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Dodge 440 to 5.9 Cummins Diesel conversion

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I made the decision to start the diesel swap in the Chieftain. Follow along and wish me luck.  D:oH! I will try to document all of the steps and problems encountered along the way in case anyone else has similar plans.
A little background. The Chieftain is a later build date 1973 Dodge RM400 chassis with the original 440/727 combination. The transmission is leaking out the front seal badly and the fluid looks and smells burnt. Also, the exhaust manifold gaskets are blown on the 440 and oil is leaking from about every gasket. Due to the plans for this RV and my access to the parts I decided the swap made sense.
The Cummins is a 5.9 6BT out of a 1989 Dodge Ram W350. Factory rating is 160hp at 2500rpm and 400 ft/lbs of torque at 1600rpm. It is a non intercooled version that I will be adding an intercooler to because of the rather heavy duty use it will be seeing. For the transmission, I will be using a diesel specific A518 out of a 1992 Dodge 4wd with a Cummins. In addition, a Gear Vendors overdrive will be mounted directly to the rear flange on the 4wd transmission with an adapter from Gear Vendors that replaces the transfer case.
Cummins diesels operate in a much lower rpm band than typical RV gas engines and, as a result, really need more gears to be effective. Use of an overdrive transmission is almost required if there is any hope of achieving typical highway speeds. The A518 I will be using has the same gearing as the original 727 it will be replacing from 1st through 3rd gears. The overdrive ratio is 0.69 and will achieve speeds between 60-65mph with the diesel. The Gear Vendor has a 0.78 overdrive and will be useful for splitting gears when hill climbing where the factory overdrive is too tall and 3rd gear is rpm limited to around 45mph. Double overdrive with both the factory and Gear Vendor engaged may be useful for interstate travel but will need to be determined once the RV is running and driving. I will run the factory overdrive off a simple toggle switch and engage and disengage it manually at the appropriate time. There are pressure switch options for automatic control of this but I have decided not to go that route. The Gear Vendor has the option of automatic or manual push button control.
Pulling the engine from the donor truck.




This is the front timing gear cover. There are a couple issues with the 12 valve Cummins diesels that should be checked. Especially when the engine is out of the vehicle as the repair is rather simple. One of these issues is a dowel pin under the cover that can vibrate loose and end up in the timing gears and cause serious damage to the engine. The term for this is KDP(killer dowel pin) and can be researched in depth on the web. The other issue is loose timing cover bolts that can do the same thing.

This picture shows the dowel pin.

The common fix is to either buy or make a metal tab to hold the dowel pin in place. I choose to make one as it is rather simple. I also Loctited all the timing cover bolts and tightened them back up.

The original exhaust manifold needs to be swapped out for one that drops the turbo down and toward the back in order to clear the floor on the Winnebago. This particular manifold and turbo came out of a 2005 Dodge Cummins turbo diesel. This may or may not be needed depending on the RV in question.

As with the 440 a front sump pan is required to clear the front axle on the Dodge chassis. Fortunately, the Cummins oil pan is reversible from front to rear. A front sump oil pickup tube is needed and is Cummins part #3920795.

Here is the oil pan installed with the sump to the front and the oil dipstick moved to the front location on the block.

This is the intercooler I found for the project. It is very well built and exactly what I have been looking for to fit in the narrow and tall front engine compartment of the Winnebago. It is a Denso unit that came out of a 1999 Mack Midliner with a 190hp Renault diesel. Core dimensions are 30.5" tall, 19" wide, 2.5" thick, and 3" inlet and outlets. This should do a good job keeping exhaust gas temperatures down.




Time to remove the 440 and 727 and prepare for the swap. Pic 1
Bumper is off, grille, and grille divider are out. Pic 2
Overflow tank, windshield washer resevoir, cross brace, radiator, and front crossmember are out. The radiator was a royal pain to remove. Pic 3
Upper shroud and fan are out. The exhaust is unhooked and the motor mounts are loose. A few more things to do but there's not much left before pulling the 440 out. Pic 4

This is totally awesome and something folks have been looking for for a long time.  Thanks so much for sharing this with us in such detail!
This is going to the top of the project board as a "sticky" and a referring topic is posted on the Dodge board.
 :)   :)ThmbUp

That's pretty neat!  Can't wait to see more of the project, and the end results!


Wow! Sweet. We've been talking about a project like this for years on Classic Winnebago's. Thanks for taking the extra time to photograph all the steps. I think your going to have many members riveted to there computers every day from now until the project is done. Have at her, good luck and we'll be fallowing you as you go. :)clap
Oh! What are you going to do with the 440? She may have a few flaws I'm sure she's got some good parts on here. Hm?


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