Ally410
31-01-2008, 01:13 PM
Hi all, first post so please be gentle ;)
As the title suggests, I have both a 2002 model Yamaha 30CV (on a custom centre console Allycraft 410 Rhino) and a 1998 model Yamaha 8hp (on either a 285 Zodiac or old Quintrex 11 footer). I've had the 30CV since new and the 8hp is recently aquired.
When I run the 30, I notice the telltale is not particularly strong, it increases a bit with the revs but overall is not a strong flow. It's been the same since new for what it's worth, and the engine has never been run in sandy/shallow conditions (all paint still intact on skeg and prop as evidence). The flow seems adequate (motor has never overheated etc.) and remains cool to the touch but is just weak. It has been thoroughly flushed with muffs after each and every outing.
The 8hp on the other hand has the strongest telltale flow I think I've seen, hurts the hand if you hold it there for a while kind of strong. This motor has not been particularly well looked after (lots of shallow water running) and as such, I needed to pull the water covers off the head and scrape out all the solidified salt and sand from the galleries. One head cover needed to be replaced due to corrosion, as well as all 3 gastkets, thermostat and collar (not to mention the bolt I snapped in the head that I had to drill out >:( ). The actual head had no corrosion and once put back together runs well.
Additionally the impellor on the 30 was just replaced as part of major service by Yamaha dealer but the 8 was changed who knows how long ago (on the to do list).
Can anyone tell me why the new (well less than 100 hrs) well looked after 30CV has a much weaker telltale flow than the neglected 8? The only thing I can think of is a difference in design. From what I understand the 30CV is an old Mariner 25/30 design that Yamaha have just kept manufacturing albeit with a few improvements here and there.
Thanks for any suggestions in advance.
Gav
As the title suggests, I have both a 2002 model Yamaha 30CV (on a custom centre console Allycraft 410 Rhino) and a 1998 model Yamaha 8hp (on either a 285 Zodiac or old Quintrex 11 footer). I've had the 30CV since new and the 8hp is recently aquired.
When I run the 30, I notice the telltale is not particularly strong, it increases a bit with the revs but overall is not a strong flow. It's been the same since new for what it's worth, and the engine has never been run in sandy/shallow conditions (all paint still intact on skeg and prop as evidence). The flow seems adequate (motor has never overheated etc.) and remains cool to the touch but is just weak. It has been thoroughly flushed with muffs after each and every outing.
The 8hp on the other hand has the strongest telltale flow I think I've seen, hurts the hand if you hold it there for a while kind of strong. This motor has not been particularly well looked after (lots of shallow water running) and as such, I needed to pull the water covers off the head and scrape out all the solidified salt and sand from the galleries. One head cover needed to be replaced due to corrosion, as well as all 3 gastkets, thermostat and collar (not to mention the bolt I snapped in the head that I had to drill out >:( ). The actual head had no corrosion and once put back together runs well.
Additionally the impellor on the 30 was just replaced as part of major service by Yamaha dealer but the 8 was changed who knows how long ago (on the to do list).
Can anyone tell me why the new (well less than 100 hrs) well looked after 30CV has a much weaker telltale flow than the neglected 8? The only thing I can think of is a difference in design. From what I understand the 30CV is an old Mariner 25/30 design that Yamaha have just kept manufacturing albeit with a few improvements here and there.
Thanks for any suggestions in advance.
Gav