Incontinence!

[Mart]

Rode home after work last night, and decided to check the radiator fan cut it when it should. After leaving it ticking over for a few minutes, the temp gauge slowly climbing, the fan eventually cut in - closely followed by a trickle of coolant from the expansion tank overflow pipe!

Is this common?
There's no water in the oil, and the bike runs great.

I've ordered a new rad cap, and checked the thermostat - OK.

Is this the first signs of head gasket failure?

[ssevy]

Depends?


Sorry, just couldn't resist

[ssevy]

Okay, now for some useful information (I hope).

I would flush your system and then install new coolant. I like the premixed stuff from Honda auto dealers, as it is cheaper than the identical mix that they sell through the bike shops. Refilling really slowly and tilting the bike from side to side to burp it should get your air out.

On my Legend, the cooling fan rarely came on, and since it has no temp gauge like my Tiger, I did this mod to lower the temp when it activated:
https://www.triumphrat.net/maintenance-tips-and-tricks-for-the-t3-classics/170450-fan-temperature-switch.html

My Tiger always runs very cool, just touching the line, and only going higher when standing in stopped traffic.

I wouldn't throw a new thermostat in until I tried flushing and new coolant first. If it continues to overheat, you can easily capture the new coolant when it drains (by the way, it drains better from the lower hose) and then test your thermostat or replace it, and then reuse the new coolant so no money lost.

You might also check your radiator fins to be sure they aren't all plugged from years of insects, etc.

[Mart]

Thanks for the info.

I've changed the coolant, and checked the thermostat on the kitchen stove with a pan of water (don't tell the wife - I may have used her favourite saucpan!).

Just to be sure, I've ordered a new radiator cap from Triumph.

Also plan on fitting a fan override switch on the bars, so I get to decide when the fan comes on.

Fingers crossed...

[ssevy]

If your thermostat passed the clandestine boil test, it's probably fine.
How is the radiator? A gradually plugging radiator usually shows a gradual increase on your gauge over time, until you exceed its remaining cooling capacity and begin to get boilovers.
I've never had a cap fail myself, but anything is possible.
Good luck and keep us posted.

[Mart]

The radiator looks clean, and seems to flow OK.
Using the info you provided, I've fitted a 95°C fan switch and relay.
So, with the new radiator cap, manual overide switch, and lower temp fan switch, I'm pretty confident that I'll have made a difference. I won't know till Thursday, and I'm off touring Germany for a couple of weeks, leaving on the Friday.

Leave things till the last minute? Not me....

Thanks for your help

[ssevy]

Just don't get the brilliant idea to change the output shaft oil seal the night before you leave...dont ask me how I know

[Geoff W]

OOH 2 weeks around Germany! Motorcycling Nirvana. If you can do the B500 do fit it in. Enjoy yourself!

[Mart]

Yes, B500 is the first port of call.

I tried to fit the lower temperature fan switch from a VW T4 last night. Although the sensor will fit in the hole in the side of the radiator, the sensor plastic body is a larger diameter than the original, and the plastic retaining ring will not fit. So no way of securing the sensor to the rad...

However, the new radiator cap seems less inclined to allow coolant to pass back to the tank, so thumbs up -  we're off tomorrow!