Engine fault

[EnglishmanInEU]

I have a E89 Z4 SDRIVE20i 135kW with less than 100K on the clock.

I bought in Europe last year and have recently passed its APK/CT (equivalent of MOT). I also had it put through a full service a few months ago (before the warranty expired to check that there was nothing needing any work. Its been all fine with an Oil+filter change a few weeks ago.

I was driving fast on the Autobahn traveling home from Germany and lost power. With a dashboard notification "Engine Fault! Reduced Power- Full engine power no longer available possible to continue journey". Pulling over at the side of the road the engine made quite a rough noise and the engine visibly shaken. I had it towed to a garage who did a dry compression test and determined there was no pressure in one of the cylinders (others were fine).

I've looked in to this as best I can but have limited no mechanical skills, it seems it will be quite expensive to open the engine up and figure out what went wrong (which could end up being a easy quick fix or could cost even more). I think my best bet is going to be a new (used) engine.

I'm looking at a like for like replacement N20B20A what I've found online seems to be from a BMW F30 would this be compatible?
these seem to vary 'naked' for €1500 to full used/rebuilt for €5000

Alternatively as it looks it will cost me north of 5k would this be a good opportunity to upgrade to a more powerful engine? I was thinking a 3L N52 or N54 are these compatible and would this make my car the equivalent of a sDrive35i?

I'm looking for advice on what Engine I should look for, any extra bits (will the ECU need reprogramming to match the engine?)
Would there be other factors such as informing my insurance company? (increasing my premium) for either swap?

[raymond.harper]

The engine swap is very involved although someone has done it https://www.youtube.com/watch?v=i6R7vxWnLSs but requires considerable time and mechanical ability. Fix the car up as cheaply as you can, probably a second-hand engine, and sell it. I know you are not in the UK but here 6 cylinder E89s are now selling below £6000

[EnglishmanInEU]

considerable time and mechanical ability

I don't have this - I guess that's the cost of the labor that i'l have to pay for.

sell it... below £6000

its a 2015 model I bought for over 20k less than a year ago, I'm hoping to keep driving it for a few more years.

I don't like the more modern (G29) soft tops. so I'm not really looking to patch up and am thinking to 'go all in' on the engine replacement.

Are you saying swapping the engine might not buy me as much time before something breaks again?

[smorris_12]

The trouble with second hand engines is, that unless you can see the car it comes out of, you don't know whether the reason the car has been scrapped is because of the engine. A neighbour has just put a second hand engine in his Merc; got it in, fired it up and found it was throwing a cam error. Turns out one of the camshafts was a tooth out on the chain. If you know the car was scrapped because of a rear end shunt or similar you can be a little more confident.

[matsmith749]

Before jumping to conclusions & swapping out the engine (massive task), why not get it to a garage & let them give you a quote to fix it?

Could be simple, could be something big - let them take a look.

Once you have a quote from them, you can consider options.

Second hand vehicle prices in the EU are typically DOUBLE what they are in the UK - so likely worth getting this sorted.

[Deepseaskateboard]

No compression sounds bad, but re-affirm the result at a place you can trust, or a specialist.

It could be as simple as replacing a piston ring. It’s just the access to it then!

Get the proper diagnosis and have the experts advise you on a solution.

Upgrading the engine is much more intensive I believe. I’m no expert, but I think you can’t just swap the engine without changing many other components and adding extra radiators, which means you may need some different trim pieces etc.
Not to mention the ECU and all the new electrics.

Personally, I would love to put the V8 from the e90 M3 in it.
Perhaps one day.... tis the dream! The GT3 car had a v8!

[B21]

If you are buying a second hand engine then it needs to come with its turbo and dme...otherwise there could be issues.

On that basis most N20 engines can be inter changed.

I doubt that your current engine is repairable.

Not practical to swap to a N52/N54..a 18i/20i/28i all good.