The 396-6.2 swap project

[Barrman]

We went at the M715 full force this morning. 3 relays installed and wired. Alt 1, Alt 2 and the 24V volt meter. Fixed the brake light switch connections one of my students messed up while doing exhaust work, put the spare tire back up, got the hood on, wired up the B/O spot light again along with my under hood work lights and then tested everything to make sure it works.

I am using my Autometer 12V volt meter to monitor ALT 1. A M35 24V volt meter will be installed in my center console where my OBA air psi gauge used to live to monitor ALT 2 by showing my the entire system voltage. We didn't get to the 24V meter before lunch. I have meetings this afternoon, so it will be a tomorrow thing.

A hand held volt meter shows both alternators are working just fine though and I will try driving it home. It needs to be driven to stop the blue smoke haze in my room. Then, I will bring it back in tomorrow with the car hauler trailer attached. Both to test out how it pulls and so I can take the cab belonging to Sermis home for painting. Something I couldn't do the past 8 months because RED was in my shop getting worked on. It will be coming out tonight or tomorrow.

We still need to wire up the heater fan, a glow plug light along with the other volt meter. It looked weird sitting in the truck with the hood on a bit ago. I haven't seen that view in months.

[k8icu]

Tim,

Glad you got the brakes working. I was worried about the same problem with the M37B3 project. The MC I am going to use is from a CUCV and the hydroboost is from a HMMWV, but when I hooked up the brake peddle and pushed fluid shot out of the MC accross the room so I hope I'm good so that's what made me think of saying check it.

I will have to reread the thread on how you hooked up a glow plug control.

[Barrman]

Joe,
I have 3 Hydroboost units at work. 2 standard thread and a metric. The pushrods for the pedal sides are all different, but the pushrod for the master is the same. I now wish I had swapped over to a CUCV master when I was putting on a new one a few days ago.

I just got home in the M715. WOW! I wish I had done this years ago or never gone gas V8. The Chug, Chug, Chug is incredible at idle. I can start with my throttle foot flat on the floor in 3rd gear and go to 4th once rolling without ever touching the throttle. I can stay in 5th down to 10 mph and smoothly go up to warp speed without effort.

I went to pick up Colton from track and had no leaks. A power steering leak was happening when we got home 5 miles later. A quarter twist on the line and it was gone.

It is a lot less noisy inside the cab than with the gasser 396. Of course, I haven't driven it in over a year so a lot of noises seem new. However, Colton and I were at warp speed and talking without raising our voices. The windows were down even.

The fan shroud is touching the fan when I give it hard throttle in 1st or 2nd gear. Along with in reverse. I will go look at that in a few minutes.

The exhaust is great. Quiet in town and at idle. Then a roar as I wind it out some.

Thanks for all the help.

[Pineyguy]

Awesome Tim. I haven't driven far or "fast" yet, but the first time I backed out of the driveway and pulled out (uphill) without touching the skinny pedal I felt pretty much the same as you. I forget- do you have the stock axles/gears yet?

[jeeper]

That went pretty quick. It isn't even Friday...

My warp speed is 45. It is pretty loud inside my cab at that speed but it is pretty quiet outside from what I'm told. Of course I still have a couple holes to patch in the firewall that I cut in for clearance. One of them is almost a foot square. That is letting some noise in I'm sure.

[Barrman]

Joe, I didn't answer your glow plug control comment because I knew I still had the boxes for my set up. Attached is the part number for the relay/control and the plug that goes on it. Super easy to connect. A ground, a keyed power on, a wire to the starter on wire and another to light up the glow plug light. You will spend a little over $110 for the set up. However, it is compact and works every time. I converted the blue bomber over in December and it is so much nicer.

We didn't get to the fan shroud. Hooking up the trailer, finding out the engine doesn't feel it at low speeds, topping off the fuel tank and getting all the old/not needed parts out of the bed took all our light. Plus we installed the top glass on RED to finish out the day.

ImageUploadedByTapatalk1363831626.671347.jpg

[Flingarrows]

Joe, I didn't answer your glow plug control comment because I knew I still had the boxes for my set up. Attached is the part number for the relay/control and the plug that goes on it. Super easy to connect. A ground, a keyed power on, a wire to the starter on wire and another to light up the glow plug light. You will spend a little over $110 for the set up. However, it is compact and works every time. I converted the blue bomber over in December and it is so much nicer.

Tim, tell me more about this. Is this a timed relay or manual?

[Mikel]

Glad to hear it's working out so well

[randyscycle]

Glad you got going and its working like it should!

I still have that 6.2 under my bench in the back room, but the 396 is still smokin' along good so far, so I just can't make myself take it out. Yet.

The difference in mileage though might make me drive the truck more often, so it still may happen sooner rather than later. I am curious to hear what your fuel mileage will end up being.

[Barrman]

Randy, this swap cost a lot more than I imagined. Clutch, pressure plate, flywheel, exhaust, hydroboost, hoses, belts, glow plugs, glow plug controller, starter, alternators, oil cooler for the engine, fuel seperator/filter, fuel lines, gaskets, 10 quarts of oil, 5 gallons of coolant are just a few of the things that really added up. I would suggest finding a donor truck so you have brakets, manifolds, down pipes and pulleys. I also went 12/24 volt so that added to my cost and complexity.

So far I am very pleased and will post mileage after my trip this weekend. Probably a lot more after that as well.

George, 1982-1984 6.2 trucks had a screw into the water jacket temp sensor/glow plug controller. 6 wires and even today they cost almost $200. It would be ok if they lasted more than a few hard bumps or at least a year. GM changed in 1985 to a dry temp sensor that bolted to the back of the engine and had the relay integral to the sensor/switch.

That is what I put on my truck. I would recommend anybody that has a 6.2 or is thinking about one to buy the 3 6.2 books on this web site:
https://thedieselpage.com/form.htm

I think volume I has an article about this controller and how to wire it in. It could be another volume though.

The controller I took pictures of the boxes is automatic and normally keeps the plugs on about 5-8 seconds.

I have 60G glow plugs and they don't care if they get used every time or not. I have not lived with one of these contollers in the summer yet. However, they turn on everytime I turn the key right now. It is supposed to not at a certian temp. Some people have installed inhibit switches so the plugs don't come on every time.

I don't like that because there is always a dead zone. The M1009 stock system has an inhibitor that keeps them from coming on if the engine is above 125°. However, the engine could be cool enough to need the plugs and not get them. This seems to be around 1 hour 45 minutes in the summer heat here. Exactly how long I am normally at a Scout meeting. I flip the starter and it doesn't start. I cycle the key, no plugs and I have to crank for 3-5 seconds.

Just some observations since I have driven the truck home and back to work with a 2000 pound trailer attached.

The HMMWV engine has a 195° thermostat in it. The gauge stays right at 196° once it gets warmed up.

Oil psi is 50 at cold idle, 45 at hot idle and 60 going down the road.

Fuel psi with just the mechanical pump on is 6 psi.

I think my front brakes need more work. Just the rears are locking up when I do more than a toe twitch with the hydroboost. We bled them some this morning, but no air. We are going to adjust the shoes this afternoon.

It sure is different driving a truck with a Detroit locker in it. I haven't in a year and forgot how my throttle determines if I am going left or right in my lane. Always a challenge with a trailer.

We messed with the fan shroud mounts and I think it is better. I couldn't get it to make noise letting the clutch out with the brakes on a bit ago. Forward or backward. We will see on the drive home.

I also forgot how much more attention the M715 gets in public. These things truly are people magnets.