Strange Looking Oil After Rebuild

[Willshook]

If you're tearing it down, I wouldn't really worry about it. The shop will pressure test and magnaflux the whole block.

[jjzepplin]

Dang! I hate when you try to save a buck and it backfires. I would start from scratch at this point. I used a reputable actual race builder for machining and line honing in Cali and built the engine myself. I have built quite a few engines though so I know what to look for.

[70STOVEBOLT]

There is absolutely nothing wrong with reusing cast pistons and honing a block. There are thousands of engines out there that were rebuilt in this manner and are running fine. That being said, yes, all of the proper measurements must be taken and any machine work done that is necessary. But I would not condemn a build just because the block was not fully machined. Another possible source of the coolant leak is from the head bolts if sealer was not used on the threads, as they go directly into the water jacket on a small block chevy.

[70STOVEBOLT]

Please report back with your findings.

[HO455]

If It's any consolation I just went through the same on my Burban. It was a failed head gasket. But it's been torn down, cleaned up and its back together now and I drove it to work today.

[jjzepplin]

That is good news! I used multi layer marine head gaskets on my 406 and that was 24 years ago. She sounds fabulous still!

[adf5565]

Originally Posted by HO455

If It's any consolation I just went through the same on my Burban. It was a failed head gasket. But it's been torn down, cleaned up and its back together now and I drove it to work today.

Yep I will keep this thread updated. Need to pull the engine before I do too much more. I pulled the valve covers the other day and they were clean, no signs of coagulation or coolant. So I’m guessing the head bolt sealant isn’t the issue.

And that’s great to hear! Did you just do a head gasket job then with some cleaning?

[57taskforce]

A small mount of Diesel in the oil will clean chocolate milk right up. Run it for a short time and change it and the filter out. If it’s really bad repeat. Do not drive it, just let it idle, you can speed the engine up a some but be gentle on it.

In your case you really need to know a few things like your piston to wall clearances and how the block was checked for cracks/if it was magna fluxed etc. I used to build engines professionally. You can reuse pistons but you’ve got to make sure the bores are still straight and that the pistons still have the correct tolerances to the walls. The intake install might not be the prettiest but it’s hard to judge the build just by this. One thing that some people don’t realize is that rarely cylinders wear evenly straight up and down. There’s less oil at the tops of the cylinders when running so it’s pretty common for them to wear in a taper, tighter at the bottom and gradually loosening up closer to the top. (below the ring line obviously) it’s really important to make sure the cylinders are still square before any honing or assembly work begins, this is also why when you bore an engine you cut the cylinders to the pistons being used, so you can be sure that not only are things square but they have the correct wall tolerances. If it were me I think I try and verify how your friend built it, how he checked for square, wall tolerances, bearing tolerances etc, before I tore into it. If you can verify and feel comfortable that he did things competently than you could proceed with changing head gaskets, Intake gaskets, sealing head bolts etc and see how it goes. It’s likely going to be a crapshoot at best not tearing it down and verifying everything though.

[Steeveedee]

Back when I was pi$$-poor, I've "rebuilt" old engines by removing the ring ridge with a ridge reamer and endured the blow-by and loose pistons. Those issues have nothing to do with coolant in the oil. Not the best way to rebuild, but cost can be an object. On the engines where I've done this, none ended up with water in the oil. Blow-by? You bet. Oil consumption? Of course, but reduced from before that cheapie overhaul.

[HO455]

Originally Posted by adf5565

Yep I will keep this thread updated. Need to pull the engine before I do too much more. I pulled the valve covers the other day and they were clean, no signs of coagulation or coolant. So I’m guessing the head bolt sealant isn’t the issue.

And that’s great to hear! Did you just do a head gasket job then with some cleaning?

Yes, I changed gaskets did and lots of cleaning.
Here's a link to the story. More photos and a pratfall for your viewing pleasure.

http://67-72chevytrucks.com/vboard/s...698377&page=46

[72c20customcamper]

Originally Posted by adf5565

Pics

Those look like hairline cracks to me

[HO455]

After cleaning with Brake Clean and inspecting with a bright light I didn't see any indication of cracking. Nothing to make me suspicious enough to break out the crank detection fluids. (Have you priced that stuff lately? Yikes!)

I've put over a hundred miles on the truck since I buttoned it up. All looks good at this point. Fingers crossed!