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Engine Sludge Removal

I removed the cylinder head from a 1999 Honda Civic DX a few months ago. I’m now ready to reinstall the cylinder head and I noticed the walls on the engine block appear to have dried engine sludge pasted all over the interior walls of the engine block. Can anyone recommend a method or procedure to perform on the engine block to remove the dried sludge from the walls without damaging the engine block? All answers are greatly appreciated. Thanks in Advance.

I believe you just need to use a ridge reamer and carefully hone the cylinders, as needed

But that’s based on your single grainy picture

It might help if you gave us a picture with a cylinder wall, and the piston is NOT at top dead center

Mind telling us WHY you removed the cylinder head in the first place . . . it would greatly affect any further responses from us

One more thing . . . this really needs to be in the “maintenance and repairs” category if you want to get the maximum amount of people to even see it. Many people don’t check under “site feedback”

@cdaquila You could move this post to the other category, and help this guy out

I removed the Cylinder Head for a project in my engine class. The engine overheated and as a result, suffered a blown head gasket and a crack in the spark plug housing in the 4th Cylinder. Here’s another photo, I’ll get some other photos and will post them in a bit.

Thanks @cdaquila and db4690

So it’s buildup in the cooling passages. I guess you could try filling the cooling system with a coolant flush for a day or two and see if it loosens it.

Hi, I changed the section to Repair and Maintenance. Thanks.

Thank you cdaquila

It is normal to find rust in the coolant passages in an old engine, there in no need to try to clean this and do not hone the cylinders.


If the engine overheated, I’d lay a straightedge on the head AND the block

You may find one or both to be warped beyond acceptable limits

The head clearly needs to be repaired, because of the cracked spark plug threads. I assume it’ll also need to be shaved, so that it is within tolerances again

To get that stuff out you’d need to soak the block in a tank of hot, aggressive cleaning solution.
That of course means removing the pistons, crank, seals etc.
That said, I don’t think the deposits are bad enough to be a problem unless you’re increasing engine power above stock or using it in a hot climate.
I say button it up and get it running, then use a coolant flush as Insightful suggested.

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@Nevada_545: Will the rust effect the cooling system?

Ok will do, Thank you everyone for your help today.

I am not saying this to be mean ,but if you don’t know your cylinder wall from the water jacket, you may be in over your head.

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I strongly suspect that engine will need to be completely gone through and properly overhauled. That leads to the cost/benefit factor.

I hope you’re not talking to me

That first picture was pretty grainy, and it was not at ALL clear if we’re talking open deck or closed deck. In that first picture, it appeared to me that we were talking closed deck.

I don’t give a . . . if anybody says otherwise

In that first grainy picture, that brown looking area sort of looks like a ridge which you would find at the top of a cylinder that’s been in use for several years. In that one lousy picture, one could conceive the area right next to the piston as being the cylinder, implying the piston is not quite at TDC.

The second picture is MUCH clearer, and now we can see that we’re dealing with an open deck construction. In THAT picture its clear that that brown looking area is the water jacket

it’s REAL easy to sit back and talk smack after seeing the second picture, which elminates all doubt as to what we’re looking at

If you were NOT talking to me, then I sincerely apologize for being defensive and using harsh acronyms

If anybody says that first picture was high quality, and everything was crystal clear . . . they are lying like a rug

I think oldtimer was addressing the OP and I agree with him.

What I can see of the cylinder wall in the second picture does not look too good. Maybe it’s the pic or something but the cylinder wall looks badly glazed. Severe overheating will do that… :frowning:


Yes, I was addressing the OP and the first pic did look like a closed deck. The OP was not looking at the bad pic but the actual engine and if he did not understand the difference between the cylinder wall and the water jacket around the cylinders then perhaps he should not be deciding what needs to be done to put this engine back together. He described the problems with his head but told us nothing about what he did to correct them.

The OP did not ask about the cylinder walls, he asked a question about the block.

@oldtimer_11: Well I could have sworn that the point of this forum was to ask for help or for a second opinion from mechanics that might have dealt with something like this? I apologize if I wasn’t clear about the cylinder wall and the cooling jackets. For any future questions I ask, I will try not to be so vague in the actual question I am asking. As I had said before, the cylinder head that I removed had a crack in spark plug housing in the 4th cylinder. I scrap the old one out and purchased another one at the request of the vehicles owner.

The Areas Shaded in Blue is where the cylinder head deck was warped and needed to be resurfaced which I did. I also inspected the Deck of the block and it is within specs and does not need to be resurfaced.

No doubt the OP seems to be on the lower end of a long steep learning curve but we should give him credit for recognizing his need for some insight and advice in his efforts to get his repair done properly. And that 1st picture along with the OP’s description is quite confusing.

I would call the brown material in the water jacket ‘scale’ myself and wouldn’t think it would cause any problems. Efforts to remove it would be more harmfull than leaving it be.

And as for warped heads, don’t most shops heat and press aluminum heads back to level to get the cam bores back into alignment and keep the compression ratios even?

edit; Now I’m getting very confused. Is Stony a DIYer or a somewhat professional mechanic?

@Stony, your last post has me more confused than usual. Help me out here.