So I purchased a used engine with only 78000 miles on it that has been sitting in a garage for 3 years. Started taking it apart to change some gaskets and parts, and was extremely happy with how clean she was under the valve cover. 0331 head, but no signs of cracks.

But my excitement bubble was quickly popped when I took off the thermostat housing and thermostat, and looked inside. So I am freaked out because it looks horrible in there, and this is the first engine I have ever been digging into. But then I thought this might be a simple common issue with engines that have been sitting for an extended period of time.

My question is: Is this something I should be seriously worried about, or something that a couple of engine flushes should take care of? After all, the internal engine components (that I can see) are spotless, it is just the coolant passages of the engine that look like this, and mostly just in the head portion, the block portion looks much better.

Please ease my mind.

THanks

 

Not unusual for a motor that's sat for several years. Run it with a good cooling system cleaner, then flush it out and keep flushing until the water runs clear...no more rust or scale. Should be good.

 

THanks so much man, you made me feel much better

 

This might be a dumb question, but what is the best way to flush it while the engine is out of the jeep? Do i need to put the water pump back on and the thermostat housing, and cap off all of hose attachments and let it soak, or just run the water and flush cleaner through the thermostat hole and out the water pump hole?

Thanks

 

That's what I would probably do.

 

So I did this last night, but without the heat from the engine being on, it did absolutely nothing. I think that I am going to have to scrape off what I can inside the water jacket with a wire brush and hose it out, then when the engine is installed, do a flush or two and hope for the best.

Any recommendations on the best stuff to flush with? I have read everything under the sun from the prestone flushes that you get at the parts store to vinegar, to oxalic acid.

My cooling system is brand new, so if I flush the system out right away with the replacement engine, I am not too worried about hurting the system too much

 

Well, that's a good thing in that there weren't any big flakes or chunks in there.
I'd find some of the GM Heavy Duty cooling system cleaner and run that once you have it up and running. GM Part Number 88861344
Dealers have it for about $8, it works better than the diluted crap you get at the parts places.
Dexcool systems have a nasty rust/corrosion problem when air gets in, if it can clean that, yours should be a cakewalk.