Thunderbird 900 Spitting Out Its Coolant

Hi all,
My 1997 Thunderbird 900 occasionally is spitting out its coolant. It seems ok on longer runs but it hates the stop start of a commute, especially if I am in the mood for spirited riding.

Any suggestions? Thank you.

 

As ever, some really helpful suggestions.
Ill check the drain hose from the expansion tank but I think it's ok.

The rad could be gunged up. The bike was refurbed by the previous owner very well but who knows what it was like before that. There was rust staining in the overflow bowl when I bought the bike. I

've tried draining the system by undoing the water drain bolt on the pump, the bleed bolt on the side of the engine and pumping water through with a garden hose. It ran clear and strong. But i am guessing it could still do that even if the finer heat exchanger parts were gunged..?

I will buy a new cap but something is making the bike get hot, hot enough to overcome the pressure seal on the cap.

I might look at the kettle descaler trick, and back flushing the rad seems like a very good idea too.

Thanks all.

S

 

Yes. Fan kicking in.

 

Rode to work and back today. V hot out there. Bike not spewed its fluid out. 50/50 mix of water and collent, plus a drain down and wash through seems to have helped.

I still want to take the rad off to rinse through while invertef though.

 

I took rad off and back flushed. Took the down pipe off that leads to the water pump. Refilled with 50/50 water and antifreeze. 2L of fluid, plus a little in the expansion tank. I think that is as per the manual. The fan did come on, but it seemed to take a while before it kicked in. I refilled it and rode to work the next day.

The sensor on the left side of the bike is a bit manky. The wire is still connected but maybe the signal is weak, making the fan come on later than it should?

I have not been able to remove and inspect the water pump. But everything seems to run clear.

 

No I have not. But I did wonder whether it would be worth getting a new one. Will look into it. Thanks.

 

The t bird does have a bleed screw. Filling up slowly leads to some gurgling and it seems to sort out any bubbles. 2L goes in which is he correct volume I believe. I fill the reserve tank to the line. A bit of expelled water would be ok but every couple of rides she throws at least half of it out.

Maybe the temp sensor / thermostat is kicking the fan in too late.

 

The bike has been reliable for years but has developed a couple of gremlins.
The green neutral light is not coming on, but this only happens when the engine is hot. I have read the other posts and will check the wire connector to see if it is corroded.

The engine was only starting on 2 cylinders. I replaced all 3 plugs a couple of weeks ago which fixed things. The right one was oily.

New plugs worked wonders but now the problem is back with a vengeance and its only been a couple of weeks.

What is causing that plug to oil up i wonder?

I am worried now that that the valves might need work, which I am not confident to do.

I am going to look at the air box today. I noticed the plastic collars that mount the box to the carbs and the carbs to the engine looked a bit worse for the wear.

I guess the carbs might have gummed up. I have had that often enough on my 2 stroke outboards. I could probably manage removal and cleaning, but it is not a 5 minute job.

I cant see a link between the coolant issue and these new symptoms, but I am happy to be educated.

Bike has done over 30k miles now. Kept under a pram cover thing. Battery new ish and well looked after.

Right, I am off to take the bike to bits. Sorry about the endless open ended questions.