Charge air leak - turbo boost

L

Luc

Member
Hello everyone!

Let's set the table:
-2006 T1N, 158", high top
-208000km
-owned it since last November
-After reading up on this forum, I order a billet aluminium resonator tube replacement
-Initial inspection at dealer didn't mention anything about resonator (so I didn't change it at that point, kept the part in the garage)
-to be noted that since then, the noisy turbo whine was all normal to me since I had never heard another Sprinter before
-Got the green diesel tune in early July, nothing special to say except all was working fine
-Last week, 2 of the lower radiator hoses started leaking during my vacation trip. Had those replaced at the dealer because I was stuck in the middle of nowhere, and got towed to Halifax (Nova Scotia).
-The very competent mechanic (seriously) noticed right away that my resonator leaked. I told him I had the part, and he was confident I could make it home (1000 kms) I actually did make it home but many stretches were in limp mode where the turbo was just disabled at the computer because of poor pressure signal I guess.
-Replaced the resonator with my aluminium part. Re-used the O-ring, didn't look bad at all.
The following day, I went again on a 3 day trip, 650 kms each way.
-On the way there, van was doing fine. Never had it this silent before in my time.
-On the way back, there was a "new" whining sound. This sound is associated to the turbo boost for sure, and I can generate it at specific boost values.
-Made it home safely, without any codes on the ECM.
-I looked for some leaks today with soapy water, but couldn't find anything. Problem is that the air leak ( I presume it's air leak) happens under load and even with a helper in "Drive" with a foot on the brake and the other on the throttle, I don't feel safe laying under the van to squirt soapy water on the charge air network.

Here are the boost values if this helps anyone
-Boost Level at which the leak becomes noticeable while driving : 1400 mbar (20.3 psi)
-Max boost going up a steep incline with wide open throttle : 2450 mbar (35.3 psi)
-Cruising boost at 50km/hr on level ground : 1150 mbar (16.7 psi)
-Idle boost : 1010 mbar (14.6 psi)

So my questions are:
-Is there a particular place I should look for the leak?
-Is there a safe way to do a static test of the charge air system?
-Anything else to recommend trying?

Thanks a bunch group!
 
M

Midwestdrifter

Engineer In Residence
The new sound may be because you no longer have a "muffler" on your turbo outlet. The boost numbers you post appear to be normal.

I would clean the boost lines well. Then watch for signs of oil spray. A leak in the charge air system will invariably spray small amounts of oil mist around the leak.
 
autostaretx

autostaretx

Erratic Member
As midwest says, look for deposits of oil spray (if it's an old leak, they'll have dried/baked to being "tarry", since new oil is being constantly applied.).

The "safe/easy/static" way to test for a leak is to force 20 psi smoke into the system (engine off)... it's a standard mechanic's test.

Some folks have recently posted photos of (ever so slightly) cracked intercoolers.

--dick
 
L

Luc

Member
Midwestdrifter said:
The new sound may be because you no longer have a "muffler" on your turbo outlet. The boost numbers you post appear to be normal.

I would clean the boost lines well. Then watch for signs of oil spray. A leak in the charge air system will invariably spray small amounts of oil mist around the leak.
Click to expand...
Cleaning and keeping an eye on it sounds like a good idea. Will do

But the change in sound was very noticeable from when I changed the resonator and drove the first 650 kms. It's only on the way back that It started to sound noisier... But my senses could be fooling me
 
L

Luc

Member
autostaretx said:
As midwest says, look for deposits of oil spray (if it's an old leak, they'll have dried/baked to being "tarry", since new oil is being constantly applied.).

The "safe/easy/static" way to test for a leak is to force 20 psi smoke into the system (engine off)... it's a standard mechanic's test.

Some folks have recently posted photos of (ever so slightly) cracked intercoolers.

--dick
Click to expand...
Is this something that is achievable at home? I imagine plugging off one end of the system (near the intake side), and making a plug for the turbo outlet hose and then a regulator for compressed air?

Or is this something dealers are equipped to do usually?
 
L

Luc

Member
Midwestdrifter said:
The new sound may be because you no longer have a "muffler" on your turbo outlet. The boost numbers you post appear to be normal.

I would clean the boost lines well. Then watch for signs of oil spray. A leak in the charge air system will invariably spray small amounts of oil mist around the leak.
Click to expand...
Well, as is always pretty much the case, the easiest things are usually what should be checked and confirmed first...

Today I went to my Audi mechanic so that he could help me troubleshoot the leak situation, as it was hard for me to do alone, before rigging it up for a pressure test. I was in the neighborhood, so I figured I would stop by. It just so happened that he wasn't back from lunch yet, so while waiting, I decided to pop the hood and clean the hoses like Midwestdrifter suggested... And guess what, while doing this, in clear sunlight, and with a new attentive eye, I quickly discovered a split in the top hose right before intake!

I was literally 500 feet from the Dodge dealership. Dropped in, they had the part in stock (it was an assembly of the 2 rubber hoses coming out of the intercooler and the plastic manifold between them) 140$ CAN, and it took me 1 hour to change at home!

Van is now quiet and perfect!!!

Now on to troubleshoot the intense rumble on hard acceleration in first gear (and no, it's not rumble strip noise, because I've got that too :) )

Thanks guys!!
 
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