New E53 Owner intro/Boost leak (I think)
 

Hi, My name is Shane and based in the UK.


I have recently bought a 2003 3.0d Manual. Its quite tired and done around 140K. I bought it to replace an old twin cab Nissan Navara and like that the X5 will be used as a daily and to tow my Mk4 Supra to the drag strip ocasionally.

Not new to BMWs, but I have been away for a while as I got into Jap stuff. My last was an e24 635csi about 15 years ago and before that had various E28s and even before that I owned a few E3s and a really early 530 (70s).

So, the new toy so far has been a nice experience and glad I made the move, much more refined than the Navara. From a driving point of view the power delivery reminds me very much of my old E300 TD Merc with the OM606 which I loved. It has the usual bits wrong, lcd needs a new display or ribbon cable repairing, all the vacuum hoses under the inlet manifold were disintergrated and I had hoped this would cure my problem, but didn't.


Under medium to heavy load conditions at around 2500 -3000 rpms I can feel boost fail and at the same time hear a hissing sound, Easing off the throttle and getting it back to vac cures it until the next time the boost builds up again and it repeats.

I have done a search and see the exhaust manifolds crack but I dont think its on the hot side. To me it sounds and feels more like a intercooler or hose split that gives out at a certain pressure. I also read that sometimes the inlet manifold can crack, I took this off at the weekend to change the vacuum hoses (that was fun and a steep learning curve) and it looks in great shape so I am pretty sure its not that. I will see if I can block off the turbo end and put some compressed air down the system and listen for a leak. Any other suggestions? Also, I have been looking around here and youtube for clues to how the intercooler comes out, does the crash bar behind the bumper really have to come off to get the intercooler out? I should mention also that I have deleted the EGR but this problem was present before I did that so its not related to the EGR.

Would apreciate any direction on this, thanks.


Shane

Welcome!
Do you know if you’re X5 is pre-facelift?
They had cast iron exhaust manifolds.
Any pics of your your X5?
And maybe your Supra....:driver:

Thanks for the reply. I will take a few pics of the X5 and put them up.
Here's from yesterday. Whats left of the vacuum pipes and the inlet going back on:
Attachment 74320


I have to admit since photbucket got mean I struggle to post pictures on these forums as I can never remember how and have to learn over again.

But I will have a go.

"No one eats the tuna in here"


Attachment 74317
Attachment 74319
Attachment 74318

Easiest way to look for boost leaks on the cold side is a smoke test.

Stick a rubber glove or two over the intake tube where it mates to the air intake, and feed the smoke line into your brake booster. Remove the valve cover cap and don't feed more than a few PSI, you don't want to pop a seal. Ideally you should also block the exhausts, but major leaks are usually obvious without that hassle.

Not sure this will work that well with a turbo in the way... Would likely need to introduce the smoke at the turbo outlet (inlet to the HP hose going to the intercooler).

And the leak may not show up without significant pressure - at least 2 bar.

Given that there are only the two large hoses and the intercooler between the turbo outlet and the EGR inlet, this section is easy(ish) to check. After the EGR is the inlet manifold - harder to check.

https://i.ebayimg.com/images/g/TW0AA...CID/s-l500.jpg

Thanks both for the reply.

OK so excuse my ignorance here, although I have heard of smoke tests, how do I generate the smoke?


Also, the brake booster on mine gets it's vac from a vacuum pump so how is the smoke goig to find its way into the inlet? And why would I need to block off the exhaust if the smoke is on the inlet side and the engine isn't running, how would it even get to the exhaust?


And yes I will need more than a few PSI as its holding boost fine right up to a point which is when the motor is under load and boosting well.


I realised last night that the stock intercoolers are made by Behr, I had almost identical symptoms on a Mercedes W210 and that was due to a split in the Behr intercooler that held up to about 1bar before it gave out, first showed up during a climb on the autobahn in Bavaria. That was a real nightmare to get at and fearing this will be the same.

Thanks again.

Edit:

OK so I have just been looking at homemade smoke machines on youtube, seems straightforward enough. But mines going to have to be pretty beffy and well sealed to get to the pressure I need to in order to get the leak to give way I guess. Does anyone know what the stock max boost pressure is on a M57? What I may do first is hook a boost gauge up so I can see what pressure it actually gives way at.

Stock boost is a tad under 2 bar (26-28psi). It varies a little on what car (530d, X5 3.0d etc.) but they are all around this. Some tuners hike it up as high as mid-30's...

Here's some engine data from my M57N, running at 2,300rpm (under load): -

Engine speed - 2316.92 rpm
Coolant temperature - 91.28 deg C maximum
Rail pressure of the last 10ms - 913.75 bar
Injection quantity setpoint without Quantity compensation control - 36.23 mg / cyc
Aspirated Air mass per cylinder - 926.33 mg / stroke
Charge pressure value - 2008.61 hPa
Linearized APP1 - 60.63%
Duty Cycle - Exhaust Gas Recirculation - 79.56%
Duty cycle - boost pressure plate - 52.78%
Atmospheric pressure - 974.76 hPa


2008 hPa (~2 bar) is bit more that twice the atmospheric value of 974 hPa (~1 bar), so this is about 14 psi (~1 bar) of boost, or half the maximum. Seems about right....

Did you spot the rail pressure - 913.75 bar? Yes, that's 13,252 psi !!! It can get a lot higher than this too!!! :wow:

Oh, one other thing about boost leaks - they can be easy to spot as there often a lot of oil vapour in the boost air which leave an oily stain around the leak. Check for oily stains on entire high pressure air system...

http://i1251.photobucket.com/albums/...5.jpg~original
image from osiris at bmwfanatics.co.za

The charge air temp sensor on the intercooler outlet pipe can fail to seal sometimes - I know mine needs sealing up (from the oily state of it...).

Thanks Wayne, all great info and exactly what I was looking for. As a side note I run just over 1.2 bar on the supra and have been down this route before chasing leaks at full boost so sort of know what I need to do.

There are no obvious oily spots in any areas I can see, certainly none around the hard or soft pipes in the engine bay, this was the first thing I looked for when I first noticed it.


Also, am I right in thinking the front bumper & crash bar have to come off to get the intercooler out, I read somewhere that the fan has to come out too? Do you know exactly what need to come out to get access?

Thanks