6.2 Diesel Observations

I do not have a 6.2 in a M715. However, I have gone from zero 6.2 experience to owning 3 vehicles with them and working on a few others in the past 15 months. I just wanted to pass on a few things I learned because a lot of us are thinking 6.2 in our M715's and it will apply.

The Injection Pump is super critical to how the engine runs, starts, sounds, idles and just "feels" when you are behind the wheel.

I had a M1010 (CUCV ambulance) at my house for the past 9 months. I was to paint it and make it run better. My first drive did not impress me. The thing was a dog, hard to start hot, lost power when the throttle was released and felt like it couldn't get out of its own way. I put a brand new IP on it and WOW. That truck felt totally different, took less than a second to start hot or cold, purred like a hungry cat and actually went somewhere.

The owner came and got it yesterday. Between the body work and the IP, he said it was like having a whole new truck the differences were so great. This was after he drove it 150 miles home through the hill country.

My M1009 was getting 20-22 mpg running 60-63 highway with stock 31x10.50 tires. About a year ago I started smelling diesel after driving it once it got below 50° outside. I also found the tires I wanted at a great price. I haven't been above 19.8 mpg since the BFG 33x12.50 AT tires were put on. This is running the same gps monitored highway speeds. Which is a 6% rpm decrease because of the bigger tires.

The ip was leaking at the throttle shaft seals. Just a few drips on some days, never a river. The idle was never steady. Sounded like a gas engine set at about 25° initial timing trying to idle. It still ran down the road great, just not as easy on the fuel as before.

Because I was doing it for another person, I had to get the 1010 done first, it got the pump first. I finally saved up the money and installed mine Friday. Totally different truck. A hill leaving my house I used to have to kind of push the truck up to the speed limit was run this morning with me trying to slow it down to the speed limit. Idle is smooth as glass, constant sound out each exhaust pipe, no diesel smell or pool in the valley and lots more power at all speeds. I will post up about the expected mpg gains. If I can stay out of the fun pedal that is.

The M1010 and the M1009 are both 1985 model trucks. The 1010 had 37K miles and the 1009 has 83K. Miles don't really matter with these things. Years do. Both pumps were stock as near as I can tell. 25 years is way to old for these things based on my experience. I would almost call a 10 year limit if I get any more of these things.

Which I just did. The payment for doing the work on the 1010 was another 1009. The new 1009 which we call RED beause it is all red and a former fire truck also has a very new and shiny IP. I found some of the records in the floor board, but I think they put on the IP in 2007. Good enough for me.

My other 6.2 truck. A 1984 USAF Suburban looks to have the stock pump in it. It starts and runs great. However, I can move the throttle open some with my hand. Such as when I am charging the a/c system yet again after another part decided to leak. Holding it steady open a little and after a few seconds, the rpms will slowly start to climb. The IP is letting me know it wants to die.

Not trying to rant or lecture. I just keep telling myself this. How often have I changed plugs, cap, rotor, points, wires, set the timing, messed with advance weights, vacuum advance cans, tuned carbs, replaced jets, set the idle and mixture on a gas engine every 5-10 years? Well, the IP on a diesel is all that plus a pump and has even more exacting tolerances.

If you have a DB2, or a VE on a Cummins. Which by the way covers all US made diesel truck engines up to 1994. Unless you know the pump is less than 10 years old. I would suggest you start saving money, shopping around and making friends with your local Stanadyne guy. You will thank me the first time you drive the darn thing.

Thanks for the good info Tim. My block is finally together. I'm just waiting for my buddy to get time to pick up his trailer and bring it over to my place.

I dont have the rebuilt pump that was on the 1st cracked block, but it does appear to be a newer pump. What was the price for the new IP? That was new, not rebuilt, right?

George,
Stanadyne keeps a very tight lid on who can work on the pumps. Sure, you can buy all the rebuild parts on ebay for around $60. The CUCV/HMMWV -34 engine manual takes you through a rebuild piece by piece. However, the pump has to be flow tested and calibrated. Only Stanadyne dealers have the equipment to do that. They charge $300 for calibration when I asked. Well, some military repair depots do to.

