Bt Doctur
Supreme Mariner
- Joined
- Aug 29, 2004
- Messages
- 19,111
A long story so I`ll try to shorten it up a bit
Twin Formula was BB now SB 6.2 motors. heavily rusted manifolds and exaust ports in heads, well worn motor puller for rebuild. new manifolds, extention, risers, heads reconned. ran for 2016 no issues. stuck valves at spring 2017 startup. heavily rusted heads, exaust ports, and manifolds. At start of 2016 manifolds and risers replaced on port motor as a precaution. Old manifolds and risers heavily rusted.Do you see a pattern developing?
Fall of 2016 port motor pulled for rebuild, manifolds rusted, head ports rusted, etc.2017 Spring, new motor installed test run 2X ,
Stbd motor attempt to start, hung valves. heads removed, heavily rusted , manifolds heavily rusted. remove and examine heads , replace with new heads ,assemble , test and put boat in service. 2 hours later port motor takes a dump, No power, backfires, etc.
Eventually pulled heads and valves were rusted and stuck. repaired heads . While port was disassembled I pulled a stbd riser and looked inside, it looked like rock salt in there with less than 2 hours run time. suspected exaust reversion.Searching the web we found other Formula boats with the same problem and a dealer who replace the twin engines 3 x because they could not find an answer.. I cannot raise the risers up with extentions and cannot lower the exaust outlets or the swim platform.So the logical answer is to extend the riser outlets.
This is what we came up with for testing. 2 inch O.D. thinwall SS tubes .It`s a drive in type fit, very snug. Based on a fancy product to reduce or eliminate exaust reversion in these motors with thru hull exaust systems.Will post the final pics after the testing period to see if the manifolds and risers are carbon covered or rusted. Stay tuned .
Twin Formula was BB now SB 6.2 motors. heavily rusted manifolds and exaust ports in heads, well worn motor puller for rebuild. new manifolds, extention, risers, heads reconned. ran for 2016 no issues. stuck valves at spring 2017 startup. heavily rusted heads, exaust ports, and manifolds. At start of 2016 manifolds and risers replaced on port motor as a precaution. Old manifolds and risers heavily rusted.Do you see a pattern developing?
Fall of 2016 port motor pulled for rebuild, manifolds rusted, head ports rusted, etc.2017 Spring, new motor installed test run 2X ,
Stbd motor attempt to start, hung valves. heads removed, heavily rusted , manifolds heavily rusted. remove and examine heads , replace with new heads ,assemble , test and put boat in service. 2 hours later port motor takes a dump, No power, backfires, etc.
Eventually pulled heads and valves were rusted and stuck. repaired heads . While port was disassembled I pulled a stbd riser and looked inside, it looked like rock salt in there with less than 2 hours run time. suspected exaust reversion.Searching the web we found other Formula boats with the same problem and a dealer who replace the twin engines 3 x because they could not find an answer.. I cannot raise the risers up with extentions and cannot lower the exaust outlets or the swim platform.So the logical answer is to extend the riser outlets.
This is what we came up with for testing. 2 inch O.D. thinwall SS tubes .It`s a drive in type fit, very snug. Based on a fancy product to reduce or eliminate exaust reversion in these motors with thru hull exaust systems.Will post the final pics after the testing period to see if the manifolds and risers are carbon covered or rusted. Stay tuned .
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