Cummins 5.9 L swap

[j2sax]

90 12 Vlv 6BT

Since the 90 is an all mechanical setup, are there any wiring gremlins to worry about? I wouldn't think so, but I wanted to make sure. It seems that all required would be for the starter solenoid, maybe some changes in the Alternator wiring (90 was pre-ecu, if I am not mistaken) and... well, I can't think of anything else.

Sort of like swapping in an old points engine, I guess!

I find out tomorrow if I get the 90, so we will see! It has a 2WD non-O/D trans... I might even run that awhile until I can find an NV4500 setup.... or maybe a good O/D Auto trans... what should I watch for? I want to stay away from the Electronic setups.

Thanks and have a great weekend,

Jesse

Jesse

[jeepmj_tj]

What radiator in yours Jeep MJ/TJ?

OP cherokee appears to have stock FSJ radiator....

i'm using the stock V8 jeep radiator. I ran it for two years with out any fan what so ever. I am now running a 16" electric fan and it only comes on while towing in the summer heat when heavily loaded or if it sits and idles after running for more than 30 mins

Since I went with the nv4500 I bypassed all the computer stuff on my motor. Had to have the alternator converted over to be internally regulated. Basically two wires to get the engine to run, trigger wire for starter relay and the fuel shut off solenoid. Obviously this is more involved but you get the idea.

[angus1]

I'm glad someone dug this up, I am doing the same swap. This Monday I am picking up the FSJ for transplant. this jeep will sit on a 60/70 combo behind a g-360 manual trans,on 37's. The only thing with wiring you might have to worry about is the alt. in the first gen dodge trucks are externally regulated. You can use this regulator ( Napa Part # ECH-vr440) Its an old style ford regulator.

[walker1271]

wow im exited

i m on my way out and havent had a chance to read all the comment.i finalllly have a source of info.i have 87 grand wagonner and swaping in 92 12 valve cummins from my rolled 2500 pu.

any help woul be great !!!!!1


is there a kit to do the swap?
does the cummins match up with the wagoneers tranny?

[The PIG Smith]

Welcome from Fort Wayne, Indiana

[Diesel YJ]

Well lets keep it going. I picked up a 89 6BT earlier this week and I will be putting it in my 83 Wagoneer Limited later. I want to use it as a tow rig and expeditionary vehicle in the future. For now its a tow rig and the 360 will have to do. I would like to sand blast the frame and paint everything like I did with my last project before I build it. I am thinking 1 ton axles to handle the stress. I have a set of 4'' skyjacker full spring lift for the Waggy before I found the motor. Will they handle the weight? I have 4.5'' Extreme duty 6 pack springs on my YJ with a turbo 6.2 and they are holding up just fine.

[Tigger4X]

I like the way this thread started, but its been rather sparce in info from the OP. Did he disappear somewhere?? I have some questions about real world operation and not many answers. I've commited myself to building a Cummins J-truck and thought I wanted to run the 5.9L, but at only 20-22 MPGs I'm beginning to re-think the 3.9L and the purported 30s MPGs.

[Phillips889]

Pm him he gave me a lot of helpful info and pics for my swap

[Tigger4X]

THANKS!!

[Mikel]

I like the way this thread started, but its been rather sparce in info from the OP. Did he disappear somewhere?? I have some questions about real world operation and not many answers. I've commited myself to building a Cummins J-truck and thought I wanted to run the 5.9L, but at only 20-22 MPGs I'm beginning to re-think the 3.9L and the purported 30s MPGs.

Most people with full size trucks and 4BTs get low to mid 20's. 30MPG claims are either VERY rare or the fruit of bad math skills.

[Bill Moore]

nice swap, I am using my M715 4bt for my tow vehicle and it does not have the reserve power that I need. I am consdering dropping in a 6bt as it will primarily be for towing. The fit looks extremely tight, but has been done before as several have noted. Dont want to do it, but consider it a must for crosscountry towing, especially in mountainous areas where the reserve power is critical. I have not intercooled the truck and probably will not due to space limitations.

[Bill Moore]

Most people with full size trucks and 4BTs get low to mid 20's. 30MPG claims are either VERY rare or the fruit of bad math skills.

btw, if you drive it conservatively without load, Im see any where from 22 to 30 mpg. But I rarely get above 60 mph.

[Mikel]

btw, if you drive it conservatively without load, Im see any where from 22 to 30 mpg. But I rarely get above 60 mph.

I think rarely going over 60MPH falls well outside the driving of the average person. My best tank was 25.2MPG driving through country roads in upstate NY with a complete 6BT in the bed. I can see getting 30 if I drive VERY conservatively (50-55 highway), but I rarely cruise under 70-75. Yes, I have a lead foot.

[Mikel]

nice swap, I am using my M715 4bt for my tow vehicle and it does not have the reserve power that I need. I am consdering dropping in a 6bt as it will primarily be for towing. The fit looks extremely tight, but has been done before as several have noted. Dont want to do it, but consider it a must for crosscountry towing, especially in mountainous areas where the reserve power is critical. I have not intercooled the truck and probably will not due to space limitations.

Bill,
What have you done to your 4BT? What are the specs? I would consider spending some time and a few $$ on that engine before pulling it. I believe a 4BT makes for a very balanced engine in a M715, in terms of weight, power, economy and durability. A 6BT kinda pushes the envelope a bit, but it all depends on what you want the vehicle to do.
Mikel

[Bill Moore]

I think rarely going over 60MPH falls well outside the driving of the average person. My best tank was 25.2MPG driving through country roads in upstate NY with a complete 6BT in the bed. I can see getting 30 if I drive VERY conservatively (50-55 highway), but I rarely cruise under 70-75. Yes, I have a lead foot.

if mine had a jtruck cab, I probably would drive closer to 70, but the M715 Aerodynamics being quite a bit worse than the jtruck (hard to believe isnt it), you really dont want to drive it over 60.