I called the 4 dealers within 150 miles of me. All wanted between $450-$550 to rebuild a pump. I visited one of the places. What you give them is a dirty leaking thing and what comes back looks brand new and is considered brand new by the factory. Even though technically, it is a rebuild.

Kind of like airplane engines. You can get a rebuild and the engine still has all its hours, or you can get a remanufacture of the same block that will now legally have 0 hours. It is a super tolerance rebuild that is as good as new. That is what Stanadyne gives you back.

There is a place in Arizona on ebay that offers rebuilt pumps for $369. Plus you ship them a core and pay for their shipping to you. These things fit in a flat rate box, so figure $30 tops both ways. I did not use them, but many people who have report great products and fast shipping.

I went a friend of a friend route for a bit less. It took more than 2 months and when I fired it up Friday night. It wouldn't turn off. I worked on it a bunch Saturday and ended up putting my old dirty pump cover on to make it turn off and on. I am waiting to hear from the friend chain if I can get another good new cover with solenoids.

I would suggest calling Stanadyne people, visit them and then choose one with a good price and that you think will tolerate you coming in with questions or problems. Figure $400-$500 anyway you go though.

Of course, you can always go to Autozone, Rock Auto or some place like that to buy a new one for $1300.

Good info. I'm hoping that the pump I'll be using will be a runner, at least for a year, so I can divert a few $$ to the axle swap. If the pump that is on there is not a good one, my buddy has a few.

As always, great pointers!! Thanks Tim! Now just move yourself and family closer to me so you can work on my truck, lol!!! Only 11 inches of snow overnight.

Mark,
Just bring your truck back to KOA June 9-16 next summer. I am taking my Scouts up there to go walk up the darn mountains.

I drove the USAF 6.2 Suburban (blue bomber) daily last week. It seemed so smooth and fast compared to the 1009. Getting into the 1009 was like stepping down in everything except noise. I have driven the 1009 everyday this week. I got back in the bomber to get to Scouts last night and it seemed slow, sluggish and rough.

To make a 4x4 with fat/tall tires and 3.08 axles go from feeling slow to feeling and being faster than a 2x4 with normal sized tires and 3.42 gears is pretty good.

Colton even remarked this morning as we were sitting at a light and not vibrating at all. "This is better than the bomber, it is so smooth."

Have you done any fuel mileage comparisons between your trucks yet?

I have a 70 mile drive to make tomorrow night. I will get that in to balance out my hot rodding around and top off next week. That will give me a good pump mpg comparison. Next tank will be no hot rodding and pulling a loaded (6BT going to Sermis) 101 200 miles. That should really tell me both power and mpg the difference.

The bomber has been getting 15-17 mpg tanks for the past few months. That is city, highway and camping with the Scouts. All with the a/c front and back on high all the time.

If you are going to see Sermis, can you bring back my air compressor for me. Then I can bring a deuce up and pick it up from you.

No problem on the compressor.

Due to the wreck Jennifer had. I got to put a bunch more miles on the new ip. It is now our most mechanically sound vehicle.

100 miles last night between getting to the ER, picking up Colton at his football game and then getting everyone home again. Because of the bigger tires my speedo
Eter is off a bit. I always use the gps for accurate speed readings. It was in the wrecked truck. I had thrown everything into the back of the 1009 before I followed the ambulance. Never had time to get it out and plug it in. It was always get in and drive.

I just guessed and kept my speed to around 65-70 indicated. I topped off this morning and had 15.8 mpg. That tank was with the old leaking ip, through a bunch of idling and tuning and my running around last night.

I got the gps out and checked my speed tonight. Turns out I was mentally off a bit. A steady 65 indicated was actually 73 gps. I was running 73-80 for darn near 100 miles and still got almost 16 mpg.

I will try to keep it below 65 so the before and after ip change numbers will be equal.

