Thermostat housing corrosion & coolant issue

[jagnut66]

Hi, 

The picture shows the state of my thermostat housing. It has been like this for a while and still functions as it should but I have noticed this same type of corrosion happening with my Morris Minor thermostat housings over the years.

I have always used the blue type coolant recommended for older (classic) engines but it does seem to 'like' the alloy housings........

However, of equal concern recently was that the mixed coolant that I put in Hetty to seems to coagulate in places, notably around the inside of the housing. This was the first mix I'd used in Hetty, which I have since disposed of, so could it be reacting with something left over from when I initially flushed her out? Although she seemed to only be filled with plain water when I bought her......

I am thinking of giving her another flush through with plain water to see if this clears up the problem.

Best wishes,

Mike.

[Pete Lewis]

i believe the current blue is less corrosive than the historic  whiich did eat any alloy parts 

jell used  happen in Oat and Gycol  manage to get  mixed 

you corrosion is not uncommon and may be from  a time ago ,

there used to be a green glycol for alloy , no clues about  4 life 

[Colin Lindsay]

There are various coolants in use presently; not just red and blue (which as Pete says will turn to jelly if mixed) but green, yellow and clear which I have in the past mistaken for water and drained completely. (Still not sure if the owner was winding me up or not) Stick to traditional blue and it's fine, although having said that I'm using the green Prestone stuff that Tesco always sells off cheap at some stage of the year in my Estate engine. The state of the thermostat itself usually tells more about the condition of the cooling system.

After sixty years there will be wear and slight corrosion of original parts, some of my housings are totally eaten away beyond use (Can't bring myself to throw them, out, for some reason) but new ones are available. Last modern that I remember having the same style and fit was early Ford Fiesta which had the take-off for the sensor on top. 

[johny]

To make things even more complicated I dont think coolant colour can be relied upon to indicate the type as the manufacturers havent agreed an official standard! Anyway all types these days should be good for alloy although perhaps some are more protective of this than others. Then of course that protection only lasts so long and perhaps the most important consideration is the coolant life...

 Ive gone to green as I now have an aluminium radiator and use the same stuff as for my motorbike but diluted from the 50% concentration that requires.