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1988 3807 aft cabin conversion (gas to diesel)

Posted: November 17th, 2024, 1:52 pm
by Tloving1
First I would like to say I'm excited to have this boat and look forward to all your comments and input.

I know that it has been beat to death about the switch and the estimated cost if I have it don't by someone but I do not plan on having it done by anyone I'm doing all work my self.

So wouldnliek to know what equipment as far as transmission, any other big ticket items I would need to buy.

I have already two LBZ engines ready to use. Props I'm ready to buy the shafts I will be having machined for me just need to know sizes and info. So basically I just need details and or prints I could follow.

Its being transported out of slip soon and I will be hopefully starting working on her over the winter.

All three engines were submerged they were not started and I know I could trying to get water out and just flush them but I would like to convert to diesel as I would like to keep as a long term boat at least 10 plus years

Any help would be greatly appreciated.

Re: 1988 3807 aft cabin conversion (gas to diesel)

Posted: November 17th, 2024, 5:02 pm
by waybomb
Whatever you do, would be great to start a thread and post pictures.
Do your tanks have a bung that's plugged? You'll need an extra bung for each fuel return.
Your transmissions, shafts, and props need to be sized for whatever torque your engines deliver.
You'll probably need to enlarge the engine room ventilation.
Fire system needs to be changed.
Are the engines turbo charged? If so, i would include a mechanical air blocking system in the case of runaway engines.

Re: 1988 3807 aft cabin conversion (gas to diesel)

Posted: November 17th, 2024, 6:42 pm
by Viper
Welcome aboard.

It's an ambitious project for sure. Consider that the engine specs might require different sized shafts as mentioned which could result in having to replace the stern tubes and logs, and the struts. I believe your current shafts 1-3/4" dia. if the same as mine.

You'll also have to check exhaust specs and minimum requirements for exhaust hardware sizing. If your boat is like mine, the exhaust goes into a manifold that's part of the hull running the length of the boat to the aft on both sides. If you have the small exhaust discharge holes at the water line, you'll have to confirm that they can handle the volume of exhaust from the new engines or modify to accommodate.

While the engines are out, I would consider replacing the fuel tanks as they the occasional one has been known to rot through. At the very least, you should have them carefully inspected.

Re: 1988 3807 aft cabin conversion (gas to diesel)

Posted: November 18th, 2024, 8:11 am
by bud37
Welcome to the forum.....check this out they have some good info as well as my advice, join boat diesel.


https://www.sbmar.com/articles/choosing ... SblNil3r_4

Re: 1988 3807 aft cabin conversion (gas to diesel)

Posted: December 19th, 2024, 8:35 pm
by MyPleasure
Welcome to the forum. I know a couple in out yacht club replaced old 3208 Cats with new 5.9 Cummins engines in their boat, and it cost over $100,000. That was going diesel to diesel, and I would imaging that going from gas to diesel engines would be a very expensive project!
Interesting idea, keep us posted.