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nissan
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Hi guys,

For information – not a new member. My log on details did not work, so had to re-join.

Few quick questions please…

Have the 2003 ZD30. Motor is well serviced and running beautifully (220,000k) on clock. Just noticed a light oil smear on the drivers side of engine along where the head joins the block. Cleaned it off and it returns but cannot see where it comes from. The motor has always and is now running smooth and great. There are no bubbles in the radiator (though I did just replace the short hose that runs from the overflow bottle to the passenger side of the motor – and up until reading the forum last night was unaware that it is possible to cause an air lock in the motor!!!). Engine temps are great and never been a problem.

Motor is not NADS equipped but standard. I pulled the PCV hose (motor running) and there is only a very, very low pressure, very little mist – hardly detectable at all, but, when I remove the oil filler cap with the motor running the cap dances on the filler hole. There is a fair pressure pouring out the oil filler cap. Is this normal or indicative of a problem?

The oil cap is clean as a whistle and there is no cross contamination of oil/water etc. The dipstick is clean also.

I don’t want to disassemble a strong working engine unless it is imperative. Worried it may be a slightly cracked head or gasket, but no symptoms evident what so ever.

Finally, does the PCV itself or hose tend to get blocked on ZD30 – as I can’t figure out why the PCV hose has very low pressure but the oil filler cap has strong pressure escaping from it. Can the PCV valve be replaced?

Will be pulling the intercooler and maybe tappet cover for a gander in a coupla days...Any suggestions?

Thanxs in advance for your thoughts guys…

Steve in Cairns
 

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either cam/tappet cover seal or the injector seals.
both are easily replaced in the vehicle, and possibly just worthwhile doing anyway to rule them out as the source.

the oil filler cap can have 'strong pressure' due to pressure waves from the pistons going up and down....there is a positive pressure wave, and then negative pressure wave - so it looks like there is a lot of air escaping. When the pressure goes up into the PCV valve these waves kinda get cancelled out, so the blowpast doesn't look as drastic as it does at the oil filler.
 
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