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Bad Compression GSR Motor

Discussion in 'General Tech and Maintenance' started by GlassHeadlights, May 31, 2012.

  1. GlassHeadlights

    GlassHeadlights West West Yall

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    Motor: '95 B18C1

    Mileage: 320,000 KMS or 200,000 Miles

    History: Second owner, original owner was a lady. Motor has been babied up until the last 15,000 miles (When I got it).

    Motor has been running excellent up until this week...beat a fox body on the highway and thats when I noticed a half misfire out of the exhaust at idle. Motor has no knocks or ticks. Cylinders 1,2,4 have 240 PSI and cylinder 3 has 190 PSI. I inspected the valve clearances and timing and thats all ok so it must be in the bottom end. It burns a bit of oil but I'm always on top of it.

    My guess is rings or a bearing is about to go. Would the knock sensor pick up a bad bearing?
     
    Last edited: May 31, 2012
  2. reikoshea

    reikoshea HS Troll...And Mod Moderator VIP

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    My guess would be rings. Generally a bad bearing wont decrease the compression.

    To answer your question about the knock sensor, no it won't except in VERY rare circumstances. Knock sensors are designed to only go off when they detect a vibration between 6khz and 8khz.

    I'd imagine you'd only find that frequency AFTER the cap has been destroyed, and not for very long after that.
     
  3. GlassHeadlights

    GlassHeadlights West West Yall

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    So the knock sensor is for detonation?
     
  4. reikoshea

    reikoshea HS Troll...And Mod Moderator VIP

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    Yup. Generally pre-detonation has a specific frequency range that the knock sensor is looking for.
     
  5. GlassHeadlights

    GlassHeadlights West West Yall

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    Alright, my dad and I are thinking I burnt a valve. So the car is getting parked and I'm going to pull the head. Really I should rebuild the thing but I'm on a college budget now :/
     
  6. reikoshea

    reikoshea HS Troll...And Mod Moderator VIP

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    I totally misread your intro post as 'Inspected the valves' and not as 'valve clearances'
     
  7. GlassHeadlights

    GlassHeadlights West West Yall

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    Lol yup. My reasoning for a burnt valve is that I've been open header for a while....my new header has broke in many places and I can't use my exhaust.

    The head should be off tomorrow.
     
  8. CAFROG

    CAFROG Honda Minion VIP

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    Pieces? What happened when you got a hold of the Private Label Vendor?
     
  9. GlassHeadlights

    GlassHeadlights West West Yall

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    Yes...pieces... -_- they didn't like the lower bracket I welded on. I'm attending a trades college for welding so I'll fix the damn thing myself.
     
  10. Dual-500

    Dual-500 Well-Known Member VIP

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    That's a good idea. I haven't done the SS work on mine yet either. But, my engine is out again, short block at the machine shop. Oops! :D
     
  11. GlassHeadlights

    GlassHeadlights West West Yall

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    Oh no! Haha time for an even more bad ass build now!

    The valves seem ok but I'll still freshen up the head. The cylinder walls look alright for their age too.

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
     
    Last edited: Jun 2, 2012
  12. Dual-500

    Dual-500 Well-Known Member VIP

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    I trashed mine draggin a Dodge Ram Hemi. Of course it's getting turned up another click or two while it's out! :D
     
  13. CAFROG

    CAFROG Honda Minion VIP

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    Brad, so you did the gasoline trick with the head off to ensure the valves are not the compression problem??
     
  14. GlassHeadlights

    GlassHeadlights West West Yall

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    The little Hondas that died tryin! :)
    Nope I'm not aware of the gas trick. :confused:

    The head has been completely stripped and ready for the machinist tomorrow. Because of the age I'm going to get it rebuilt anyways. Hot tank, valve grind, valve seals and I might talk to him about porting. I'd like this thing to be a screamer one day.

    [​IMG]
    [​IMG]
    [​IMG]

    One of the cam cover bolts was bent and narrow in the middle (if you look closely) factory defect?

    [​IMG]
     
  15. dc4dude

    dc4dude Member

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    maybe overtorqued????
     
  16. Dual-500

    Dual-500 Well-Known Member VIP

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    Could have been overtorqued, but to change to that degree, unless the tempering is way off - I'd say just a defect at manufacture. On many threaded fasteners the threads are applied via rolling dies and not cut.
     
  17. CAFROG

    CAFROG Honda Minion VIP

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    Did you check the bottom of the head (deck) with a nice and true metal straight edge?

    Gasoline trick is super old school... when you place the head on a bench upside down (bottom of valves exposed) and pour gas into each dome (cylinder). If they stay the same level....no leak that caused compression. If some disapears....found a problem (like valve seats/job/etc.) Narrows down the culprit :shrug:
     
  18. GlassHeadlights

    GlassHeadlights West West Yall

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    Crikey! I may have overtorqued it! The threads in the head didn't look good. (I had this head apart to do the LMAs before) I'll order a new one.
    Nice I shoulda done that! I'll keep that for future reference.

    The head was dropped off today for cleaning/inspection/ect.

    I have some questions regarding the block rebuild, thread :moved: to my original build. lol :rolleyes: http://hondaswap.com/auto-multi-media/brads-ej1-coupe-521145/
     
    Last edited: Jun 5, 2012
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