Boost leak symptoms on N55 - how to diagnose

about 1 month ago· 16 posts

Suspecting a boost leak on my N55 335i. Symptoms: - Loss of power above 4000rpm - Slight whistling sound under boost - Occasional check engine light (underboost code) How do I find the leak? Ive heard about smoke testing but dont have the equipment. Is there a DIY way to find boost leaks? Common leak points on N55 anyone?

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Replies (2)

CodeMaster BMW

about 1 month ago#1

N62 V8 is a great engine once the common issues are sorted. The sound alone is worth the maintenance costs.

16 posts · 0 rep

HybridTurboGuy

26 days ago#2

Classic boost leak symptoms on N55: loss of power under boost, hissing sound from the engine bay, and boost not reaching target (check with MHD or BM3 data logging). The most common leak points are: charge pipe (the plastic one cracks), intercooler boots, and the turbo outlet. To diagnose, you can do a smoke test - plug the intake and pump smoke through the system. Any leak will be visible. A boost leak tester costs about 30 EUR and is a must-have tool for turbo cars.

16 posts · 0 rep

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