Author Topic: First timer...'84 CUCV  (Read 870 times)

Offline frotosride

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First timer...'84 CUCV
« on: July 31, 2020, 07:55:38 PM »
So I'm fairly new to Automotive diesels and would love some help just to hear it run. A little background, I do a lot of commercial diesel work some for friends and lots for work but they are all substantially bigger than this like for instance a Fairbanks Morris 38 1/8 ND to a little smaller Cat C16 and even smaller Deutz diesels . So I'm not completely diesel stupid.

The what: 1983 1984 K5 CUCV Blazer, 6.2 Detroit, I believe it had a TH400 and NP208 but they are in a jeep now. 10bolts front and rear.

The person I got it from drove it around a good bit before taking the trans and transfercase out so I know it will, did run about a year ago. Some of the glow plugs are shot but he said it fired up without them so I'm not completely worried about replacing them especially since the temps here have been in the mid and upper 90's.

From a wiring stand point what do I need?
Starter 12 or 24VDC?
Is there a fuel shut off solenoid or what turns the engine off and where is it?
Are there filters I need to check and drain moisture from?
In-tank lift pump? Can I put a Jerry can on the cab and gravity feed?
Any "Definately don't do this" I should be mindful of?

Here's a link to the few pics I took last time at the parts field.
https://photos.app.goo.gl/juD2WakGwHWbnc13A

As always thanks for your time and input.
« Last Edit: August 14, 2020, 10:23:03 AM by frotosride »
"Beat it like a red-headed ford"
1987 v10 Silverado, 87 R10,83 K20, 83 cucv 6.2 Detroit
2006 Boulevard M109R 109 cid,2019 M109R BOSS
2009 Jeep XK, (future LS Swap)
GSXR 750 engine awaiting go kart

Offline Mr Diesel

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Re: First timer...'83 CUCV
« Reply #1 on: August 09, 2020, 02:40:20 PM »
-Starter system should be 24 volt, unless someone converted it (unlikely).
-There is a fuel shutoff solenoid. It is contained inside the fuel injection pump. There is a terminal on it. 12/24 volt power to the terminal activates the solenoid and allows fuel to flow into the pump. No electricity = no fuel and engine stops immediately. One positive wire to the injection pump is all the engine needs to stay running.
-I'm not real familiar with the minor differences in the CUCV, but being based on the civilian K5 I think you should have water drains built into the fuel tank for that year. Use a Google search and include the keyword "1983" at least to narrow down the search since later years removed the tank drain feature. Look for pictures that matches what you see on your vehicle. The 1983 pickups had a drain petcock located on the exterior frame rail back by each tank.
-The rectangular fuel filter on your firewall has a port for a water-in-fuel sensor. If everything is still hooked up and working right it should tell you when any water is detected at the bottom of that filter (via light on the dash).
-No in-tank lift pump, it should be a mechanical pump on the engine in the usual GM position (front passenger side of engine). Gravity feed will probably get the engine running because the injection pump has some limited ability to pull fuel, and you don't need much pressure at all to run this engine (at least at idle and low fuel demand conditions).
-Definitely do not use ether on this engine, unless you disconnect the glow plug relay or circuit. The glow plug circuit cycles on and off on a cold engine, so they do come back on intermittently after the initial warm up. I have used small amounts of ether to start them with the glow plug circuit disconnected. It makes it much easier to fire it up if the fuel system has been opened/air allowed in the fuel lines.

These are actually great engines, but you must learn to accept their power limitations. Like all engines it has some quirks and weaknesses, but overall is extremely simple with very little that can even go wrong with it. The engine has changed very little from its debut in 1982, and is still being manufactured as an improved version called the AM General Optimizer 6500 (6.5L).
1976 C20 Crewcab, 6.2L/SM465
1982 K30 Crewcab , 427TD/TH400
1983 C30, 6.2L/TH400
1983 K30 Crewcab 454/700R4
1986 K10 350/400. 1989 K30 cab/chassis 454/SM465

