QSB 5.9 425 HO

[Richard Geczi]

A good friend of mine is looking at a 2008 36 Tiara with QSB 5.9 425 HO Cummins. Are those engines reliable, and what should he be looking at with 850 hours. Does anyone out there have these engines and what do you have to say about them? Good or bad. Thx RjGeczi [email protected] 757-472-9944

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[aubreewebb75]

When buying a boat with a used engine, it is important to consider several factors:Maintenance history: Find out how regularly and well the engine has been maintained. Maintenance records and regular inspections may indicate that the engine has been properly maintained and cared for.Use and operating conditions: Find out how and where the vessel with this engine has been used. If the boat has been operated in harsh conditions or spent long periods of time in salt water, the condition of the engine may be affected.Condition Check: It is recommended that you have your engine inspected by a mechanic or specialist to assess its current condition. They can point out any problems, signs of wear, or potential problems that may require attention or repair.

[Rob Schepis]

Very good engines the day they left the factory.  No inherent vices with them.  That much we know and that is all we know at this point in time.  The 850 hours tells that they actually got put to use about 60 hours a years since then.  What about the other 8,700 hours per year for 15 years?  That’s the clock that could be  doing (and usually does) the real damage.

Lots of variables as to today’s condition of the engines.  The engine room environment, dry or wet?  The salinity of the water that the boat was slipped in?  Freshwater flush?  The maintenance history of all of the seawater circuit components, mainly the aftercoolers? Those are the concerns that focus on marine age of the components and cosmetics of the engine exterior and any corrosion issues with the vast amount of electrical components.  We know based on this boat that the engines are under the helm, not under a leaky rear deck.  What we don’t know is the possibility of a broken engine room vent/hose letting in salt water or salty air, a weeping seawater hose, a neglected PSS shaft seal that’s spraying a radius of salty mist, etc etc…

Tiara did a decent job on the exhaust setup on the boats in the mid 30 foot range so I am thinking that your riser/exhaust is setup safe.  Those engine rooms are usually a little tight with lots of gizmos and the genset stuffed in the middle but not the worst engine room to work and the QSB pump will be easier to access than the 6BTA pump of the earlier models.  The oil pan is also 1″ deeper than the mechanical B so less prone to overfill and whipping.

The other thing that needs investigating is how the engine is loaded (propped) and the nut behind the wheel (the operator).  You will need sea trial data and compare the fuel burn (GPH) that the displays are telling you vs. the GPH on the spec sheets provided by Cummins (available on our website for free).  If she is using more fuel at a specific RPM than the spec calls for there is too much prop under the boat.  Forget about hump speed where the boat is trying to get on plane, you need to focus on the cruising rpm’s.  And the boat must be fully loaded with fuel, water, persons and gear when obtaining this data.

Proper fuel filters and filtration is also very important. 

Have any pics of the engines and engine room?

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Tony Athens

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