Coolant leakage - how worried should I be?

[Richi]

Yep, the waterpump is due for replacement... some time ago.

There goes 300 bux

[Mikkel]

There goes 300 bux

Yep - $313.99 to be exact. Better than having to get a new radiator though... they're more than a grand.

I just hope it won't take too long to get it.

[imdying]

You could take the old one to Smiths Regrinds to see what the say about rebuilding it.

[Mikkel]

You could take the old one to Smiths Regrinds to see what the say about rebuilding it.

According to the workshop manual it needs replacing if:

1. There's coolant leaking from a small hole on the back side of the pump.
or
2. There's corrosion and/or damage on the impeller blades.

1. is where the leak was at. And the impeller blades and housing are both quite corroded.

[Max Preload]

The 'small hole' is usually just the drain so coolant doesn't make it's way into the oil via a leaking seal (there's one seal either side of the cavity on the shaft that the hole drains). They can still often be dismantled and successfully repaired.

Have you had a timeframe for the new part? (I love a laugh!)

[Richi]

According to the workshop manual it needs replacing if:

1. There's coolant leaking from a small hole on the back side of the pump.
or
2. There's corrosion and/or damage on the impeller blades.

1. is where the leak was at. And the impeller blades and housing are both quite corroded.

The water pump sounds fine. You better get that radiator looked at

[Mikkel]

I got my new waterpump today - nice, shiny, sleek and pretty - and I've had the radiator checked (and it works without leaking).

So I'm almost set for putting it all back together.

Now, the temperature gauge on the dash doesn't read out correctly. Replacement gadget is fairly expensive... and so I was considering getting hold of a digital temperature gauge that I could fit into the dash where the old unit sits right now.

So, has anyone got some brands and models of digital temperature gauges that they could recommend?

[Max Preload]

What makes you think the gauge doesn't read out correctly when you haven't even reassembled, filled & 'burped' the cooling system? The senders don't work in steam or hot air and are usually located where the air pockets form.

Given you had a leak, then you'd have had such a pocket. I would suggest you put it all back together, fill the cooling system, run the bike until the thermostat has been open a few minutes (check the lower hose temperature to verify), switch it off and allow to cool, check and top up the coolant as required and restart.

Besides, if anything, it's most likely for the sender to be faulty, not the gauge itself.

[Mikkel]

What makes you think the gauge doesn't read out correctly when you haven't even reassembled, filled & 'burped' the cooling system? The senders don't work in steam or hot air and are usually located where the air pockets form.

Given you had a leak, then you'd have had such a pocket. I would suggest you put it all back together, fill the cooling system, run the bike until the thermostat has been open a few minutes (check the lower hose temperature to verify), switch it off and allow to cool, check and top up the coolant as required and restart.

Besides, if anything, it's most likely for the sender to be faulty, not the gauge itself.

I've replaced the sensor already.

There was no significant travel on the gauge even when the system was filled with coolant and the bike allowed to heat up to the point where the fan kicked in (~95 degrees celcius). The only movement from the guage was a movement equivalent to approximately the width of the cool-marker.

The gauge is not dead - but I believe it's not working properly. There is a fairly long-winded procedure to check if the calibration is ok, but I haven't bothered with it. The sensor is new, the electrical connections are ok - through exclusion the gauge should be the problem.
Unless, of course, as you say there has been an air bubble sitting right at the sensor. I find that unlikely - but I'll consider the geometry of the system and decide whether it is at all plausible.

[Max Preload]

Is the sender under the thermostat housing or on top of it?

[Mikkel]

On the underside. I'll do some tests tonight. Had a chat to a mate who's an auto electrician and he said that earthing problems at the thermostat housing could result in a reduced readout at the gauge.

[Max Preload]

On the underside. I'll do some tests tonight. Had a chat to a mate who's an auto electrician and he said that earthing problems at the thermostat housing could result in a reduced readout at the gauge.

They normallly bolt the housing to the frame via a bracket, but it's possible.

[Mikkel]

Ah, the pitfalls of 2nd hand bikes.

Tonight I did a couple of experiments and I observed the following.

If the temperature sensor is removed from the thermostat housing, given a good earth connection (wire to lower triple clamp in this case) and then dunked into hot water (80-100 degrees celcius) the needle moves to approximately a third of the full scale.

So after having concluded that earthing was the issue I had another look at the workshop manual and concluded that somebody had put the earth-wire onto the wrong bolt - the one which holds the thermostat housing onto the frame (incidentally it's isolated with a rubber bushing to reduce vibrations).
See the 1st picture - the red ring indicates where the earth-wire was connected and the green ring where it's supposed to be.
Another somebody (ego) failed to make that connection...

Anyway, I decided to check up on the thermostat as well. So I took it out and chucked it in a pot filled with water. I hooked up the cooking thermometer and heated up the water. The thermostat started opening around 64-66 degrees (manual say 58-62, but that's close enough for me since I dunno how precise the cooking thermometer is).

However, I do think that somebody (maybe the one from before) failed to use distilled water with the coolant. See picture 2.
Should I scrape out those deposits or just leave them as they are?

[Max Preload]

So the red circled bolt is an electrically poor connection to the thermostat housing by virtue of it being a vibration damping mount of rubber. That makes sense. That bolt looks substantially bigger though - how did it fit?

No need to use distilled water (you want demineralised anyway if you're being that fussy). The build up looks very minor anyway and is most likely because of the bad earthing of the housing causing electrolysis not mineral deposits.

[Mikkel]

So the red circled bolt is an electrically poor connection to the thermostat housing by virtue of it being a vibration damping mount of rubber. That makes sense. That bolt looks substantially bigger though - how did it fit?

The diameter and thread of all four bolts are the same. I suppose somebody may have thrown one of the original ones away and replaced it with something else during a (perhaps the) botched maintenance job where the earth-wire was misplaced.

No need to use distilled water (you want demineralised anyway if you're being that fussy). The build up looks very minor anyway and is most likely because of the bad earthing of the housing causing electrolysis not mineral deposits.

Depends upon your location I'd expect. I understand we have quite soft water here in Chch, dunno where you'd have hard water in NZ - but if you did calcium deposits like those will occur when water is heated close to the boiling point. I've seen much worse in electrical kettles in Denmark (very hard water) than what's inside that housing...
I should be able to get deionised water at the lab if I wanted.