View single post by Judson Manning
 Posted: 04-26-2005 02:34 pm
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Judson Manning

Joined: 03-14-2005
Location: Atlanta, Georgia USA
Posts: 406

JHs tend to have a lot of blow-by by nature of the piston-to-wall clearance, and to complicate matters, the engine wasn't originally designed for Positive Crankcase Ventilation.

The MkI's crankcase ventilation was so much an afterthought, they needed the vapor separator I mentioned.  The JH5 incorporated more 'positive' ventilation by adding the tube from the oil filler neck to the airbox.  It didn't get 'perfect' until the Esprit had to start passing emission requirements 10+ years later.

The blow-by gasses contain much more unburned hydrocarbons (HxCx)than they do combustion by-products (H2O, CO2, NOx, etc.).  These unburned hydrocarbons are what contaminate your engine oil, and cause smog.  It's the same principal as cows breaking-wind (methane C2H4) contributing to global warming.

By routing the blow-by back into the engine, it at least gets the chance to be burned into H2O & CO2 instead of being vented directly to the atmosphere as HxCx.  The trick is to keep oil from contaminating your intake...hence the separator.

Granted, the JH isn't the most ecologically friendly vehicle on the road....but I'm at least trying to do my part to save the planet.