Compression Test Hot Injector Removal

Discussion in 'VW Mk3 Jetta, Passat TDI and other/older diesels' started by ftm1776, Jul 23, 2017.

  1. ftm1776

    ftm1776 New Member

    Joined:
    May 26, 2014
    Messages:
    21
    Car:
    1991 VW MK2 Jetta 1.6 Diesel, Engine code ME, Non-turbo, 5 speed AWY transmission, No AC
    Location:
    Vancouver,WA
    Mods:
    Coming up on rebuild time....
    Bentley say "normal operation temperature". About 180F for my cylinder head.

    Is it a good idea to first remove the injectors with the engine cold and clean the threads and apply some anti-seize?? Then warm it up.

    I'm a little concerned about taking the injectors out of a hot aluminum head. I was taught no to do that on my old Beetle plugs.
     
  2. crsmp5

    crsmp5 Well-Known Member

    Joined:
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    1,550
    Car:
    85 kubvan
    well on a tdi the glow plug is removed to check compression... no idea why any one would remove a injector..

    but no the injectors are not threaded into the head.. only the crows foot..
     
  3. ftm1776

    ftm1776 New Member

    Joined:
    May 26, 2014
    Messages:
    21
    Car:
    1991 VW MK2 Jetta 1.6 Diesel, Engine code ME, Non-turbo, 5 speed AWY transmission, No AC
    Location:
    Vancouver,WA
    Mods:
    Coming up on rebuild time....
    My Bentley (VG92) says: "Using a 27 mm deep-well socket, unscrew the injector from the cylinder head." Page 6-22.
    Figure 5-28 shows the exploded view of the fuel injector with threaded lower body, a match on my vehicle.

    The Harbor Freight compression tester has adapters to use either the injector or glow plug location.
     
    Last edited: Jul 23, 2017
  4. crsmp5

    crsmp5 Well-Known Member

    Joined:
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    Car:
    85 kubvan
    must be why i said tdi not idi...

    so now common sense... steel comes outta warm aluminum with ease vs cold in heat expansion crap... so i think a smart person gets it good n warm.. does compression test.. lets cool over night does cold test.. then puts back together.. how i do it.. but idi heads love to break the injector thread boss.. so.. unless your looking for a excuse to put a tdi-m in.. id drive it till you were ready too..

    you can buy a mk4 tdi long block for far less then a rebuilt idi.. add in a rover pump and your golden.. and people sell them for 350-1k online.. depending on rebuilt or not... so think worst case 2k in cost vs rebuilding a old idi.. more hp, more effecent, runs cooler.. no more pre cup weakness... slowly converting my fleet into tdi-m
     
  5. audi1z

    audi1z Member

    Joined:
    Oct 16, 2010
    Messages:
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    Car:
    Audi 80 1Z Engine
    I understand you want to do some maintenance with your Jetta in the signature.
    Threaded injectors were indeed used with the earlier turbodiesel engines, but not later with TDIs. The injectors are unscrewed using a 27mm deep well socket (I still have one).

    Never (un-)screw anything from or into a hot cylinder head, you risk the threads.
    Compression testing is requested to be done at ambient temperature. Your manual seems to be wrong.

    Added: and do not lubricate the threads!
     
    Last edited: Jul 24, 2017

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