Thanks for the offer Darren but i think it may have a crack in the cylinder wall ,It seems strange that when Nick first had the boat it had a crack in a cylinder which makes me think that the exhaust setup may let some water up and the thing has had a hydraulic effect ,with the head gasket blown out between 6 and 8 and 3 cylinder destroyed .I will have to strip the block out and take it in to see if it is definitely cracked and can be sleeved .
Ken
B-PEE
Re: B-PEE
Hi Ken - I think you are on the right track with the hydraulic effect, that piston / gasket failure has all the signs of a previous hydraulic issue
The ring land crack looks mostly old with just a few spots keeping it in place until the last workout.
Could be a cracked cylinder wall was the initial culprit because you need a lot of water in the cylinder to apply high pressure to the cylinder wall
More likely just enough water to exceed the combustion chamber volume then at almost TDC very high hydraulic load on piston / gasket
just my 2 bobs worth - good luck with it
The ring land crack looks mostly old with just a few spots keeping it in place until the last workout.
Could be a cracked cylinder wall was the initial culprit because you need a lot of water in the cylinder to apply high pressure to the cylinder wall
More likely just enough water to exceed the combustion chamber volume then at almost TDC very high hydraulic load on piston / gasket
just my 2 bobs worth - good luck with it
Re: B-PEE
B Pee is back together ,i think the past problems have been solved .I kept asking myself how can water be getting into the cylinders and have discovered that if i set the marine manifolds at the same angle as the engine which is a unusual setup and connect the garden hose to the water outlet pipe a percentage of the water runs back down the manifold ,this would not matter if the engine was running but if you were to wind the engine over with out it starting the pump will push water down the manifolds . I have fitted the over head pipes now and hope it has solved the problem .Boats only seem to cause trouble when you add water .
Ken
Ken
Re: B-PEE
I have added a couple off pictures ,one of the engine angle in the boat and a second with the manifold set up as it would be in the boat .A few extra inches of 1/2” stainless tube may have saved a couple of engine rebuilds.
Last edited by Greg on 07 Jan 2019, 06:18, edited 1 time in total.
Reason: Pictures reoriented
Reason: Pictures reoriented
Re: B-PEE
Your manifold might have a fault from new , when these manifolds are poured , entry points each end of manifold at the same time, hot alloy runs to the centre. If it cools down flowing she might not bond as one at the centre. This creates a fault line and when started expands opposite centre exhaust ports and fills pots with water. Pressurised manifold off the motor with a hose and block off exit.
Doc.
Doc.
Re: B-PEE
B Pee is ready for a water test ,it’s had a few mods since last try .
No 3cylinder sleeved and all bores honed .
8 new pistons and rings from summit tracing .
Rods checked fir straightness and new bearings .
Cam drive water pump and timing case .
Valves reseated and heads milled .
Carby downsized to a 650 spreadbore twin pumper and a Mallory twin point dissy . I had these sitting around a think they look more old school .
The over head pipes didn’t last long ,first try they melted my timing light wire and I burnt my arm trying to salvage it plus hitting my head a couple of times .
I have reversed the manifolds to slope down and modified the pipes ,the battery had to be moved to under the Bach seat . So all should be good until we reach the next boat ramp .
c
No 3cylinder sleeved and all bores honed .
8 new pistons and rings from summit tracing .
Rods checked fir straightness and new bearings .
Cam drive water pump and timing case .
Valves reseated and heads milled .
Carby downsized to a 650 spreadbore twin pumper and a Mallory twin point dissy . I had these sitting around a think they look more old school .
The over head pipes didn’t last long ,first try they melted my timing light wire and I burnt my arm trying to salvage it plus hitting my head a couple of times .
I have reversed the manifolds to slope down and modified the pipes ,the battery had to be moved to under the Bach seat . So all should be good until we reach the next boat ramp .
c
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