Questions about head gasket, blow by, valve seals - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• Questions about head gasket, blow by, valve seals by hamradio on 12 Nov, 2007 14:09
• Ok,
  First off, what exactly is blow by?
  
  Next, I'm almost certain my headgasket is blown (oil leaks out right under the coolant fitting on the front of the block).  When I replace it, can I just use new head bolts from germanautoparts, or do I have to use arp head studs?  What's the advantage to using head studs on a 1.6na diesel?  
  Next, my IP is starting to pour.  Can I purchase a new main seal off ebay, tear the old seal out, put the new seal in, and be fine?  How tough is it to reseal a whole pump?  
  Last, when I pop my oil cap off, after running it or even briefly starting up and shutting it off (like running it for 5 secs), I see smoke slowly rise out of the hole.  Are my valve seals shot?  Is this normal, or is something really wrong?
  
  Thanks.
• #1 by jtanguay on 12 Nov, 2007 16:58
• head bolts are one time use only.  never ever re-use them (unless you have NO other option but come on... at like 1-2$ each.. if that... why not?)
  head studs can be re-used but read the instructions that come with them.  some specify the use of special moly lubes or regular oil, and torque specifications can change when using them (moly requires less torque than reg oil because of the reduced friction.  yes friction accounts for a portion of the torque value.)
  
  Soooo some people love stretch bolts, some people love studs.  if you've got money to burn why not studs?  :wink:
  
  blow by is caused by pressures leaking past the rings on a worn engine.  the gasses then flow into the sump area pressurizing it, thus sending it to the dip stick tube, through oil return holes in the block/head, and even past the rings on cylinders that are not on their power stroke, back into the breather hose which flows back to your intake.  if its really bad, it can gum it up really good.  
  
  rings such as totalseal (www.totalseal.com - i am not affiliated in any shape/form) seal by using a two part ring that sits in a groove.  the two rings are offset to create a total seal!  check their site for more info.
  
  re-sealing an old pump is not easy.  i would start by taking it to the nearest car wash (manual kind) and just degrease the crap out of the pump first.  make sure to get it as clean as you can, but don't go too nuts as you don't want to short anything out.  that way you have a clean pump and hopefully won't get any dirt inside.  CLEANLINESS IS OF THE UTMOST IMPORTANCE when working inside the pump.  no dirt whatsoever inside.  if that scares you to do work on your pump, good.  :lol: at least you'll take care when doing it.  next, search the forum for the post i think it is.. injection pump breakdown with pics.  re-sealing the pump off of the car is probably easiest to maintain cleanliness, but then you need timing tools and a bentley manual would be invaluable.
  
  go here: http://www.veg-injection-service.com/store/ for the pump rebuild kits, and at least you'll know its a bosch product.  again i'm not affiliated.  
  
  hope that helps.   i get smoke out of my oil cap hole too.  i'm not worried.  not a whole lot though.  as for the valve seals, dunno...
• #2 by hamradio on 12 Nov, 2007 20:30
• Ok.  I'll just buy new stretch bolts, don't have money for studs.  
  
  As for blowby, how do I know if it is happening?
  
  I own a bentley, also.  Pump is very clean from me cleaning my bay.
  
  Thanks.
• #3 by Black Smokin' Diesel on 12 Nov, 2007 20:38
• Quote from: "hamradio"

  Ok.  I'll just buy new stretch bolts, don't have money for studs.  
  
  As for blowby, how do I know if it is happening?
  
  I own a bentley, also.  Pump is very clean from me cleaning my bay.
  
  Thanks.

  
  
  Blow by is really bad when the oil get into the intake (coming from the breather) and you feel the engine rev by itself. It mostly happens on the highway or at steady speed where it's most noticeable. Some smoke from the oil cap is normal, no need to worry about that. If you valve seals were shot, the engine would "run away", meaning it would madly rev by itself until it has burned all the oil or seized.
  
  Best way to know if you have blow by problem is a compression test and leakdown test.
• #4 by burn_your_money on 13 Nov, 2007 04:54
• If you remove the oil cap with the engine running and white smoke is billowing out you have a serious blow by problem. You are probably looking at 350 PSI and shot rings.
  
  What seal is leaking on your pump? Some are easier to change then others and you can get away with changing just one seal most times
• #5 by hamradio on 13 Nov, 2007 11:19
• Ok.  Thanks.  I don't think my engine billows smoke while running.  As for the seal, the main seal is leaking.  I'd like to replace as many seals as easily possible, though, so biod doesn't get other stuff leaking.