Hiss, air leak?

**Squirtydog** · Monday 25th November 2013, 12:56

Have started to notice an unusual hiss noise on harder acceleration on occasions.
Seems to come from behind the instrument binnacle.
Any offers?

I know that I need a new exhaust manifold gasket but that is a different noise.

**M-R-P** · Monday 25th November 2013, 13:14

Do you have a boost gauge? if not, there's nothing behind the DIM that can make that noise.

**V70 Graham** · Monday 25th November 2013, 13:16

A snake....don't laugh, it's been know to happen.

**M-R-P** · Monday 25th November 2013, 13:19

"Snakes on a Volvo" just doesn't have the same blockbusting ring to it I'm afraid

**V70 Graham** · Monday 25th November 2013, 13:20

Originally Posted by M-R-P

"Snakes on a Volvo" just doesn't have the same blockbusting ring to it I'm afraid

Awwww phooey, thought I was onto something then lol

**graemewelch** · Monday 25th November 2013, 15:56

only thing i could thing of is a split pipe in the turbo intake pipe. could be anything though.

**Squirtydog** · Monday 25th November 2013, 19:34

Thanks... I'll have to have a general check over with someone who knows what they're looking at.
Failing that I'll buy a mongoose.

"I've had it with these mother££££ing snakes in this mother££££ing volvo!"

**thebadger** · Monday 25th November 2013, 19:38

Could be a leak in the recirculating valve on the turbo.

Basically your BOVs diaphragm has sprung a hole & it's probably letting gasses escape.

Unfortunately the only way to check it is to remove it see what state the rubber part is in.

**Squirtydog** · Monday 25th November 2013, 19:41

Originally Posted by thebadger

Could be a leak in the recirculating valve on the turbo.

Basically your BOVs diaphragm has sprung a hole & it's probably letting gasses escape.

Unfortunately the only way to check it is to remove it see what state the rubber part is in.

Something to look at when I get my exhaust and down pipe then? In the meantime get some WD40 on all the bolts as often as I can.

**thebadger** · Monday 25th November 2013, 19:52

On the T5 it's a tricky one to get to, it's 3 10mm bolts hold it onto the turbo body, if you follow the hose back from the TCV you'll find it on the top of the turbo behind the actuator.

The bottom bolt is the real bugger to get to.

Worth the checking as its a cheap(ish) part to replace & I think that Forge may do an uprated version for the KKK turbo. I have the t16/t18/t19 version from forge and it's a nice bit of kit. My old one was showing wear, but hadn't popped.

**claymore** · Monday 25th November 2013, 20:02

On the 850s there is a vac servo on the brake pipe for the cruise control, (That might spring a leak?)don't know about the p2s

**Squirtydog** · Monday 25th November 2013, 20:11

I have noticed that I can hear what I assume is the BOV these days if I think about giving it a squirt then back off the throttle. Don't think I heard it before. Any significance?

**Squirtydog** · Monday 25th November 2013, 20:13

Originally Posted by claymore

On the 850s there is a vac servo on the brake pipe for the cruise control, (That might spring a leak?)don't know about the p2s

Did read about these springing a leak but it doesn't relate to braking so I discounted that.

**thebadger** · Monday 25th November 2013, 20:14

Well it should open when you let off the throttle or open the clutch.

It's sounding like the culprit.

**claymore** · Monday 25th November 2013, 20:14

But it has vacuum there at all times

**M-R-P** · Monday 25th November 2013, 20:16

have you fitted an induction kit or air filter recently?

**Squirtydog** · Monday 25th November 2013, 20:18

Did have a K&N cylinder on for a short while but changed it back a few weeks ago...

**thebadger** · Monday 25th November 2013, 20:20

Yeah, there's vacuum, but the diaphragm seals in boosted gasses & releases them when the car comes off boost. So it sounds like a hiss outside of all other normal sounds. It may also be impacting your fuel efficiency.

**Squirtydog** · Monday 25th November 2013, 20:22

Originally Posted by thebadger

Yeah, there's vacuum, but the diaphragm seals in boosted gasses & releases them when the car comes off boost. So it sounds like a hiss outside of all other normal sounds. It may also be impacting your fuel efficiency.

Getting real warm here... MPG has dropped. Put it down to just doing town miles but was not convincing myself really.

Had a misfire yesterday too. 60/70 mph, not hard throttle. Came off morotway. Revved a few times. Single backfire and fine again. Just ordered new plugs as they are coming up to 30k.