Getting oil out of engine coolant passages?

[jangell]

About four months ago I got my 3.0L engine for my swap. For about three months it had been upside down on the engine stand while I waited for gaskets to arrive and took care of some other things. While most of the oil and coolant had been drained before the engine was shipped, there was still a fair bit left in it that got all over the floor when I turned the engine upside down. I even noticed one of the exhaust manifolds had filled with oil during this process.

I finally reassembled the bottom of the engine, flipped it back over, and took off the intake manifold. When I removed the Y pipe, oil was filling the right side (as viewed from the back of a DeLorean) hole was filled with oil, not coolant. This was the same side that had the exhaust manifold filled with oil.

I figured I'd try draining it out form the plug above the oil filter. When I took it out, I was greeted with what looked like plastic seal. It was actually dried oil that had been pushed against the plug. I used a pick to remove quite a lot of it, but I"m sure there's still much I wasn't able to get to. No oil or coolant actually poured out of this hole, and the hole in the top of the engine where the Y pipe hooks up is still filled with oil.

So my questions are:
- How can I flush coolant passages, preferably while the engine is out of the car?
- Is it Really Bad that there's dried oil in the coolant passages? Meaning, is it possible to clean them?

I want to be clear that I don't believe the engine has a leak between the coolant passages and the oil galleys. I believe that because i had the valve and timing covers off while flipping the engine, the remaining coolant and oil were free to flow wherever they wanted, and it just dried in the engine a bit after a few months. I really just want to figure out how to get it out.

Here's some pictures of what I've got:

- Where the "Y" pipe hooks up t the engine, full of oil (sorry for the poor quality picture).
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- Coolant drain plug above the oil filter removed, showing dried oil
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- Gunk pulled out of the passage with a pick
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I haven't taken the heads off this engine. I was hoping to avoid that, but I've done it before on my old 2.8L engine, and I have gaskets for everything, so I can do it if you guys think that will make it easier to clean everything out.

It's also not a huge deal if this problem is larger than I thought and I have to get another 3.0L engine; they're not that hard to come by and they're not very expensive. It would be nice if I didn't have to, though.

While I'm here, I also had to replace a core plug on the flywheel end of the head on the same side of the engine. After finally hammering it out, I glanced inside the hole and saw a little corrosion on the aluminum from the coolant. I'm guessing it's nothing to worry about...
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There's also some gunk visible in the passage where the water pump hose goes into the other head (driver's side):
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Thanks!

-- Joe

[jangell]

I decided to take off the cylinder head. I was greeted with a liquid oil filling one of the cylinders, and a dried oil and coolant mix filling the cavities around the liners. Here are some pictures:

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I'm trying to decide what to do about this. It's not clear to me if this happened because I assumed the engine was drained before being shipped and didn't check before I flipped it over about three moths ago, or if this existed beforehand.

If it's the later, I'm not sure how that would have happened. The cylinder head gasket seemed fine to me when it removed it from the head, so I don't think it's that.

I have zero interest in removing the pistons and liners. While I did that on my 2.8L as an exercise in learning about the engine, I'm not as confident about putting everything back together properly. I will note that the 2.8L engine did not have oil and coolant in around the liners, even though some did pour out when I flipped the engine.

At the moment I'm trying to clean out the gunk with picks, but that can only go so far. I'm thinking of using pressurized water to remove more of the gunk, on the off chance that would work. I've noticed rusted metal flakes coming out as well, which isn't terribly reassuring.

What I'm wondering is if I should give up on this engine and buy another one. 3.0L engines aren't expensive; I'm just wondering if it's worth it to keep going or not.

Thanks!

-- Joe

[vwdmc16]

I'd say you will need to tear down to a bare block with some thing to hold the cylinders and then you can properly pressure wash the coolant jackets with some strong degreaser too.

[jangell]

I have some large washers and bolts that I can use to keep the liners in place while I pressure wash (I used them on my old engine so I could turn the crank without shifting the liners). The main trick is going to be finding a source of water -- the garage I rent to work on this doesn't have any facets or hoses. I'll have to ask the landlord if the adjacent building he owns has a hose somewhere.

Or I can get can get a drum or something to hold a bunch of water from one gallon jugs brought from home, and use that to fill the washer. Whatever works. :)

Thanks!

-- Joe

[jangell]

I finally got this taken care of. It took a few weekends, but the passages are now as clean as they're going to get. The coolant jacket in the block and the passages in the head were filled with this stuff.

The short version is that I scooped out all the gunk I could, and used a pump-to-fire Super Soaker in lieu of a pressure washer to force more of the gunk out, sprayed in degreaser (Simple Green, in this case) to try to break down some more of the oils, and used picks to break up some of the harder material. The cylinder heads were similar, although I also filled the coolant passages with vinegar to break up more of the gunk. I was able to bring those home and flush them with hot water in the sink as well.

They're no longer obstructed, although there's some yellow residue on the surface of the passages that I'm not really worried about. The longer explanation can be found on my blog: https://joe-angell.squarespace.com/repairs-and-maintenance-blog/2014/7/13/oil-mud-in-the-coolant-passages (scroll down a bit; I also talk about removing the heads at the beginning of that post).

Thanks again for the help

-- Joe

[DMC5180]

I know this is a little late, but I would have taken it down to the bare Block and had the whole thing Hot Tanked at local Engine repair/machine shop. All the crud and oxides would have been eliminated.

[DMCMW Dave]

I know this is a little late, but I would have taken it down to the bare Block and had the whole thing Hot Tanked at local Engine repair/machine shop. All the crud and oxides would have been eliminated.

Yeah. With all it's been through the odds of the cylinder liners still being sealed at the bottom are pretty low anyway.