Knock in Diesel intake

[roscoe07]

I have put this problem on forum before but problem still exists. 07 D40 STX Diesel. There is a knock coming from the housing where air enters the engine. The last rubber air inlet hose attaches to the housing on the front upper drivers side of the engine. If I listen with a screw driver it is loudest on this metal housing. On a petrol engine I would call it the throttle body.

Anybody have any ideas?

Also I have oil leaking from the junction of this hose and the "throttle body". I presume its coming thru the air hose from the turbo.

 

[Dave]

Got a pic of the area your talking about ?

 

[roscoe07]

Not sure how to put a pic in here. Tried cut and paste. How do i get in this thread?

 

[Old.Tony]

Roscoe, the oil is expected to be there but shouldn't be leaking out. Resolving that issue might resolve the knocking as well.

The rubber hoses should have clamps that hold them in place. If these clamps are done up too tightly they'll pinch the hose eventually allowing a leak to occur. Air in that hose peaks at about 20psi (some say up to 24psi and that might happen if you're absolutely hammering it). Since the oil vapour coming out of the Positive Crankcase Ventilation hose (PCV) is heading that way, any of those hose joins is likely to let some out.

To stop (or at least reduce) the oil going in there, fit a catch can.

If there's a leak, it might not be constant, but it could be "puffing" and that may be heard as a knock. I'd suggest that you fix the hose(s) and see if the sound goes away.

 

[roscoe07]

Hey tony thanks for that. As you are an old hand whats the best way to put a photo into the reply box. I the only way i can see is to use a URL which is a bit odd.

 

[Old.Tony]

I do it this way:

1) Use 'Go Advanced'
2) Click 'Manage Attachments' (in the 'Additional Options' section down the page)
3) Click 'Browse' and find the image on my computer, then click 'Upload'
4) Click 'Close Window', finish editing the text and click 'Submit Reply'.

You CAN also right-click on the image link which appears just above the 'Manage Attachments' buttons and "copy link location" then click on the picture icon ("Insert Image") and paste the link in the box that appears, which makes the attached image appear in the body of the text.

 

[roscoe07]

Picture of offending area.

 

[tweak'e]

check the breather hose. if theres no oil in it, then the oil could be from turbo.

i would just pop that hose off and check that butterfly setup hasn't broken anything or is loose.

 

[Old.Tony]

The air hose looks swollen, that's for sure.

In this picture, see the plug I've marked "this plug" ?

Assuming that fixing the rubber hose doesn't resolve the issue,

If you are hearing the knocking sound, unplug that plug and see if the sound goes away. Alternatively, look at the EGR valve (which is attached to the pipe marked "Block EGR here"). Remove its plug and see if that gets rid of the sound. You might have a faulty EGR valve.

 

[roscoe07]

Thank you thats great.

 

[roscoe07]

BTW what is the fitting that "this Plug" is attached to?

 

[Old.Tony]

It's called a throttle chamber in the manual. Since diesels don't need a butterfly to regulate air, you'll have to wait for Dion or someone else that's smarter than me to tell you what it is.

 

[tweak'e]

usually its a engine shutoff butterfly. i only have manual for the early D40's which shows a vacuum operated one. they often double as overboost protection.
an electric one is possibly a variable one to control airflow in conjunction with egr.

 

[roscoe07]

I have removed both cables but the noise persists. I definitely comes from the housing in the picture. However with no effect on the performance or the mileage I think I will just wait until whatever it is breaks. LOL I could see me replacing very expensive parts to try and track it down.

 

[Old.Tony]

Did you reclamp the large hose leading into that? It's obviously got a leak and its high pressure (approaching 2 atmospheres).

 

[roscoe07]

Yep i pulled the hose off and looked to see if it was leaking. Cleaned oil from rubber and metal and reclamped. Its very tight now.