MAGK944

If it bothers you why not spray it with plastic primer & top coat, white, black or color match to car. Just leave a strip unpainted to check the level. If you really want a "lifetime" tank buy the aluminum one on Lindsey Racing.

86 951 Driver

New turbo tanks are so expensive now.

Tom M'Guinn

Someone should cut through a yellow one and see if the discoloring is limited to the surface or if it's discolored all the way through the plastic. If it's all the way through like it seems, then not sure any cleaner stands a chance...

pkt1213

I've always wondered about adding a sight glass to the stock tank.

beamishnz

I've had a pretty good long look at it and the colour discoloration is predominately on the inside and predominanately where the plastic has been in contact with the coolant - it is less stained in the area above the water line.

It is not a deposit, or a stain a such, it is a discoloration.

I think with the arsenal of products I've tried with no effect that there really isn't anything that will reverse that discoloration.

The purpose of the test was to check all the suggested options (and some more) and see if any of them worked.

It doesn't bother me too much ... I was just curious and was particularly keen to try out the RestOBright system which captured my imagination

Obviously, you can paint it but the challenge was to see if you could restore it back close to new ... my conclusion is that you can't so hopefully my posts will stop fellow rennlisters wasting hours trying.

Voith

Scan and reprint in 3d

88Silver924S

I have had my car since new. Both the coolant tank and the windshield washer tank were white when new. The windshield washer tank is still white while the coolant tank is yellowed. Are they made of the same plastic? Same environment except the coolant tank has antifreeze and heat from the coolant. The washer fluid I believe is mostly an alcohol based fluid which is also a mild oxidizer if I remember my high school chemistry properly. Perhaps any leaching bromides were oxidized by the alcohol over time and sprayed on the windshield (slowly over the years) and hence no yellowing? The antifreeze contains rust prohibitors which might prevent this oxidation?

Question:
1) does the yellowing/staining harm anything or is it just cosmetic?

Thanks for conducting the experiment and reporting the results beamishnz!

Voith

Cosmetic.

I will buy new tank and use waterless coolant. Maybe the problem is in water.

beamishnz

I'm almost certian the plastics will be different in the washer bottle and the coolant reservoir. The coolant reservoir has to cope with high temps and pressure which is a much more challenging environment.

My guess is that the discolouration is the heat combined with a reaction with the coolant over an extended time. I doubt it is the water element of the mix ... more likely the coolant chemicals and/or impurities in the water.

The sad thing is that from everything I've tried I conclude that it is irreversible. Not the end of the world because they don't look that bad, and if you really care you can buy new ones. Some report that the new ones hold up better to staining. I suspect they are made to a different spec of plastic now. I'm a supporter of the view that the original plastic was off white ... look at the bottom leg of your tank or the double thickness rim that has not been exposed to heat ... that is my guess of the original colour.

The filler neck of the tank is made of a completely different opaque white plastic.

Not that I'm obsessive, but I am waiting for a reply from Geiger Plastics as to whether they have changed the spec of the plastic form the original tanks. I love a finite answer rather than endless discussion