Mandarb

[KSSIII]

No. There is no fuel inside the intake manifold, this is an IDI diesel engine. Fuel is injected into small combustion chambers built into the heads.

I do alot of work with older carburated cars, But looking into this things is like a whole new world now haha. Hydrallic Brake booster, dual altenator, dual battery,. Never really worked with fuel injection either. Man I got a lot of homework to do...

 

[campfire]

I do alot of work with older carburated cars, But looking into this things is like a whole new world now haha. Hydrallic Brake booster, dual altenator, dual battery,. Never really worked with fuel injection either. Man I got a lot of homework to do...

Those are pretty straight forward. The hydrobooster is just a hydraulic piston assisting the brake pedal (much like power steering). The dual-voltage electrical system is more confusing than a civilian truck, but is actually less complicated overall (IMO). The CUCVs are missing a whole bunch of normal electrical circuits. Things like dome light and the radio circuit, not to mention optional circuits like power locks or windows. I'm in the middle of my 4th column/pedal swap right now, it's a bunch less fun in a trimmed out truck vs. the sparse wiring that these trucks have.

The cornfusing part is that the starter motor and the glow plug feed operate on the 24V circuit instead of the standard 12V circuit that runs everything else. Including, oddly enough, both the starter solenoid and the glow plug relay. The rationale is that this truck can be jump-started from a 24V military vehicle, but everything not required for starting is running a normal 12V wiring harness like a civilian truck. It's not a huge amount of work to convert to 12V if you decide you don't like the dual system, but otherwise the faster cranking that the 24V starter provides is quite welcome.

 

[campfire]

As for fuel injection, the diesel cycle is not like the gasoline cycle, nor is its fuel injection very similar. It's a compression ignition cycle instead of a spark ignition cycle. The incoming air (no fuel) is compressed until it's hot enough to ignite the fuel directly. On these engines the fuel is mechanically injected into each cylinder near the peak of the compression stroke. So you have a spider-array of tubes leading from the injection pump to each cylinder's injector, and the fuel pulses are timed like how you would time a distributor (and it does even have a similar appearance). The "throttle" input doesn't throttle the air, it just adjusts how much fuel is injected during each cycle. Your "ignition" wire (the pink one at the front of the engine) is operating a fuel shutoff solenoid, the only way to stop a self-igniting process. The fuel will only ignite when it is hot, so for cold starting each cylinder has a glow plug heater to pre-warm the combustion chamber.

That's the basic run-down. It's not complicated, but it is quite different from playing with a Quadrajet or a Holley. Any issues that you have are likely to be different, too (but they mostly have to do with either getting fuel into the engine or getting it warm enough to ignite). Being an all-mechanical engine (aside from the fuel shutoff solenoid), the engine is pretty much immune to electrical gremlins, any issues will likely be mechanical.

 

[KSSIII]

As for fuel injection, the diesel cycle is not like the gasoline cycle, nor is its fuel injection very similar. It's a compression ignition cycle instead of a spark ignition cycle. The incoming air (no fuel) is compressed until it's hot enough to ignite the fuel directly. On these engines the fuel is mechanically injected into each cylinder near the peak of the compression stroke. So you have a spider-array of tubes leading from the injection pump to each cylinder's injector, and the fuel pulses are timed like how you would time a distributor (and it does even have a similar appearance). The "throttle" input doesn't throttle the air, it just adjusts how much fuel is injected during each cycle. Your "ignition" wire (the pink one at the front of the engine) is operating a fuel shutoff solenoid, the only way to stop a self-igniting process. The fuel will only ignite when it is hot, so for cold starting each cylinder has a glow plug heater to pre-warm the combustion chamber.

That's the basic run-down. It's not complicated, but it is quite different from playing with a Quadrajet or a Holley. Any issues that you have are likely to be different, too (but they mostly have to do with either getting fuel into the engine or getting it warm enough to ignite). Being an all-mechanical engine (aside from the fuel shutoff solenoid), the engine is pretty much immune to electrical gremlins, any issues will likely be mechanical.

