Bike has run hot - what to check and diagnostics

[Kenny Dave]

I went on holiday and had a bit of a disastrous trip with the bike. Long story short, she's run without coolant for quite a long time so has run ever so hot. There are two coolant pipes that go into the head around the barrels, the o-rings for these have, incredibly, melted.

So that I know how to sort, although whether it's possible we'll see. What I'm asking about is what else I should be checking and looking at in this situation. I'll test it thoroughly next weekend after I've got a plan of action, I've only had a brief look so far.

The head gasket seems to be ok, although it's just under where it's leaking from so it's hard to be sure. The coolant I think is draining in slowly, and didn't all drain after I filled it and pulled the plug. Could this be something normal, non circulation or some such? I'm totally inexperienced with coolant systems. I'm worried that the rubber has run into places it shouldn't be There is rad weld in the coolant system, about 4 times as much as suggested on the bottle, so maybe this too.

Any advice greatly appreciated. And yes, I am a stupid and lucky boy that it didn't seize and chuck me off.

[darrsi]

I'd imagine you have a blocked circuit, and the fluid has been dumped out of the overflow pipe of the expansion tank.

Drain the system and put a hose on the top to push any gunk out, then get some Radflush from Halfords, add and fill up with water, including the correct level in the expansion tank, and i'd personally leave it in and run the bike with it for 3 days to give it a proper clean up. Then flush the system and re-fill with a good pre-mixed motorcycle coolant.

It's more than likely that the Radweld has clogged up the finer pipes, so there's a small chance you'll fix one problem but open up another, so may end up replacing something! There's a strong chance that the pipes that form your carb heater circuit will be blocked too, which is not really a problem now but can cause you problems like carb icing in winter. I doubt very much that Radflush will clear them as the pipes are quite narrow. 

Obviously replace the parts you think are knackered firstly.

With any luck you may get away with it.

[markbubble]

id check you havnt got any coolant in your oil which is sometimes a sign of head gasket failure(but not all gasket fails cause oil in water and water in oil)why did you put any rad weld in was the rad leaking?if it wasnt the rad the rad weld wont usually cure anything
as already mentiond flush your full system out and reverse flush it as well a few times and maybe ride a while and do it all again to be sure
good luck with it

[Fazerider]

To clean out the melted O-ring material from where the pipes enter the cylinder head you'll need to take the carbs off... which will be a good opportunity to clear the carb heater circuits too.
If the Radweld was to bodge a leaking radiator you can find an aftermarket replacement (Delkevic) at about half the price of a Yamaha one.
As markbubble and darrsi say, you've got to get that gunge out of the system.
First thing I'd do before running the engine again is change the oil. Firstly, bike oil has a hard enough life as it is, overheating it drastically will have knackered it. Secondly, you may be able to see any water that has found it's way in there during the flushing process which would indicate a head gasket problem (at best).
Good luck.

[Kenny Dave]

Thanks peeps, some good tips there. The oil looks clean, like oil not emulsion, although I'll change it as advised and look at it properly when it comes out, and get the carb pipes super clean. Or in fact, just switch them for the spares I have and clean the rubber tubes. It's whether the block is due to the radweld or the o-ring rubber getting somewhere it shouldn't that is concerning me most I think

If it's blocked, I shouldn't run it I think? So how can I use the rad flush to help, just leave it sitting in for a bit?

The radiator failed several times. The repairs were successful, but I had to pinch off the cross pieces which I think increased the pressure in the other cross pieces and caused repeated failures. Or just because they've all experienced the same conditions so have failed at about the same time. It was cracking across the edges of the cross pieces, it really crumbed in the end. I've learned that a radiator in bad condition should be replaced, even if it is working.

I made some poor decisions to say the least in needing to get back quickly for work, not helped by stroppy rip off Italian mechanics, and other friendly but ineffective ones. What I should have done is ordered one from Delkevic or the one I got from eBay and sat tight. I didn't get back any quicker than if I had in the end.

The Delvevic tip is a top one, I've already ordered a pattern one from eBay though, new but providence unknown.

[Fazerider]

The oil looks clean, like oil not emulsion...

I wouldn't expect to see emulsion there. If the bike's been running very hot any water in the oil will have boiled off, if any has found it's way in afterwards it'll have settled as low as it can get. It shouldn't hurt to run the engine briefly, just long enough to get any water to form emulsion so you can empty the old stuff out.

[darrsi]

I personally leave Radflush in for 2 days, but that's when i have a minor problem!

3 days for you, in this weather, and go out and have fun on the bike, to give it a good clear out!