1991 ST1100 Water Pump

Oldbikefixr · Apr 14, 2016

I'm building up a set of likely spare parts for my 1991. Been keeping up with the rebuild of the ST1100 water pump so I started checking.
Partzilla shows that for the 1991, water pump number 19200-MT3-000 is obsolete. Water pump for the 1992, number 19200-MY3-010 is still available (1992-1994). Both years have the oil cooler collar at the oil filter.

What's the difference between the two pumps?

naedlaen · Apr 14, 2016

Just read this today - https://www.st-owners.com/forums/showthread.php?139508-blown-head-gasket/page6 scroll down to the post by John O.

John OoSTerhuis · Apr 14, 2016

The USA 91 pump does not have a pass-through port and nipple for the 92-95 engine's internal crankcase breathers' output (front of right head) . 91s' engines vent crankcase air/vapor out a port at the rear of the engine to an external breather chamber (by your right shin).

I can dig up some pictures if really needed. Bottom line though - 91 pump in 91s only. 92-95 pumps fit a 91 just fine, I've seen one installed. No problem. The extra port is unused.

John
via iPhone 6

Oldbikefixr · Apr 14, 2016

John OoSTerhuis said:
The USA 91 pump does not have a pass-through port and nipple for the 92-95 engine's internal crankcase breathers' output (front of right head) . 91s' engines vent crankcase air/vapor out a port at the rear of the engine to an external breather chamber (by your right calf).

I can dig up some pictures if really needed. Bottom line though - 91 pump in 91s only. 92-95 pumps fit a 91 just fine, I've seen one installed. No problem. The extra port is unused.

John
via iPhone 6

That's what I was hoping for, John. No photo necessary. New parts for a 25 year old bike will soon begin to thin out. Didn't want an unusable spare in my stash. Thanks.

1991 ST1100 Water Pump

Oldbikefixr

naedlaen

John OoSTerhuis

Life Is Good!

Oldbikefixr