Twin 6.2L Diesel Powered - Chris Craft Commander
By Steve Burt
Lucky Max is a Chris Craft Commander (Sports Cruiser model) built in Michigan in 1972. She is 31' long and approx 10' wide. The hull is fiberglass, constructed before the folks really knew the true strength of fiberglass. This means that the material is thicker that what you might find on a boat built today, but also, I believe it was all "hand-laid" at that time. I have not yet been able to confirm weights, but I've been told that the boat would probably scale around 7 tons.
When the boat was new it would have had gas engines, possibly 454 Chevy engines, which would have provided the power necessary to get the boat up on plane and produce speeds approaching 20 knots or more. In the early 1990, the boat was purchased by a new owner who decided to re-power it using diesel engines.
The previous owner owned a limestone quarry, and all of his light trucks had 6.2 diesels since the early 80's. He swore by the engine so therefore (for dependability) he bought two for "Lucky Max" and did the marine conversion himself. All of the brackets for the auxiliary equipment and forward motor mounts appear as though they were fabricated in his shop.
The Borg Warner marine gear boxes are geared 3:1, and incorporate the aft engine mounts. The engines are naturally aspirated and all electrical/electronic related equipment was removed, including the glow control components. The glow system now employs a pair of automotive type solenoids and cockpit mounted switches, one for each engine, which are individually activated.
The previous owner ran the boat very slow, and reported that at 1600-RPM, the boat would do about 6 knots and consume about 1.25 gals/hr/engine. At 2000-RPM she'll be doing 10 knots and consume 2.5-gph per engine. At this point in time I can only confirm one of the numbers, which is at 1600-RPM the boat is moving at 6 knots.
I realized early in the game, that my port engine was overheating and that my starboard engine was near "end of life". The starboard engine ran very smooth, and sounded more like a 350 gas engine, and it had been a used engine when it was installed. The Port engine was essentially brand new in the early 90's. At 1600 RPM, I ran the boat fairly steady between May 26, 2008 and October 15, 2008, and it burned less than 100 gallons of fuel. In October of 2008, I took both engines out and stored them. I was in the process of building a new home and garage, and only started working on the engines in late winter of 2008/2009.
The reason for the overheating was apparent once the manifolds had been removed. Both sets were in bad shape in terms of being plugged, and the risers were badly deteriorated. Luckily, the engines are glycol-cooled utilizing (2) 49 tube brass & SS heat exchangers.
So started the refit and a name change to "Lucky Max". I'll be sure to post pictures and progress updates. I won't be going in the water this year but will be ready for 2010 although I'm sure my project "list" won't be complete.
Where do I stand now? I replaced the starboard engine with a recently rebuilt unit that was originally intended for a pickup truck. However, the owner's truck would not pass the provincial safety inspection, so the engine became available. The engine had a low time of just 5000 kms, and the gentleman was able to show me the receipt for the rebuild, which cost him more than $7200 - including a new block assembly.
I've stripped this engine down, and have cleaned and painted the block. I've also rebuilt the starters and alternators because once the engines are back in the boat, I see no way to get the starters off. I'm bead-blasting everything that can be blasted, and wire-brushing everything else. I'm using a bio-degradable degreaser to remove oil and fuel, and then use brake cleaner to remove the degreaser. Before priming, I'm using a "Rust Converter" (made by RUST CHECK) which sprays on rusty surfaces and encapsulates the rust making a paintable surface. So far it seems to be working well.
I have to replace the valve covers because they have rusted through and one of my oil pans has a hole in it. (I am having trouble finding this tin-ware after market, and to date have only located one relatively good set of valve covers). The overall poor condition of the engines' appearance could be contributed to the boat not being covered during our Canadian winters and water from snow and ice melting on the afterdeck, found its way into the engine room and directly onto the engines.
The marine manifolds and exhaust risers were previously provided by OSCO Motors. It took me several days and some help from the folks on the Chris Craft Commander Website, to find the replacement parts. There has been a lot of frustration trying to source these "conversion parts" out of the United States and I have been tempted to jump in the truck and drive to New Jersey myself. However I have a friend who is the Office Manager of a new marina getting underway in my area and I know he has been working really hard to find the right parts at the best price. I finally placed the order with OSCO, and after paying nearly $4000, I should have the exhaust systems completed soon.
It is interesting to note that I asked members of the Chris Craft Commander Club if they knew of anyone else who used these 6.2/6.5 diesels to power their boat. No one has spoken up yet, but one of the senior members commented that he had heard that someone was considering a marine conversion using the Duramax, but no additional details were available.
So for now, I'm cleaning and painting engine parts, but I'm really focusing more on the work that I need to do in the boat while the weather is warm. I still need to rewire it, replace glycol tanks, clean and repaint the engine room, and the list goes on.
I am compiling a number of questions for The Diesel Page and will be relying heavily on everyone's support as I head into the homestretch in late 2009 or early 2010. The Diesel Page
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