270cdi - hissing and rough.

[fastboysparky]

My ML has a terrible hissing noise when the boost comes in. It sounds like someone turned the fan heater on full. When driving, the noise seems to come from the passenger side and there is excess black smoke from the exhaust when accelerating.
When you stop and rev it from under the bonnet it sounds ok apart from being a little lumpy and rough. Any ideas please.

 

[Xtractorfan]

Split or loose turbo hose. you may even have one or two injectors blowing past, give u something to go on

 

[fastboysparky]

Split or loose turbo hose. you may even have one or two injectors blowing past, give u something to go on

Turbo hoses are all ok. I had the turbo overhauled as the bearings where going and the spindle was tight. Injector seals are fine. Intercooler is fine. Just removed the front cat tonight. Gonna run it round the block tommorrow to see if the hissing goes. That is if i can hear it over the engine.

 

[Xtractorfan]

There again hissing and black smoke ..check the vacuum pipes to the EGR valve

 

[fastboysparky]

What is the EGR valve and where can i find it?

 

[fastboysparky]

I have driven it without the primary cat this morning and even though it is noisy, the hissing can still be heard. I have reassembled the cat and all the left side of the engine and i am now looking at the right hand side of the engine. Having removed the flexible hose from the intercooler to the plenum chamber, their is a aluminium bodied valve of some sort which is operated by a vacuum hose, i cleaned this only 2 week ago and it has build up on it already, is this normal? When i start the engine and rev it the valve opens and closes. There does not seem a great amount of air coming from the intercooler, is this normal? I have just thrown my spanner set at the wife, is this normal?
Any ideas.

 

[fastboysparky]

Everything is now reassmbled. Took the car out and gave it a good caning. Hissing noise still there. Boost OK and black smoke calmed down.
Put bonnet up and reved the engine, no hissing.
Put in reverse and keeping foot slightly on brake, reved it until boost started to come on and hey presto, hissing is back.
Got the wife to do the same whilst i stood next to the car, the hiss is definately coming from around the left hand side of the engine but i cannot pinpoint it. I'm off to plumbers store for a smoke pellet.

 

[luders79]

Hello,

The hissing noise you are proberly hearing is the boost pressure leaking from the inlet manifold port shut off flaps! they break up and come lose in the bottom of the inlet manifold! If you look just below the manifold the should be a thin metal strip connecting all the flap to the motor which bolted to the underside of the manifold! If the metal strip has come off some where i think your find that a flaps your probelm! Hope this is of some help!

Lee

 

[colechelle]

inlet manifold also spilts at the rear, prob wont see it unless you remove it!

 

[fastboysparky]

Thanks
I spent hours yesterday removing the whole side of the engine and eventually got the manifold off. There was one flap missing which is the hissing noise and the flap was inside the inlet port against the valve which is probably why it was running rough, i managed to get the flap out with some extra long nose pliers.
Can i buy a repair kit or is it a complete new manifold.

 

[colechelle]

whole new manifold im sorry to say!!

 

[skilledhandz]

Replaced my inlet manifold a few weeks back £640 from Mercedes.