Timing belt change and water pump

PLUMMAN · Mar 31, 2013

Just getting ready to order water pump and parts to change this out. I wonder what parts to order for water pump replacement on a 94 model with 130k?
I had just planned to replace the belt and decided to change the pump. How many o-rings, etc? Suggestions from those that have replaced the water pump. Thanks!!

ST1100Y · Mar 31, 2013

MHO: w/shop manual showing the indicators, proper torque wrenches, t/belt, idler + spanner pulley, w/pump + gasket + O-ring (pre '96 model with oil cooler); do not loosen/remove the clutch cover, pry the plastic part out underneath and cut that obstructing rib out before re-installing. Well, and while having the radiator out anyway: coolant stat + O-ring, radiator cap, coolant hoses(?), overflow hose, radiator drain plug + gasket, fan-stat... check fan motor/bearings, check propeller mounting on shaft, check motor wiring/ground connection for corrosion.

maximark · Mar 31, 2013

I'm in same situation except, I wasn't planning on touching water pump. Hoses, t-stat with o ring, tensioner spring, reserve tank since I can't see if anything is in. I also have 94 with 130K on it.
why does the radiator cap has to be replaced?

Mark

PLUMMAN · Mar 31, 2013

Mark,
The radiator cap holds the pressure for the cooling system at 16 pounds of pressure. These do fail and the sealing gaskets on the cap crack.

ST1100Y · Mar 31, 2013

To replace the w/pump too is kinda 'risk management'... changing the timing belt is already quite some work, getting the pump done too while at it adds only minor efforts to this... especially compared to the disappointment of having done the belt, to then notice a failing pump seal like 2~3 months later, meaning having to go through all the work again... If the plastic of the coolant overflow reservoir isn't brittle, pour 1~2 hands full of pebbles into it, add a mix of detergent and water and shake well

This will remove like 99% of the crud in there, making it look like brand new. Interesting side note though: since I've moved away from Castrol stuff and changed to BelRay MotoCool, the reservoir of my ST stays absolutely clean... anyone else made observations that some coolants tend to stain that vessel, while others don't?

maximark · Mar 31, 2013

ST1100Y said:
To replace the w/pump too is kinda 'risk management'... changing the timing belt is already quite some work, getting the pump done too while at it adds only minor efforts to this... especially compared to the disappointment of having done the belt, to then notice a failing pump seal like 2~3 months later, meaning having to go through all the work again... If the plastic of the coolant overflow reservoir isn't brittle, pour 1~2 hands full of pebbles into it, add a mix of detergent and water and shake well This will remove like 99% of the crud in there, making it look like brand new. Interesting side note though: since I've moved away from Castrol stuff and changed to BelRay MotoCool, the reservoir of my ST stays absolutely clean... anyone else made observations that some coolants tend to stain that vessel, while others don't?

You mean that I don't have to replace the actual pump just the seals? Cause pump is like $300 and all together with hoses etc. it's coming to good chunk of $.

ST1100Y · Mar 31, 2013

Nah, you can't change the shaft seal of the pump... and if, that's where it starts to leak (normal mechanical wear, will appear some when over 80~100K...). It'll start as a small leak, thus unnoticed for quite some time at first (only 5~6 drops while warming up at first), but still a risk for the head gaskets though... its the call of the vehicle owner though...

nhdiesel · Mar 31, 2013

In the old days water pumps were rebuildable. Now they are replaced as an assembly. The seals themselves don't usually start leaking because only the seal is bad- the seal goes bad because the bearings wear out, and the shaft gets a lot of play. The excessive play is what causes the leak- either just because the shaft is moving, or because the additional movement of the shaft actually wore the seal.

For anyone replacing a belt who wants to check the pump, once the belt is removed grab the pump pulley by hand and try to move it around. If there is any horizontal or vertical movement- any shaft looseness at all- replace the pump. It might now be leaking right now, but it will be soon. If there is no looseness, turn the shaft by hand. There should be a small bit of drag on it from the tight seals rubbing on the shaft. If the shaft spins very freely, then the seals are fairly worn and will most likely be leaking before too long. If the shaft isn't loose, you can decide whether to replace the pump now while in there, or wait to see when it starts leaking. Still a good idea to replace it now.

