cooling system swap when going from OBDII to OBDI

[LukeG]

so i'm swapping the motor out of my 98 m3 into my 95 m3 and am wondering what the reason is for having so swap the cooling system lines that are routed under the intake manifold? I see everywhere saying that you have to, but why? i dont see why i cant just retain them and swap the fan shroud and expansion tank assembly.

[m2pc]

so i'm swapping the motor out of my 98 m3 into my 95 m3 and am wondering what the reason is for having so swap the cooling system lines that are routed under the intake manifold? I see everywhere saying that you have to, but why? i dont see why i cant just retain them and swap the fan shroud and expansion tank assembly.

On earlier engines they used rubber lines across the top of the intake manifold, but on later years (like my 97) they switched to hard steel lines for some resaon.

I thought I read somewhere that swapping the lines was necessary in order to properly plumb to the heater core, coolant solenoids, etc.
Not 100% sure on that though -- free bump for anyone else that knows!

[LukeG]

heater core hose bolted right up...seems like the tb will bolt right up, the expansion tank i will use from my 98 and that seems like it will bolt right up...

i'm just going to try and put everything back together and maybe then i will find out for sure lol

[LukeG]

to answer my own question and whomever it may be helpful to, you need to put the rubber lines back in because the bracket that holds the IAC will no bolt to the block with the metal lines in the way.

also, if anyone is interested....when using OBDII manifolds on a OBDI, bmw actually sells O2 plugs. i can't seem to find the part number, but they are offered for the z3 manifolds