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More 6.2 questions

Discussion in '1982-Present GM Diesel' started by DukeBoy88, Apr 13, 2004.

  1. DukeBoy88

    DukeBoy88 1/2 ton status

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    I've been changing filters and fluids and have come across the following on my '85 M1008

    The previous owner has replaced the rectangular fuel filter with a napa spin on canister filter. It has petcocks to drain and bleed air and 3/4 npt inlets and outlets bushed down to 1/4. At first I thought this was the filter system from the 82-83 6.2. but there isn't a secondary filter or heater as my chiltons shows. Is this a problem? would it be an advantage for me to switch back to the rectangular style? (the wiring harness is there, but the base is not, and I don't know why it was eliminated)

    In a previous post about a starter mount, I was told there is supposed to be a mounting strap on the front of the starter. does anyone have a picture? I don't believe I have one.

    My injection timing marks do not line up, is this as easy as loosening the three pump mounting bolts and lining up the marks?

    How much oil residue in the intake is ok?

    Before I bought the truck, the owner replaced the front springs and shackles. I have about 1/4" clearance between the spring and frame as the truck sits level. I'm wondering if these are the correct shackles. how much clearance should there normally be?

    Thanks in advance, Dave
     
  2. arveetek

    arveetek 1/2 ton status

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    See if you can look up your Napa filter micron ratings or what it was originally used on/for and compare that to the stock filter. The rectangular filters are known for leaking, and it's common to replace them with a spin-on filter. That's what I have on my truck. But I have two of them, a primary and secondary. The primary unit filters out the bulk of crud and junk from the tanks, the secondary does the fine filtering before the fuel goes into the injection pump. You want to make sure the filter you have is not just a primary filter, otherwise your fuel will not be getting filtered enough.

    I wouldn't bother switching back to the rectangular style. If you need to replace the filter you have for some reason, just go with a Racor spin-on unit.

    The front starter brace is a bent angle-iron piece, about three to four inches long. It bolts the front of the starter to the block. If it's missing, it only costs a few dollars from the dealer. I'm assuming the 24 volt starters use the same brace?

    As for your timing marks, they don't have to be lined up. If the pump mark is to the driver's side of the block mark, then that means your timing is advanced, and is probably okay.....I would leave it alone. If your pump mark is to the left of the block mark, then that means the timing is retarded. The lines are just for reference. When the engine was first assembled, the motor was timed, and then the scribe marks were made. If the injection pump has ever been serviced, then those marks don't mean much anymore. Plus, it's common practice to advance the timing for more power and to take up worn timing chain slack.

    It's normal for the inside of the intake to be oily.

    Casey
     
  3. DukeBoy88

    DukeBoy88 1/2 ton status

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    Thanks Casey,

    The pump timing is retarded by your description. the opposite edges of the marks touch but the pump is on the passenger side. would this cause any noticable difference?

    I'll check what type of filter this is. In a two stage filter set-up, does the primary come before or after the lift pump. My current filter is after.

    I'll go ahead and order the brace, and see if I can find out where it mounts, if it mounts 24v.

    thanks again. /forums/images/graemlins/thumb.gif
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I run a Racor and then a spin-on after my lift pump.

    Pump timing does make a big difference, I'd try lining up the marks if it's currently retarded. I have my pump marks 1/16" to the right currently and it makes good power there without being too noisy.

    As for your shackle question, you should have a little more room there than 1/4". Perhaps the spring eye bushings are worn...

    It is common for that spring to hit the underside of the frame when wheeling, so a lot of guys either build or buy slightly longer shackles to fix the problem. I built a set of shackles 1/2" longer than stock for my truck.

    Looks like Casey got the rest of your questions answered.

    rene

    Edited due to dyslexia /forums/images/graemlins/whistling.gif
     
  5. DukeBoy88

    DukeBoy88 1/2 ton status

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    Rene, when you say 1/16" to the left, are you saying your timing is 1/16" retarded?

    I just checked what my filter was, all the writing was on the back it says "NAPA Gold - Fuel/Water Seperator - Primary 3123" I'm assuming there should be a secondary filter after this one. I'll try to track one down today, does anyone have a sugestion of what to use? I will look up racor to see what they offer.

    I'll check the frame mounted spring bushings, not sure why I didn't look there, or I did amd they were fine so I didn't remember. If there good, I'll fab some longer shackles.
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Thinking 'right'...typing 'left'. Post edited.

    My timing is advanced by 1/16". Sorry for any confusion.

    Rene
     
  7. DukeBoy88

    DukeBoy88 1/2 ton status

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    Found out the current filter is a 12 micron. how far should I filter down to?
     
  8. DukeBoy88

    DukeBoy88 1/2 ton status

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    I corrected my pump timing, it was loose. Made a huge difference /forums/images/graemlins/peace.gif . is there a gasket in between the pump and the housing? I'm tracking down an oil leak and didn't know if it might have originated there since it was loose. I'm going to pressure wash it today and park over cardboard and try to find the leak.
     
  9. arveetek

    arveetek 1/2 ton status

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    12 is rather large. I think the factory filter is 10 micron, but I could be wrong about that. A lot of guys like to filter down to 5 or even 2 micron. Of course, the newer, electronic high-pressure (20,000 psi) diesel injection systems are more affected by dirty fuel than our older, more robust Stanadyne (2000 psi) systems.

    You might look at the back of your intake manifold. Some of the early 6.2L diesels used a smaller, finer, secondary spin-on filter mounted on the rear of the manifold, pointed down in the valley. Could be somebody has swapped fuel filter systems.

    My primary filter is located on the frame, back by the fuel tanks, before the lift pump. I'm not sure if the factory 82-83 spin-on primary filter was before or after the pump. I know it was mounted on the firewall, but I can't recall if it was before or after.

    Casey
     
  10. arveetek

    arveetek 1/2 ton status

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    I just looked up the correct spin-on primary fuel filter for a '82 K5 w/6.2L diesel, and it came back as Napa 3123. I bet that means you also have a Napa 3124 secondary filter on the rear of your intake manifold.

    Chevy dropped the dual spin-on filters in 1984 and went with the Model 80 rectangular filter from then on until 1992, I believe. I don't know if somebody swapped filter systems on your truck, or if this is the correct setup for the military vehicles. I don't have any experience with the military trucks at all, just what I've read and studied on the 'net. Could be they retained the older system, which wasn't a bad setup at all, just a bit harder to service. When you think about it, a primary and secondary filter is the only way to go. The primary screens out the larger junk and water, while the secondary finely filters out the fuel before entering the inejction pump. I'm not sure why they went with just one filter later.

    It may very well be that you have the correct, factory fuel filters on your truck already.

    Casey
     
  11. DukeBoy88

    DukeBoy88 1/2 ton status

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    No filter on the back of the manifold, thats what I looked for initially. the line goes directly from the 3123 to the injector pump. would it be a good idea to follow this filter with a racor 2 micron? or replace it all together.
     
  12. arveetek

    arveetek 1/2 ton status

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    Yes it would be a wise thing to add a secondary filter between the current filter and the injection pump.

    Casey
     

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