Offline bd

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Re: First timer...'83 CUCV
« Reply #2 on: August 10, 2020, 09:56:16 AM »
I disagree with a couple of points.  The starter, alternator, fuel pump solenoid, and glow plug systems, etc. are all 12-volt appliances.  Air in the fuel is a major source of poor starting and running issues with any automotive diesel.  I agree that you should NEVER use starting fluid!  However, WD40 works well as a substitute for ether w/o imparting damage.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline MIKE S

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Re: First timer...'83 CUCV
« Reply #3 on: August 10, 2020, 05:59:03 PM »
Agree. 12 volts. 2 batteries in parallel. Never ever ever ever ever think about staring fluid in this engine. One of my employees back in the day used starting  fluid on his 83 diesel and it broke a wrist pin in half. I had to go in and replace one piston and rod. Not fun. The original design injector pump used to have fiber ring inside that would come apart and cause no start. Would have to send out pumps to be rebuilt and updated

Offline bd

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Re: First timer...'83 CUCV
« Reply #4 on: August 10, 2020, 07:33:44 PM »
The elastomer ring update wasn't a sure fix either.  The Stanadyne pumps continued to manifest ring disintegration, it just took a little longer.  Broken wrist pins, pistons, and less commonly, cylinders, occurred more frequently in the 6.2s than in gasoline powered engines.  And, blown head gaskets were very common.  But the biggest issues were from air bubbles in the fuel stream; it didn't take much to induce plaguing drivability problems.  Swollen glow plugs continued to be a problem inherited from 5.7 days, largely due to controller timing issues.  So the 6.2s definitely had idiosyncrasies.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline fitz

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Re: First timer...'83 CUCV
« Reply #5 on: August 12, 2020, 08:40:14 AM »
   CUCV's were made from 1984 - 1987.
   Your option code sticker shows that your truck is an 1984.
   That sticker also shows that your truck came with dual alternators (its 24v from the factory).  Your photo only shows 1 alternator.  Someone's been playing around with the electrical system in that truck.  They could have installed a single 24v alternator,  but I'd bet it's been converted to a 12v system.
   From the factory the truck had a 24v starter and a 24v glow plug system.  The glow plugs themselves are 12v.  There should be a resistor on the firewall ( it's missing on your truck) that steps the 24v down to 12v for the glow plugs.  The problem with this system was if 1 glow plug burns out, the remaining 7 each received more voltage, untill the next 1 burns out, and so on down the line untill the system no longer functions. Bd can probably explain the math behind all of that.
   The theory behind the 24v starter and glow plug system was so that a truck with dead battery could be jump started off of the heavy duty Military vehicles that are 24v.   Does your truck still have the little round electrical port on the front grill on the passenger side?  That's where the Military battery cable plugs in to jump start it.  It's designed so you can jump start it (or provide the jump) without opening the hood.  It's a great system when everything works right (and you have the right jumper cable).
   As far as draining water from the fuel, there should be a drain valve on the fuel filter housing.  I replace the factory fuel filter set up with a spin on fuel filter set up with a hand primer made by Wix. This makes bleeding air from the system quick & easy after a filter change.  Another benefit to replacing the original filter housing with the spin on filter set up is that it eliminates a fuel sensor on the back of the housing.  This sensor is only found on Military trucks (not civilian trucks) and has an O ring that dries out and can cause air leaks.  On CUCV's that sensor is wired into the diagnostic port located under the dash in front of the 4x4 shifter.   I think of it as a prehistoric "service engine soon" system.  The diagnostic equipment needed to decode that information are hard to come by, so I feel that it's not hurting anything by eliminating that sensor.  For $100 or so the spin on fuel filter base with the hand primer is money well spent.
   As for the lift pump, its located on the passenger side of the motor just like a typical small block chevy.
I can get you any pictures you need as you get your truck sorted out. 
« Last Edit: August 12, 2020, 08:44:02 AM by fitz »

Offline bd

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Re: First timer...'83 CUCV
« Reply #6 on: August 12, 2020, 10:22:08 AM »
That's great information that clarifies what Mr. Diesel stated!  So Fitz.  Were only CUCVs fitted with 24-volt systems?  The factory wiring diagram, and from recollection all of the 6.2L powered trucks that came into the dealership for repair over the years, were consistently 12 volts.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline MIKE S

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Re: First timer...'83 CUCV
« Reply #7 on: August 12, 2020, 11:14:12 AM »
Yes good information. I was basing what I know from my experience from the civilian models. Learn something every day.

