In my never-ending quest to fix my poor idle, while the forum was down I changed my badly-worn camshaft sprocket to fix the slackness in the timing chain which I guessed was causing the shaky idle and exhaust 'burbling' as the cam timing jumps back and forth. To remove upper timing cover need to remove the thermostat and radiator hoses, so I replaced them. Took out the radiator and flushed that, and also flushed out the block (highly recommend opening the bolt under the exhaust, it was full of sludge that I had to poke at to loosen).
Unfortunately that didn't fix it, and there was still slack in the chain so I decided to change the timing chain. Because the M30 crank pulley is bolted on with approximately 1000nm of torque there was no way I was taking the lower timing cover off. So I researched "master link chains" - you can buy them 'broken' and then with a motorbike chain tool can fasten them together. I used the old chain to feed the new one through. Thought I'd share my pics of that because it can be helpful to know for any car, you don't have to take the whole front apart to change a timing chain. I also replaced all of the tensioner parts.
It didn't really fix my bad idle, maybe it's slightly better, but coasting is now no longer stumbly and it still drives like a go-kart.
Easy timing chain change
Easy timing chain change
1979 528i - Sold