Rebuild Detroit 453N's or repower?

A 4-53 rebuild can be accomplished for very little money compared to the cost of a re-power with new diesels. Their lesser efficiency will never outpace in fuel cost the investment in new motors. Rebuild what you have properly and you will likely never wear them out.

Just a guess, is this in a Hatt 48 LRC?

Hi,

I will second the above post and recommend rebuilding the Detroits.

They are a great old lump and will give good service if looked after reasonably well, it will be a lot more economical to rebuild them than to re power with anything "modern"

The others may be right. But I'd at least look at the cost of a pair of American Marine Ford diesels.

http://www.amerdsl.com/

By the way, where is it your looking to find a mechanic to rebuild those Detroits?

+3 with SeaEric and K1W1.
The rule of thumb is replacing engines will cost roughly twice the cost of those engines...it ain't 'Plug 'n play'; there are ancillary items plus Mr. Murphy to contend with.

I don't think more hp would push the displacement hull any faster. I was on a 42' Grand Banks that was powered by the new American Lemans, they were well old technology married to an ECU. I don't think you could get more fuel efficient than the 2 stroke DD's you have and I too would recommend rebuilding them and going another 10000 hours with them.

Wasn't implying you would get any more speed or efficiency out of the Fords at least. Although you might.

I was recommending them because they are bullet proof, easy to work on and very long lasting. So they are worth a look if you are thinking of re-powering that type of boat.

I agree that they are bulletproof, but you're not gaining enough by going to them. The Grand Banks had a terrible harmonics through the vessel at idle speed which cleared up with a little throttle, the technology on the engines is the same old same old when it comes to gaskets and oil leaks, and they didn't run as good as something else I would repower with such as a yanmar , John Deere's or similar IMO. This was a professional installation, and I think the engines were $60k for both with the necessary controls and electronic displays

Really, he cannot go wrong rebuilding what he has, and IMO repowering wouldn't gain anything useful for the money spent.

That seems like stupid money for a Ford repower. A lot of it must have been in the electronics. Which you don't need for those engines. And Lehman's are not known for having much of an oil leak problem. Certainly nothing like Detroits. The beauty of the Lehman's is the fact that they are old tech. Simple to work on and no chance of getting stranded because of a electronic hiccup.

That rumble at dead idle is a classic GB/Lehman thing. There are a couple of ways to stop it. The easiest and cheapest is, as you noted, to bump the throttle up just a bit and it goes right away.

Absolutely do the re-build. Those naturally aspirated engines will outlive most writers on this forum. I put a pair into a workboat in the mid 70's - 110 hp and they are going strong.

150 hr checks and put in another gallon of oil! Oil changes every other week on continuous operated boats. The last rebuild on that pair was at 28,000 hrs and they are still stroking along on a push boat. You carry four sets of everything mechanical on push boats. If something breaks, you can replace it on the spot, because stopping at marine stores along the route isn't an option.

Boy howdy. So much so that loose items, keys, sunglasses will all end up on the deck if you don't bump em up a couple hundred...

i vote rebuild......

in this application it makes sense.......

4-53's

I ran a pair in a 31 Bertram for years. Slow but very economic. The main thing is to keep fresh belts on them. Same for all 53;s . Same weakness in the V8's in my 41 Hatteras. Also some of the clutches ran at very high pressures, so pay attention to the oil hoses.