Foulweather Jack wrote:Q1: what are valid statistics for the useful working hours of a VERADO engine?
I do not believe there are are any valid data available about the useful working hours expected for any particular engine, other than anecdotal reports from individual engine owners.
A VERADO engine built in 2006 would be a first generation model. Soon afterwards Mercury made a number of improvements and made the second generation VERADO engine.
In c.2006 a rating of 250-HP on a VERADO was typical. The maximum power then was perhaps only 275 or 300. Subsequently the VERADO in-line six-cylinder engines were further enhanced to be rated for as much as 450-HP. On that basis one would infer that operating the engine at a restricted power of only 250-HP would engender long service life.
On the other hand, an engine made in 2006 is now 16-years-old and may need some repairs.
The description of “unreliable” does give a need for concern. Any time a single-engine-boat’s engine is deemed unreliable there will be anxiety about the engine.
To cure the anxiety and unreliable operation by buying a new engine is certainly an option, although perhaps an expensive cure.
Foulweather Jack wrote: Q2: should I stick with Mercury for a re-power engine?
If all or most of the engine rigging can be reused by buying another Mercury engine, there could be a cost savings. Investigate carefully what rigging components of the current VERADO engine could be reused, such as
- the proprietary DTS electronic remote shift and throttle controls,
- the proprietary electro-hydraulic power steering helm, pumps, lines, and actuator,
- the proprietary Smartcraft engine instrumentation, and
- the propeller and hub kit in use now.
There could be significant cost saving in a re-power by reusing all the 2006 rigging, but then you may be bringing very old rigging to the new engine. The gremlins that made the old engine unreliable may have been due to the old rigging, negating the value of a new engine.
Foulweather Jack wrote: Q3: would changing to a different engine brand, for example to a Yamaha engine, give an advantage?
The notion of an “advantage” has many realms. If you meant “more reliable” we again do not have any data available. The biggest advantage that might occur with another brand might just be working with a different dealer whom you find to be more helpful or more cooperative or more available for service or more eager to have you as a new customer.
Foulweather Jack wrote:Q4: what will be the cost of re-powering a 2007 235 CONQUEST?
At today’s prices, a new 250-HP engine might cost $25,000. All new steering, remote controls, instrumentation might cost $5,000. Removing the old engine, all the old rigging, installing the new engine and all its new rigging could cost several thousand in labor charges. On water testing and propeller optimization will add more costs, and at the least perhaps $700 to $800 for a new propeller and new hub kit.
The cost of a new engine will be offset by the proceeds of selling the old engine, or from a trade-in value. The current value of a 2006 VERADO 250-HP engine with a history of being unreliable is unknown to me. The value could also depend on your location and the presence of a Mercury dealer who sells and supports the in-line six-cylinder supercharged VERADO engines and other VERADO owners in your area looking for a used VERADO engine.