best/easiest engine swap

[Bill W]

"
...it obviously ran well enough to blow the bed off.

'Tanner'

 

[m139h2otruck]

There are a couple of guys in the Nashua/Milford area here in NH that have installed 3-53 Detroits in M-37s, using GamaGoat engines and 5 speed OD duece transmissions. I know one of them is a daily driver. Sorry, don't have their names.

 

[doinworkinvans]

...it obviously ran well enough to blow the bed off.

'Tanner'

Got a parts truck for free that has an amazing bed on it so there will be one on there soon!

 

[Tanner]

Got a parts truck for free that has an amazing bed on it so there will be one on there soon!

'Tanner'

 

[Tanner]

There are a couple of guys in the Nashua/Milford area here in NH that have installed 3-53 Detroits in M-37s, using GamaGoat engines and 5 speed OD duece transmissions. I know one of them is a daily driver. Sorry, don't have their names.

3-53. Loud. Heavy.

Did I mention that they are loud & heavy engines?

There are better, more recent diesel options available - question is, how much do you want to spend? Do you want to stay gas powered, or look at an oil-burner motor swap?

'Tanner'

 

[Oldfart]

OK - so here goes. I got this truck from a buddy who has two more and was just an extra project. Im in love with it and want it to be as good as it can so I can enjoy it. Granted, due to work schedule I have only at most 2 days a week to work on it. Its only been run up and down the path some here at the house due to the fact im not enitrely comfortable taking it anywhere else. Brakes seem to be ok. Shifting doesnt seem too bad, kinda rough at times (although it could be me). What most bothers me is the engine. It isnt a stock M37 engine I dont believe. It looks exactly the same but there are reasons to make me think its not. First thing that gave it away for me is that the oil dipstick on M37 engines thread into the block. The oil dipstick on here has no threads in the block you have to mash it in, like it was formed in or something. Same goes for the oil filler neck. Also the throttle linkage had to be shortened some to work right. Coming from the bellhousing on the carb something just wouldnt line up just right so it had to be adjusted a little. Im thinking it could just be a civy power wagon motor?? Ill try to get some pictures up of my truck and engine soon which you guys will be able to see exactly what it looks like. Power doesnt seem to be an issue. It frustrates me the most that it seems like everytime i turn it on ive got another oil leak somewhere. Very frustrating to me, and exactly why I dont trust it to ride just up the road a little ways. Im also not that good at engines which limits me some. Ive learned A TON by working with this thing, just ready to be able to enjoy it. For instance, i think now its leaking oil from where the fuel pump bolts up to the block. Maybe the seal is bad there?? Once i post pictures of the engine maybe you guys can lead me in the right direction. Thanks for all your help and ill do my best to describe whats going on and such. Thanks again!

It does sound like a civilian engine retrofit. How ever, it could be an older (WW2) military engine. If it is a correct engine, it should have T245 xxxxx stamped on a boss at the top of the block just under the head on the passenger side front. The military exhaust and intake manifolds are different as well. There are carb elbow mounting bracket bolt locations on the military manifold.
There are many Mopar engines that will bolt in as replacements. Dodge, Plymouth, DeSoto and Chrysler flat head (L head) 6 cylinders for a considerable range of years (until the slant 6 came out.) I think the last civilian vehicle was the 58 Dodge PU. However, Mopar continued to produce for the military up until 1968 with continued production of the M37/M43. In addition, the flathead 6's were used for all sorts of stationary engine applications as well as in industrial equipment. The Mopar flathead 6 came in two block sizes. The larger block is almost exactly 2 inches longer and the displacements were 251 and 265 ci. I installed a Chrysler Industrial 265 in my M37 that came out of a forklift. It is fully balanced and will turn more than 7000 rpm which tends to shorten ring life.
I was with Jollyroger a while back when he bought a NOS swap kit for a smallblock Chevy to an M37. That was a little after he traded for an M37 with that kit and a sbc installed. The Chevy trans is used which requires some modification of the floor pan over the transmission. I have ridden in an M37 with the Detroit Diesel Gamma Goat engine (I think it had a deuce transmission as well) that really got up and down the highway. All sorts of conversions have been done and I suspect many more are in the wings.

 

[doinworkinvans]

Plans for tomorrow...I think I traced an oil leak coming from where the fuel pump bolts up to the block. Gotta make a new gasket for that and see what happens. Also need to replace the breather line from the oil filler neck to the air cleaner elbow. There's no line there now so that could be building up pressure and causing leaks. Hopefully this will help a little something!

 

[doinworkinvans]

So I took the fuel pump off and I seem to have gassy oil coming out of the fuel pump when I turn it over. Obviously fuel would come out but this is rather oily! Also my oil is rather gassy as well when I checked it. Bad seal somewhere? You guys know tons more than I do so any help is greatly appreciated! Also just incase it makes a difference its the diaphragm type fuel pump not the old school glass bowl one. Thanks again!

Daniel

 

[doinworkinvans]

So I took the fuel pump off and I seem to have gassy oil coming out of the fuel pump when I turn it over. Obviously fuel would come out but this is rather oily! Also my oil is rather gassy as well when I checked it. Bad seal somewhere? You guys know tons more than I do so any help is greatly appreciated! Also just incase it makes a difference its the diaphragm type fuel pump not the old school glass bowl one. Thanks again!

Daniel

 

[Oldfart]

If your fuel pump is the double action type (pumps air for the windshield wiper) you most likely have a split diaphragm. This allows fuel to drip into the crankcase. A single action pump would drip on the ground. A crankcase diluted with gas tends to thin the oil and can take out the bearings if not corrected fairly soon. Gasoline in the crank case can also cause the engine to run rough and in what would appear to be an over rich or choked throttle condition

 

[doinworkinvans]

Thank you sir! Could I have bad seals in the pump? A bad pump?? What would be letting the gas into the crankcase?

 

[Tanner]

The fuel pump diaphragm & seals are a common pump issue; the seals deteriorate with age/use/lack of use/etc...

There was comment on forum in past about the newer seal kits being of so-so quality -

Check the M37 Forum for comments -

'Tanner'

 

[sak778]

Sounds like it's time to rebuild or replace your pump. I personally don't know what options you have.
Also this new reformulated gasoline with 10% ethanol added to it is wreaking havoc on classic vehicle fuel systems who's older rubber isn't compatible with the ethanol in the fuel.