2L-TE Boost Leak (1 Viewer)

[CRSWA]

Hi all. I'm out of ideas. I need a little help from the 70 series hive-mind.

A couple of months ago, I started hearing a high-pitched wailing noise coming from the engine whenever it was under load (typically about 2k RPM going uphill). I also noticed a fine spray of oil coating everything on the intake side of the engine. A boost leak seemed logical, but it wasn't clear where all the oil was coming from.

I installed new couplers on the turbo piping and got some good clamps. That changed the pitch somewhat, but didn't get rid of the leak. The turbo piping had a lot of oil in it. Finally, I pulled the throttle body off and made some new gaskets. Still leaking. Still blowing oil.

My theory about the oil is that after I installed a catch can on the PCV hose, it caused enough back pressure to cause blow-by in the turbo oil seals. I removed the catch can and am venting the PCV through a hose to atmosphere. If that doesn't reduce the oil problem, then I think it's safe to say my turbo needs rebuilding.

As for the boost leak, it's definitely coming from the left (intake) side of the engine, It doesn't appear to affect power, it just makes a high-pitched scream that scales up and down with boost pressure. Anybody encounter a problem like this before?

 

[JimmyPrado]

Haven’t had the problem but could you take some TP and move it around the intake side? Might find the leak that way. Tossed my catch can as well and don’t miss it. Sure it’s oil and not diesel?

 

[CRSWA]

I’ve used my hand to feel every joint in the turbo piping at idle and couldn’t feel any leaks. I’m pretty sure it’s only happening under medium to heavy boost which I can’t simulate with the hood open, of course. It does give me an idea though. I wonder if I can set up some sort of telltale on the joints that will indicate where the leak is after a test drive.

It’s definitely oil. My dipstick confirms that.

 

[GTSSportCoupe]

I've had boost leaks a few times now and they sound like what you're describing. For me it's almost always around the throttle body area. Above or below. Maybe remove it, clean the surfaces super well with a razor and put it back on with some RTV Silicone. Make sure to let it sit for a day before driving so the silicone cures properly. Another area to check is where the EGR used to feed into your intake manifold. Not sure how you blocked that off, but make sure it's not leaking there.

Regarding the oil usage, the PCV on these engines throws out a tremendous amount of oil spray. It's just a poor baffle design in the valve cover. I doubt it's related to your turbo. Usually when the turbos wear out and start using oil (or you have high crank case pressure), the oil comes out the seal on the turbine side of the turbo into the exhaust (not the compressor side - unless its really really bad).

 

[CRSWA]

Thanks Nick. What's interesting about this is that it wasn't until I pulled the PCV hose off and redirected it to a catch can that I started getting the noise and losing oil into my intake. Weird, right? It's exactly the opposite of what I would expect.

I'll check the EGR blank and pull the throttle body this weekend and RTV the gaskets. When I made the new gaskets, I just used standard intake gasket material. That shouldn't make a difference, right?

 

[GTSSportCoupe]

Thanks Nick. What's interesting about this is that it wasn't until I pulled the PCV hose off and redirected it to a catch can that I started getting the noise and losing oil into my intake. Weird, right? It's exactly the opposite of what I would expect.

I'll check the EGR blank and pull the throttle body this weekend and RTV the gaskets. When I made the new gaskets, I just used standard intake gasket material. That shouldn't make a difference, right?

Did you have the outlet hose from the catch can still feeding back into the intake? If so, it's possible oil was still getting through it.

I suppose if your crank case pressure was getting really high it is possible oil could come out the turbo compressor journal.... Have you checked the play on your turbo? Also, maybe pull the dump pipe and just make sure there is no oil coming out the turbine.

Standard gasket material should be fine for sure. Maybe wipe a bit of RTV on them and make sure to torque everything good and snug?

 

[GTSSportCoupe]

One final thought, I wonder if your turbo is actually on it's way out? Is it possible the noise is from the turbo it's self? Definitely check the shaft play and for oil in the dump pipe.

 

[CRSWA]

Did you have the outlet hose from the catch can still feeding back into the intake? If so, it's possible oil was still getting through it.

I suppose if your crank case pressure was getting really high it is possible oil could come out the turbo compressor journal.... Have you checked the play on your turbo? Also, maybe pull the dump pipe and just make sure there is no oil coming out the turbine.

Standard gasket material should be fine for sure. Maybe wipe a bit of RTV on them and make sure to torque everything good and snug?

