Orange coloration in manifold

[jkaiser77]

Just took off the exhaust manifold, and one of the chambers has a distinct orange coloration. All the other chambers are black.

I'd been having problems with excessive blow by, so I'm starting an overhaul. Wondering if this orange coloration offers any clues...

[Ken Rockwell]

Someone used cheap sealant. Buy the stuff rated for 1200 degrees. But you have something bad that's causing it to turn to powder. Like a bad exhaust valve. And blow by is when you have bad rings or a warn piston. I doubt you would have orange powder if your pistons were worn out. You would have smoke pouring out of the valve cover.

[ndutton]

Looks like rust to me. I think you're getting water where it doesn't belong. I suggest a manifold pressure test is in order.

[jkaiser77]

Thanks for the quick response, Ken. Maybe the blow by is caused by worn rings on a different piston?

Regarding sealant, on P1-3 of the Moyer Manual, he says "I do not put any sealer on the manifold gasket unless I have some reason to fear a water leak around the base of the studs (like after installing a threaded bushing insert). In any case, I've never seen any need to put sealer on the manifold side of the gasket"

Thoughts?

[joe_db]

Looks like rust to me. I think you're getting water where it doesn't belong. I suggest a manifold pressure test is in order.

+ 1 Looks like water intrusion.

[edwardc]

Agree, it looks like rust.
Normally, I would have suspected water or vapor backing up from the exhaust, but that would start at #3, the closest to the exhaust, and this appears to be on #1, the farthest from the exhaust (unless you have a V-drive engine which usually connects the exhaust to the opposite end of the manifold).

[Ken Rockwell]

I was talking about head gasket sealant. Only on the manifold if you couldn't mill it down. Maybe it is rust. I would think the rust would have some blackness on it. Sounds like you should do some kind of pressure test on the manifold. I figured water would end up in the back, unless your engine was tipped forward. Was it blowing any white, black, or blue smoke. Did you hear sizzling in the manifold after you shut off the engine? Tell us any and all symptoms, great post by the way, I hope it's not a hole in the manifold.

[jkaiser77]

Here are the symptoms, Ken, from my post last November. (Link below)

"Although the engine works, white smoke comes out the exhaust, oil pressure is low (Cruising 20psi, 5 - 10psi at idle), and smoke comes out the oil intake at higher speeds ... I did a compression check and all four cylinders are right around 100psi."

I don't remember hearing any sizzling from the manifold after shutting off the engine. To be honest, I wasn't expecting anything wrong with the manifold bc I was pretty sure my issue was the piston rings.

Maybe I have a new issue...

http://www.moyermarine.com/forums/showthread.php?t=9885

[jkaiser77]

Thanks, edwardc. Correct, it's piston #1, furthest from the exhaust.

Question: You say piston 3 is closest to the exhaust. The firing order is 1-2-4-3, but the piston order is 1-2-3-4, right? That's how my pistons are lined up according to the numbers stamped on top of the pistons.

Also, the arrow stamped on top of the pistons is pointing towards the propeller, not the flywheel. That's correct, right?

[jkaiser77]

FYI - This was the exterior of the manifold before I took it off. Note the orange coloration on the left circle, close to piston #1.

What ARE those circles btw?

[Al Schober]

That looks like nice fresh rust to me. Source of leak might be the manifold (pressure test) but I'd also take a look at the block near the #1 exhaust valve. This is the time of year for cracks in the block to magically 'appear'. Don't spend money fixing this until you're sure it's NOT the block.
Blowby = bad oil control rings: ie: the lower rings. Suspect they are badly worn and just going along for the ride. This is NOT inconsistent with good compression (upper two rings).

[ndutton]

What ARE those circles btw?

Those are core plugs, a necessary evil of the casting process.

edit:
Al's advice is spot on. Before proceeding you need to find the water source so your efforts are directed at the problem. If the head is still on the block the water jacket should be pressure tested separately and in addition to the manifold. Here's the equipment you need to perform the test:

http://www.moyermarine.com/forums/showthread.php?t=10146

[jkaiser77]

Ugh, I just took off the head. What steps should I take? Pressure test the manifold?

Given that my core plug is rusted, is there a chance that's the source of the leak?

According to Wikipedia:

"Core plugs can often be a source of leaks due to corrosion caused by cooling system water. Although modern antifreeze chemicals do not evaporate and may be considered "permanent", anti-corrosion additives gradually deplete and must be replenished. Failure to do this periodic maintenance accelerates corrosion of engine parts, and the thin metal core plugs are often the first components to start leaking."

[ndutton]

Core plug first
The leaking they're talking about is from the water jacket through a rusted steel core plug to the outside. It does not leak into the exhaust passage as your original picture indicated. Any Afourian worth his salt uses brass core plugs and they don't rust. Your seepage/rust at the plug appears to be around its rim rather than a plug breach, easily solved with replacement if the manifold tests successfully. No way does core plug seepage result in exhaust port water incursion.

Pressure testing
A pressure test of the manifold is indicated for sure. Expect a leak around the core plug but more important is a breach into the orange exhaust port. Any indication of leakage there and the manifold is done. I'm hoping the manifold is toast because the other possibility is worse, namely . . .

Since the head is off carefully inspect the block for a hairline crack in the area of the #1 exhaust valve. You could be getting cooling water into the exhaust that way too. Let's hope not.

[edwardc]

Thanks, edwardc. Correct, it's piston #1, furthest from the exhaust.

Question: You say piston 3 is closest to the exhaust. The firing order is 1-2-4-3, but the piston order is 1-2-3-4, right? That's how my pistons are lined up according to the numbers stamped on top of the pistons.

You are of course quite right. #4 is closest to the exhaust. I've got that 1-2-4-3 sequence so ingrained in my mind, it just came out without thinking about it.

My bad.