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6.2 origin question

Discussion in '1982-Present GM Diesel' started by tRustyK5, Nov 17, 2002.

  1. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    OK, I've read here the 6.2 was designed from the ground up by Detroit Diesel for GM. Now that I have one to look at (and clean...) I noticed something odd.

    At the back of the motor is a plug with a hold down bracket. It looks very much like a distributor hole and a distributor hold down bracket. Why would any purpose built diesel engine have a distributor hole?? /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif

    Rene
     
  2. jeffro

    jeffro 1/2 ton status

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    It runs the vacuum pump and/or tach drive.
     
  3. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    That's where your vacuum pump goes. Diesels don't produce vacuum like a gasser, so the truck needs a source of vacuum to power the accessories. It operates on the exact same principles as a distribitor, so I imagine the engineers "borrowed" the concept from a gasser and incorporated it into the diesel design.....
     
  4. Tybee

    Tybee 1/2 ton status

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    That seems like a good question. I know its for the pump but why not a belt driven pump? How are the vaccuum pumps on the larger detroit engines?
     
  5. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    OK, now for what seems like an obvious question...why isn't there a vacuum pump on my 6.2?

    Is there supposed to be one...or did i get some oddball?

    Rene
     
  6. OFFRDK5

    OFFRDK5 1/2 ton status Premium Member

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    Theres just a big hole there where the distrib should be? If you do and its open I would call the guy and ask him what happened to it. Really important thing to have!!
     
  7. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Your 6.2 DEFINITELY should have come with one. On the plus side, unless you plan on using a tranny with a vacuum modulator(which I highly doubt seeing you're so goddamn keen on your 465/forums/images/graemlins/wink.gif), the only purpose the vacuum pump serves is to power your accessories(vent control, cruise control).

    You really should have a vacuum pump, but I *believe* the motor can still run without it in place.

    FWIW, I replaced mine about 5 years ago and the only place I could find one was at ....gulp..... the dealer. It cost me about $350 CDN for a brand new pump, not a rebuild. However, someone her told me that there are rebuilt vacuum pumps available now......
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I suspect there isn't a pump there because the motor was originally mated to a 465...therefore no vacuum modulator to feed. Mine has a round steel plug with a dist hold down in it's place.

    I'm prolly picking up a C30 parts pig...it's a 6.2 and it does run although the guy thinks the injector pump is bad. It starts real hard but runs OK after that. I'm thinking it may be glow plugs or a controller? Anyways, the truck will have all the little bits and pieces I need to complete the swap, and it's only $300 US

    Paulie...just imagine all the 6.2's low end grunt multipied by 6.55, then by 1.96 and finally by 4.56. It'll "Tow a house" or climb a shear wall if it so desires when it's done.

    rene
     
  9. arveetek

    arveetek 1/2 ton status

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    Do you know what your 6.2L came out of? The 89 and up trucks use a belt-driven vacuum pump instead of the gear-driven style, and therefore had a cover plate installed in place of that pump.

    Yes, the 6.2L was designed by Detroit, but I don't know why they chose to use that "distributor" style vacuum pump. It is exactly the same as the distributor on a gasser engine. The vacuum pump also drives the oil pump, so your cover plate still should have a gear on the end of it which drives the oil pump.

    Casey
     
  10. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    My 6.2 came out of a 85 K20 with a SM 465. It also has no EGR...so it must have been a heavy emissions truck?

    Rene
     
  11. arveetek

    arveetek 1/2 ton status

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    The J code engines are heavy duty and the C code engines are light duty. You probably have a J code, no EGR. Usually found in 3/4 and 1 tons.

    The '85 would have had a gear-driven vacuum pump from the factory. Either the engine was not original or the PO removed and plugged the pump.

    Casey
     
  12. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Obviously I can't say for sure but the plug looks like a factory piece and it looks to be original...I'll make sure to take a pic and post it. So I guess I got a J-code then...saves having to look for a J-code manifold later/forums/images/graemlins/wink.gif

    I'll poke around my Chiltons for a while and see what I find (probably nothing...)

    Rene
     

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