For the catch can, I ran the outlet down to the bottom of the engine compartment. For the two months it was on, it collected only a small amount of oil. I've removed it and am now just running the hose from the PCV to the outside.

Another factor that's puzzling is that until this issue popped up, my engine was tight as a drum. No measurable oil loss at all. Ever since I fiddled with the PCV outlet, I've been losing about a quart per month. Probably a coincidence, but I think I may put it back the way it was just to eliminate it as a possible source of the problem.

 

[CRSWA]

One final thought, I wonder if your turbo is actually on it's way out? Is it possible the noise is from the turbo it's self? Definitely check the shaft play and for oil in the dump pipe.

Yeah. Replacing the turbo was my next step in the process. I haven't done anything with it yet because it still seemed to be putting out plenty of boost and wasn't making any noise, but if the oil seals are gone...

 

[saltycoconuts]

Yeah. Replacing the turbo was my next step in the process. I haven't done anything with it yet because it still seemed to be putting out plenty of boost and wasn't making any noise, but if the oil seals are gone...

I’m on the same ship as you as far as the whining sounds indicating a boost leak. Unfortunately it’s for my 13bt, coming from the intake side of my engine. It’s been a headache to figure out but I just got new turbo clamps and will re-torque the intake manifold during that process.

 

[Dprio34]

@CRSWA , I had a high pitch noise at the same freq as you. My problem turned out to be, I didn't use a thick enough gauge steel to blank off the back of the exhaust manifold. There was a slight warp on the blank off plate that was causing it to squeal as you describe. I replaced with 3/16th steel and it solved the problem. I believe the noise and the oil leak to be separate issues. I also scrapped the stock gasket and used RTV to seal the blank off plate. Hope that helps.

 

[CRSWA]

@CRSWA , I had a high pitch noise at the same freq as you. My problem turned out to be, I didn't use a thick enough gauge steel to blank off the back of the exhaust manifold. There was a slight warp on the blank off plate that was causing it to squeal as you describe. I replaced with 3/16th steel and it solved the problem. I believe the noise and the oil leak to be separate issues. I also scrapped the stock gasket and used RTV to seal the blank off plate. Hope that helps.

I hadn't considered that, but it really makes a lot of sense. It would explain why all of the work I've done on the intake piping and throttle body have made virtually no difference in the noise. I'll let you know if that turns out to be the problem. Thanks.

 

[Musafir]

Hi all. I'm out of ideas. I need a little help from the 70 series hive-mind.

A couple of months ago, I started hearing a high-pitched wailing noise coming from the engine whenever it was under load (typically about 2k RPM going uphill). I also noticed a fine spray of oil coating everything on the intake side of the engine. A boost leak seemed logical, but it wasn't clear where all the oil was coming from.

I installed new couplers on the turbo piping and got some good clamps. That changed the pitch somewhat, but didn't get rid of the leak. The turbo piping had a lot of oil in it. Finally, I pulled the throttle body off and made some new gaskets. Still leaking. Still blowing oil.

My theory about the oil is that after I installed a catch can on the PCV hose, it caused enough back pressure to cause blow-by in the turbo oil seals. I removed the catch can and am venting the PCV through a hose to atmosphere. If that doesn't reduce the oil problem, then I think it's safe to say my turbo needs rebuilding.

As for the boost leak, it's definitely coming from the left (intake) side of the engine, It doesn't appear to affect power, it just makes a high-pitched scream that scales up and down with boost pressure. Anybody encounter a problem like this before?

View attachment 1998919

What size are those couplers? Diameter and length.

 

[CRSWA]

What size are those couplers? Diameter and length.

As I recall, the coupler from the turbo to the crossover pipe is 2.25" while the throttle body intake requires a 2.25" to 2.5" adapter.

 

[Musafir]

I hadn't considered that, but it really makes a lot of sense. It would explain why all of the work I've done on the intake piping and throttle body have made virtually no difference in the noise. I'll let you know if that turns out to be the problem. Thanks.

So what was the cause of the sound? I had the same issue after doing the EGR delete and randomly just went away after a long drive.

 

[jmylie]

I will be replacing my turbo soon also. Oil leak thru the turbo bearing. Not significant but a leak.

 

[CRSWA]

uzimuffin - The source of the noise was the EGR blank off plate. I smeared some gasket sealant on there and the noise stopped.

jmylie - My turbo is also leaking oil. I have a new turbo sitting on the shelf waiting to go in, I'm just procrastinating. Maybe post some pictures of it when you do yours.