I have noticed a hissing noise which seems to be coming from under the intake manifold with the engine running.
I have checked all of the hoses that I can get to and now believe that I either have a cracked EGR Hose or the Secondary Air Hose connector is loose just above the starter Motor.
After fiddling around to try to get to where the noise could be coming from, I am now at the point where I either have to remove the intake manifold or the starter to get to where the noise is coming from.
I don't see any way to get to the back of the engine either from above or below to even get my hand in there.
Has anyone else had a similar issue or problems in this area?

My next step is to try a smoke test on the hoses to see if that shows anything obvious.
I am reluctant to pull the intake as I haven't done this before and am concerned I might just make things worse.
Any suggestions would be greatly appreciated

 

It could be your intake manifold gasket giving up? If you're gonna remove that manifold, make sure you have a new gasket for it.

Also, since you're already there, you should replace the ******* hose. EAC3454. It'll never be easier.

 

Thanks, I need to do a smoke test first, hopefully that will point me in the right direction.
The Intake Manifold Gasket looks like a big job, lots to remove or get out of the way. I'll start trawling the forum for a guide, just in case.
I had another listen and it is in the vicinity of the starter motor and behind the throttle body, under the intake manifold.

My coolant hoses seem fine at the moment, but while I'm in there, I may as well.

Isn't the b*****d hose MNA4510BF?

 

If you have a smoke machine, By all means use it. Remove air cleaner and rubber band a latex glove around the intake of the Mass air flow sensor. Use the vacuum line from the fuel pressure regulator to plumb into the smoke. Short burst only. When done with diagnosis, recheck your self with all ready attached equipment.

Larry Louton

 

Thanks. I'll check the intake manifold via the vacuum line to the FPR.
I am also going to check the EGR and Secondary Air hoses from the other side as they are easier to get to there.

So is the EAC3454 hose called that because it's a big job to replace? The MNA4510BF hose maybe just looks scarier than it is.

 

Hello Nobeel, The EGR valve blocks off the pipe work at the intake. The air injection pipe work goes to the air pump so it really isn't involved unless it only hisses while cold or when the pump is running. I don't have any pictures and or part #'s. Send back pictures if you have time. Don't make problem big before you know it.

Larry Louton

 

What Vee said if you pull the intake manifold, but go one step farther - go ahead and replace the water rail gaskets. The b*st*rd hose mounts to the water rail. I've renewed b*st*rd hoses 3 or 4 times without removing the intake. I've had to pull the intake off twice, always to replace water rail gaskets. T'ain't fun, but you can do it. Plan to roll it up and over onto the cam/coil cover there are some wiring looms woven into it that you do not want to search out the end points and try to disconnect.

 

Greetings to all, I agree with the treating the engine to replacement of ******* hose and gaskets and flange gaskets while the intake manifold is displaced. Nobeel , Have you tried a spray bottle of water in small increments while the engine is idling. Thinking injector seals and or intake manifold flange gasket. The gasket usually blows out on the under side.

Larry Louton

 

Here's the update.
I finally got some time to look into this and thank you all for the advice, which has really helped me to figure out the issue.
I did a smoke test on the Intake Manifold and this showed nothing. I then tried the brake cleaner method of lightly spraying in the vicinity of the noise, still nothing.
Today I took the fuel injector cover off and used the soapy water method and although there were no bubbles I could hear the water being blown or sucked by a leak
It was around the 4th from front fuel injector on the engine side seal. After removing the fuel injector harness and rail, I removed the 4th injector and found that the O-ring had been pinched and was not sealing correctly. This is where the hissing noise was coming from.
I used a spare injector seal from an old set and reinstalled everything. Now the hissing noise is gone, I can still hear something but I think it is probably the normal air flow within the engine (trying to not be paranoid).
I'm going to order a set of injector O-rings in any case as they are probably due for a refresh, hopefully that will close the book on this issue.
One thing that I'm not certain about is why the engine ran so well with air getting into the mixture. I had no error codes or anomalies with fuel consumption or misfires.
The only thing I noticed on a test drive was that the fuel MPG's is updating every 10-15 seconds which used be every few minutes, is that normal now?

Once again, thanks for the support.


There's the bugger

O-ring removed

 

I didn't think that a broken injector O-ring would make such a noise. For some reason I still feel doubtful but it did make a difference.
I am planning to replace all of the O-rings and injector baskets as this seems to be a cheap and easy job, so will post results when that is done.
For now I have a before and after video, which shows the hissing noise before and after I replaced the one O-ring.