Re: E30 coolant bypass hose caveat

[alex.fadeev@xxxxxxxxxxx]

"Russ Maki" <rinard@domain.elided> wrote:
> While doing the timing belt service on my '87 325i recently (M20 engine),
> I decided I'd change the 15-year-old main coolant hoses and bought some
> aftermarket replacements from my favorite mail-order discount parts
> supplier. The upper and lower rad hoses fit fine, but the bypass hose
from
> the thermostat housing to the water pump passed a little closer to the
rad
> fan than the original. It cleared with maybe half an inch to spare,
though,
> and it was a tight fit there with even the factory hose, so I let it go.
>
> A week or so later, while driving in traffic the low-coolant light went
on.
> I pulled over and found the front of the engine wet -- yep, the fan had
worn
> a pinhole in the bypass hose. I picked up some duct tape and distilled
> water, patched the system and left the reservoir cap cracked open to keep
> the pressure down (we can get away with this in Wisconsin in summer) and
> managed to get home.
>
> Picked up a factory hose from the dealer for $11 (the aftermarket one
cost
> me $9) and noted a subtle but obvious difference in the profile. A
half-inch
> trim from the aftermarket product might have made it fit better, but the
> point is that there was a problem with fit.
>
> Something to keep in mind when swapping out those aging rad hoses.

Russ brings up a very good point: always compare the aftermarket parts you
install to the OE parts you remove. I had run into a quite a few cases when
a supplier would either mistakenly send me the wrong part or a part they
though would work but which in fact does not fit.
With regards to the upper M20B25 hose, it's a good idea to tie strap it to
a metal lever sitting in front of the engine valve cover. In fact, there
should be a plastic clamp on top of that lever that is intended to hold
that hose in place. However, nine times out of ten it is missing.

alex f

------------------------------