Digger1 · Mar 31, 2013

ST1100Y said:
....If the plastic of the coolant overflow reservoir isn't brittle, pour 1~2 hands full of pebbles into it, add a mix of detergent and water and shake well....

Good technique.....ice cubes work, too!

Digger1 · Mar 31, 2013

nhdiesel said:
...The seals themselves don't usually start leaking because only the seal is bad- the seal goes bad because the bearings wear out, and the shaft gets a lot of play. The excessive play is what causes the leak- either just because the shaft is moving, or because the additional movement of the shaft actually wore the seal......

FWIW...

Back in the day, I had an '81 GL1100 that I put a lot of miles on. Went through a bad streak of wearing out water pump mechanical seals.

Finally (with the help of Motorcycle Consumer News magazine) figured out that the antifreeze I was using (silicate formula) was tearing up the mechanical seals.

Went to a no-silicate antifreeze....end of problem.

Not absolutely certain this applies to our ST1100's, but I'm pretty sure that it does......

George · Mar 31, 2013

No need to fuss with the water pump at 130K unless it's showing serious signs of a leak. They'll go 200 if all else is okay. Timing belt at 130 is good. Check the idler pulley and tension pulley too. coolant hoses are prone to failure in that time frame.

PLUMMAN · Apr 1, 2013

George said:
No need to fuss with the water pump at 130K unless it's showing serious signs of a leak. They'll go 200 if all else is okay. Timing belt at 130 is good. Check the idler pulley and tension pulley too. coolant hoses are prone to failure in that time frame.

Thanks George,
I went ahead and ordered the pump as I figure before the timing belt is due again it will be 220k. SO I'm replacing both pulleys and the pump with this timing belt.

ST1100Y · Apr 1, 2013

Digger1 said:
Not absolutely certain this applies to our ST1100's, but I'm pretty sure that it does......

It does...

maximark · Apr 1, 2013

PLUMMAN said:
Mark,
The radiator cap holds the pressure for the cooling system at 16 pounds of pressure. These do fail and the sealing gaskets on the cap crack.

Are we talking about same cap? I'm thinking the cap on top of t-stat housing, the one that you unscrew by hand and look in. Like the cap on top of car radiator

ST1100Y · Apr 1, 2013

maximark said:
Are we talking about same cap? I'm thinking the cap on top of t-stat housing, the one that you unscrew by hand and look in. Like the cap on top of car radiator

Exactly the cap in question. Its spring can weaken over the years, leading to lower coolant system pressure, thus a lower boiling point; and its seal is rubber, which ages over the years and will unavoidable start to crack and leak one day.

Slasher · Apr 1, 2013

Digger1 said:
Good technique.....ice cubes work, too!

I used a handful of pennies. I guess they are still good for something after all.

Slasher · Apr 1, 2013

ST1100Y said:
Exactly the cap in question. Its spring can weaken over the years, leading to lower coolant system pressure, thus a lower boiling point; and its seal is rubber, which ages over the years and will unavoidable start to crack and leak one day.

If you have a cooling system pressure tester or you can borrow one with the correct adapter, you can easily test the cap to see if its still venting at the proper pressure. As cheap as rad caps are though, you can just as easily swap it out for peace of mind.

MV_Dave · Apr 1, 2013

George said:
.. Timing belt at 130 is good. Check the idler pulley and tension pulley too. coolant hoses are prone to failure in that time frame.

George, are you saying that the timing belt replacement can be put off until 130K instead of the recommended 90K miles?

George · Apr 1, 2013

I personally use 110K, but even then original belt looks nearly new. Do the visual inspection, if no signs of deterioration, let it go. OTOH, there have been cases of belts letting go at much earlier mileage, so ya buys yur ticket 'n ya takes yur chances. I suspect most belt failures are because of a bad bearing in one of the pulleys (water pump, idle pulley, tensin pulley) allowing the belt to slide forward or backward and get chewed up at the leading or trailing edge.

Slasher · Apr 1, 2013

I changed mine out at 35,000 lol! I was changing everything when I bought the bike to start fresh. I could still even read the green Honda part number on the timing belt so I put it up on the shelf. Maybe I'll put it back in at 135,000!