coolant impeller corrosion

[andyggg]

Hi, long time reader first time poster here.


i recently had to remove the coolant impeller cover on my k75 95' and found the impeller had strange corrosion (see photo attached).


the impeller and coolant were replaced only about 6 months ago, so it seems the new coolant has attacked the cadmium (i think) coating on the impeller and nut.


i just grabbed any coolant at the time (http://www.supercheapauto.com.au/Product/Tectaloy-60-Plus-Radiator-Coolant-1-Litre/1549   << was this stuff)


my question is has anyone else seen this? or would anyone have any clues what ingredient would cause this to happen so it can be avoided.


cheers.
andrew

[Martin]

I vaguely remember something about not using Tectaloy in Bricks along time ago. Someone in the BMWMCQ had problems with it. There is a post by one of the BMW gurus about avoiding certain coolants high in certain chemicals. If I can find it I'll post it. Then I found that the  OEM coolant is pretty well on par price wise. I have stuck with it and I have been using it for twenty years with no problems, I change it every two years.
Regards Martin.

[Martin]

Needs to be silicate, phosphate, borate and nitrite free. Check to see if Tectaloy contains any of these.
Regards Martin.

[TX brick]

For use in vehicles NOT requiring antifreeze protection!

[Laitch]

i recently had to remove the coolant impeller cover on my k75 95' and found the impeller had strange corrosion (see photo attached).

How long have you had this bike, Andrew?
How many miles have you ridden it since you bought it?
Why did you need to remove the pump cover on a relatively newly replaced pump assembly?

That corrosion might be caused by mixing plain water rather than distilled water with the coolant. The Tectaloy SDS doesn't specify that distilled water is used in their compound. It might just be filtered water. There is also no disclosure of anything but ethylene glycol as an ingredient. If it were my bike, I'd follow Martin's lead concerning future coolant choice and mix it yourself so you know its proportions. Most top-quality, long-life coolants without nitrites are suitable for these bikes if mixed with distilled water.

[andyggg]

ive had the bike for a year now as a project, finished a few months ago. not many miles at all since completing but originally had 80K miles on it. the water/oil pump seals had failed previously (but there was no corrosion at the time with original coolant).


recently had the pump cover off in the process of replacing the valve stem seals.


ill make sure to look for a  silicate, phosphate, borate and nitrite free solution or see if i can get my hands on the bmw stuff.


 

[Laitch]

ill make sure to look for a  silicate, phosphate, borate and nitrite free solution or see if i can get my hands on the bmw stuff.

Please post a photo of your project. Many of us are interested in the work of others and ideas that are developed then.

[Motorhobo]

My understanding was that any coolant OK for aluminum blocks will do fine -- it's the distilled water that makes the bigger difference.

[BrickMW]

[quote author=Motorhobo  it's the distilled water that makes the bigger difference.


 :2thumbup:
Here is a brief and informative read on the subject.

[The Mighty Gryphon]

Is the impeller actually pitted under the deposits?  The photo looks more like calcium/mineral deposits from dissolved solids than actual corrosion.   Cooling systems(and batteries) should always be filled and topped up with distilled water.

It's odd that the aluminum pump body shows no sign of any build up.  It's possible that the pump body runs just cool enough not to get a build up, whereas the impeller does not have the external cooling and runs hot enough to get the mineral deposits.  I vaguely recall that the surface temperature threshold is around 165F.  We see similar problems in the small marine diesels on the sailboats I used to work on.

Drain. flush and refill with a good long life anti-freeze mixed with DISTILLED water.

Just my two cents.

[andyggg]

there was no pitting but its eaten away at the coating on the impeller and bolt. today i purchased some bmw blue coolant, with any luck it will be a long time before i see that impeller again.


below is the bike in its current state.

[Vespa no more]

It's that Sydney water - it's like acid  rain. Second only to London tap water for radioactive Ph levels.
Get one  of our American colleagues to send some Rocky Mountain spring water for extra protection.