I did notice that not a single hill slowed me down any and very little throttle was needed. More to follow.

Tim, what is the tire size on the 1009?

Stock on a m1009 is 31 x 10.50. I have BFG 33 x 12.50 A/T's on it now.

According to the gps my odometer is off 6%. The speedometer though is about 12% slow. But, it varies so I never really pay attention and just use the gps on the highway. While keeping it 5 under in town.

Oh, actual size of the stock tires was 30" and the new tires are 32".

ok, cool

I haven't had a chance to put fuel in the 1009 since last week, so no mileage numbers.

I have had to mess with the totally mysterious glow plug/fast idle/cold advance system on the Bomber this week and thought I would share. Because if you are swapping in a 6.2, you will likely use at least one of them, if not all 3.

The 6.2 from the factory had 3 temperature senders:

Drivers side front cylinder head above the #1 injector- Temp sendor for the idiot light and if you had the 1 diesel truck with actual gauges, the gauge.

Drivers side rear of the valley-glow plug temp sender (military)/ glow plug temp sender/control (civilian)

Passenger side rear of cylinder head above the #8 injector or passenger side rear of the valley-fast idle and cold advance temperature switch.

The temp sender is just that and a mechanical or electric sender can be put in there for that purpose. Just like any other gas or diesel engine.

The glow plug sender came in at least 2 civilian versions and only 1 military version that I am aware of. It basically turns on the glow plug system no matter the version if the water temp is below 125°. Depending on the version, the "brains" of the system could be on the sensor, on the inner fender or under the dash. Put a pipe plug in this hole and just use a momentary switch for the glow plugs unless you are swapping over an intact system from a donor.

The fast idle and cold advance temp switch is the one that I am playing with this week. It really is a switch and a sensor. Constant power goes in one terminal and if the sensor says the water temp is below 75°. Then it sends power out the other terminal. The rest of the time, no power goes out.

The power going out is the green wires on the IP. One wire to the fast idle solenoid which has enough power to hold the throttle open a little, but not move it open. You have to do that by flipping or tapping the throttle pedal once the power is on. Then, it will hold the idle speed up. Factory spec is 650 rpm hot idle and 800 rpm fast idle.

The other green wire on the IP is the cold advance solenoid. Becuase the 6.2 NA engine has like 22:1 compression and is inderect injection. It only has to get a little bit of heat inside the chamber to make fire. The cold advance lets the fuel get there sooner so the colder slower fire has more time to build and make power which keeps the cold engine running.

That is the function and theory. When I picked up the bomber for Warthog a year ago next Thurdsay, he had me take it to my class. We did a bunch of other work before starting was even attempted. The fast idle solenoid never worked, but the truck started great. Took 5-10 seconds each time, but it fired up every time. A few months later, it was ready for some test driving. I started trying to get the fast idle to work and found the wire cut. I fixed it and the solenoid didn't work. I figured the problem was somewhere in the mysterious wiring system and didn't even test it for power.

It ran and I didn't worry about it. Then it became my truck and I started daily driving it once the a/c worked. I still didn't worry about it. Then it started getting below 60° some mornings. Those mornings were hard to start. I started to worry about it. A few test showed power was getting to the solenoid.

That silly solenoid is listed on the O'Reilly site as $247. Thankfully, Warthog has a truck stored at my place with a good solenoid on it. Simple swap later and I had the thing working and adjusted. Except, 10 minutes later it was still on and not turning off.

I unplugged it and idle returned to normal. Not a stuck solenoid. I unplugged the cold advance and no change in the engine. It was also burned up. That meant the switch was bad. Except nobody seems to actually have that switch. Sure, NAPA list it for $6? and amazon list it for around $20. Nobody seems to carry it though. Back to the Warthog donor truck. Different size threads.

