S.O.S. - Part Deux

Thanks Brian. Definitely a confusing diagnosis with the battery cable issue I was having that day. Don't know why I didn't put that together sooner. I am thinking that a hydrolock might more common when sitting or cranking for an extended period due to the lack of exhaust gases flowing out the manifold /riser, if it is a minor leak. But really have no idea. The article you sent really makes me want to pull the exhaust manifolds or at least risers and have a look!

Yes, I do have the one-way rubber flaps installed. Curious why you asked - I have read in other threads on this site that the flaps are unnecessary.

I guess it makes sense that the manifolds would be hotter now. Cylinders that aren't firing aren't generating any heat.

How is the temp gauge reading? Also, not sure if you mentioned if you checked the impeller etc. Are you pretty sure you're drawing in enough cool water (ie bucket test)? Worth checking before you pull the manifolds.

That's awesome that you got it running well

76,

Did you have to do much tuning on that new carb or was it mostly plug and play?   I am glad you do not have bigger problems at this point.

Donald

Cool,

Thanks for the response.

Donald

76tique wrote: Yes, I do have the one-way rubber flaps installed. Curious why you asked - I have read in other threads on this site that the flaps are unnecessary.

Does anyone know the purpose of these flaps?

Thought I would update this post...I've run another 40 gallons of gas through the boat and no signs of any water in the oil. Risers are still running hot with some steam out the exhaust on acceleration. I finally pulled them off to check out the gaskets tonight (way easier than I thought) and just as I suspected the gaskets were installed backward, with the blocked off part forward. Hopefully hot riser problem solved.

From what I can see, there isn't much corrosion going on. Didn't see any obvious water path through the gaskets. I was going to have the manifolds pressure tested, but now I am not so sure I want to remove them. Worried about breaking off bolts in the heads. I am thinking of just cleaning up the riser mounting surface and reinstalling with new gaskets. What do you guys think?

Some questions on reinstalling...

1. Should I use some kind of gasket cement? P/O seems to have used something.
2. How much torque on the bolts? I can't find a spec in the service manual.
3. There is some corrosion on the bolts. Good idea to swap to stainless? Or stick with these and use never seize? Never seize a good/bad idea for any reason?
4. What is the best way to clean mounting surface? I have scraped off with a razor blade. Was thinking of using emory cloth and a flat block to try and smooth out a bit, particularly the aft part of the water jackets where there seems to be a little corrosion.


Pics: note the risers are wet b/c I flushed with a garden hose to remove some rust scale above where the blocked off gasket was. Deposits inside the port manifold dropped out of the front of the riser when I pulled it off. I didn't see any obvious cracks/leakage looking down in the manifolds.

Port Manifold:


Port Riser:



Starboard Manifold:



Starboard Riser:



Any and all opinions appreciated...I am looking to get the risers reinstalled within the next couple of days. As always, thanks for your input guys!!

Tom - I recommend cleaning up the mounting surfaces by getting a flat wood block (short 2x6 for example) & stapling some emery cloth to it. Then keep it flat on the surface & sand until cleanup. No gasket sealer is needed. Run a tap into the threaded holes for cleanup of threads. Use new stainless screws. Torque to about 20 ft lbs. Use anti-seize on the threads.    Great that you found the problem.

Jllogan wrote: 76tique wrote: Yes, I do have the one-way rubber flaps installed. Curious why you asked - I have read in other threads on this site that the flaps are unnecessary. Does anyone know the purpose of these flaps?

Justin, the purpose of these flaps is to prevent water from being forced up the tailpipes when the boat is in reverse.