cover breather

hi all
i did change the rocker cover and its from 4EFE , the difference as you know is the breather port location and size , as the 4EFE breather port diameter is smaller than the 4EFTE one is there liability for any problems ?


Super Moderator
I would say it will probably be fine.

However, I would prefer to fit a 4efte cover or modify your current one if possible. It must have been done done for a reason by Toyota


Member +
it will only become a problem if you are planning to run 'heavy' boost which will generate elevated crank case pressure that will need a way to vent. if you are unlucky, seals at your plug silos and dizzy may give way and start leaking oil mist. if you are really unlucky, you'll pop your dipstick and splatter oil all over the place.


Member +
Certainly helps relieve pressure from the crankcase with a worn engine.
But the air breather is also designed to let air in to dilute the vapours that are removed in conjuction with the PCV .
With higher boost you have more fuel present which results in more fuel vapour in the crankcase and water vapour so more vapour dillution and removal is needed.
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thank you all . i will remove it and fit the 4efte one back as soon as i can , i noticed one change in the car when i fit the 4efe cam cover that the idel rpm droped from 900 to 700
any relation between cam cover and the rpm ?