How To Drive Your Jeep All The Way Underwater (And Back Out Again)

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A Cummins-diesel powered Jeep Wrangler is pretty cool. But a diesel Jeep that also works as a submarine? It’s a redneck James Bond dream come true!

This wacky project is the latest brainchild of 4x4 expert and Dirt Every Day host Fred Williams, backed by Cummins and a few other aftermarket outfits.

The donor truck/build base is a 1997 Jeep Wrangler, the first year of the “TJ” bodystyle, and nicknamed “tubesock” because reasons.

After having gone on adventures in various configurations, the Dirt Every Day team decided to hack out Jeep’s the 2.5 liter four-cylinder engine and create an entirely custom mounting cradle for a Cummins ISF 2.8. A 540 pound diesel mill rated to 160 horsepower and 266 lb-ft of torque.


In the video Cummins rep “Steve” explains that the engine is “about 300 pounds” lighter than the 4BT, a commonly discussed and sought-after diesel swap for smallish off-road trucks like the Wrangler, Bronco, FJ, Blazer and Scout.

The downside of the ISF is that it’s electronically controlled, meaning there are a lot of little wires that need to be sealed before the engine can expect to operate underwater.


Once the Cummins goes in, a New Venture 3550 transmission is mated up, some big tires are put on the wheels and a hilariously tall snorkel is fitted to the intake for the Jeep to make its maiden voyage across the bottom of a murky pond.

A diesel engine is generally more waterproof than a gasoline one because gas motors tend to have more little breathers or places of potential water ingress. There’s also the fact that it’s not too uncommon to find a fully mechanical diesel, with no electronics at all, whereas a gas engine still needs electricity somewhere to make the spark plugs work.


Of course there’s more than just the engine to worry about– axles and transmissions have breathers too, and you’ll want to make sure your truck has a whole lot of little snorkels ready if you really want to turn it into a boat. Or you could just kick back and see how Fred fares.