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The mkiv Supra Owners Club

Boost pressure reverberating


Dreamscape36

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Hi people

I have just replaced my stock BOV with a Bailey dump valve but I am getting reverberation through the dump valve basically, for want of a better way of putting it, it is farting.

The original BOV I believe was stuck open so I was getting a horrible grinding sound on depressurizing, when I held the throttle so it was kind of half open, half releasing.

I get a decent whistly dump now but it continues to dump like an echo afterwards several times and reverberates the internal part of the dump valve causing the horrible noise.

Any feedback, ideas or information would be greatly received.

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I spoke to the manager of Bailey Motorsport today and he told me they didn't make a BOV for a twin turbo but he said that didn't matter I just had it on the wrong outlet/inlet so I swapped them round and got no dump at all then so put it back.

So I am now back to square one with a horrible noise and no further in to resolving what it is :'(

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looking at the video the dump valve is open when its idling, it should be closed (will draw unfiltered air into engine), so will need adjusting or stronger spring, you may have issues with noise with the lenth of hose that you are using, dump hose not the signal hose, as chris wilson said it may be a nipple and adjuster in one on the end, try screwing that in first and see if you can get the valve to close on idle, hope this helps.

 

regards chris.

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Well I have now discovered that the vacuum nipple only undoes the nipple itself for replacement I guess and doesnt adjust the pressure. Also the vaccum hose its connected to has a constant suck so it is always going to hold the plastic collar open.

I guess I will have to wait for my new hoses so I can make it shorter to see if that helps.

Tearing my hair out here!!! Argh :(

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could you not take dump valve apart and put packers/spacers to increase tension on valve?.

the valve should only open when the throttle is let off, a few notes that may help you understand how to adjust your dump valve, when the car is idling the vacuum going to the dump valve is not enough to open it but when the throttle is let off whilst driving the vacuum will be higher than that at idle and will open the dump valve so venting any boost pressure.

you said in your last post that there is a constant suck that is correct, the suck varies with engine speed and throttle position and also sees boost pressure.

hope you get it sorted, regards Chris.

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Thanks Chris for your input I am finding it really helpful, I am going to the garage tomorrow to shorten my hoses and fit it as it should be. I will see if that solves the strange noise problem. But your pm was great, gave me more understanding of the whole system, I will try your suggestions after the correct fitting thanks again, will keep you posted.

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