Offline frotosride

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Re: First timer...'83 CUCV
« Reply #8 on: August 12, 2020, 12:30:48 PM »
-Starter system should be 24 volt, unless someone converted it (unlikely).
-There is a fuel shutoff solenoid. It is contained inside the fuel injection pump. There is a terminal on it. 12/24 volt power to the terminal activates the solenoid and allows fuel to flow into the pump. No electricity = no fuel and engine stops immediately. One positive wire to the injection pump is all the engine needs to stay running.
-I'm not real familiar with the minor differences in the CUCV, but being based on the civilian K5 I think you should have water drains built into the fuel tank for that year. Use a Google search and include the keyword "1983" at least to narrow down the search since later years removed the tank drain feature. Look for pictures that matches what you see on your vehicle. The 1983 pickups had a drain petcock located on the exterior frame rail back by each tank.
-The rectangular fuel filter on your firewall has a port for a water-in-fuel sensor. If everything is still hooked up and working right it should tell you when any water is detected at the bottom of that filter (via light on the dash).
-No in-tank lift pump, it should be a mechanical pump on the engine in the usual GM position (front passenger side of engine). Gravity feed will probably get the engine running because the injection pump has some limited ability to pull fuel, and you don't need much pressure at all to run this engine (at least at idle and low fuel demand conditions).
-Definitely do not use ether on this engine, unless you disconnect the glow plug relay or circuit. The glow plug circuit cycles on and off on a cold engine, so they do come back on intermittently after the initial warm up. I have used small amounts of ether to start them with the glow plug circuit disconnected. It makes it much easier to fire it up if the fuel system has been opened/air allowed in the fuel lines.

These are actually great engines, but you must learn to accept their power limitations. Like all engines it has some quirks and weaknesses, but overall is extremely simple with very little that can even go wrong with it. The engine has changed very little from its debut in 1982, and is still being manufactured as an improved version called the AM General Optimizer 6500 (6.5L).
Thanks for the reply, I a huge ether guy on high compression engines. The fact that I'm keeping it and not LS Swapping it is proof I have settled for its oddities and lack of power unless I come across a good deal on a another diesel,...it staying.

   CUCV's were made from 1984 - 1987.
   Your option code sticker shows that your truck is an 1984.
   That sticker also shows that your truck came with dual alternators (its 24v from the factory).  Your photo only shows 1 alternator.  Someone's been playing around with the electrical system in that truck.  They could have installed a single 24v alternator,  but I'd bet it's been converted to a 12v system.
   From the factory the truck had a 24v starter and a 24v glow plug system.  The glow plugs themselves are 12v.  There should be a resistor on the firewall ( it's missing on your truck) that steps the 24v down to 12v for the glow plugs.  The problem with this system was if 1 glow plug burns out, the remaining 7 each received more voltage, untill the next 1 burns out, and so on down the line untill the system no longer functions. Bd can probably explain the math behind all of that.
   The theory behind the 24v starter and glow plug system was so that a truck with dead battery could be jump started off of the heavy duty Military vehicles that are 24v.   Does your truck still have the little round electrical port on the front grill on the passenger side?  That's where the Military battery cable plugs in to jump start it.  It's designed so you can jump start it (or provide the jump) without opening the hood.  It's a great system when everything works right (and you have the right jumper cable).
   As far as draining water from the fuel, there should be a drain valve on the fuel filter housing.  I replace the factory fuel filter set up with a spin on fuel filter set up with a hand primer made by Wix. This makes bleeding air from the system quick & easy after a filter change.  Another benefit to replacing the original filter housing with the spin on filter set up is that it eliminates a fuel sensor on the back of the housing.  This sensor is only found on Military trucks (not civilian trucks) and has an O ring that dries out and can cause air leaks.  On CUCV's that sensor is wired into the diagnostic port located under the dash in front of the 4x4 shifter.   I think of it as a prehistoric "service engine soon" system.  The diagnostic equipment needed to decode that information are hard to come by, so I feel that it's not hurting anything by eliminating that sensor.  For $100 or so the spin on fuel filter base with the hand primer is money well spent.
   As for the lift pump, its located on the passenger side of the motor just like a typical small block chevy.
I can get you any pictures you need as you get your truck sorted out. 
Lots of great info, I do still have the jumper post in the front grill. I haven't searched any pics of where the second alternator is normally mounted but based on the one that's in there still I'm not sure it's been converted to 12vdc as much as just picked through. I also say this because of the person who gave it to me thought the same thing but had to use 24vdc to get it to fire.
 I know that several glow plugs have burst and I'm guessing that with no advice about upgrades, there's not any real remedy(?).
"Beat it like a red-headed ford"
1987 v10 Silverado, 87 R10,83 K20, 83 cucv 6.2 Detroit
2006 Boulevard M109R 109 cid,2019 M109R BOSS
2009 Jeep XK, (future LS Swap)
GSXR 750 engine awaiting go kart

