1.5 solid 11mm head on 12mm 1.6 block?? carnage pics inside.. - page 1 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• 1.5 solid 11mm head on 12mm 1.6 block?? carnage pics inside.. by riceatingrabbit on 03 Jun, 2009 21:44
• UPDATE
  
  ok, I've run into a snag..
  
  I know that lots of people have put mech heads on  hydro blocks..
  
  but, I have just discovered a major difference between the two, and I need to know what yall are doing about it.
  
  The hydro block/head has two oil ( return?) holes on the front of the engine and the mech one does not..it only has the one in the center..
  
  see the difference in the gaskets:
  
  
  
  the block:
  
  
  
  and the head I am trying to get on it:
  
  
  
  
  heres how I see it:
  
  the extra hole must be a return hole.. because on the broken hydro head, its just a drain hole.. just like the one in the center but smaller..
  
  so, given that, oil is flowing down... So since the mech head doesn't have the hole, the one in the block will just be blocked and unused.
  
  AM I RIGHT?
  
  with that in mind, I should be able to bolt up the mech head with the mech gasket and be golden.. correct?
  
  
  but.. I think of another problem: why is the extra hole there on the hydro motor? maybe its because the hydro head is more thirsty for oil, and the block pumps more.. so am I going to be filling the head with oil? and not have adequate draining power? hmmm...
  
  I am really trying to get this sucker running, so, If you have ANY input please post..
  
  
  THANKS!!!
  
  
  Original post:
  
  HI!
  
  I know that this is probably a pretty common question on here and i know that i'm going to get the " search" comments.. and i have... but i want my own thread!!
  
  and i figure that you guys are nicer that the vortex crowd so i have my fingers crossed
  
  
  OK, heres the scoop:
  
  I just finished putting together an "new" ( 80k mile ) engine to replace the blown 1.5 in my rabbit..
  
  
  
  and... last weekend i had it going..
  
  
  
  it was running really well until the pump skipped time... The next morning i tore it back down to re time it.. yall know the procedure..
  
  I like to lock the crank in addition to the pump and cam... then loosen the cam gear to take any slack... I have had very good luck doing it like that and this time was no different.. except for one thing...
  
  
  I FORGOT TO TIGHTEN THE CAM GEAR!!!!!
  
  
  a few nasty clanking sounds later and the new motor was toast...
  
  
  
  
  
  
  
  
  TOAST!!!
  
  I feel like such an idiot for that..
  
  
  thats the background, heres the new situation:
  
  I am hoping that my pistons are ok ( I haven't been able to get the head off yet because i dont have the right tool ... gonna try and get one tomorrow.. ) what are the chances of that?
  
  
  and if they are, I can slap a new head on it and go...
  
  Ive already put too much money into this car...
  
  and i dont really want to go for a new head..
  
  especially because i have a very pretty ( CRACKLESS ) 1.5 solid lifter head sitting in my shop..
  
  its ready to go.. no expensive machine work required..
  
  pics:
  
  
  
  
  
  So, I am wondering about other people's experiences with this setup? is it's level of reliability any different that any other head?
  
  I have read about people drilling out the holes for the head bolts... is that safe? is there any other way? will there be head alignment issues?
  
  also, what do you do about the oil return on the front of the head? does it need to be machined to the diameter of the one on the block? or can it be left there?
  
  optimally, i would like to drill the head bolt holes and use stock 12mm head bolts and hopefully not have to mess with the oil return...
  
  
  that way ( assuming that the bottom end is ok) i can do this for the cost of a head gasket kit..
  
  what do yall think?
  
  
  
  
  
  
  
  
• #1 by riceatingrabbit on 03 Jun, 2009 22:11
• hmmm.. havent thought of the prechamber volume..
  
  does anyone know if they are different than the 1.5 head? maybe i could offset the effect by running the thickest gasket?
  
  
• #2 by maxfax on 04 Jun, 2009 01:00
• THe oil return does require some addressing..  You will need to make/use something like this, http://www.vwdieselparts.com/1.5-1.6.htm, with a 1.5 gasket... You'll probably need to ream the head bolt holes in the gasket to use the 12mm bolts...
  
  Drilling the head for 12mm bolts isn't too awfully scarey..    Measure and use the proper bit (I forget the exact size) I believe the head bolt hole that feeds oil to the head is a tad larger.... A drill press for this is highly recomended...  It's just too darn hard to hold a hand held drill perfectly straight, and you do need to drill these very straight!
  
  The precups are indeed smaller..   I suck at math but roughly it bumps the compression up to 23:1 I think....  A thicker gasket should help a bit (haven;t done the math to know exactly)..  But it would depend which gasket you already have too...
  
