The 396-6.2 swap project

[monty]

What size tires are you running?

[Barrman]

11.00-16 Michelin XZL tires.

[Barrman]

Driving home from work yesterday, the Blue Bomber started making a funny vibration. I didn't have time to look at it last night. Fearing it could be a separating balancer. I left it parked until I could look at it today. Turns out the long passenger side motor mount bolt had slipped out enough to let the engine side of the mount touch the frame. When I picked up the truck from Ft. Sam almost 3 years ago the nut for that bolt was missing. I kept forgetting to put one on there all this time. I guess I get to do it this weekend once I lift the engine back up some.

However, the bomber parked and Jennifer needed to drive separate gave me an excuse to drive the M715 to work.

Now that parades and shows are over for me until November. I have no troop seats, no hard top and just the bikini top. First time for the 6.2.

I had a blast with the all around vision for the first time in years. The 6.2 chug chugged along just great and I got a few thumbs up from other drivers as I was going along in the nice and cool 94˚ this afternoon.

I had to stop at the store on the way home. When I got back in, the glow plug relay did not energize for the first time ever. It was finally hot enough to not need them. It did do an after glow for about a second once I fired it up.

Some had asked how the relay worked in every day driving so I thought I would write about it. I have been pleased with it both in the Bomber and M715.

[fishtail]

So dumb question>>

If the diesel engine is hot from running, you shut it off for a few minutes, the engine is hot enough yet to ignite the mixture without the glow plugs?

And there is a sensor in the relay to detect that?

Just trying to understand those beasts more.

Scott

[Barrman]

You explained really well Scott. Yes, there is a sensor in the glow plug controller/relay.

The theory on the indirect injection diesels is that below 125˚ water temp it will need glow plugs to help start. The civilian 1982-1984 system had a sensor that screwed into the coolant port on a head and then turned a relay on or off. Besides a possible leak, they broke pretty regular leaving the relay on all the time which burned up the non regulated 9G, 11G and 13G glow plugs. Or, they just didn't turn them on which caused the engine to not start.

The second improved design is the one I switched the 1984 Blue Bomber over to last December and installed on the M715. No coolant passage contact. It bolts to the outside of the cylinder head, has a sensor and the relay is part of the unit. Only 4 wires too. Compared to the 8 on the old civilian unit.

The now 30 years later design 60G glow plugs can be left on since they are self regulating. The controller I used in the M715 does about 5-8 seconds of glow and then 1-4 periods of after glow depending on how cold it is. The M715 has started every time I have tried to start it in less than a second of cranking in temps ranging from 28˚ to 94˚. I think this controller along with 60G plugs are the way to go.

The M715 has the faster turning 24 volt starter and a pair of Optima red tops. The bomber has almost 2 years old 60G plugs in it. They have been abused by being left on with the old controller for 10-15 minutes some mornings. It has a 12 volt starter and a pair of cheap Autozone 600 CCA batteries. I let the controller cycle twice on mornings below 50˚ and it starts right away. Just a single cycle and I might have to crank for 3-5 seconds.

The CUCV trucks had a military truck specific glow plug system which has a sensor in a water port and a very primitive printed circuit board. Both of mine are working great now with new cards in them. When and or if they go bad, I will switch those trucks over to the system on the M715. I will go looking, but I know I posted part numbers and more details about the relay in this thread already.

[Barrman]

One of the things I was looking forward to with the 6.2 swap was the ability to let the truck sit for a long time and not worry about the fuel and getting it on the road again.

I didn't mean to, but that is what happened the past month. We left for Scout summer camp on the 14th and were gone 10 days. The weeks before that trip, the M715 didn't even get looked at much less started up. I didn't keep a log, but figure at least 30 days of no running.

This past Saturday morning I get a call at 0800 from a co worker. Their '05 Duramax truck was not starting and they needed to tow it into town for getting worked on. Would I do it? Once I figured out they didn't want me to spend the day trying to fix it in their field and only wanted a tow to town. I started getting pretty excited about using the M715 for this.

Colton and I threw a few tow straps in the bed and headed out. The 6.2 started instantly as soon as the glow plug light went out. Like I had driven it a few hours before instead of more than a month. I did check all the fluids first and they were perfect.

8 miles of nice highway speed driving we figured out the guy didn't have a simple fuel filter bleeder screw problem and instead a major fuel supply problem. We hooked up the tow strap and started pulling him.

Anybody that has tow strapped another vehicle on the road knows the driver of the front vehicle has to really think things through or it turns into a neck snapping torture drive. I told the guy we would run about 25-30 mph and that he was my brakes so anytime I raised my hand, he was to start stopping us. He understood that and braked us just fine.

My problem was the hills. I wanted to top them about 25 so I could slowly speed up as we were going down the other side to keep tension on the strap and not get over 30 at the bottom. I was just chugging along in 5th at 30-33 and could never get it down to 25 going up the hills. I was idle governored out of going that slow.

We ran 30-35 instead. I was very impressed with the 6.2. Plenty of power and no problem at all pulling the 4x4 long bed 4 door.


Once done, Colton and I ran some errands in town that had us shutting the truck off a bunch. It was already 92° when we started this trip at 0900. Well over 100° by the time we were done. The temp never got over 198° and the glow plugs didn't come on after our first start at home.

I am so glad the 396 died so I could do this swap. Now if I could just get somebody to buy my 396 pieces so I can start more projects.

[Mikel]

That's the nice thing about diesels. When I bought my 4BT it had sat for several years. I put a battery in the van, cranked the engine for two seconds and it started idling right away!

[Warthog]

When are we going to see all the after completion pictures?

[Barrman]

On my truck? I haven't taken any and will get on that soon.

I fired up the M1009 for the first time in 3 weeks tonight. First crank and it was purring away. I so love the diesel world.

[Barrman]

I had to go to a Scout leader meeting 35 miles away last night. It was 105° outside, I would be driving into the sun the entire way and chances were the building where we were to meet would be hot because the a/c probably didn't get turned on until people started showing up. So, of course I took the vehicle with the least amount of sun protection, no a/c and that likes to slow broil my feet.

The M715 needed a good highway run since it hasn't had one in a few months. I ran 55-60 all the way and of course started smelling the transfer case getting hot as I was getting there. The 195° thermostat has always had the 6.2 in the 193-198° range. In the heat and higher speeds yesterday it was in the 199°-202° range. If I slowed down below 50, it would drop right back down to normal.

The pay off and the reason I drove it was the ride home. Full dark, wide open road in the middle of nowhere and cool feeling 90°-95° temps. There is just something about the 360° view, nice exhaust note and refreshing air swirling around that makes the time and effort involved in the truck worth it.