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    Thread: Elantra CRDI - Excessive Crank Case Pressure

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      Elantra CRDI - Excessive Crank Case Pressure

      I am researching engine rebuilds.

      I have a 2006 Hyundai Elantra CRDi which has clocked 105k kms.

      I am having an issue with oil spitting out of the dip stick tube - with the engine idling and the dipstick pulled out (not otherwise) - esp if you have come back after a hard drive . There is also mild blowby. I have changed the PCV (pollution control valve) but the problem persists.

      This is indicative of excessive crank case pressure. I have no idea what else can contribute to this. According to the A.S.S this there can only be the PCV or excessive blowby. In my case I changed the first and the second - while I have blow-by its very marginal and no where close to what can be termed 'excessive'. The car's oil consumption is also okay (about 500ml between oil changes).

      Last I checked - my compression was around 18kgs (about 255psi) across all the cylinders. The company spec for a new engine is 30kgs (about 430 psi). 18kg is their prescribed lower limit below which they mandate a rebuild. The only issue with this was the engine had to be tested when hot, but had cooled down completely by the time they got around to doing the compression test. I have seen all kinds of variations being tabled between hot and cold compression tests. So I am assuming the compression will definitely come up when hot.

      What crank case pressures does is to counter the piston travel (sapping power) and stressing your oil seals etc (they can even fail). This also forces oil back up past the rings and gets burnt in the combustion chamber.. in worst cases this can result in a runaway!

      So how does the crank case gases travel from the crank to the vent in the head? Can these passages get clogged? I also read on some forums that a leaking vacuum pump can also end up pressurising the crankcase.

      This got me thinking about possible causes worth investigating and solutions if any.. IDEAS pls!
      Last edited by kb100; 25th Nov 2011 at 19:03.
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      PCV = Positive Crankcase Ventilation Sujit.

      yes, the passages could be clogged but your low compression [even when cold] would indicate bad ring sealing. guess there is no way to confirm this short of dismantling your engine and measuring your bore. you could also take the head off and perform a simple leak test.

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      Quote Originally Posted by kb100 View Post
      So how does the crank case gases travel from the crank to the vent in the head? Can these passages get clogged?
      Usually via oil drain galleries. Passages can get clogged if there is excessive sludge buildup, but in that case the oil in the head will not drain down into the sump either. So if oil can drain down to the sump then pressure will be balanced between crankcase and head. Increased crankcase pressure and low compression tells you to get ready for a bottom end rebuild in the near future.

      Leaking vacuum pump? You mean the vacuum pump used for brake booster? How is it connected to the crankcase?

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      Sujit, I guess there is no way to really be sure unless you open up the engine. And pray all you require is change of rings.

      If not I think you must just get a brand new block and stop worrying for another 1.5L kms

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      I am DISGUSTED with the SHEER IGNORANCE that the service guys possess these days! I have repeatedly found myself in situations where we knew more than them! Would you all believe it if I told you a bunch of people who have been with Hyundai Dealership right from inception had NEVER heard of a PCV valve! In fact I had to PROVE it to them the damn thing exists! They claim they have NEVER changed one in their lives!

      According to the company there can only be two reasons for Crankcase Pressure... Blow-By and blocked PCV Valve. Would you believe they don't even have the equipment to check Crank Case Pressure! Actually they haven't even heard of it!!!!! (The specific part is prescribed in their own service manual!)

      There can be FIVE reasons for excessive crankcase pressure.

      - Obstruction or damage to the Rocker cover breather.
      - Defective Air Compressor (Vacuum Pump)
      - Defective Turbocharger
      - Worn or damaged Valves
      - Worn or damaged Cylinders.

      Pls see the attached advisory from Detroit Diesel (the same engine) giving detailed steps to diagnose! (There are three pages of it - so please open up the whole article.)

      Given the relative lack of blowby, I will attack the first three first - in reverse! Thank you Techie for the heads-up!

      Click image for larger version. 

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      Last edited by kb100; 26th Nov 2011 at 10:33.
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      I dont really know if this could be related. In my Zen which had done about 2.5L+ Kms, an additive for enhancing engine compression was added. This additive supposedly sticks to the piston which is out of shape and makes sure there is no loss of compression. This eventually got stuck to the tapped/valves. Did you do something similar to this in your car? I mean an additive to enhance compression?

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      What you are looking at is worn piston rings or worn pistons. Check if the oil spits out from the dipstick when you rev the engine standstill. 90% chances are there for the oil to spit. Personally seen this on Accent CRDis and Elantra CRDis.

      You can use Bardhal - No Smoke or Rislone- Ring Seal or Compression Repair Solutions... These are additives/detergents that can restore your vehicles
      performance. I recommend Rislone than Bardhal. Do this every oil change and you can go with this for atleast next 50k kms..

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      Quote Originally Posted by kb100 View Post
      I am DISGUSTED with the SHEER IGNORANCE that the service guys possess these days! I have repeatedly found myself in situations where we knew more than them! Would you all believe it if I told you a bunch of people who have been with Hyundai Dealership right from inception had NEVER heard of a PCV valve! In fact I had to PROVE it to them the damn thing exists! They claim they have NEVER changed one in their lives!
      happens most of the time to most of the people here.. and same is the case with doctors, we know about our diseases more than them..
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      Quote Originally Posted by shyam View Post
      This additive supposedly sticks to the piston which is out of shape and makes sure there is no loss of compression. This eventually got stuck to the tapped/valves.
      More on this please
      Quote Originally Posted by XenonPro View Post
      Accent CRDis and Elantra CRDis.
      what is with accents and elantras? I see atleast one in every local garage with engines or gb taken apart and most are 60-90K run.

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      Quote Originally Posted by agn View Post
      what is with accents and elantras? I see atleast one in every local garage with engines or gb taken apart and most are 60-90K run.
      I have seen many Accents ( know its a 3 cylinder and may be the loss in balance paves way for pistons to eat up the walls.). But dont know about Elantra
      in workshops as you said. Improper oil change must be the culprit..

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