Rust/Corrosion in engine block cooling jackets

[i6Therapy]

I am in the process of replacing a head gasket due to overheating. Here is the "long" story:

Took car to twisty mountain roads, had fun, camped the night. In the morning, I started on my 5hr journey home. Began to overheat an hour into traveling. The second the light came on, I shut it down and coasted to a gas station. Filled up with distilled water. Waited for the system to bleed out all the bubbles and continued on my way. 30min later, temp light comes back on. Shut it down and coasted to another gas station/place that sold water. Refilled it with distilled water and drove 2-3 miles to a Uhaul where I loaded it up and took it home. I let it sit about a week and then began teardown. Coolant system out and intake manifold off. Work/life got in the way and it sat for a year in the back of my shop. I figured I had all the bad water out of the engine and was fine to let it sit.

Fast forward a year and I now have the head removed and off the get decked at the machine shop and now working on cleaning the block up to receive the freshly milled head. And I notice rust and corrosion in the water jackets (intake side) and on the exhaust side what looks like a rust layer that you can poke through to see a bit of remaining water in the block (similar to how paint will crust over if you leave the top of the can off).

When I took off the cooling system a year prior, everything was clear and clean.

Here are some images of the cooling jackets *please note that I have already poked a screwdriver through the layer of rust on each respective picture:


Lets get a little closer:


And finally all the way in:


Lets check on another one, yup all the same:


How about the rear lower port...yes very bad:


What happens if you poke a screwdriver down into the jackets....well thats not good:



Here is the water pump....everything looks brand new...odd:


On to solution. I have heard that you can use vinegar or CLR to attempt to clean out the block....should I try this? I really dont want to take the motor out and send it off to get fully cleaned at the machine shop. Any advice?

[i6Therapy]

*double post

[samy01]

what are we looking at in the first two pictures ? the block ? why is there light falling into tha canal if you shine into the cylinder ? Is there a hole ?

[blckstrm]

I've seen vinegar used to dissolve rust before - I don't see the harm in trying that first. Flushing it while it's disassembled won't be easy - but easier than pulling the block.

[Edit] I'd leave the crust so you have an easy visual of how well that's working.

[pbonsalb]

You should use a cooling system filter when you run the engine again. Just run it on cheaper coolant like Zerex G05 that is fine for this engine, and clean the filter a few times. Remove the filter after a few thousand miles. I have one I use in the upper radiator hose after changing a head or on a new motor. I have one that looks like this (brass screen inside) but there are others:

https://golanproducts.com/product/radiator-filter/

[i6Therapy]

Samy01 - I am shining an LED flashlight into the water jacket of an adjacent cylinder to cast light into the whole area so that I can get a somewhat decent picture.

blckstrm - went with CLR...corrosion was just so bad I need something strong!

pbonsalb - Good idea

Did a little more work today.....Here are some photo updates:


Taped up everything so water wouldnt go all over the place:


Used an exacto to cut out the water jackets:


Had this little tool sitting around to flush out my boat motor (50hp Honda). Not sure where I got it, but it worked great to shoot water into the jackets. Water pressure on very low so that it doesnt overflow but just runs out the drain plug.


It took about 20-30min and probably 50 gallons of water but think I got all the sludge and loose rust out. Here is what it looks like on the ground. nasty.


Used a funnel and poured in some CLR. Had to jack up the rear of the car so that the motor was level and I could fill the motor evenly:



And now here is why I have lost a lot of hope. As the CLR is working its magic, I decide to inspect the rest of the motor....and to my horror I found some bad bad news. Looks like the #5 cylinder has some very serious scoring. Perhaps from letting it sit for a year and water was in the cylinder? Oh I hope not....but whatever the case, take a look:






So now what!?! I realize I cant overbore these blocks and a quick search turned up no used blocks in decent condition. I dont want to do the whole M52 block and swap out all my S52 stuff (and lose some displacement). New blocks are $4500. Nope. How much to sleeve the block? Should I just button it back up and hope for the best? Will that cylinder be toast in a matter of days or....?

[Braymond141]

That wall staining is pretty normal. Happens to anyone with an engine that sits. The skirt expansion marks seem excessive though.

M52 are S52. You just bore it out to accept your S52 pistons. There is no difference.

[i6Therapy]

Braymond141 - Thank you. Glad I dont have to be super worried about those stains.

Can you elaborate on skirt expansion marks seeming excessive? I am assuming you mean the marks that run in line with the piston stroke? I had my flash on the camera and they are significantly more pronounced than in person.....but they are very mch present and they are on all cylinders roughly the same amount. The motor does consume a bit of oil....wonder if this is the reason right here.