I tried to start the truck this morning with just the glow plugs and it didn't want to. 4 glow plug cycles later and a little throttle play while cranking got it to fire up and smoke white a bunch. I need the cold advance working along with the fast idle. Fixing the cold advance is going to mean pulling the top cover off the IP and either swapping it out or pulling parts out and swapping them. A cover swap takes about 5 minutes once you figure out a pair of pliers and a 1/4" socket are all you need for everything.

Sorry for the long post, but I wanted to convey why the green wires on the IP are important and why if swapping in a 6.2 it is a good idea to keep the fast idle and cold advance switch in the system.

Man, my truck seems like a little rascals fixer upper compared to all the research and tracking down on the solenoids you do. The previous owner just put in a simple click switch for the glow plugs (I count to 5 on Colorado cold days), and a switch for the fast/cold idle. I'm fearful to even open it up because I think faith alone is what is keeping that stuff running. If I touch it, it will break, lol! That's about half the reason I haven't even started on my 6.2 swap. The other half is I'm a incompetent engine mechanic, lol!
All you guys seriously impress me when I read about the fixes and inprovements you make.

Good info Tim. I have the wiring ready for the 6.2. I'll be using the floor switch for the manual glow plug relay. My engine is done. I am hoping that my buddy had time to trailer it over tomorrow or Sunday afternoon.

Jennifer has been daily driving the 1009 for the past few weeks. She treats every stop light like a drag race oppertunity. I topped it off Thursday evening and she had gotten 16.4. Way below what I normally get. Of course, in the Suburban I used to get 2-3 mpg's more than her too. Arrive in the same amount of time but use less fuel.

She called me the other day while she was running errands over lunch in it. "You are in trouble...this thing is so fun to drive. Lots of power, great visibility, I am about 5 feet up in the air and I can go through drive thru lanes without even thinking about what I am going to run over. I like it, you can't have it back. Go find your own."

She will give it back once it gets hot again. She really, really likes a/c.

We have been invited to Beaver Creek Colorado for a week at Christmas by her sister and family. The 1009 became our transportation. I wanted to get an accurate read on what fuel was going to be running 70 for 1200 miles each way. We drove to College Station to meet up with some of my old Corps buddies Friday evening. I kept it pegged at 70 gps the 140 mile round trip. Attacked hills when I normally let the speed drop off some and drove in town like a sports car. 17.9 mpg for that run. Basically, 2325 rpm cruising.

This week we have about 300 miles of driving to do and I have put her on a 65 gps red line. Everyone who owns one of these non overdrive trucks says 65 mph is the fuel drop off. The torque curve shows 1800-2200 as the peak area. 65 mph with my tires is 2158 rpm. We will see what we get.

Then I will try to hold her to 60-62 gps, 1992 rpm, for a highway run or two and see what that gives us.

Oh, we cancelled the ski trip. Spending that much money, (Ski rental, lift tickets, fuel, resort food for a week and ski clothes) when we need to buy a real family daily driver just doesn't make sense. Would have been a fun MV adventure though.

I like to answere these posts as follows:
First: You do not really need the cold advance. The engine will run evenly even at 650 rpm when cold at -20 °C (something like -4°F) after starting. The idle up to 750 rpm is not realy neccessary.
Second: Any seal will get old. If the engine did not run for more than a year the seals tend to get hard. So they have the tendency to start to drip slowly. If you run your truck on somewhat regular bases, at least for 15 years nothing will happen with the seals. The seal set is some $10, and you can replace them by youself, if you keep your working place kleep like a surgery room. Thakes with some training less than one hour when the pump lies on the table, my best time was 45 minutes. (Shwitch on the brain is required!)
With my M715 with a 6.2 l Diesel I have a fuel consumption of about 18 L /100 km without trailer and up to 22 l/100 km with trailer (depending on the terrain) (12.9 mpg solo up to 10,6 mpg w/trailer). With my M1009 I had an averange between 22 and 14 mpg depending on the use and terain (hilly, flat, with trailer, solo).
Wolf

6.2/6.5 glow plugs came back into my life last week and I needed a part number I know I posted back when I did the M715 6.2 swap. So, I did a search and came across this thread in my way to that thread. Here is the story:

The 6.2 in the M715 has worked flawlessly for almost 8 years now. Same with the one in the m1009 and Colton’s m1009, RED. Bomber too, but it went away a few years ago for other reasons.

