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, Sat, 22 Jan 2005 19:21:16
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Over pressure in the PCV:
I still susptect that the PCV is not the cause of the overpressure. It just can't handle the amount of blowby gasses created by another problem. The only source for this is turbo boost pressure or gasses from the combustion chamber getting into the crankcase. So that typically means gas leaking past the head gasket sealing rings, loose head bolts, or past the pistons. Past the pistons can be bad rings/pistons, or pistons that have cracked. Cracked pistons means knocking and that suggests heavy oil mist getting in through the PCV system, but that is the end result not the cause, a chick and egg riddle. But ECU software could create knocking and piston damage. (There have been suggestions of the ECU doing lean AF during throttle transitions off of max boost, but still with enough manifold pressure to be at risk.)
So if the crankcase gets pressurized, how can that affect lubrication. If if means that the oil is consumed rapidly and you run low or out of oil, then there is a damage mechanism. Another possibility is that gas leaks past the HG seal ring and finds its way into the oil passages. If its an oil drain back passage, that is simply more gasses in the crankcase. If the high pressure gasses found there way into an oil feed passage, the oil would be blown out of the lubrication system to some extent. Gasses getting past the HG seal rings would evil from a chemistry point of view and fits in with the earlier posts of 'the problem' damaging the oil. Excessive blowby past piston rings would also be damaging to the oil from a chemistry point of view.
So it would not be any surprise if the problems was related to the loose head bolts. I have read posts where the problem with the head bolts was fixed for 2002 production. I have two 2002+ engines to worry about. And perhaps all of this crap goes back to the ?1997? switch to soft (cheap) stretch bolts and some automated torque machine that was totally bogus from the get go. Stretch bolts are tolerant of a certain degree of over torquing. But if they are not tight at all, then the problem lies with the process and not the bolts.
And as aways, Quality Assurance QA is responsible for qualifying the machine as been 'process capable'. They apparently failed in that, and furthermore, they should have been doing hand torque work on at least one engine per shift to detect any systematic problem with the torquing machine. That is the reason for their existance, that is what is so horrible about the head bolt problem, it could not occur unless someone was not doing their job. And it is the job of the QA Engineers to know about things, not be told what to check. So someone is incompetent or does not give a damm. Heads should role and there should be folks on the street for this. But in Sweden, that probably means a huge check from the government....
posted by 68.95.11...
, Sat, 22 Jan 2005 19:21:16
, Sun, 23 Jan 2005 18:38:13
, Sun, 23 Jan 2005 19:51:09, Sun, 23 Jan 2005 11:58:59, Sun, 23 Jan 2005 18:24:11, Sun, 23 Jan 2005 11:21:47, Sun, 23 Jan 2005 12:05:25, Sun, 23 Jan 2005 15:43:43, Sun, 23 Jan 2005 18:54:12
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