coolant hose P/N tip

[Robert Bondi]

While working on ordering a set of coolant hoses for my 77 530i w/ 80-81 528i FI, I finally noticed why I'd seen so many recent posts asking about
hose P/N differences between early and late E12s.

In many cases, realoem shows a 9/79 cutoff on coolant hoses. Pulling up windows for both a 77 530i and an 81 528i, I noticed many of those P/Ns are the same across the "up to" and "from" 9/79 boundary; therefore, there are a lot less interchange problems than one is led to believe....

Having updated my car with many 528i items, I can say the only cooling hose differences occur in conjunction with older water-heated aux air valve. This affects a few hoses going to the middle of the coolant return pipe and 1 formed hose plumbing the TB.

[wkohler]

It seems that the differences in all of the hoses mostly have to do with running around EGR stuff. I put all 528i hoses on my 530 and heater hoses are where the pipe around the back of the head was, and the 530 hose is routed around the air pump, etc.