Hi all, My 1997 Thunderbird 900 keeps 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. The loss of coolant seems to be from the filler cap (the twist on one). No other leaks are apparent. The spray pattern from the residue suggests it is getting hot and then being forced out of the cap. I have tried bending inwards the cap flanges to make it seat more snuggly. The inner spring seems to function ok. No obvious perishing of the rubber mount ring. It did this a bit when i first bought the bike a few years ago. I drained it all down, removed various pipes and flushed it. If memory serves I could not actually get the water pump off but the ol girl behaved herself after a good flushing. Because it has been losing coolant I have been too cheap to mix in 50% coolant. I'm wondering if water only is less effective at managing the heat. My next step is to flush her out again and do a proper 50/50 water and coolant fluid mix. Any other suggestions? Thank you.
Hot coolant should never get past the filler cap outer seal, it should go into the expansion tank. Is the pipe to the tank and the tank breather clear? If they are I'd fit a new cap.
Even if it is the head gasket, the coolant should get expelled through the expansion tank overflow, not the filler cap.
This may not be as drastic a fix as you think, given it is ok on longer runs that is the clue, as has been suggested fit a new radiator cap, you shouldn't need to modify the cap you have on the bike, this can exasperate matters, the rad can become clogged up on these older machines, it is 27 years old after all, whilst the build quality of the early Triumph's were good, the rad core can easily become full of sediment, especially if it has not had any regular coolant changes, if the rad if clogged up then it will spit out fluid as it is not circulating correctly, I would try this first before digging deeper, if the head gasket had failed I would expect oil contamination in the coolant, and the sump, it could be the thermostat sticking but this I doubt as it would what you describe on short and long runs. Hope this helps and ride safe all from an ageing Rocker.
Take the rad off and back flush with a garden hose. Tap pressure would be suitable and by reversing the flow it has more chance of dislodging any build up that has occurred. Keep going until and shaking etc. only gives clean water coming out. Running neat water in future is most definitely a bad idea with regard to corrosion, especially considering the multiple metal types in the system. I did similar to the above, only 6 months or so ago, on a ZX9 that kept shoving rusty coloured water out and it resolved the issue.
As ever, some really helpful suggestions. I do not think the head gasket is blown. No leaks or smoke. I don't suspect the thermo switch either as it seems to switch on and off at the appropriate time. 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
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.
Ok so she is still losing coolent. It is quite annoying and cannot be doing the engine any good. It is not a leak. I don't think its the filler cap. I took rad off and back flushed. No debris and it looked pretty clean. Drained the system again. Took the down pipe off that leads to the water pump. Didn't seem blocked. Refilled with 50/50 water and antifreeze. Once she was all back together again I let it idle for about 10 mins. Water widdled out around the centre stand, obviously via the expansion tank overflow hose. Maybe I over filled it? 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. About half an hour of fast commuter traffic. The "hot" dash light came on towards the end. It was ok on the way home, and I was not nursing it, giving it some beans. When I took the tank off there was water in the expansion tank. I topped up via the filler cap and she took just under a litre. Its all a bit odd. 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. Recently, one cylinder was a bit reluctant to fire on start up. It would kick in after 20 seconds. So I have changed the plugs. Right one was quite oily and looked different to the other two. Probably not an issue related to the coolent problem. Oil looks fine. I don't think it is a blown gasket. Any ideas? Thanks
Have you considered testing or changing the thermostat ? A quick Google search shows they might no longer be available. But also shows some car model stats will fit.
Did you squeeze the pipes with the engine running to expel any air in the system? On my bike (T509) I just went round all of them and also leant the bike both sides . Is there a bleed screw at the top of the radiator on your bike, sorry but I haven't owned a T bird so wouldn't know? Did you fill the overflow tank to the marked level? If so it may just be finding its own level, many of these and later Triumph triple engines run perfectly fine with the overflow tank half full, mine included. If the water is coming from the overflow tank you may find it stops spitting out at a lower level, worth a try. As for the cap, there are a few recommendations out there if you google search or go on triumphrat site, my bike will surely be different to yours so I won't recommend the one I know. From what you say I'm sure your head gasket will be ok and hopefully an easy fix.
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.
I have always found that if the coolant expansion tank is filled to the max Triumphs tend to expel coolant until they settle on a lower level usually just above the min level line. I always fill mine just above the min level without any issues.
