Orange coloration in manifold

[ndutton]

Please do the same test but this time spritz some diluted liquid dish soap on all the threaded fittings, core plugs and Schrader valve. Any leak in those areas will show up in the form of bubbles. This test is intended to eliminate external factors.

Dilution should be 1 part soap to 2 parts water.

[jkaiser77]

Wow, bubbles everywhere. Tried cranking things tighter but they're about as tight as I can get.

Next steps?

[ndutton]

Hmmm, the leaks could account for the pressure drop meaning the test does not necessarily condemn the manifold. Maybe take apart and reassemble with more/different sealant? Did bubbles form at the core plugs?

Sounds like a similar but slightly different test is needed. You said you had acetone on hand. Try pouring some into a water inlet taking care to keep the exhaust ports dry, reinstall the test apparatus and pressurize. Look for signs of wetness in the exhaust ports.

Something that might be happening (a guess at this point) is there may be the breach we suspect but it's minor until the manifold is heated, then it opens up making it much worse in use.

We should not be convinced as to the health of the manifold either way yet.

[jkaiser77]

This might be a crazy idea, but what about covering the threaded fittings with silicone to (hopefully) create a better seal? Then retesting with the diluted soap?

[ndutton]

My experience with threaded fittings is applying sealant to the outside rarely if ever works. Maybe I'm not understanding how you want to use the silicone.

[jkaiser77]

I was thinking of putting silicone where the male and female components meet, i.e. where the bubbles came from.

[ndutton]

Whatever works. We want to test the manifold, not the threaded pieces necessary for the test.

[Don Moyer]

Block test

I'm willing to believe for now that the manifold is OK and it's time to test the block. You won't be able to do a pressure test with the head removed, but you can carefully fill the water jacket in the block with water while watching the rusty spot in the exhaust port. If you see any water seeping from the rusty area you will have found your leak. Don

[JOHN COOKSON]

Try some green food coloring in the water. Or better yet put a fluorescent dye in the water and look around the suspect area with a black light in the dark.

TRUE GRIT

[Ken Rockwell]

I would put it together and run it outside the boat, just to make sure it's not blowing white smoke. I'm guessing by the nice looking surfaces, that any crack either, does not exist, or would be too small to see. Maybe it's just a bad head gasket. If it smokes you can take the suspects to a machine shop. Or just buy a parts engine if you think process of elimination is cheaper/faster.

[edwardc]

...I used thread seal tape and tightened things pretty hard. ...

...Wow, bubbles everywhere. Tried cranking things tighter but they're about as tight as I can get.

Next steps?

In my experience, you have to use three full wraps of the teflon sealing tape in order to get a good seal. It works by getting compressed into the bottoms of the threads and sealing that space. If there's not enough thickness of tape, a long spiral void is left and will leak. Tightening won't help.

[jkaiser77]

Update:

The machine shop pressure tested the manifold, and it's totally fine. Just needs some new freeze plugs.

He also said the head definitely needs to be resurfaced, so I'm wondering if that offers a clue. The head came off pretty easy, and its gaskets were far less stuck to the head/block than other gaskets I removed. I'm wondering if water maybe snuck into cylinder 1 that way?

Still waiting on the magna flux test for the block.

Here's a photo of the head when it came off: