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Thread: few questions on rebuilding 2.5l

  1. #1
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    few questions on rebuilding 2.5l

    bought a used turbo head and had it gone over. it was pressure checked resurfaced and valves done now thats its clean i noticed there a small chip next to the valve, it must not effect the valve seal area- is this fine or will it be a problem?





    secound question, engine was bored for replacement sealed power pistons, .030 should i have to check the ring gap or is that only when you re ring stock pistons ? rings are not installed (yes i know hyper pistons are weak)

    plasti-gauge bearings, got std bearings for rods and mains, old ones where great shape do i check them all or ?
    Last edited by Fox; 05-29-2015 at 12:39 AM.

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    Buy my stuff!!!!!!!!!!! :O) Turbo Mopar Vendor turbovanmanČ's Avatar
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    Re: few questions on rebuilding 2.5l

    Always, always, always check ring gap as well as other clearances. I would just pull the valve out and have a look.
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    Moderator Turbo Mopar Staff Force Fed Mopar's Avatar
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    Re: few questions on rebuilding 2.5l

    Some of those Sealed Power replacements are actually cast, not hypereutectic.
    Rob M.
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    Re: few questions on rebuilding 2.5l

    That chip looks like it took out some of the seat (at least in the top pic)..that is major no bueno..there may be a crack in the seat. Inspection mandatory!

    Checking ring gap is so easy theres really no way to justify not doing it unless you just took the engine apart twice in 48 hours or something like that...

    I personally dont check main or rod bearings anymore when I am taking the engine apart for an unrelated reason. If its the first re-assembly after you just got things machined then I would check it to verify everything is as it should be.

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    Re: few questions on rebuilding 2.5l

    ok then i'll check the ring gap and plastigauge everything, this is how i received the head back AFTER it was checked and surfaced and all that. it was not ran yet. so i should i take it back then ?

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    Buy my stuff!!!!!!!!!!! :O) Turbo Mopar Vendor turbovanmanČ's Avatar
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    Re: few questions on rebuilding 2.5l

    I don't check my own per say but buying someone elses, yes, its a must. Also, its been known for suppliers to put standard bearings in when they should be oversize etc.
    1989 FWD Turbo Caravan-2.5 TIII, GT35R, auto, a/c, cruise, pwr windows/locks, fully loaded with interior and ran with full exhaust. RETIRED FOR A FEW YEARS! 12.57@104 :O)
    1984 Chev Getaway van, 6.2 Diesel with a remote mounted turbo setup burning WMO-For sale.
    2003 GSW 2.0L TDI, auto, fully loaded, modified, 360K-wife's.
    2004 GSW TDI, 5 speed, fully loaded, modified.

    Aurora ignition wires for sale. Link to info

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  7. #7
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    Re: few questions on rebuilding 2.5l

    the valve sealing area is fine, lets just say the chip is cosmetic. will this cause pre-ignition ?

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    Re: few questions on rebuilding 2.5l

    Smooth it out, will be ok.
    1989 FWD Turbo Caravan-2.5 TIII, GT35R, auto, a/c, cruise, pwr windows/locks, fully loaded with interior and ran with full exhaust. RETIRED FOR A FEW YEARS! 12.57@104 :O)
    1984 Chev Getaway van, 6.2 Diesel with a remote mounted turbo setup burning WMO-For sale.
    2003 GSW 2.0L TDI, auto, fully loaded, modified, 360K-wife's.
    2004 GSW TDI, 5 speed, fully loaded, modified.

    Aurora ignition wires for sale. Link to info

    Super60 roller cams or custom/billet cams. Link to info

  9. #9
    turbo addict Turbo Mopar Contributor
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    Re: few questions on rebuilding 2.5l

    Quote Originally Posted by Fox View Post
    the valve sealing area is fine, lets just say the chip is cosmetic. will this cause pre-ignition ?
    Quote Originally Posted by turbovanmanČ View Post
    Smooth it out, will be ok.
    I think it would be a much bigger deal if it was next to the exhaust valve but no point ignoring it when its all apart. I wonder what caused that damage, of it that was already there.
    Brent GREAT DEPRESSION RACING 1992 Duster 3.0T The Junkyard - MS II, OEM 10:1 -[I] Old - 11.5@125 22psi $90 [U]Stock[/U] 3.0 Junk Motor - 1 bar MAP [/I] 1994 Spirit 3.0T - 11.5@120 20 psi - Daily :eyebrows: Holset He351 -FT600 - 393whp 457ft/lb @18psi 1994 Spirit 3.0T a670 - He341, stock fuel, BEGI. Wife's into kid's project. 1990 Lebaron Coupe 2.2 TI/II non IC, a413 1990 Spirit 3.0 E.S. 41TE -- 1993 Spirit 3.0 E.S. 41TE -- 1994 Duster 3.0 A543 1981 Starlet KP61 Potential driver -- 1981 Starlet KP61 Parts -- 1983 Starlet KP61 Drag 2005 Durango Hemi Limited -- 1998 Dodge 12v 47re. AFC mods, No plate, Mack plug, Boost elbow -- 2011 Dodge 6.7 G56

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    Re: few questions on rebuilding 2.5l

    my guess is it was damaged by a previous rebuild, it appeared very good shape and there aren't even cracks between the valves except for cyl1. i got it from a tbi car in the junkyard but its a TS head and has turbo exhaust valves.

