[M2guru]

Looking to gather information about the best way(s) to perform a boost leak test on the N55.

On a car I used to have (DSM) I would have to rotate the crank to a specific degree BTDC (beyond top dead center). I assume the same has to be done with the N55? If so, what is the process? (I could try the process of elimination on this but looking to see what y'all think.)

Also, what is the preferred method of blocking off the intake pre-turbo in order to pressurize the intake? I see the various testers out there, but I'll likely build my own to save cost.

Thanks in advance!

[AmuroRay]

Please post this on the F30 side

[c0riolis]

M2guru I've done a few boost leak tests on mine very recently since I was replacing the charge pipes and inlet and wanted to check that everything was still tight.

I used this kit:
https://turboboostleaktesters.com/bm...llet-aluminum/

I highly recommend it, it comes with everything you need and the owner is super helpful if you have any questions.

Now the annoying part is that you need to remove the inlet to do that, which is a pain in the ass.

[M2guru]

Thanks c0riolis. Did it come with any instructions regarding rotating the engine to a certain degree BTDC to ensure the intake valves are closed? Perhaps my olden days are too old and that's not needed for the N55. I recall having to do that plus plug up the PCV valve on the DSM.

AmuroRay I'll try to do that tonight.

[AmuroRay]

Originally Posted by M2guru

Thanks c0riolis. Did it come with any instructions regarding rotating the engine to a certain degree BTDC to ensure the intake valves are closed? Perhaps my olden days are too old and that's not needed for the N55. I recall having to do that plus plug up the PCV valve on the DSM.

AmuroRay I'll try to do that tonight.

I got you.

[AmuroRay]

Originally Posted by yupetc

Buy this conundrum and install it at your pre-turbo inlet.
https://www.ebay.com/itm/14296307920...3ABFBMgoG3sf5i
You may need to take it to a machinist and machine the diameter to fit. I bought this thing and it's about 2mm too big for my X5's turbo inlet. After turning it on the lathe and take out 1mm of radial meat, it fits like a glove for me. I use the adapter directly to inject air in 5psi increments (from a compressed air source).

I also tandemed an air pressure regulator to control the pressure.

.

[AmuroRay]

Originally Posted by yupetc

I didn't do it with any TDC/BDC orientation, but I could just be lucky that all valves are in position to seal. I think all of our valves are clocked to at least shut the air down either at intake or exhaust valving. Unless some lashed race cams are installed, my opinion is we should be able to leak test regardless. I'm saying this because I've performed plenty of smoke tests in the intake side, and I've never seen smoke pass through the exhaust when I put a lot of smoke in there.

^

[c0riolis]

Originally Posted by M2guru

Thanks c0riolis. Did it come with any instructions regarding rotating the engine to a certain degree BTDC to ensure the intake valves are closed?

No need to do this, just make sure that you leave your oil cap open because the air will leak through the piston rings since they are not lubricated and you do not want to pressurize your PCV system -- but it's all detailed in the instructions (you can find them on the page I linked).

Also, you need a decently-sized compressor for this, I had to upgrade my small 1 Gallon compressor as it could not pressurize the system to more than 15 PSI and even then it was constantly running which made it impossible to hear any potential hissing.

[M2guru]

Thanks AmuroRay!

[AmuroRay]

Originally Posted by M2guru

Thanks AmuroRay!

Of course

[E36M3]

Don’t forget to insert thin feeler gauges between the valve cover and head to block off each intake cylinder port that feeds the PCV system or run the risk of rupturing the diaphragms built into the valve cover and get a leak that will be misleading.

[c0riolis]

Originally Posted by E36M3

Don’t forget to insert thin feeler gauges between the valve cover and head to block off each intake cylinder port that feeds the PCV system or run the risk of rupturing the diaphragms built into the valve cover and get a leak that will be misleading.

You don't need to do that, the boost leak test kit is designed to be used in a way that keeps your PCV system safe.