Coolant

[Jonty]

Hi all

I’ve posted re this before but have more info. My coolant is bubbling like a bubble bath. It will start small bubbling when cold and also foaming and when hot it will look like a kids bubble bath in the reservoir.

The standard response and my initial reaction was head gasket. However it has never overheated (and doesn’t over heat now) and I have had a mechanic run the gas analyser test, a compression test and a full leak down test. It passed them all with flying colours and everyone is baffled.

There are no coolant leaks I can see anywhere and it’s not losing coolant.

Would anyone have any ideas? Also could a head gasket be gone if it’s passed all those tests?

[David T]

If it passes the combustion gas test, the head gaskets are OK. My guess is some kind of contamination. My advice would be to do a chemical flush. First do several rinses with plain water, then add a chemical cleaning, followed by several more flushes. Once you are satisfied you have the system clean, refill with 50/50 anti-freeze and water. When flushing and rinsing I would do the major components separately, ie, the motor, the radiator, and the heater. Be sure to fully bleed all the air out when you fill with anti-freeze. I recommend the "good old green stuff" aka Prestone. I use the concentrate but if the water in your area is hard, then buy the premixed stuff so you don't have to add water. "Back in the day" auto stores used to sell a 2 part cleaner. The top part of the can had the acid and you used that for a while and then you dumped it out and filled the system with water and the contents from the other end of the can to neutralize the acid. Because a lot of motors these days have aluminum you can't use anything that aggressive. They still sell 1 part cleaners that are safe to use on aluminum. Just flush and rinse, if in doubt do it some more to get all of the cleaner out.

[Jonty]

Thanks David

That was my mech’s suspicion as well. My only hesitation is that the restorer who had just replaced the water pump and coolant said he can’t think why the coolant would be contaminated but no harm in trying the flush. David my mech mentioned that usually refill coolant using a vacuum system to avoid air pockets. I haven’t see discussion of this much in the forums. Do people do this with Deloreans?

Cheers

[Nicholas R]

When the mechanic tested the exhaust gas, did he also test the coolant?

I recently had the exact same issue in one of my non-DeLorean vehicles (coolant boiling after minimal running). The exhaust gas tested fine, but the actual coolant tested positive for exhaust gas. My head gasket was just barely allowing combustion gas to leak into the water jacket, heating up the coolant.

You can test the coolant yourself with one of these kits: https://www.amazon.com/Block-Tester-...s%2C159&sr=8-3

[David T]

While there are many ways to fill with coolant, I also use the vacuum method. I have found that if you do it that way it reduces the amount of air that has to be bled out. It reduces the amount of time to fill and bleed the system, that's all. I missed exactly what did he test when you said your mechanic did the "gas analyzer test"? I assumed you meant testing the coolant for combustion gasses. If you didn't perform that test yet then I urge you to have that test done. Testing the exhaust gasses out the tailpipe won't tell you if you have a popped head gasket (if, in fact that was what he did).

[Jonty]

While there are many ways to fill with coolant, I also use the vacuum method. I have found that if you do it that way it reduces the amount of air that has to be bled out. It reduces the amount of time to fill and bleed the system, that's all. I missed exactly what did he test when you said your mechanic did the "gas analyzer test"? I assumed you meant testing the coolant for combustion gasses. If you didn't perform that test yet then I urge you to have that test done. Testing the exhaust gasses out the tailpipe won't tell you if you have a popped head gasket (if, in fact that was what he did).

Thanks - they tested the coolant with an exhaust gas test kit (the chemical one which changes colour).