I liked the engine so much that 5 years ago through the help of Warthog I started another project. 1987 3/4 ton 4x4 Suburban. Surplus GEP 6500 that needed new heads was put in it. 4L80E transmission, Banks Sidewinder turbo and a few years of body work along with fitting it all together. I have been driving it around a while making all of the parts get along and making it better.

However, it never got to take a long trip. Sure, a few hundred miles and home happened a few times. But, mostly just local and daily driven. A serpentine belt system kept the truck 12 volt starter and charging system. It has always started ok. But, never as fast in any temperature as the 24 volt trucks.

I was convinced it was starter speed. Because it wanted to start, but needed to sling a second or 5 more sometimes. 100° or 24° outside temp never really seemed to make a difference. That is why I was convinced it was starter speed and not the glow plug system.

Just to be sure a few months ago I changed all 8 Delco 60G glow plugs out with fresh ones. No change. So, I used the O’Reilly’s warranty and traded the starter for another. Reduction gear in both cases. A hair improvement, but not the same as the 24 volt trucks.

I have a 1988-2000 Delco glow plug relay/control module in it. It works, the wait lite comes on and voltage is getting to all the glow plugs. I decided to live with it.

The older kids in my Trail Life troop decided they wanted to climb the highest mountain in Texas. Guadalupe Peak is about 600 miles from here. Perfect chance to use the Suburban named Cowdog for what I built it. Long distance travel at highway speeds in comfort with off road ability once there. While getting decent fuel mileage.

200 miles of city and up to 75 mph speed limit driving had me at almost 17 mpg. 82 mph for 317 miles on I-10 into a head wind while gaining a few thousand feet of elevation knocked me down below 14. But, I was passing people all the way and punching a big hole in the wind for the people following.

Our camp ground was at 3600 feet elevation. It was 35° the next morning and the truck didn’t want to start. The same temperature here at 428 feet the day before had been a normal 2-4 seconds of cranking start. It took 3 tries but it finally fired up and ran after about 10 seconds of trying.

Almost 10 hours later after reaching the summit it was 74° and we were at 5800 feet. A normal glow plug wait had it just cranking and cranking and cranking again. It finally fired with a huge while smoke cloud. I didn’t understand what was wrong.

White smoke from a diesel means not enough heat. So I knew it had to be glow plugs. But it ran so good once started I didn’t want to tear into it 600 miles from home and just let it be once I verbally the wires were connected and tight. The next morning was the same lone start issue. Voltage was still being drawn so I figured the plugs were still there and still heating.

I could only come up with elevation as the variable that had really changed. 10 hours of driving and thinking had me convinced it had to be elevation and just how diesels are in the mountains. I’ve never had a diesel above 500 feet, so I didn’t know.

Research once home had me thinking myself a fool. Then I got in the M715 to run to town and realized the exact same glow plugs with the exact same controller were glowing about twice as long as in the Cowdog. Next I got into a m1009 which has a totally different way of controlling the glow plugs. It glowed even longer than the M715. I got in the other m1009 and it was also an extremely long time compared to the M715. 15 -20 seconds longer. Found it.

I got in the Cowdog and took notice of how short the glow was. When it was finished. I tried to cycle it again and it wouldn’t. I tried the same in the M715 and it cycled over and over again. My controller was bad in the Cowdog.

I put a new one in a day ago and it was the same short glow period. But, I could cycle it back on again right away. A double cycle gave about the same glow period as the m1009 and it started faster than it ever has before. About the same as the 24 volt trucks.

Now I just need a reason to go back to altitude and see what happens.

I read somewhere that you could add a resistor to the controller to make the glow plugs stay on longer.

Thanks Steve. You gave me a topic to search.

