MerCruiser 3.0 Alpha One, melted water tube base

[Aig-man]

Hello, has anyone ever encountered a melted water tube base like this one? Our engine overheated. It was our first outing with this otherwise seaworthy 1989 Sea Ray. May have been the cruddy impeller, which I’ve since rebuilt, but have yet to replace this water tube.



It took little drill bits, a pencil-style soldering iron, and a blow torched socket to get the nasty plastic melted out enough to get the bolts out.



What would you do with this really nasty-looking corroded upper pocket area? Would this be a bristle brush with WD-40, or is there something else you’d hit it with?

 

[Grub54891]

Those do melt when overheated. clean up the mating area with a wire wheel and out a new fixture on. Check the exhaust flappers and I bet they melted also.

 

[Aig-man]

Thank you very much

 

[Aig-man]

Boat fixed, runs like a champ! look at the long-neglected manifold and exhaust riser. The dude must've took them off and soaked them in his bathtub for two years, what a chump.

Exhaust manifold water inlets...




Exhaust riser




Exhaust riser (Manifold side)

 

[Paintman1960]

Wow!

 

[achris]

Looks like normal salt water use to me.. probably about 6 or 7 years worth.

 

[Aig-man]

Aha, salt water’s kinda harsh.

 

[ThaBiggT]

Yup, Salt water boat. get yourself a set of new ones and slap Them on. What did the flapper valves look like? if they are not in place you will need to pop the outdrive off and look for them.

 

[Aig-man]

When we replaced the riser, the exhaust flapper was just not there, like it disintegrated into the twilight zone. My brother-in-law who helped, he checked the entire exhaust pipe, found nothing.
Man the boat runs so much better now.

 

[Aig-man]

Thanks for the input, I was wondering what you guys would do with a gearbox gear oil leak… Is there a set of O-rings (besides the one little one by the impeller housing) where the bottom part meets the top part, or would it be something to do with the prop?

 

[achris]

Thanks for the input, I was wondering what you guys would do with a gearbox gear oil leak… Is there a set of O-rings (besides the one little one by the impeller housing) where the bottom part meets the top part, or would it be something to do with the prop?

You need to pressure test the drive and replace that seal.

 

[ckirk]

Did you replace the manifold as well as the riser? If not how did you get the new riser to seal to the manifold with the deteriorated mating surface? I have a similar condition on a '99 3.0L although nowhere near as bad. My thought was to use some high temp RTV gasket sealant during reassembly, taking care not to block the water passageways.

 

[poconojoe]

You need to look for the exhaust shutter metal flappers. If they were there before the overheat, they most likely fell down into the exhaust and maybe even as far as inside the out drive. I found one in my drive.
Those metal plates can cause a blockage and an overheat condition. They can also lodge in the exhaust and cause a rust out.