  My daily driver has a 1.5 block and head with a 1.6 crank rods & pistons..   Bascially the sam compression you would have with the 1.5 head on a 1.6..   Never actually checked the compression on it, but I have had no need to either... The darned thing runs DARNED great, and gets a consistant average mpg of 46 - 49 with mixed highway city driving.. And my driving habits are not fuel economy friendly.. I probably have about 75,000 miles on it now..
  
  The only problem I have with this setup is that I was being cheap and impatient and used head bolts during assembly....  Block cracked right from the get go..    Hence the reason I preach so much about the use of head studs...
  
  
  
  
  
  
  
  
  
• #3 by saurkraut on 04 Jun, 2009 05:57
• Stock 1.5 CR is 23.5:1
  
  Stock 1.6 CR is 23.0:1
  
  1.6 Block + 1.5 head:  25.3:1
  
  The swirl chambers are smaller in the 1.5 head.
  
• #4 by riceatingrabbit on 04 Jun, 2009 06:52
• It might be a long shot...
  
  I have a 1.6 mech head that is cracked...but it has good prechambers... I wonder if I could swap them into the 1.5 head?
• #5 by jtanguay on 04 Jun, 2009 06:58
• what if he say bought a bare 1.6 head from prothe and swapped the 1.5 junk in? would it even fit or are the valves bigger? seems like a lot less trouble than prepping the block for a mech head AND dealing with the extremely high CR, although this beast would start at -30C without glowplugs 
  
  damn dude... that is one tough lesson  judging by the damage to the head, i would almost have to say that the pistons shouldn't be too damaged, as it didn't happen at speed. there should only be imprints of the valves, and hopefully no mushrooming.
• #6 by riceatingrabbit on 04 Jun, 2009 07:04
• the damage diddnt happen at speed... it happened at start up...
  
  crank....crank....crank.... FIRE!.... CLANKCLANCKCLANK..... stop... it was a really really bad noise..
  
  
  
  
  
• #7 by maxfax on 04 Jun, 2009 13:51
• Quote from: saurkraut on 04 Jun, 2009 05:57

  1.6 Block + 1.5 head:  25.3:1

  
  Yeah, thats it!!
  
  I definitely had no problems starting the daily driver at -20 F with a gasser starter 
  
  Although I was using rather crude methods to measure, it does appear that the difference in chamber volume is in the head casting, not the insert...
• #8 by rabbitman on 04 Jun, 2009 14:50
• Sorry to hear that, it looks terrible.
  
  Going by the fact the your cam broke I'd say the pistons got hit pretty hard.
  
  X2 on swapping prechambers and using the 1.5 head.
• #9 by burn_your_money on 04 Jun, 2009 15:26
• I'd run the 1.5 head on the 1.6 bottom end. Your peak cylinder compression will still be lower then a turbo engine (I think). You would probably need to fiddle with the pump timing
• #10 by maxfax on 04 Jun, 2009 16:16
• Quote from: burn_your_money on 04 Jun, 2009 15:26

  You would probably need to fiddle with the pump timing
  

  
  Good point here too..  Mine chatters like a Chinaman in the arctic at 1mm..  .94 Has been working good for me, with burning WVO most of the time it's about ideal....  If I ran plain ole diesel all the time I woudl probably run a bit less...
• #11 by theman53 on 04 Jun, 2009 16:30
• It ain't that bad just swap the cam and get some new valve shims maybe a valve or 8 and your good to go
• #12 by riceatingrabbit on 04 Jun, 2009 22:02
• ok....
  
  i got the head off...
  
  and i come bearing good news! i think...
  
  each piston had a valve print in it...
  
  but, i cleaned them up, and all but one of the valve prints were in the carbon...
  
  I have one SLIGHT print on the number four piston, I couldnt even get a good pic of it... and its hard to see unless you run your finger over it and feel it..
  
  is that a problem or am i good?
  
  also, I noticed some pitting ( from fuel knock?) on the leading edge of some of the pistons... (see pics)... is that a problem?
  
  pics:
  
  
  
  
  
  
  
  
  
  
  
  
  
  what do you guys think?
  
  
  
  ALSO: I noticed that i can move each piston side to side a timy bit in the bore... is that normal???
  
  they are all moving the same amount, so i have my fingers crossed that it isnt a big deal...
  
  
  
• #13 by 88jetta350 on 04 Jun, 2009 23:44
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• #14 by Smokey Eddy on 05 Jun, 2009 00:42
• if the pistons didnt move at all i think there would be some metal on metal contact not metal on oil on metal on oil on metal contact
  a little play is good me thinks.
  i am sorry for your loss. Prothe sells new cam shafts for 55 US at least he did last year...
  nice looking engine buddy.
  
  We've all made silly mistakes. Be thankful that didn't happen at higher rpm.