Intake manifold corrosion on rear coolant ports

[lotzagoodstuff]

So I've got my intake pulled off to do an intake manifold gasket. I'm going to do valve springs while I'm in it this far, but when I looked at the bottom of the intake manifold, I've got some pretty fair corrosion at the rear of the manifold where the rearmost coolant passage see's the bottom of the intake manifold.

I realize this car is over 25 years old, and dissimilar metals do tend to corrode, but is this normal? I can certainly post pics if necessary, just trying to get my ducks in a row before reinstalling everything.

Thanks for the help/insight

 

[Nick Micale]

It is normal if the cooling system was not maintained properly.

Antifreeze quickly goes acidic as the additives are used up and you probably have the same situation in your aluminum timing cover.

We do not need to use antifreeze here, but in the cold areas it should be dumped every Spring.

 

[mybuick]

supposed to use distilled water but nobody does

 

[Dave Dunbar]

It is normal if the cooling system was not maintained properly.

Antifreeze quickly goes acidic as the additives are used up and you probably have the same situation in your aluminum timing cover.

We do not need to use antifreeze here, but in the cold areas it should be dumped every Spring.

Just plain water? What about rust? And is there not a lubricant in the antifreeze for for say the water pump seals?

 

[earlbrown]

RMI-25 and plain water make a better coolant in areas that don't have issues with freezing.

 

[kidglok]

RMI-25 and plain water make a better coolant in areas that don't have issues with freezing.

thats all i run once its above freezing

 

[Nick Micale]

RMI-25 and plain water make a better coolant in areas that don't have issues with freezing.

That is very true, but when you must use antifreeze, you should also add RMI-25 for added protection as antifreeze has a minimal additive package, and it is very quickly dissipated and then you end up with corrosion and deposits.

RMI-25 is the only radiator additive that contains protection against corrosion, cavitation, electrolysis, lube for the water pump, and will actually clean the system without caustic chemicals.

Oh, I did not mention it also has a pH stabilizer for acid-alkaline balance which especially is protection on attacks of aluminum parts like intakes.

Here is something to remember from your high school chemistry class, when 2 dis-similar metals are place in a solution this causes electrolysis, actually a small electric current, which will erode metal, again aluminum is the sacrificial one in our cooling system.

 

[lotzagoodstuff]

I always run coolant additive, I've got a diesel that has to have it for corrosion and anti-cavitation. I will do a complete flush and make sure I get the proper stuff in the coolant system when I've got the engine back together.

I guess my specific question is: should I worry about the corrosion on the bottom of the intake? Is this pretty common or should I look for another intake? I'll try to post some pics later today to show the amount of corrosion.

Thanks

 

[earlbrown]

if it's not paper thin and about to break through, run it.