Re: E30 coolant bypass hose caveat

["Russ Maki" <rinard@xxxxxxxxxx>]

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.

Cheers,
Russ Maki
Ixonia, Wis.

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