26 lbs boost, head gasket...poof - page 1 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• 26 lbs boost, head gasket...poof by rodpaslow on 11 Oct, 2011 10:02
• I have a vnt where my control cable came apart and I fixed it and was trying to set it when it hit 26 psi and the head gasket went poof. on the back side of the head leaking oil and engine will not run.
  
  I've got all the good stuff, metal head gasket, arp head bolts to 110 ft.lbs.
  
  I've heard of people going up to 30 lbs of boost.  What have I missed, as I would like to stick with about 25 lbs of boost.  Is it too high for the aluminum heads?
• #1 by vanbcguy on 11 Oct, 2011 10:55
• Boost levels aren't nearly as important as EGTs / coolant temperature.  Do you have an EGT gauge?
  
  Also you list a metal head gasket, are you running this on a 1.6TD or an AAZ? Do you know if your head was surfaced well enough for the metal gasket?
• #2 by RabbitJockey on 11 Oct, 2011 14:30
• what vnt do u have?  back pressure could have had a lot to do with it as well, especially if your vanes were not fully open at 26psi.
• #3 by R.O.R-2.0 on 11 Oct, 2011 17:26
• my head gasket left the engine at around 35psi.. on a 1.5D..
  
  you have a VNT15 also, right?
  
  making that much boost, the turbo is about ready to fly apart..
  
  i run my vanes in the open position, and get about 18-20 psi if i leave my foot in it..
  
  
• #4 by nathan_b on 11 Oct, 2011 17:29
• 25 psi should not make any vw head gasket go poof instantly. something else is up.
  
  also, with leaking hg, engine should run, sounds to me like rod made friends with block....
• #5 by RabbitJockey on 11 Oct, 2011 17:51
• Quote from: nathan_b on 11 Oct, 2011 17:29

  25 psi should not make any vw head gasket go poof instantly. something else is up.
  
  also, with leaking hg, engine should run, sounds to me like rod made friends with block....
  

  
  25 psi from a vnt15 is probably over 30 psi in the exhaust, or more especially if the veins are not entirely open.  keep in mind what the exhaust side is doing.  and at 25 psi vnt15 is blow lots of hot air, plus a *** load of back pressure, its not a good situation
• #6 by Alcaid on 11 Oct, 2011 22:46
• Also there is a big difference between 26psi @ 2000rpm and 26psi @ 4000rpm (turbo efficiency, peak cylinder pressure, EGT) At what RPMs did you blow your HG?
• #7 by R.O.R-2.0 on 12 Oct, 2011 08:47
• ive never had a gasket blown soo bad that it wouldnt run..
  
  even when i blew the head off my 1.5D and cracked 7 head bolt holes, i still drove it home the next day. it took 5 gallons of water to go 2 miles tho..
• #8 by rodpaslow on 12 Oct, 2011 09:08
• I certainly hope its nothing else than a head gasket.  It would start and run for a few seconds, but I've had a head gasket go a while back on a 1.5 I had and it starts and has a thick/grey cloud like that 1.5. To me that means it using oil from the motor.  There were a couple of oil spots on the ground from the back of the engine I saw after I had it towed home.  It's a '92 1.6 td with a vnt15.  Metal AAZ gasket.  My egt was not working at the time, I have it in the wrong spot.  I will be drilling an adding it to the right spot after taking the head off.  As for setting of the VNT, vanes were mostly closed at this point as it was full throttle and I see I'm MUST need to add a boost can as it may have overshot 26 pounds...roughly 3200-3400 rpm at the time.
  
  Coolant temp was right at normal, as I'm on boost it starts from about 200° and goes to 212-220° depending on how long I'm on boost.  I never lost any coolant as that was the first thing I checked.  Normal coolant pressure was being held even after the "poof". 
  
  Question I have too is if I add a boost can (vnt boost can reversed) as boost rises to a point the can starts to work, will not boost decrease as pressure rises?
  
  Whats the easiest way to check if anything else had been damaged with the head off.  Check that all pistons protrude roughly the same amount?  That will ensure I haven't bent a rod?
• #9 by R.O.R-2.0 on 12 Oct, 2011 09:22
• yea, theres no way your METAL head gasket crapped the bed at 26psi..
  
  my FIBER gaskets last better than that. i think something else is your problem..
• #10 by fatmobile on 12 Oct, 2011 21:57
• Timing belt probably jumped a tooth on the injection pump.
  
   I pegged the gauge on my 1.5D with a VNT,.. about 35psi, if I didn't have ARP studs it probably would have done the same as ROR's.
• #11 by R.O.R-2.0 on 13 Oct, 2011 07:35
• yup. something isnt right. that head gasket is fine.. i almost hit 26 psi yesterday on my 11mm stock n/a 1.6 (stock fiber gasket, and stretch bolts)
• #12 by rodpaslow on 13 Oct, 2011 09:03
• Well I was able to do some work on it last night.  I have everything off the back of the engine except the turbo.  What was weird is when I pulled the intake about 1/4 litre of oil poured out onto the floor (It was enough to coat most of the floor below the engine).  Where would that oil come from?  My first thought was the turbo.  Once I take that off I will check the cool side and make sure it's not full of oil and I can check my intercooler as well.  It they don't have any oil it had to come from the engine.   If they have oil, is my turbo cooked?  I have a spare vnt if I need it....
  
  Well see what else I can fine tonight as an issue.
  
  I was thinking I might pull the injectors out and turn the engine over before I pull the head.  Clear any oil that may be in it, but the injectors back in and see if it will start.  The more I read this the more I think its not the head gasket.
• #13 by vanbcguy on 13 Oct, 2011 10:56
• Wow, that's a lot of oil in the intake...
  
  Generally oil in the intake is coming from the breather, but that sounds like WAY more than I'd expect.  Any chance the turbo drain line was blocked somehow?  What condition is this engine in otherwise?
  
  Usually the turbo wouldn't puke that much oil out the cold side even if its seals were completely gone, since the cold side is pressurized most of the time whereas the oil drain is at atmospheric, so there shouldn't be any oil pressure there to leak out.
  
  Hmm what kind of breather do you have going on?
• #14 by rodpaslow on 13 Oct, 2011 11:11
• And there wasn't much oil, I don't think any oil came out the hot side, there was just a bit on the outside of the turbo.  I'll be removing it tonight so I'll know a bit more then.  Then engine before this had about 15k miles on it, relatively new rebuild with no previous issues.  I was just at full bore when this happened.  1.6 td with a vnt15, going hard on the throttle.