1987 Cooling System Expansion Tank-Green Slime

[Richard P.]

The expansion tank is constantly fouled with a green slime that resembles pond scum. Does anybody know what this is and is there a treatment of some sort that would provide a permanent solution. I remove the tank, flush it and fill with a bleach solution and let it sit overnight. It always returns.

[Joe L.]

Re: 1987 Cooling System Expansion Tank-Green Slime

The expansion tank is constantly fouled with a green slime that resembles pond scum. Does anybody know what this is and is there a treatment of some sort that would provide a permanent solution. I remove the tank, flush it and fill with a bleach solution and let it sit overnight. It always returns.

Richard------


I think you're referring to the coolant recovery reservoir and not the expansion tank. However, what you describe is quite common. The exact thing also occurs with Dex Cool, in fact to an even greater degree. I don't know what causes it or how to prevent it. I doubt there is any cure.

[Edward J.]

Re: 1987 Cooling System Expansion Tank-Green Slime

Richard, You may want to flush out the system and switch to a newer type anti freeze, Motorcraft make a great anti freeze that is yellow and has a long life and does not have the problems like older green and orange Dexcool.the best was to flush the system is to drain radiator first then remove the thermostat housing and remove one of the pipe plugs on the lower driver side of engine block and take a water hose and turn water on slightly , careful not to overfill while the system drains from below.also just.

I Believe GM had a TSB addressing sludging of the cooling systems in the mid 90's. They talked about temp. of the engines being to low. thermostat not opening or closing at the correct temp.

[Richard P.]

Re: 1987 Cooling System Expansion Tank-Green Slime

Joe and Ed: Thanks for your replies and suggestions. I only drive this car a day or two per month so part of the problem may be it does not reach operating temperature often enough. Guess I need to drive it more which I should be doing anyway.

[Mark S.]

Re: 1987 Cooling System Expansion Tank-Green Slime

It comes from mixing non-compatable coolants. ie: dex-cool and inexpensive green.

[Richard P.]

Re: 1987 Cooling System Expansion Tank-Green Slime

Mark, do you know if the slime is a biological growth or is it a chemical reaction product due to the non-compatible coolants?

[Patrick N.]

Re: 1987 Cooling System Expansion Tank-Green Slime

Richard, You may want to flush out the system and switch to a newer type anti freeze, Motorcraft make a great anti freeze that is yellow and has a long life and does not have the problems like older green and orange Dexcool.

+1
Also, Motorcraft Dot3 break fluid is superior. I use both in my 88.

[Edward J.]

Re: 1987 Cooling System Expansion Tank-Green Slime

Mark, do you know if the slime is a biological growth or is it a chemical reaction product due to the non-compatible coolants?

Richard, many coolants can be blended , BUT the Dexcool and green is a no- no. they are not chemically compatible.

[Duke W.]

Re: 1987 Cooling System Expansion Tank-Green Slime

Motorcraft make a great anti freeze that is yellow and has a long life and does not have the problems like older green and orange Dexcool.

No, Motorcraft doesn't make it. Chemical companies like Dow manufacture it to the orginal patented (now expired) BASF formula that was first used on Mercedes Benz cars back in the eighties. It's now factory fill for Ford and Chrysler and is available in the aftermaket as Zerex G-05. You can also buy the same blend under their own house brand names at Ford, Chrysler, and Mercedes dealers, but it will be a lot more expensive than what an auto parts store charges for G-05.

For a 1987 Corvette my recommendation is Zerex G-05.

Ford DOT 3 fluid is not really any better than most other glycol-based fluids. It might have a slightly higher boiling point than requied for DOT 4, but it doesn't meet the DOT 4 wet boiling point spec, which is why they can only label it as DOT 3.

I use DOT 4 in all my cars - whatever brand is available at the lowest price.

Duke

[Joe L.]

Re: 1987 Cooling System Expansion Tank-Green Slime

Mark, do you know if the slime is a biological growth or is it a chemical reaction product due to the non-compatible coolants?

Richard-----

I highly doubt that the slime is biological, either algae or microbial. Algae require light for metabolism (photosynthesis) and there's precious little of that available to an automotive cooling system. Even the coolant recovery reservoir, which is translucent, is in the dark most of the time. Also, the coolant is virtually "sterilized" every time the engine comes up to operating temperature.

As far as mixing incompatible coolant goes, I don't think that the answer, either. For many years my cars saw only Prestone green (which, incidentally, I'm now phasing out of use for all my cars that used it) and they still experienced the "slime" you describe. Also, one of my cars had only had Dexcool in it from day-one and it probably has more of the "slime" than any of my other cars. Otherwise, the coolant system is very clean, though, and virtually rust-free.

[Dick W.]

Re: 1987 Cooling System Expansion Tank-Green Slime

Richard-----

I highly doubt that the slime is biological, either algae or microbial. Algae require light for metabolism (photosynthesis) and there's precious little of that available to an automotive cooling system. Even the coolant recovery reservoir, which is translucent, is in the dark most of the time. Also, the coolant is virtually "sterilized" every time the engine comes up to operating temperature.

As far as mixing incompatible coolant goes, I don't think that the answer, either. For many years my cars saw only Prestone green (which, incidentally, I'm now phasing out of use for all my cars that used it) and they still experienced the "slime" you describe. Also, one of my cars had only had Dexcool in it from day-one and it probably has more of the "slime" than any of my other cars. Otherwise, the coolant system is very clean, though, and virtually rust-free.

Green slime has been a problem for over 50 years that I know of. It is not as common as it once was but still occurs. Years ago we cured it by using a cooling system additive. I have seen radiators completely clogged by the crap.

If you stay with the green antifreeze I advise you to get a cooling system additive from Cummins (DCA2), Ford (FW 16), Fleetgard DCA4), or Wix (24056). It will also greatly extend the useful life of your antifreeze.

[Duke W.]

Re: 1987 Cooling System Expansion Tank-Green Slime

I think the green slime is silicate drop out, which the green stuff has had in large quantities for a long time. Modern anti-freeze formulations have little or none. The green stuff is totally obsolete and has been for well over a decade.

G-05 is the new "universal" anti-freeze that will protect all cooling system materials in both vintage and modern cars.

Duke

[Dick W.]

Re: 1987 Cooling System Expansion Tank-Green Slime

I think the green slime is silicate drop out, which the green stuff has had in large quantities for a long time. Modern anti-freeze formulations have little or none. The green stuff is totally obsolete and has been for well over a decade.

G-05 is the new "universal" anti-freeze that will protect all cooling system materials in both vintage and modern cars.

Duke

Silicate dropout causes another whole set of problems. The solution then becomes very abrasive. We saw that problem in the late '70's and early '80's in hd engines. You should see what it and causation can do to cylinder liners. Actually eat holes in them.

[Jim T.]

Re: 1987 Cooling System Expansion Tank-Green Slime

MY 1985 and 1996 LT4 have not had any mentioned green slime. Bought the 1985 in 1992 and first coolant change installed DEX-COOL. The last coolant change I flushed the system and installed ZEREX G-05. The 96 original owner has always had DEX-COOL since new. Next coolant change I am thinking about changing to ZEREX G-05.

[Donald O.]

Re: 1987 Cooling System Expansion Tank-Green Slime

When I bought my 2006 Buick 3.8L, new, it came filled with Dexcool. I immediately drained and flushed and refilled with G-05.

I'm surprised noone here has mentioned Evans Coolant as its waterless.