Swap N52b25 with N52b30

khalidfh

khalidfh

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Hello

I have E89 23si with N52b25 engine 3 stage manifold. Unfortunatly, the engine gave up and need overhaul or swap.
The mechanic offer me N52b25 and N52b30. He said it is possible to swap to b30 without any issue. The engine does not come with DME.
After reading some articles, it is straight swap but DME must be remapped and flush otherwise the performance will be the same.
Unfortunatly, most of the articles I red, did not give feed back after swapping or what has been done after that.

So, any advice or recommendation? Is it easy to do DME flush and remap?
the goal is not only raising the power from 215 bhp to 250+ bhp, but I red that b30 is more reliable.

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I can't help you with your question, but can I ask what happened to your engine for it needing to be replaced ?
 
Bombur said:
I can't help you with your question, but can I ask what happened to your engine for it needing to be replaced ?
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It is jammed. It is not cranked. Not sure why, but I did so many thing probbly the last one is the main cause but all others have contribute to this jamming.

The engine was fine, don't consume any oil, performe very well. It is 2011 done 250,000 km. I bought it as used car with 11 owners before :LOL:. This is the first factor, it might dealt with ignorance... I change oil every 7000 km using 5w30 but swap to 5w40 then back to 5w30.

Last drive, I run rev the engine to the red, but never exceed to the red. On each drive I rev the engine to the limit, the sound is unbeleavable. This can be a factor, but not causing sudden jam.

When I did last oil change, the spring snapped and I saw the man strugle to put everything back correctly, I found the inner part of the cap is broken and missing the inner part. Spring is there but loose. Could this be a reason, maybe but I did not get any warning.

Now, this is the action. I was worried about detroiration of valve seal elasticity and become stiff. So I am using LIQUI MOLY stop oil leak bottle before any oil change for two weeks running inside the engine. Last time I saw a video review and recommend that AT 205 can rejuvenates all rubber seals & gaskets in engines. What I noticed is that AT 205 cannot mix with oil and always seperate. What I did is use a tube and inject a bottle of AT 205 to the valves through the oil change cap. I should run the engine imediatly but instead I thought if I leave AT205 for two hours it might work better. I travelled and left the car for a week. When I get back the engine rattle and directly low oil pressure warning pop up on the dash. I thought this will go away once the engine warm up. But it did not. I left the car overnight, and run it again but still. I did oil change, the red warning goes away for a minute but came back. I took the car to the garage but it seems it is too late. Engine jammed.
 
I'm sure those with experience of these engines will give their thoughts. The N52 is a reliable engine, yours is high mileage.
 
Sounds like you are saying the internals of oil filter is broken.
The thing that looks like spring has O ring blocking oil returning straight to sump.
Might have starved engine of oil and seized.
 
flybobbie said:
Sounds like you are saying the internals of oil filter is broken.
The thing that looks like spring has O ring blocking oil returning straight to sump.
Might have starved engine of oil and seized.
Click to expand...
Exactly, this is inline with what the mechanic told me, oil starvation due to broken filter cap.
 
Bombur said:
I'm sure those with experience of these engines will give their thoughts. The N52 is a reliable engine, yours is high mileage.
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Really, is 250,000 high milage??
I thought this engine can last up and more than 500,000 km
 
I don't think 250,000km is particularly high mileage for an N52 engine. There are a couple of E86 owners on here whose cars have done over 200K miles.

But as your 2.5 is dead it needs replacement, so a 3 litre makes perfect sense!

Sorry I can't help with your question but good luck with the swap. :thumbsup:
 
The mechanic has 730 with inline 6 and it is already passed 500,000 km, but he is driving style is easy on the gas.
 
I remember an E34 at the local BMW dealer that regularly came in for servicing in the early 2000s that was on 400,000 miles. Moving to fuel injection and then better cylinder linings killed off knackered bores and blue smoke.
 
Seeing as your question is about feasibility:

Yep, totally doable and at very low cost. Swap engine and flash the 30i map to the ECU. This can be done for free with the right knowledge.
 
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