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mwestcrew

Member Since: 09 Dec 2019
Location: South Warwickshire
Posts: 247

2011 Defender 130 Puma 2.4 HCPU Baltic Blue

High Pressure Hissing Noise

My truck has started making a loud hissing noise intermittently on acceleration.

Truck has all silicone boost hoses, BAS alloy intercooler, de-cat, modified inlet tract.

I've looked at all the usual places for holes in the pipework (steering linkage chafing etc), checked all hoses are on properly and clips tight, inspected the intercooler as best as possible without removing it.

There is no apparent loss of power, no MIL, no fault codes.

Engine is 2.4

Anybody got any ideas please?

Really hard to find a boost leak single handed as it doesn't build boost when revved stationary.

TIA 2011 130 Utility Body
2005 110 Van

8th Jan 2024 2:53pm

geobloke

Member Since: 06 Nov 2012
Location: Nottinghamshire
Posts: 4410

Check all hose clamps, hoses for splits and the intercooler for splits as well. If the intercooler has a popped weld it is often noticeable by a weep or oil from the split.

You haven't recently added a snorkel or changed the snorkel top have you? These can increase induction noise lose to your head.

8th Jan 2024 3:27pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20325

Check the torque of the fixings of the air inlet manifold above the MAP sensor to the block, all of them against the WSM torque settings.
Signs of oil deposits / blow by residue can be a sign.

Just something to look at, 10NM rings a bell to me on the manifold to block bolts but consult the WSM.
I found that one bolt was 7NM, the rest were torqued correctly on one fixing nearest the front which meant I had a minor boost leak for a long time.

That ever so slightly loose bolt was enough to induce a little boost leak, the tell tale sign was oil deposits around it but even then wasn’t so easy to find.
Also check hoses and Intercooler too as suggested, and also the steering column shaft for rubbing on the hose turbo side as well, it’s seriously close.

Good luck. ⭐️⭐️God Bless the USA 🇬🇧🇺🇸 ⭐️⭐️

8th Jan 2024 5:02pm

geobloke

Member Since: 06 Nov 2012
Location: Nottinghamshire
Posts: 4410

That reminds me. Check the little o-rings on those sensors as well. If one is broken it could allow air to bypass the sensor and hiss under load... Didn't think of that until the above post

8th Jan 2024 5:50pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20325

Ah yes, it was the MAP sensor ‘o’ ring I was thinking it may have been but wasn’t in the end but is known to do so.

⭐️⭐️God Bless the USA 🇬🇧🇺🇸 ⭐️⭐️

8th Jan 2024 10:01pm

Ianh

Member Since: 17 Sep 2018
Location: Essex
Posts: 1997

Also worth checking the airbox lid is correctly fitted, that the air filter is seated correctly and that there are no cracks in the airbox.

9th Jan 2024 12:06am

mwestcrew

Member Since: 09 Dec 2019
Location: South Warwickshire
Posts: 247

Thanks guys.

Some useful additional things to check over and above the usual things that I have already checked. 2011 130 Utility Body
2005 110 Van

10th Jan 2024 1:59pm

Daphne

Member Since: 22 Nov 2023
Location: Kent
Posts: 25

2015 Defender 110 Puma 2.2 HCPU Fuji White

Turbo to manifold flange nuts are tight and gasket is good, mine started doing it when the bottom flange nut had mysteriously disappeared 😀

19th Jan 2024 10:26pm

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