One of the weak points for these cars I see all the time but never discussed is the cylinder head to thermostat coolant hose.
Around 100k+ kms is when you are vulnerable, the heat just makes the plastic brittle and tends to crumble when you remove it. As you need to remove this hose to do the oil filter housing gasket, it is a real pain when you discover its broken. In my case, 2 years ago this hose let go at Winton Raceway and luckily was able to drive the 3 hours home. The flange is quite high up in the cooling system so you will not lose all your coolant. I have already replaced this hose with a stock one but I want a more robust solution.
Luckily there are billet fitting available on ebay. There used to only be 1 available on the market, now theres many of them on ebay from taiwan. I ordered it over a year ago from the original source here:
https://www.ebay.com.au/itm/BMW-335i...MAAOSwuMFUdSD-
The biggest hassle is that the hose is crimped on the plastic fitting and you have to salvage a hose to put on the new fitting. You can cut the crimp clamp off but that always results in damage to the rubber hose. I found the best way is to cut the flange off the plastic hose, crush it (i used a hydraulic press but you could use a vice) and the plastic will crack and you can fit the new fitting.
I dont like worm clamps, especially in this case where you would never undo it. The fitting is supplied with a decent worm clamp, that wont cut into the hose. Some of the cheaper fittings come with crappy worm clamps which will tend to extrude the hose rubber thru the small holes in the clamp.
A crimp clamp is a much better idea so I purchased this:
http://www.ebay.com.au/itm/B12-00704...53.m2749.l2649