Grand Banks Discussion Forum

[ed taulbee]

I am looking at a 42 Grand Banks with cummins 6BTA 250hp. I am not familiar with these engines. How do they compare to Lehman 135's re fuel consumption/efficiency, longevity (time to rebuild) and cost of maintenance and parts.

Thanks for the responses.

[Mike Negley]

The reports from GB owners with these engines have been very favorable in terms of performance and maintenance. Since they are nearly twice the size of the Lehman there is more iron to heat up and therefore more energy loss, but at low RPM's the fuel would not be significantly greater. If you join www.boatdiesel.com ($25 annually) there is a huge amount of information on these engines.

[ed taulbee]

Mike, thanks for the information. What is the basic difference between the Cummins 210hp and the 250hp? Will this difference affect longevity of engine at 25ohp?

[Mike Negley]

I am no expert on Cummins, but I believe there are four ratings for the 6BTA5-942 depending upon the duty (continuous or intermittent) and cooling configuration (jacket or seawater). The basic engine is shown as a 6-cylinder, 5.9 liter 249 SAE BHP at 2600 RPM, continuous medium duty. It is turbocharged and aftercooled. Your best source would be to contact Cummins at 803 745-1620 with the engine serial numbers. The engine is no longer in production, but parts are still available. Engines in trawlers are so lightly used their longevity is primarily based upon the owner's responsibility to see that proper maintenance is performed and the engine is never allowed to overheat (usually a result of poor maintenance). Turbo-charged engines will incur slightly more more expense since the turbo runs at very high speed and adds some additional stress, but this is minimal in trawlers if run at low RPM's.

[byronjr]

Ed, I have these engines in our 1991 46 Classic with over 5000 hours and they have done very well so far. Besides the obvious and standard maintenance items like changing water pump impellers annually and keeping track of hours on the serpentine belt, the only "weak" point of these motors I have been told to watch, is the idler pulley for the belt but that is after multiple thousands of hours.
With computer balanced propellers, at 9 knots, we recording 3.5 GPH and just under 4 GPH at 10 knots. Parts and maintenance assistance are readily available and with the serial numbers from the engines sent to Cummins, I was able to get a custom parts book for my motors as delivered to GB. It is also much easier to get outboard of the in-line 6 than the V-8 for service. Everyone I have spoke with here in the Northwest has been pleased with these engines.
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Byron
GB46Cl #094
Eagle's Gig

[Sleepah]

Ed, I have a pair of 1973 Ford Lehman 120's in my GB-42. The Cummins is probably a fine engine, but at 250hp it is double my 120hp. And that translates into fuel usage. I manage to burn less than 4 gal per hour and that includes both diesels and quite a bit of generator time. I believe that gentleman who quoted 4 gph was talking about each, meaning 8 GPH. So I do 8 knots and 4 gph and he does 10 knots and 8 gph. And at the current price of fuel, I'm happy at 8 knots.

Howard
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Howard
1973 f/g GB42 CL #362
10th fiberglass 42 built
"SPARTINA"
Padanaram, Mass

[byronjr]

Sorry Gentlemen, I should been more concise. The boat averaged 3.97 GPH total, for both main engines and generator, during a trip from Bellingham to Alaska and back over 8 weeks. The average speed was approximately 9 knots. Shows the importance of a clean bottom, properly balanced propellers, and well maintained engines.
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Byron
GB46Cl #094
Eagle's Gig

[Sleepah]

Byron,

Sorry about that. I stand corrected.

Howard
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Howard
1973 f/g GB42 CL #362
10th fiberglass 42 built
"SPARTINA"
Padanaram, Mass