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-BT-700-Combustion-Leak/dp/B01N1NA22J/ref=sr_1_3?crid=2MPYNERD5O6VM&dchild=1&keywords=coolant+exhaust+gas+tester&qid=1602249120&sprefix=coolant+exhaust+gas%2Caps%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).

[Josh]

vaccum fill is the best way to fill the coolant system in a delorean. If you are doing it any other way you are making things difficult for yourself.

[Jonty]

Thanks Josh

[Parzival]

Just to add to this, I have yet to see a Delorean that does not bubble in the over flow, especially if you have a coolant bottle that has the return from the head right around where the water line is. Its churning it up there, even if its just under the water line it will pull air in from the surface and churn it up.

If bubbling in there means a blown head gasket then I know like 8 local Deloreans with blown head gaskets, and non that don't.

Also I can't imagine a situation where your engine is pushing that much combustion into the cooling jacket and not causing your radiator cap to constantly purge. Does you over flow tube stay dry?

[Jonty]

Just to add to this, I have yet to see a Delorean that does not bubble in the over flow, especially if you have a coolant bottle that has the return from the head right around where the water line is. Its churning it up there, even if its just under the water line it will pull air in from the surface and churn it up.

If bubbling in there means a blown head gasket then I know like 8 local Deloreans with blown head gaskets, and non that don't.

Also I can't imagine a situation where your engine is pushing that much combustion into the cooling jacket and not causing your radiator cap to constantly purge. Does you over flow tube stay dry?

Thanks for this. Yes the return line is very close to water line but I have emptied a bit. Come to think of it the bubbles are worse after is emptied some so maybe you are onto something as it’s probably stirring up even more. I was getting a very small amount of overflow when the reservoir half or more full but now it’s only 1/4 it is not overflowing at all or loosing any coolant (or overheating). I’m also wondering if there is a bit of contaminant in the coolant (as it was recently changed) that might exacerbate the bubbles (it is really a kids bubble bath in there not just a few here and there).

[Parzival]

Thanks for this. Yes the return line is very close to water line but I have emptied a bit. Come to think of it the bubbles are worse after is emptied some so maybe you are onto something as it’s probably stirring up even more. I was getting a very small amount of overflow when the reservoir half or more full but now it’s only 1/4 it is not overflowing at all or loosing any coolant (or overheating). I’m also wondering if there is a bit of contaminant in the coolant (as it was recently changed) that might exacerbate the bubbles (it is really a kids bubble bath in there not just a few here and there).

If you are getting foam like soapy water, you may have a contaminant that has amended the surface tension of the coolant (Like adding dish soap to water) Giving it the ability to hold bubblers of air.
My coolant bottle has been at half full for a 1000 miles, over flow tube is bone dry after even the longest drives in mid Florida summer. My temperature gage fluctuates between the 1/4th mark, and about half way between that and the 220 mark.

[cdrusn]

I hate to disturb the boo birds but I would never use the "green stuff" coolant. There are so many improved antifreeze products why not use them. I use Zerex 05 in my
1988 Mercedes 560SL, all aluminum engine. I currently use Dexcool in my 1984 Porsche 928 but will shift to Zerex when I get around to it. I run Dexcool in my Delorean.
I had a friend that used the green stuff in his 450SL mercedes but he never changed it every 2 years as recommended. He asked me to look at it when it wouldn't start. When I pulled a plug to run a compression test it shot out green antifreeze that had eaten quarter size holes in the heads because of delectric corrosion (steel and aluminum plus water equals an electrical charge that eats metal). Dexcool and Zerex last at least 10 years between flushes. Also use distilled water from the grocery store.:race:

[David T]

Use what you want but the Delorean was designed for the green stuff. In any car, if you don't test and change it when you are supposed to, you will get all kinds of problems and newer cars are very fussy about what kind of stuff and how often to change it. The newer coolants can't be mixed with other kinds of coolants and have very strict conditions as to how often to test and change besides some of them are VERY expensive. There is no particular advantage to using these "exotic" coolants in a Delorean so why would you want to? Use the green stuff, test it every year and flush it out and refill every 5 years with 50/50 concentrate and soft water. If the water in your area is "hard", by the pre-mixed stuff so you don't have to add water.

[cdrusn]

The recommended change for conventional or "green" antifreeze is every 1 to 2 years. The manufacturer, Prestone, recommends every 2 years. Most "exotic" antifreeze can
be changed at 5 years or even longer. It's just a matter of chemistry. Deloreans were built 40 years ago when antifreeze was all green, that's why they used it. All expensive European and most expensive domestic cars (i.e. Corvette) uses Dexcool or Zerex 05. Corrosion from not changing the green stuff can show up in the radiator, the water pump, sensors, etc. and cause overheating. I don't drive my Delorean much so why would I want to change the coolant every 2 years with just 200 miles or so on it? If I wanted to keep my Delorean like it was built 40 years ago I wouldn't be using Mobil 1 oil, new rubber belts, improved shocks, etc. We need to keep our cars maintained in the 2020s not the 1980s.

[David T]

I have many cars and work on many cars that use the green stuff and 5 years is easy to do if you test every year. Never had a problem unless it got mixed with something like Dexcool or by mistake someone puts plain water in or windshield washer fluid or I have seen brake fluid too. While there are many things that are technologically advanced over what was available in the 80's, Prestone is still a good choice for a permanent type anti-freeze for a Delorean.

[Jonty]

Hi all

Well today I just noticed a very small pinhole or crack beside the bleed screw on my thermostat cover. Very weird but I wonder if this would be enough to add all the air in seeing to the coolant?

[Bitsyncmaster]

Hi all

Well today I just noticed a very small pinhole or crack beside the bleed screw on my thermostat cover. Very weird but I wonder if this would be enough to add all the air in seeing to the coolant?

That doesn't look like a stock bleeder. If you buy a new cap, get a new bleeder also. I bet it's the wrong thread and the PO over tightened it.

[Jonty]

That doesn't look like a stock bleeder. If you buy a new cap, get a new bleeder also. I bet it's the wrong thread and the PO over tightened it.

Thanks I never noticed that. I bet your right. I have a Toby self bleeder system coming so that will swap out for the wrong bleed screw.

[Jonty]

Actually I think the bleed screw is the same as supplied with the DGo water pump

[David T]

Looks like someone installed a reducing bushing and stuck a bleeder screw into that. If they forced it, by over tightening or wrong thread it could have cracked the housing. Replace the housing and get the correct bleeder screw.