e34 - e30 engine swap

Post Sat Jan 22, 2005 3:57 pm

Can anyone here shed any light on whether the e34 525 lump is the same as the e30 325? Ie are they both M20's (including engine mounts)

Just wondering as despite only covering a tiny 111k and being regularly serviced and run on fully synthetic oil since day one of it's life. My 325 is beginning to sound less than healthy. There is a horrible rumbling from the engine between 1 - 1.5k rpm - I am assuming it is cam bearings as it sounds quite close to the rocker cover. When you rev through that range it clears, but comes back when the rpm drops back. Slightly worse as the engine heats up.

Anyone had any experience of this before? Has anyone replaced cam bearings? I'm contemplating picking up a scrap engine from the breakers and getting a mate to just swap it in rather than go through the hassle of a rebuild

Post Sat Jan 22, 2005 4:12 pm

I didn't realise that - any idea when the change came in? Was it the same time as the face lift (ie with smily headlamps?)

Post Sat Jan 22, 2005 4:36 pm

The E34 525i came with both the M20 and M50 engines.

I think the basics of the M20 are the same between 3-5 series but Im not 100% sure. Someone on here should be able to tell you.

The M50 2.5 24v is a good place to start if you want to do the conversion.

Post Sat Jan 22, 2005 5:19 pm

Cam bearings are line bored into the head and non replaceable dude.

Just to clear up one of your original questions

You checked the usual suspects first ? cam belt tensioner pulley bearings, water pump etc etc.

If it rotates it makes noise M8, @ those miles that engine should be minty fresh internally .

all the e34 engine will fit inrto the e30, the sump is the correct way round so the worlds your oyster.

Go on, stick an M60 4.0 V8 in there

Post Sat Jan 22, 2005 6:37 pm

Cheers for your help guys

I had not thought of the M50 engine .... think any thing bigger than a 2.5 would be a bit

- if not for me driving it then on the bank balance

May just stick some good 'ol Castrol GTX in and seen if that reduces the noise having a thinker oil

Post Sat Jan 22, 2005 6:40 pm

I am pretty sure it is not anything else. It's had a new cam belt and tensioner recently, so I'd hope they'd be ok

Post Sat Jan 22, 2005 11:03 pm

Could the rockers need to be adjusted?

Post Sat Jan 22, 2005 11:48 pm

I don't think the noise caused by rockers out of adjustment could really be described as a rumble.
Did the noise appear after you changed the cambelt and tensioner, or was this an attempt to cure it? First suspect when fault finding is the most recently replaced item
You'll struggle to find a replacement engine with as few miles as the one you have, and better the devil you know..

Post Sun Jan 23, 2005 8:46 pm

yes I agree, mileage wise she is still very young. I think I might try some thicker oil as at the last oil change it did help for a while. The cam belt has been in for a few months so I don't think it is that

Post Mon Jan 24, 2005 11:25 am

Does the E34 sump fit an E30 okay? Only reason I ask is that the sumps are different and the E34 dipstick goes into the sump and not the block like an E30 - and there's not always a drilling in the E34 block for an E30 dipstick. What about threaded holes in the block for the E30 engine mounts? I thought the early E34 had different mounting holes?