4.3 Manifolds???

[SeadawgVB]

Had the boat out last weekend for it's dewinterize shakedown. (I know it's late, but I got excuses...) Seemed to be running well, so I took out across the channel to a new destination. After about 20 minutes the engine did not want to do more than 3000-3200 RPM. First thing I thought of was gas, gummed carb, along those lines. Made a U-turn headed back to the ramp. But hung back and ran the boat hard for and hour or two, dragging a big tube with teenagers on board, and the engine seemed to clear whatever was ailing it earlier.

Running the engine back at home on the hose, I noticed water coming out of the propeller hub with the exhaust, I don't recall that before.

I was planning on going out this evening, but there was something in the back of my mind giving me some misgivings. I haven't checked the manifold / elbow joint in a while, so if water had leaked back into the engine through the exhaust, I didn't want to have a hydro-locked engine on the ramp...

Broke out the hose, and the engine fired right up. But the I noticed the engine sounded like it was stumbling and missing while I was out checking water flow. Low and behold water was coming out thru the hub with some exhaust. As I was watching, the water stopped, the engine cleared up. Then the water came back and the engine started running ruff again.

Trip canceled, break out the tools. I pulled off the risers and the manifolds looked almost new, the risers were looking somewhat ragged.

HERE'S THE QUESTIONS:

Water doesn't normally come out of the hub, does it?

Could the risers themselves cause this kind of thing.

Does anyone ever replace only their risers and not the complete exhaust assembly?

I pulled the manifolds off as well, but they still seem to LOOK like they are in good condition.

 

[Bt Doctur]

1 Water doesn't normally come out of the hub, does it?

2 Could the risers themselves cause this kind of thing.

3 Does anyone ever replace only their risers and not the complete exhaust assembly?

4 I pulled the manifolds off as well, but they still seem to LOOK like they are in good condition


1 yes
2 yes, they dump the water into the Y pipe and it comes out the reliefs and the prop hub
3 yes, if the remaining items are serviceable
4 then reinstall them with new gaskets
'

 

[DeepBlue2010]

What kind of cooling system you got, open or closed? Full closed systems runs anti freeze in the exhaust manifold, so those will outlast the risers/elbows. As Bt said, water out of the hub is normal.

 

[SeadawgVB]

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So here (I think, I'm still getting the hang of this forum.) are pictures of the manifolds and risers mating surfaces.

 

[SeadawgVB]

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And here are a couple of pics of the tail end of the risers.

Any reccomendations as to what to replace / reuse?

 

[DeepBlue2010]

You need to clean all the rust (shooting with pressure washer works great) and post pictures. The water passages and the thickness of the mating areas are what you supposed to be most concerned with. If the water passages are almost closed with rust, this means the water will be restricted, time to replace.

If the mating area became too thin (the rust ate it away) the gasket will not seal and this would lead to bigger problems. Also time to replace.

The last two pictures in post #4 looks like the water passages are completely blocked with rust.

 

[SeadawgVB]

Snip.....

The last two pictures in post #4 looks like the water passages are completely blocked with rust.

Yes, those last two pics are the risers, the intenals and the exhaust tail pieces looked to be toast. The manifolds looked to be decent, and I did the acetone leak test, without any leaks. So I purchased new risers and re-installed the manifolds last night, which prings me to a new question:

The new manifold / riser gasket seems to be made of a similar material as the manifold / head gasket. (Like a graphite impregnated thing.)
Do I use Perfect Seal gasket sealer on this gasket?
Should I be using Perfect Seal at this joint? (I'm know that any leak here is BAD.)