Hi, I’m trying to buy a replacement part for my K75, but am really struggling to identify it. I’ve searched the OEM parts bin etc, but without success. Could anybody help me please? It’s driving me nuts!

Looks like the thermostat housing.

Point-Seven-five wrote:Looks like the thermostat housing.

Thank you!

The housing is an integral part of the radiator body. It isn't available as a replacement; only the parts attached to it it can be replaced, parts 2, 3, 4, 5 in the drawing below from the Max BMW parts fiche.

I’ve figured out the problem, or rather Thom from K Bikes in the Netherlands did. Rather than trying to sell me something, which he would have been perfectly entitled to, he pointed out that the radiator had been moved by the previous owner, who ran the coolant pipe outside the hole in the engine block. The weather here is too dark and miserable to tackle it right now, but when Saturday comes….   Thanks for your help @Laitch and @Point-Seven-Five. I will endeavour not to be so stoopid in future. Can’t promise, mind you, but I’ll try.

The RT had the under hose outside the engine, the naked and K75S had it through the engine.
If your K is a naked or S, nothing is moved by previous owner.

Arlina wrote:The RT had the under hose outside the engine, the naked and K75S had it through the engine.
If your K is a naked or S, nothing is moved by previous owner.

Yep. If the bike started life as a K75RT then it has that hose in front of the cam cover. When BMW retrofitted the K100RT fairing to the K75, they used a K100 gas tank and radiator. There's a bracket at the bottom of the radiator that moves it forward to make up for the "missing" front cylinder.