'78 2F cooling system quiz

Aug 9, 2005
Decatur, Ga
True or False:
Over time, coolant/antifreeze becomes very acidic.

(Once I noticed the thermostat that I was going to replace anyway, was broken and the spring was laying in a puddle of the green stuff at the bottom of the housing, I decided to look at the system a little further. Took off the lower thermostat housing and found that it was heavily/deeply pitted in the area where it attaches the the engine just below the valve cover. Took it in to NAPA, since I was going there anyway, and ask them if they have ever seen this. They told me that the fluid turns acidic over time and will do this is not changed frequently enough. If this is false, what would cause it to pit so heavily, almost all the way through the metal?)

True or False:
There are two types of coolant/antifreeze. One kind for modern engines that are not prone to rust on the inside, and another kind for engines that tend to accumulate rust on the innards. This latter type has some sort of fine grit in it to scour away rust deposits inside the cooling system.

If this is true, what type of fluid do you long time cruisers use, and is it easily found at AutoZone or AdvancedAuto?

Since my cruiser sat for a good number of years in a barn in St Louis until this past August and indeed, the coolant does turn acidic, and has eaten its way through the thermostat and its housing, should I consider replacing the water pump too? How do I tell if I need to replace the water pump?



Nov 14, 2004
True or false:
Yours is the most fxxxed up question posted here in over a month?


Where are my keys?!
Jun 2, 2004
Wheat Ridge CO
Ask the same question to a Rover guy.... :D

Three words: dissimilar metal corrosion

Antifreeze never goes bad, ask any farmer. They just filter it and put it back in.

The new type of antifreeze does not contain silica (sand) and is said to prolong the life of your waterpump. Some mention aluminum and steel but I dont know the science behind it. As far as I knew, antifreeze was ethylene glycol. Maybe that changed...
Jul 18, 2005
Wellington, NZ
antifreeze contains either ethylene glycol or propylene glycol - these are the two different types and they dont mix.
It also contains anticorrosive agents and these wear out.
Ethylene is by far the most common type.
If you do a full drain/flush you can run which ever you want.

put the t/stat back on and do a pressure test - that will give you a good idea if w/pump needs replacing or not.
Jan 22, 2003
Andrew is right on the mark about antifreeze. The coolant properties of raising the boiling point and lowering the freezing point do not change over time, only with the concentration. What DOES change over time is the anti-corrosive property. I do not have my antifreeze "filtered", just replaced. But when the chains DO recycle your coolant, they usually add some waterpump lubricant and anti corrosion schtuff to the mix.
I have my systems in all my vehicles changed every two years and the ones with "red" antifreeze get flushed and changed to "green".

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