to fulfill two requirements ... something electrical in contact with the coolant .. and isolated from ground. Anything that fulfills those two and is energized all the time.

I was thinking about the electric fans too. The radiator is probably isolated from ground, rubber mounts, rubber hoses ... if the fan mounts are metal in contact with the radiator and there is any kind of voltage leakage ... could cause electrolysis in the radiator. But I don't imagine there is any power running the fans with the ignition off.

Maybe something touching the heater core .. unlikely.

Does it have an aftermarket electric temp gauge?

Volt Ohm meter might help. Put one lead on the neg. side of battery, dip the other in the coolant in the radiator without touching anything and see if there is any voltage showing (with the ignition off).

  #36  
Old 04-22-2021, 05:39 PM
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So ... what's the low down?

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Old 04-22-2021, 07:01 PM
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Mmmm.
I had the car to the mechanics and they checked everything over. They did find a metal clip touching the bottom of the radiator so they readjusted it. I rechecked the radiator cap the next day and there was a small amount of pressure there but not as much as previous times.
So, I'm not really confident that this has fixed the problem.
I am still trying to track down an auto electrician who understands all about the electrolysis thing.

  #38  
Old 04-26-2021, 08:06 PM
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Update.
I finally got hold of an auto electrician I used to use many years ago and have had the conversation with him regarding this problem. While he wouldn't rule out electrolysis, he also wouldn't rule it in until he has had a good look over the car and problem. I read him some of the comments from here and he has taken them all onboard, so thanks for your suggestions. He is going to try to make some time this week to head over to my house and have a look.

Will keep you posted.

  #39  
Old 04-26-2021, 08:50 PM
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Some reading for you. https://www.northernradiator.com/knowledge/Electrolysis

https://www.freeasestudyguides.com/electrolysis.html

Some copy/paste: info

Electrolysis damage in an engine cooling system is caused by unintended electrical currents that flow from voltage differences that exist in the engine coolant jacket, the radiator, and the heater core. The damage can include rapid corrosion, pitting, flaking, and pinholes. ... The engine coolant is the electrolyte.

How do you remove electrolysis from coolant?
To solve this chemical electrolysis problem:
The cooling system must be thoroughly flushed using Interject Coolant Flusher, which is not acid based, to clean and neutralize the system. It should then be refilled with a 50/50 mixture of new antifreeze and distilled water.

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