The 396-6.2 swap project

[Barrman]

I topped it off on the way home. 302.1 miles and 20.1 gallons. I will just call it 15 mpg. I will take that all day long.

The gauge was steady just touching the 1/4 tank line with 8 gallons left. If the tank really is the advertised 28 gallons. I did an experiment years ago with a vacuum gauge to determine a stock fuel pick up needed exactly 1 gallon in the tank to work. That means 7 gallons left usable. Or, a true range of 390 miles. I fill all the way up to the cap, so do I get an extra gallon or so over the factory guys?

I picked up Colton from football practice in it with the trailer still attached. It was fun to watch the already driving upper class men come out, look, look again and then point. When a freshmen came out, jumped behind the wheel, started it up and pulled away they kind of just stood there. It was a much better showing than the push starting Mini experience Monday.

[Mikel]

I topped it off on the way home. 302.1 miles and 20.1 gallons. I will just call it 15 mpg. I will take that all day long.

The gauge was steady just touching the 1/4 tank line with 8 gallons left. If the tank really is the advertised 28 gallons. I did an experiment years ago with a vacuum gauge to determine a stock fuel pick up needed exactly 1 gallon in the tank to work. That means 7 gallons left usable. Or, a true range of 390 miles. I fill all the way up to the cap, so do I get an extra gallon or so over the factory guys?

I picked up Colton from football practice in it with the trailer still attached. It was fun to watch the already driving upper class men come out, look, look again and then point. When a freshmen came out, jumped behind the wheel, started it up and pulled away they kind of just stood there. It was a much better showing than the push starting Mini experience Monday.

That is pretty good.

[Barrman]

One problem with a large fleet of vehicles is sometimes small things don't get taken care of. I discovered one of those small things yesterday living with the 6.2 in its first winter.

I drained the gasoline from the fuel tank a year ago and put in diesel. I added a water separator/fuel filter with the engine. The engine has always started in less than a second no matter the weather. Yesterday we were down to 25˚ and it stayed below freezing all day. I jumped in the truck to go get hay. It took about 4 seconds to start. Then after about 15-20 seconds of running. The idle sped up and then it died. It would not restart but I got lots of blue smoke out the pipe when I tried. I left it alone.

I last filled up in September. Full summer grade diesel for sure. I added Powerservice for winter a few weeks ago and ran it at least 30 minutes afterward. I figured my problem yesterday was either jelled fuel or frozen water in my filter.

Instead of just swapping in a new filter I wanted to figure out which it was. Today we got over 50˚. I let is sit until I figured everything was above freezing. I cranked it for 10 seconds, it burped once but didn't start. Sit to cool the starter for 1 minute and then another 10 seconds of cranking got the same result. Another rest and the 3rd try had it running like nothing had happened.

I let the engine idle up to full temp and then drove to town and back without issue. I ran out of daylight today but will open the drain on the separator to see how much water I get out. I figure it was frozen because jelled fuel would not liquify again.

I also figure this 6.2 gave me trouble because it had gasoline in the tank that might or might not have all drained out compared to all my other trucks which have been diesel from the start.

Just another lesson learned.

[Mikel]

A small amount of gasoline in the tank should not have caused you problems. It is an old trick in cold climates to mix a bit of gasoline in diesel to keep it from gelling at low temperatures.

[Barrman]

I got to do 252 miles with the 6.2 today. Most of it all at Warp Speed(54mph). We ran into bad rain and then freezing rain with 25-32 mph head winds. Yet, the fuel gauge still shows more than 3/4 tank left of fuel. It isn't accurate, but the 396 never got more than 170 miles with the same gauge before it was stuck on empty.

The 195˚ thermostat sure made it possible for us almost to be warm. Well, actually going into the wind we both got cold with coats on. However, anytime we ran cross wind the person on the down wind side got warm and the up wind side got colder. Down wind runs had us both warm.

We loaded the truck at 75˚, left with it at 45˚, got down to 38˚ on the road, through the front, loaded up parts and talked to Gary in 70˚ clouds and then had 28˚ with freezing rain and 16˚ wind chills when we got home. What a crazy weather day.

RainX is the best thing I have ever found for being able to see out of a M vehicle in the rain. We put on a fresh coat this morning before we left and it worked great.

[Mikel]

You have tripled your fuel economy?? How bad was the 396?

[Barrman]

The gauge isn't linear. Chevy sender which means it lives in full and then drops like a rock. I am estimating 15 or so for the run yesterday. Maybe up to 17. The 396 once got 12.4 on a similar drive. Mostly I was happy to be over 10 though. 8-9 was normal.

Hmm. I was going to use tapatalk to put pictures up from yesterday. It seems they have updated and don't work like they used to. I will get it figured out one of these days.




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[Barrman]

Mileage update:

The run I wrote about in the above post ended up being 14.92 mpg once topped off.

Then Colton taught his girlfriend to drive a standard, we drove to an airshow 90 miles away, did a few parades and I did a 10 mile 67 mph speed run last week just to see how it did at my self imposed 2600 rpm red line. All on the next tank. I topped off last night and it was 14.98 mpg.

Almost 300 miles on a hair more than 20 gallons is just mind boggling to me for the M715 after all those years of worrying about fuel as soon as I got past 150 miles to the tank.

We also swapped out the doors for the roadster set a few weeks ago and put the back seat in. The diesel has made this truck much more fun to drive. So much so that the M1009's are being left at home when we have a short run to make that doesn't require a/c.

Wanted to throw in the latest fuel numbers because that seems to come up a lot.

[jeeper]

That's good info. That 396 was pretty thirsty huh?

Now you have me wondering what I actually get. I was guessing I was getting 15 and I don't have overdrive.

[Barrman]

Time for another Friday update.

Colton turned 16 Wednesday and got his license too. He left the license place in RED going back to school. Once school was over, he went to his girlfriends. They ended up going to subway for food and back to our place for a picnic down at our tank.

He was pretty proud of himself when they pulled up in RED. They parked it and rolled the windows up. I asked why close it up since he had to take her home and it was still 98° out? "Oh, I was going to do that in the M715." Jennifer laughed and laughed while I just shook my head. I asked the girl who was dressed nicely if she was ok riding in the convertible with half doors and she said it was fine. I said it was ok.

They left after dark. Her parents had some kind of birthday thing for him and it was a few hours before I heard the 6.2 rumble. I figured if he wants to drive it then he can cover the seats back up and all that in the dark by himself. He finally came in just grinning from ear to ear and laughing. I asked what was going on? "Dad, that truck is soooo muuuuuch fun!" They both thought the clear night was best seen from it with the mellow 3" exhaust note.

I am so glad I went diesel. It has been months since I put fuel in that truck because it has been so darn hot. I didn't worry a bit about if it would start, overheat or how much his little drive was going to cost me in fuel. All things the 396 had associated with it. Plus, with the 6.2 I don't have to worry about how fast he is going. Slow is all he can do.