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1995 S4s Won't Build Boost, Loud Whooshing Under Load- Blow off valve or wastegate? - Page 2 - Induction/Turbo/Chargecooler/Manifold/Exhaust - The Lotus Forums - Official Lotus Community Partner Jump to content


1995 S4s Won't Build Boost, Loud Whooshing Under Load- Blow off valve or wastegate?

Go to solution Solved by jonwat,

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An audible "whoosh" is just so typical of a BOV. I'd double back onto that trail, can't think of anything which could generate a comparable sound. 

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Easy way to check your plenum gaskets. Start the car. With a small diameter piece of plastic tube, one end in your ear and run the other around the gasket position. If it is sucking or blowing, you’ll hear it as clear as a bell. 

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Makes sense.

It looks like only modifications to the stock vacuum lines to accommodate the BOV is a T that goes into one of the lines running on the back side of the engine. It seems pretty simple to just pull it and place a cap on the T or even just use a barb splice to reconnect the stock hoses.  The vent tube is external and just hangs down so that is pretty easy.

Suggestions on where to get a good replacement hose to span the intake to the charger cooler?

I will definitely test the plenum too.  @ramjet thanks for the tip there.

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SJ will sell the stock piece of silicone tubing to replace the Tee where the BOV is.  Or you can buy the correct diameter from hundreds of vendors on E-bay etc.  I forget what the diamter is 2.5" or 2.25" I believe.   You get what you pay for their, quality all over the map.

In 5 minutes you can pop the BOV out and manually push the plunger in and out and see if that is likely the problem.  My last one could be disassembled and I could see where the plunger had deteriorated and was sticking.  

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11 hours ago, Bomb Factory said:

so its just the one part number that gets me both parts of the gasket or do I need to order two?

Give them a call & ask, they were always helpful to me whenever I had a query :thumbup:


John W

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