Offline fitz

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Re: First timer...'83 CUCV
« Reply #9 on: August 12, 2020, 09:15:49 PM »
Bd,
   As far as I know, the 1984 - 1987 CUCV's are the only 73-87 style GM trucks that were 24 volts.  I'm not sure what the early 80's Canadian Chevy Military trucks had ( probrably something metric, ha ha).
   Frotoside,
   The electrical system on the CUCV's takes a little getting used to.  Anyone see the movie Joe Dirt with David Spade?  There is a great line where Joe Dirt's Father explains " it's like how exactly does positraction on a plymouth work? It just does".  That about sums up my understanding of a CUCV electical system.  I know just enough to keep a well maintained system up & running.  I'm not sure why a lot of people convert these trucks to 12v.  I've seen people do it a few different ways and it makes trouble shooting a problem tough.  A well maintained 24v system can be reliable. 
   The best advice I can give you is to keep good batteries in it.  I'm sure we have all had times where we left out headlights on in a gas truck and the engine turns over slow but fires up.  That ain't gonna happen in a CUCV.  There is a starter relay under the dash that likes to stick when it sees low voltage.  The stuck relay leads to burnt up starters & a fried wiring harness (melted fusable links).  If you hear the motor turning over slow, stop, dont force it, waite untill you can jump start it, recharge, or replace the batteries.
  What are your plans for this truck?  Mechanical parts are relatively cheap for them.  Lots of guys part out the pick up trucks to get their hands on the Dana 60 front / 14 bolt rear.  Finding the turbo 400 / 208 shouldn't be to hard.
  As far as the glow plugs, most people eliminate the resistor on the firewall ( the one I said was missing on your truck anyway) and run the glow plug relay directly to 12v ( i can show pics of how to do it).  Once your glow plugs are running off 12v, it's a great system. My truck has been set up like that now for 6+ years with no burnt out glow plugs.
 
   
 

Offline fitz

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Re: First timer...'83 CUCV
« Reply #10 on: August 12, 2020, 09:20:27 PM »
Here's a picture of the dual alternator set up.

Offline frotosride

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Re: First timer...'84 CUCV
« Reply #11 on: August 14, 2020, 10:31:44 AM »
Fitz, thanks, that makes it kinda obvious that one is missing and the upper mount is gone as well. I will take the one on it off and test it. One to be sure it's good and two to see if it's 12 or 24v alternator. Hopefully I can find legible part numbers too look up as well.
"Beat it like a red-headed ford"
1987 v10 Silverado, 87 R10,83 K20, 83 cucv 6.2 Detroit
2006 Boulevard M109R 109 cid,2019 M109R BOSS
2009 Jeep XK, (future LS Swap)
GSXR 750 engine awaiting go kart