87-k75c coolant leak

[JEFFBUSK]

I have a 1987 K75C with a coolant leak behind the water pump though what looks like a weep hole.How serious is this and can I fix it myself ?

[cjack]

I have a 1987 K75C with a coolant leak behind the water pump though what looks like a weep hole.How serious is this and can I fix it myself ?

The easy way is to buy a new waterpump with the updated seals, etc. But you can rebuild the old one. Also, there where were some changes in the rotor and how it was attached to the shaft and also changes over the years in the seals. I would probably just replace the pump, but the short answer is yes, you can fix it yourself.
Check the IBMWR tech articles for K bikes here:

http://www.ibmwr.org/ktech/water-oil-pump-rebuild.shtml

There are excellent procedures and pictures of what is involved.

[JEFFBUSK]

Thankyou for the quick reply and good information.Jeff

[deilenberger]

I have a 1987 K75C with a coolant leak behind the water pump though what looks like a weep hole.How serious is this and can I fix it myself ?
The weeping is likely to continue - but the possibility of catastrophic failure is rather low - BMW used a unique seal design for the water pump that fails very slowly. It isn't a standard rubber lip seal.

While you *can* possibly rebuild the pump - for an almost 20 year old pump - if it was me - I'd just go for the new one. The parts to rebuild it are about $80 or so now.

The newer design parts are not easy to install (the older ones were MUCH easier..) and I know a number of people who have attempted this - and ended up destroying the parts. They then went and bought a new pump.

There is also a good possibility that your water/oil/pump shaft is corroded making the likelyhood of a good seal low.

A new pump is probably in the $350 range (check Chicago BMW - they have good discounts..) and for peace of mind - that's what I'd go with.

Best,

[Burnszilla]

I have a 1987 K75C with a coolant leak behind the water pump though what looks like a weep hole.How serious is this and can I fix it myself ?

I'm curious.. how many miles are on that bike?

[bmwmick]

I'm curious.. how many miles are on that bike?
Stephen,
Just for another DATA point, My 1993 K1100LT with 136K on it just this morning started dripping coolant from the weep hole. Local dealer only had one of the (3) needed seals in stock so I'll probably just replace the pump assembly and then maybe rebuild my original if I find the impeller and shaft are in good condition. It's not too unusual for the ceramic seal to fail at this mileage. My bike has had coolant flushes every two years since new.

[JEFFBUSK]

I have 37K miles on the bike.I keep the bike in an unheated garage and it got down to a -10 degrees temperture.It seems to leak more when it get real cold.I will keep an eye on it to see if it gets worse.

[gurniel]

Jeff: My K75C 1987 was leaking coolant when I got the bike about 4 years ago. I ordered a new pump ($375) but when I took off the old pump there was some build-up of corrosion between the water pump and the block. Amazingly, there was an "O" ring (seal) there that was obviously losing its elasticity. I replaced the "O" ring for about $4 and canceled the order for the water pump. The bike hasn't leaked a drop since.

Be careful about replacing something you don't need too because the water pump/oil pump is a pretty nice piece of equipment. It wouldn't surprise me if it lasts forever. It is not like a car's water pump because it is driven off the end of a shaft and doesn't have any belt pressure on it. However, if yours is definitely leaking out the weep hole then it might indeed be the pump and not the "O" ring that I replaced.
Bob in NC