I already knew there were at least 4 factory GM glow plugs used over the years with only the newest being the self regulation type. 5G, 9G, 11G and 60G. People have hooked up a 60G to a battery and left them on 8-24 hours without failure, swelling or explosion. I have 60G plugs in all of my engines.

I knew GM had the CUCV glow plug system, the 1982 initial 6.2 system, a 1984 revised system, the 1988-1992 system and then the 1993-2000 system for the OBD II computer run injection pump trucks with a turbo.

What I learned new is that the self regulating 60G glow plugs didn’t come along with the 1988 controller. I am using the 1988 version controller. All of the non 60G glow plugs hit 1400° just about immediately. But, if left powered more than 12 seconds they could actually explode or at least start to swell.

So the 1988 controller does an 8 second glow cycle. The 60G plugs need 12-16 second glow to get to full temperature. My double cycle of just turning the ignition on, waiting for the wait light to go out, turning the ignition off then back on real quick. Gives me 16 total seconds but not at full heat.

I had seen the diesel performance sellers all had their own “glow extender” kits. Basically, an older Ford starter relay wired to a push button switch inside the cab that could be held down to keep the voltage going. I’m sure they work, but I want a system that works for who ever might be needed to drive my truck without special instructions.

Researching “resistor added to 6.5 diesel glow plug controller “ thanks to Steve resulted in 30 years of people complaining about and fixing this problem. A 5 Ohm 1 watt resistor added to terminal C of the controller plug adds 4-5 seconds to every glow period. A 10 Ohm 2 Watt resistor adds 8-10 seconds.

I think I will do the 5 Ohm mod first and see what results I get.

The reasons I am using the 4 pin 1988-1992 controller are several. It doesn’t need access to the coolant system to function. It has a temperature sensor in it that when the outside temperature is over 80° and the engine is warm, it won’t even turn on the glow plugs. It can also be mounted just about anywhere a person wanted. I have mine bolted to the inside rear of the drivers side head. Central to the wiring and out of the way.

Quote:

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Originally Posted by Barrman

Thanks Steve. You gave me a topic to search.
I have mine bolted to the inside rear of the drivers side head.

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Wow! Your suburban has a head in it for the driver. :eek: I actually kinda prefer stopping occasionally to stretch my legs though.

Hope the resistor idea works for you.

My F250 has 450,000 miles on it and has been hard to start in cold weather for the last 50,000 miles or so. Changed the glow plugs and controller and diagnostics say they are working, but the long cranking and white smoke says otherwise.

The resistors should be in my mail box after work today. I hope it works too.

I will actually be driving the Cowdog full of campers a week from Friday to some private land between Rock Springs and Junction on 377. It will be another good test.

I thought your 6.0 had a heater grid instead of glow plugs?

nope. 6.0 has glow plugs.

Two years later and I was searching for the same part number I was then again. So, since I found this thread for the same reason twice. I am going to put them here as well.

The GM glow plug controller I put on the M715, Bomber and Cowdog is a BWD R3076.

The 4 pin plug that goes with the controller is a BWD PT363.

I found it on post 166 of my M715 6.2 conversion thread.

I was looking for the part number 2 years ago because of the failed glow plug controller in the Cowdog. I tried the resister idea Kwai brought to my attention and it didn’t change start time any. I finally broke down and added the Ford relay and a push button to “extend” the glow time to a minimum of 12 seconds in hot weather and as much as 25 seconds in cold weather. I also did all 8 glow plugs again. Both helped. The best help was after my guaranteed for life O’Reilly’s starter started making weird noises after the 4th replacement. I bought a brand new AC Delco unit. Now for the first time ever my 12 volt engine spins as fast as my 24 volt units.

Jennifer and I spent 2 weeks playing at overlanding in the Colorado mountains last summer. 11,000 feet and cold starting at 35° was just like home and 100°. So, that is not a worry anymore.

I was looking for the part numbers today because I did a video months ago about the different 6.? Glow plug control units over the years. Somebody asked what the part number for the pigtail was and I found this thread again looking.