Thats really odd, after swapping out my pedals, and removing the transmission. I'm not getting a response whats soever from the engine when cranking it over. Not a pop it just keeps turning. I felt almost sure it was electrical. Maybe im not getting fuel somehow

 

[campfire]

One pleasantly simple thing about these engines...there is no tuning. You don't care about main jets or idle jets or accelerator pumps or A/F ratios or spark plug gapping or replacing points and condensers. If you get fuel into the engine, and it is hot enough to start, it will run. Period. There is no crummy running (unless something's broken), it just runs. Nor do you even have any smog equipment. It's dirt simple.

 

[campfire]

Thats really odd, after swapping out my pedals, and removing the transmission. I'm not getting a response whats soever from the engine when cranking it over. Not a pop it just keeps turning. I felt almost sure it was electrical. Maybe im not getting fuel somehow

I'd bet that you bumped a wire somewhere in the process.

Check for 12V on the pink wire going to the IP. You will hear an audible click from the fuel shutoff solenoid when it cycles. Unplug it while the key is on, you should hear it. That is the only electrical input required to run this engine. You will, however, find it downright impossible to start at this temperature without glow plugs, so bumping that wire would also cause similar symptoms.

 

[campfire]

The GP relay sits on the firewall (on military rigs), check there for power and also make sure that it is cycling properly. It is the red relay in this picture (though stock color is black). It should cycle on and off every few seconds when you first turn the key on. That's if yours is still stock, modifying GP circuits is a pretty common practice.

6.2 diesels idling

• campfire
• Jul 22, 2016

 

[KSSIII]

The GP relay sits on the firewall (on military rigs), check there for power and also make sure that it is cycling properly. It is the red relay in this picture (though stock color is black). It should cycle on and off every few seconds when you first turn the key on. That's if yours is still stock, modifying GP circuits is a pretty common practice.

6.2 diesels idling

• campfire
• Jul 22, 2016

Thankyou for the guidance Campfire, I will check on the pink wire and relay tomorrow after class. Its about time i get to know my about my diesel more

 

[KSSIII]

Got the diesel running no ppower to the relay, thankyou campfire. the tranny is in (now waiting on adaptor gaskets) adaptor is welded

 

[KSSIII]

Got the diesel running no ppower to the relay, thankyou campfire. the tranny is in (now waiting on adaptor gaskets) adaptor is welded

almost done may have it finished by the end of the week if everything goes right

 

[KSSIII]

Now I got the rear axel of the mud truck out

Now
I'm contemplating weather I should swap it in or not. the gear ratio is 3.73 I believe, can I keep my stock axel as 3.08? The gears have been welded together i see and there is water contamination

 

[tRustyK5]

Please tell me that adaptor wasn't MIG welded as it appears to be. If so you now have a paper weight...

Cast Iron has to be carefully welded using NiRod which is a high nickel welding rod. Pre heat is crucial, as is a very slow cool down after (8-10 hours). I generally peen the weld surface as well to alleviate as much stress in the part as possible. It's a great material, but it's rigidity is it's Achilles heel during welding.

 

[KSSIII]

Please tell me that adaptor wasn't MIG welded as it appears to be. If so you now have a paper weight...

Cast Iron has to be carefully welded using NiRod which is a high nickel welding rod. Pre heat is crucial, as is a very slow cool down after (8-10 hours). I generally peen the weld surface as well to alleviate as much stress in the part as possible. It's a great material, but it's rigidity is it's Achilles heel during welding.

It was mig welded only choice I had.. at this point I just want to slap it together and see how it goes, I was just gonna leave the crack and worry about it later but we'll see where this goes

 

[tRustyK5]

No point assembling that, it'll be a waste of gaskets, fluid, time etc. With as much weld as I see I wouldn't be surprised if the weight of the T-case is enough to just break the adaptor in two.