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    Re: few questions on rebuilding 2.5l

    the valve seats are under alot of compressive force because they are an interference fit..I would be disturbed by something like a chip missing from one of them..combined with how much thermal stress they deal with that seems like a time bomb

    at the very least it suggests poor quality work as far as installing the seats and or subjecting them to trauma...

    is the chip missing from the seat or the head? hard to tell from the pics. if its from the head id probably just ignore it..although really that is also not good..but way better than it being the seat itself.

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    Re: few questions on rebuilding 2.5l

    chip is in the head only, really not to happy about it but don't want to trash it after just having the work done on it. i know my machine shop didn't cause it they wouldn't be careless and damage something like that

  13. #13
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    few questions on rebuilding 2.5l

    I would definitely bring it back to the machine shop. You risk dropping a seat if you don't confirm it. Dropping a seat equals instant carnage. Personally I wouldn't run the head myself with it like that. It's repairable but most likely not cost effective to do so

  14. #14
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    Re: few questions on rebuilding 2.5l

    Quote Originally Posted by moparmike70 View Post
    I would definitely bring it back to the machine shop. You risk dropping a seat if you don't confirm it. Dropping a seat equals instant carnage. Personally I wouldn't run the head myself with it like that. It's repairable but most likely not cost effective to do so
    Am I correct that the problem with repairing that is that once you add material with TIG, you'd have to bore out the seat counterbore bigger than it previously was, which would mean a special seat would need to be made just for that bore? Can they make a custom seat on the spot no big deal or is that not a standard procedure? I would think a bigger OD off-the-shelf seat could be fit in, then the ID could be cut to size during the valve job using standard procedures?

  15. #15
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    Re: few questions on rebuilding 2.5l

    The seat would have to be removed for sure and replaced. As far going to a larger seat od I'm not sure if they would have to do that or not.

  16. #16
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    Re: few questions on rebuilding 2.5l

    Quote Originally Posted by moparmike70 View Post
    I would definitely bring it back to the machine shop. You risk dropping a seat if you don't confirm it. Dropping a seat equals instant carnage. Personally I wouldn't run the head myself with it like that. It's repairable but most likely not cost effective to do so
    This, I would do this.

  17. #17
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    Re: few questions on rebuilding 2.5l

    ok thanks everyone, will take it back tomorrow or friday and if necessary i'll just have a different head rebuilt

  18. #18
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    Re: few questions on rebuilding 2.5l

    rings are Hastings 2M4206 030 (marked moly on box)

    ring gap measurements

    piston___ top____ 2nd ring___ oil control rings
    1-_____ .017_____ .013________ .035__.035
    2-_____ .017_____ .013________ .035__.035
    3-_____ .017_____ .014________ .032__.032
    4-_____ .017_____ .013________ .032__.035

  19. #19
    turbo addict Turbo Mopar Contributor
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    Re: few questions on rebuilding 2.5l

    If the damage is only in the head this is a huge waste of money.
    Brent GREAT DEPRESSION RACING 1992 Duster 3.0T The Junkyard - MS II, OEM 10:1 -[I] Old - 11.5@125 22psi $90 [U]Stock[/U] 3.0 Junk Motor - 1 bar MAP [/I] 1994 Spirit 3.0T - 11.5@120 20 psi - Daily :eyebrows: Holset He351 -FT600 - 393whp 457ft/lb @18psi 1994 Spirit 3.0T a670 - He341, stock fuel, BEGI. Wife's into kid's project. 1990 Lebaron Coupe 2.2 TI/II non IC, a413 1990 Spirit 3.0 E.S. 41TE -- 1993 Spirit 3.0 E.S. 41TE -- 1994 Duster 3.0 A543 1981 Starlet KP61 Potential driver -- 1981 Starlet KP61 Parts -- 1983 Starlet KP61 Drag 2005 Durango Hemi Limited -- 1998 Dodge 12v 47re. AFC mods, No plate, Mack plug, Boost elbow -- 2011 Dodge 6.7 G56

  20. #20
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    Re: few questions on rebuilding 2.5l

    no this was a free engine i received that needed a rebuild, in the process i found the chip near the valve (after work was done on the head) the lower end definitely needed to be rebuilt. bores where worn and rings where all froze up on the pistons, being the first time ive done this just have some questions and don't know the proper specs for everything, thats why i'm asking

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