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The mkiv Supra Owners Club

Found the problem with my BOV


Jake

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I think this might have been something to do with it.

Looking at the wear on the metal part it looks like my BOV hasn't been sealing for a long time.

 

 

http://www.imageshack.us/img1/783/BOV2.jpg

 

better pic of the worn BOV body :

http://www.imageshack.us/img2/4504/BOV3.jpg

 

 

A few of questions:

 

What improvement am I likely to see when I replace this broken BOV with one that actually seals properly?

 

Why did my car still behave normally with a constantly open BOV?

 

Will the fact that the BOV obviously hasn't been working right for ages have caused any damage to my turbos or anything else?

 

What about the missing part of the washer/seal thing? Has that gone through the 2nd turbo when it broke off? That can't be good, right?

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Originally posted by Jake

I think this might have been something to do with it.

Looking at the wear on the metal part it looks like my BOV hasn't been sealing for a long time.

 

 

http://www.imageshack.us/img1/783/BOV2.jpg

 

better pic of the worn BOV body :

http://www.imageshack.us/img2/4504/BOV3.jpg

 

 

A few of questions:

 

What improvement am I likely to see when I replace this broken BOV with one that actually seals properly?

 

Why did my car still behave normally with a constantly open BOV?

 

Will the fact that the BOV obviously hasn't been working right for ages have caused any damage to my turbos or anything else?

 

What about the missing part of the washer/seal thing? Has that gone through the 2nd turbo when it broke off? That can't be good, right?

 

Jake

 

This thread is very confusing to me so please correct me if I'm wrong.

 

AIUI your car was running fine but you spotted oil around the pipes of the BOV.

 

Oil around the BOV can only be a symptom of a problem, nothing whatsoever to do with the BOV as it shouldn't have any oil passing through it.

 

Are the pipes that go into the BOV oily at all, at either end?

 

My first instinct is slightly worn turbo seals, but without seeing the car its virtually impossible to diagnose with any accuracy.

 

Now to answer you questions

 

1) If its actually leaking you should see the boost you're loosing go to the engine so theoretically slightly more power.

 

2) I don't believe it was constantly open, if it was, you car wouldn't have behaved normally. It may have been leaking slightly and this could have reduced boost a bit.

 

3) I wouldn't be worrying too much because it has been leaking.

 

4) The missing part could have gone one of two ways, either straight into the engine, or through the turbos, depending if there was vacuum or pressure at the BOV when the piece decided to make its bid for freedom. Either way, in theory, is not good, but if the car is still running OK, you've got a good chance of having got away with it. It's only a bit of rubber, through the engine it probably wouldn't hurt anyway, through the turbos, it could be more damaging.

 

HTH

 

Geoff

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This thread is very confusing to me

You and me both Geoff!

 

AIUI your car was running fine but you spotted oil around the pipes of the BOV.

Correct

 

Are the pipes that go into the BOV oily at all, at either end?

Yes they are both oily at the end that connects to the BOV. Please see the picture here

 

 

I don't believe it was constantly open, if it was, you car wouldn't have behaved normally. It may have been leaking slightly and this could have reduced boost a bit.

It was leaking a lot Geoff. Look at the picture in my initial post in this thread, the seal is mostly missing. It was still providing some amount of restriction but not very much, I could easily blow through the BOV. I can't understand how the car was still managing to make 1.25 bar of boost. Seems like nobody else can understand it either! I guess I'll just have to replace the BOV and see what happens then.

 

Thanks for you thoughts, much appreciated.

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Jake,

Maybe your turbos are boosting to say 1.35bar but some of it was bleeding off through the dodgy BOV. Path of least resistance rules say that you won't immediately lose all your boost pressure through the BOV if it opens while the throttle plate is open as well, just a percentage of it. It's only when you shut the throttle that the boost has nowhere else to go but through the BOV - only then does it flow everything.

 

The oil would probably have come from the PCV hose that comes from the left hand cam cover into the cast ally air pipes, it's the only source of oil anywhere remotely near the BOV, and having a constant flow due to the leak would account for the relatively large amounts of external contamination. See if you can get the big hoses thrown in free with your replacement BOV, to stop blowby :)

 

Geoff, your answer number one doesn't make any sense :confused:

 

-Ian

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Originally posted by geoffvalenti

if the car is still running OK, you've got a good chance of having got away with it.

Ah! I've just remembered something: According to the receipts I got with the car it had "new turbos" fitted at 96,000 Kms (59,500 miles)

Looking at the state of the metal part inside the BOV the broken seal has worn into the the metal (see pic above) so it must have been like that for a long time, right?

I'm thinking that the BOV seal breaking off might have been the cause of the turbos failing back then.

 

Does that sound like a reasonable conclusion?

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Ian C Wrote:

 

Geoff, your answer number one doesn't make any sense

 

 

I was answering Jakes question

 

>What improvement am I likely to see when I replace this broken BOV with one that actually seals properly?

 

I replied: If its actually leaking you should see the boost you're loosing go to the engine so theoretically slightly more power.

 

 

I probably should have included "when you replace it"

 

I agree it, when read on its own it doesn't make a lot of sense :(

 

With the question I think it still stands :)

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Yeah, Geoff, that makes more sense :)

 

Jake - the seal would have been spat out into the non-compressed side of the turbos and got dragged into one of the compressor wheels which would really ruin it's day so you're probably as close to the truth as you're ever gonna get :)

 

-Ian

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