Orange coloration in manifold

[Tim]

How did the block look when you took the manifold off? Was there rust in the same area on the block?

[Mo]

Pressure test the exhaust manifold.

[jkaiser77]

Here's a photo of the engine block. Some rust, but not as bad as the manifold. Didn't notice any hairline cracks in the block.

The internet tells me I can pour acetone in the exhaust manifold as an easy first test for leaks. Anyone tried this before?

[Tim]

I'm not sure why acetone would be any better than filling the manifold with water and looking for leaks into exhaust ports. The best thing to do, as previously mentioned, is to pressure test the manifold.

I'm hoping that the problem is with the manifold since most of the rust is in the manifold. It seems like if the block were cracked most of the rust would be in the block.

[jkaiser77]

Apparently acetone is better at finding leaks.

"Water is 4 times as viscous (thick) as acetone and has a MUCH higher surface tension."

http://forums.iboats.com/forum/engine-repair-and-maintenance/mercruiser-i-o-inboard-engines-outdrives/295908-testing-exhaust-manifolds-for-leaks

[ndutton]

There are three passageways inside the manifold: intake, exhaust and water. We are looking at the possibility of a crack or hole between the water and exhaust passageways in the immediate area of #1 and again, INSIDE the manifold. This is why modest air pressure makes for a good test, it doesn't require a visual inspection of areas you can't see anyway for pass or fail.

I'm sensing a reluctance to try the pressure test, not sure why.

[JOHN COOKSON]

"Water is 4 times as viscous (thick) as acetone and has a MUCH higher surface tension."
[

Water is less expensive than acetone and a lot less explosive. Water under pressure mimics the working environment of the manifold better.

TRUE GRIT

[jkaiser77]

No reluctance to do a pressure test, Neil. Had some spare acetone so figured I'd try that simple test first. Don't have the equipment for the pressure test yet. Trying to limit my runs back and forth to the closest hardware store here in rural Maine.

[joe_db]

You can plug one end and just blow in the other for a real quick test!

[Ken Rockwell]

You're burning water in cylinder one. That's the white smoke. But that cylinder should be clean so I think you might have a problem in the manifold. Also you would see where water was getting in, like a small line of rust. As for the pressure test, did you try putting one hand over the cooling port and blowing in the other. Sometimes tiny cracks open up when it heats up, I have a bad crossover pipe that dripps a little when it heats up then stops. If you have a tiny crack in the manifold, juat add air. Finding a crack in the block may require a machine shop. Rotate the crank so that exhaust valve is open. Look for any small lines of rust.

[Ken Rockwell]

If you're blocks cracked, I've got one almost ready to be put back together. I'm in upstate New York. $1500 obo.

[ndutton]

You can plug one end and just blow in the other for a real quick test!

To clarify, Joe's talking about the water ports on the top of the manifold, NOT the rusty exhaust port. Let's get the testing done before buying anything, Okay?

[mpleahy]

A4 parts

I live in Bangor and have a good manifold, and a cleaned and resurfaced head and block.

[ndutton]

Hey Kaiser, did you ever test the manifold? Whazzup? Don't leave us hangin'.

[jkaiser77]

Ok, here's the update...

I did two pressure tests using equipment in the photo below. I used thread seal tape and tightened things pretty hard.

Pumped the pressure to a little over 20 psi. In both tests, pressure dropped to about 12-13 psi after 30 minutes.

I'm assuming this indicates the manifold has a leak? If so, should I take it to a machine shop to get it professionally checked out?