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· blind rebuilder
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I'm wondering would it be straight swap for e34 2.0 to a 2.5 except for the ecu. Things like manifolds auto trans any electrical etc.
Kindest
Nick

E34 1995 520i M50 HB62 auto made in Dingolfing Germany
 

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im not 100% on all of things, but the following i definately know is different between them:

the B20 intake and throttle bodes rubber flex pipe etc is all different between the engines (narrower on the B20 as it doesnt need as much air),
the MAF sensor is different,
ECU different
alternator is different in most cases, sometimes the b20 runs the 120A b25 alternator if the engine is ex-E34 though
coil packs same
crank sensors/timing wheel is the same.
spark plugs the same

then you may run into the issue of where the engine ame from, if it is ex-E34 then you will be fine, but if its ex-36 then:
mount points different
sump different
oil pickup different
dipstick and tube different
all of these can be replaced with your e34 stuff though from your current engine, and is cross compatable between b20 and b25 etc
 

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I would like to add that the engine coolant temp sensor is 2 pol on the 2,5 an 1 pol on the 2l,

if you are using the 520 instrument cluster your temp gauge will not work at all with the 2 pol sensor might be a good idea to change it while the engine is out of the car. '

I did the same swap last year , swapped out the 2l vanos with a 2,5 non vanos and manual transmission the diffrence is amazing :wow:

good luck with the swap :)
 

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ok, that would mean you would have a cluster that comes up with all the OBC warnings though, unless the 520i clusters are the same as the 525i clutsters where you are? on my UK import, the 2L have a different cluster to all other E34s, i have never seen another E34 like it.
 

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I think all 520 use the same cluster , it lacks the check control system that the 525 has so it doesnt come up with warnings like a bad bulb or low oil etc.

The 525 cluster is not plug and play in the 520, Im not sure how much work is needed to make it work but the plugs on the wiring harness are different and the 525 also has one more plug so I would imagine you would have to swap the wiring harness.

anyway I run my 2,5l on the 520 cluster and everything apart from the temp sensor will work without problems, so just swap the engine coolant sensor from the 2l to the 2,5l.

Under the intake manifold there are 3 plugs the engine coolant sensor is the one in the middle.
 
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