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Old 11-02-2012, 02:12 PM
Tech II Tech II is offline
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Re: 2000 Lesabre - Massive vacuum at oil cap

My first answer would be the o-rings at the PCV valve and MAP housing, but you have already replaced those....wouldn't hurt to double check though....

If not that, the only thing I can think of would be lower intake gaskets leaking.....

One thing to try: Remove the oil fill cap...get a can of carb cleaner....attach red tube to nozzle....stick tube in the valve cover at the fill cap......use your hand to seal the tube in the valve cover....have someone start the car.... then with the vehicle running, give a couple shots of carb cleaner into the valve cover....if the idle changes, then you know the carb cleaner is being sucked into the intake, which it shouldn't.....could be a bad lower intake gasket....could be the gaskets were replaced on the vehicle before and were incorrectly installed(moved during installation, not properly torqued, etc.)....could even be a crack in the lower intake, though I have never seen one....

Has vehicle been scanned for codes?
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