SR20DET Bad Headgasket? Something else? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Monooxide · 04-03-2009, 06:10 PM

The HG can fail and still yield good compression numbers. The HGs main job is of course to seal off the combustion chambers but also remember that it divides off the oil galleys and coolant passages from the block to the head. If one of those were to not seal from coolant passage to oil galley this would give you the exact issue.

Be sure coolant isn't getting into your oil as this can damage bearings. Also, if there isn't coolant in the oil really this would point even more to the above mentioned problem because the Oil Pressure will be higher than the coolant therefore the oil will flow from the oil galley to the coolant passage and the coolant wouldn't be able to flow into the oil galley.

Good luck.

04-03-2009, 06:10 PM	#13
Monooxide Zilvia Addict Join Date: Mar 2005 Location: Farmington/Flint, MI Age: 37 Posts: 675 Trader Rating: (8) Feedback Score: 8 reviews	The HG can fail and still yield good compression numbers. The HGs main job is of course to seal off the combustion chambers but also remember that it divides off the oil galleys and coolant passages from the block to the head. If one of those were to not seal from coolant passage to oil galley this would give you the exact issue. Be sure coolant isn't getting into your oil as this can damage bearings. Also, if there isn't coolant in the oil really this would point even more to the above mentioned problem because the Oil Pressure will be higher than the coolant therefore the oil will flow from the oil galley to the coolant passage and the coolant wouldn't be able to flow into the oil galley. Good luck.