[skromak]

As the title goes, I'm getting the timing chain replaced. Is there anything else worth doing at the same time whilst the engine is out?
Thanks!

[Phil325i]

Guide rails and slide rails for sure, but I imagine they'll come as part of the kit...

[nemz]

Need to replace the 3 bolts on the camshaft sprocket, the bolt holding the high pressure pump sprocket and the left hand threaded bolt holding the oil pump sprocket. Technically, you're supposed to replace all of the bolts holding the rear engine cover but I've always re-used and added a little blue thread lock, it's not going to come off when there's a gearbox bolted to it as well.

Sump bolts can be re-used, don't forget to use the high pressure pump sprocket puller which is included in 99% of the timing tool kits.

The rear seal can be tricky depending on what kit, this is supposed to be installed after the rear cover has been fitted. If it's put it in first, it's really tight and inceases the risk wiping off the gasket compound on the top edge of the rear cover, potentially leading to oil leaks down the line.

If you're doing the fuel filter at the same time, run the fuel bleeding procedure in ISTA before attempting to start the engine. Once started and everything looks okay, continue in the same service function to bleed the high pressure side (it'll run at 2000rpm for 10 minutes) ideal for leak checking.

Clean the inlet manifold, I use the castic soda method.

Examine the EGR valve operation, if it jams see if you can clean the mechanism with a brass brush and brake cleaner to get it operating smoothly and returning to it's default position (lubricate with ceramic high temp grease only). If it doesn't move smoothly they're cheap enough to replace, run the EGR service function if new one is fitted (note, it should be connected before fitting with ignition on, otherwise it can be damaged during install) or if you manage to fix the original and it operates throughout it's entire range smoothly and returns.

Don't forget there's different size bolts holding the gearbox to engine, the smaller pair of the large bolts go into the top hard to reach locations. If you put a long bolt in the wrong hole and tighten it too far, it's "buh bye" engine.

Not too hard to do, I do it from underneath with the gearbox out method. Satisfying to hear then run after the chain has been done, definitely sound much healthier.

Checkout "Vaslov" on Youtube, he does the best N47 timing chain replacements. Youtube Russian translation can be iffy but it's really easy to follow.

Good luck, if you're doing it yourself