 

[campfire]

I'd pass on the 12-bolt. You don't want a welded carrier (if I understand what you're doing), the water contamination means it's due for a good cleaning, and I personally would avoid running 3.73 gears with a 6.2 on stock size tires without overdrive. Especially if you don't have a reason to swap out the front, I'd stick with what you already have. If you're hoping for decent road manners with a 6.2, keep the cruising engine speed around 1800RPM. Personally, mine doesn't hit 1800RPM until about 75MPH (3.08 gearing, 29" tires, 0.70 O/D transmission). That's a bit on the anemic side, but you're on the other end of the spectrum. In stock form an M1009 hits 1800RPM around 55MPH, changing that to 3.73 gears brings the sweet spot down to 45MPH. Even bumping the tire size up to 33" only brings that cruising speed up to 48MPH. So if you switch to 3.73 gearing you will be overspinning the engine on the highway. In my opinion, these engines get loud and obnoxious when the speed climbs, and the fuel economy tanks. So I don't see the benefit of gearing down unless you want lots of low-end grunt. It has its place, but my bet is that the mud truck in question wasn't running a low-speed diesel engine.


P.S. - The gearing options are detailed in that chart that I posted earlier.

 

[KSSIII]

I'd pass on the 12-bolt. You don't want a welded carrier (if I understand what you're doing), the water contamination means it's due for a good cleaning, and I personally would avoid running 3.73 gears with a 6.2 on stock size tires without overdrive. Especially if you don't have a reason to swap out the front, I'd stick with what you already have. If you're hoping for decent road manners with a 6.2, keep the cruising engine speed around 1800RPM. Personally, mine doesn't hit 1800RPM until about 75MPH (3.08 gearing, 29" tires, 0.70 O/D transmission). That's a bit on the anemic side, but you're on the other end of the spectrum. In stock form an M1009 hits 1800RPM around 55MPH, changing that to 3.73 gears brings the sweet spot down to 45MPH. Even bumping the tire size up to 33" only brings that cruising speed up to 48MPH. So if you switch to 3.73 gearing you will be overspinning the engine on the highway. In my opinion, these engines get loud and obnoxious when the speed climbs, and the fuel economy tanks. So I don't see the benefit of gearing down unless you want lots of low-end grunt. It has its place, but my bet is that the mud truck in question wasn't running a low-speed diesel engine.


P.S. - The gearing options are detailed in that chart that I posted earlier.

Thats true its too much work, and not really worth the cost. Ill keep my stock axels

 

[campfire]

Thats true its too much work, and not really worth the cost. Ill keep my stock axels

Are you familiar with the factory Gov-Lock locker that the M1009s came with? Those carriers have a habit of fragmenting, even under light usage. Just wanted to make sure that you were aware of their spotty track record.

Aside from that, you're not likely to have issues with your stock axles.

 

[KSSIII]

Are you familiar with the factory Gov-Lock locker that the M1009s came with? Those carriers have a habit of fragmenting, even under light usage. Just wanted to make sure that you were aware of their spotty track record.

Aside from that, you're not likely to have issues with your stock axles.

Yes ive heard about them malfuctioning, ive been worrying about that too. I dont care if its an open or a locked rear end much.Id like to get rid of it but dont really got the $$ or really the time either

 

[campfire]

Yes ive heard about them malfuctioning, ive been worrying about that too. I dont care if its an open or a locked rear end much.Id like to get rid of it but dont really got the $$ or really the time either

I have a spare carrier and a spare axle lying around. How many splines do your axle shafts have? It should be a 28-spline axle, but later trucks got 30-spline axles. If it's 28, I may be able to help.

 

[KSSIII]

I have a spare carrier and a spare axle lying around. How many splines do your axle shafts have? It should be a 28-spline axle, but later trucks got 30-spline axles. If it's 28, I may be able to help.

Ill have to verify tomorrow