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E46 M3 (2001-2006)

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Old 03-29-2019, 04:45 AM
Simas323 Simas323 is offline
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Location: Lithuania
Join Date: Mar 2014
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Mein Auto: E36/5 323Ti
S54 low compression in all cylinders

Hello everyone,

I swapped E36 with S54 engine and upon starting it up I found that it has low compression in all cylinders (6bar or ~90PSI) as well as quite a big blow-by on idle if I remove the PCV hose. I googled extensively, and couldn't find similar issue on S54 besides HG, but that would be one or two cylinders low on compression and other symptoms blown HG. All I have is rough idle and rich mixture (0.76-086 on both O2). On high revs it breaths really well, just has no mid-range kick. Here is backstory of the engine and what has been done to it:

Bought the engine from 05' RHD SMG E46 M3 cabrio with ~140k miles. After I bought it I've got rod bearings changed (crank and rods were fine, old bearings looked quite worn but no bronze or scratches), VANOS fully rebuild, valves adjusted. The only worrying thing was quite gunky head from rare oil changes

Also, as the car was SMG I doubt that it could be money-shifted or limiter-abused. High blow-by leads to some kind of piston sealing issue and my thinking is that it might be stuck piston rings from lack of frequent oil change or driving.

What are your thoughts? Do you know any similar cases like this?

I will have car ready for test driving next week and my idea is that by driving really hard with fresh oil it might help to unstuck those rings, but before doing that I want to make sure that I wouldn't damage it even more.
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