Coolant expansion bottle - level not moving

[MonkeyJim]

From my RC8R thread but thought it might get more visibility here

Thoughts please?

[dansp1]

level in the system is low and or the pipe from expansion tank to system is blocked

[MonkeyJim]

6 minutes ago, dansp1 said:

level in the system is low and or the pipe from expansion tank to system is blocked

Thanks for the speedy reply.

It *shouldn't* be either of those things, but I'll check.

[Thunderbolt]

Have you got a bubble between the two ends?

 i.e. there is sir trapped in the pipe between the expansion and the rad?

Is the expansion a pressurised expansion or an overflow? Is the pressure cap on the rad or the expansion?

 I don’t know enough about your bike to tell.

[MonkeyJim]

1 hour ago, Thunderbolt said:

Have you got a bubble between the two ends?

 i.e. there is sir trapped in the pipe between the expansion and the rad?

Is the expansion a pressurised expansion or an overflow? Is the pressure cap on the rad or the expansion?

 I don’t know enough about your bike to tell.

Well the set up seems mostly the same as I've had before on the R1 and K6.

As in pipe goes from rad cap into a bottle which then has an overflow / is vented to atmosphere.

Unlike a jap bike with the usual half-turn metal cap, on the RC8R the rad cap is a screw-on plastic one and the pipe comes straight through the middle of the cap and goes to the external bottle.

This probably shows it best.

Threaded metal spigot on top of rad is where the black plastic cap fits (rated 1.4bar)

Pipe runs through centre of rad cap into bottom of reservoir bottle, which has overflow pipe exiting from the top and down to under the bike.  Cap on reservoir bottle is just a screw on plain cap, not pressurised at all

 

 

Edited April 29, 2020 by MonkeyJim

[CMSMJ1]

I agree with @dansp1

 

I would go low coolant in the first instance and a blocked hose for my second guess

I'd run it til hot and get it burped a bit - it should be moving, as if it is not then there will be some positive pressure in it somewhere when getting hot, and negative when trying to cool - blocked tube?

[MonkeyJim]

Update.

Yesterday I checked the coolant level in the radiator and it had dropped down.  Not much, probably about the same as I found this morning (see below)

It was definitely full when I bled the coolant, so I topped it up, ran the bike again up to temperature enough for the fan to come in. 

And left it overnight.  This morning, the level had dropped again.

 

and so had the level in the reservoir bottle (which does at least indicate there's fluid moving in the pipe between the two?)

 

So I've topped up the radiator again, opened the bleed screw on top of the rad.

It was too early this morning to run the bike again but I'll do that today. 

Interestingly, I've asked about this on the FB owners group and a few people have said

'ignore what it says in the manual, it needs to be go out for a ride and the level will settle'

Also a couple of people have said the level in the bottle doesn't change when the bike is hot.

One very kind guy in Florida went and marked his level and ran his bike up to temperature for me:

this is COLD

And this is HOT, 208^oF = 98^oC

Pretty much exactly the same.

I must admit I never really paid any attention to it before, so I can't remember if my level moved when hot, or not.

I'm guessing not?!

 

Edited April 30, 2020 by MonkeyJim

[dansp1]

Is that OAT coolant? if so is that what was in it from the factory?

[MonkeyJim]

1 minute ago, dansp1 said:

Is that OAT coolant? if so is that what was in it from the factory?

it is, and that's what is meant to be in it, and what was in it before, from what i can tell.

I know what you're thinking, I did think that already.

[MonkeyJim]

Another helpful UK owner has just sent me these, same thing, level doesnt change from cold to hot

Edited April 30, 2020 by MonkeyJim

[Thunderbolt]

I really like your pictures and your very logical methods.

 I don’t know your bike but I would try and burp/bleed the system.

 I think you have some air trapped.

It’s obviously a bugger to bleed. 
I would run it up to temp, fan on, then check till it stabilises.

[CMSMJ1]

1.4 bar pressure on the cap is decent - it'll need to be hotter than that to be pushing it into the reservoir.  At least you have no leaks then - so....get it hotter!  pressured system will go over 100 degrees

[Thunderbolt]

Agree with the above, fan on, get it hot.

 

 But I think that it will stabilise .

[bobert]

My 990 level doesn't change cold to hot, if the pressure in the system isn't high enough to overcome the rad cap spring then the overflow won't increase, I would keep an eye on it after a ride/few cycles and then not worry about it. 

Fun story: when I worked for Honda years ago a new accord came back with a sized engine, didn't bother to diagnose, Honda just sent a new engine. Fitted it and took for a drive, temp went straight up, pulled over and found the rad cap valve had stuck open, emptying the system. A 50p part killed the first engine, and almost killed the second... 

[MonkeyJim]

Thanks all

maybe I'm just being paranoid but I was starting to relive nightmares past, chasing a coolant problem on my R1 which took ages to diagnose and ended up being a head gasket gone.

(I've checked the RC8R's oil and it's still nice clean oil, not mayonnaise)

It was all working fine before so there's no reason why the radiator cap or head gasket might have failed.

I was panicking that the coolant level in the bottle wasn't changing with engine temperature, which has been my experience on previous bikes.

But it looks like the RC8 / other KTM's don't work the same way.

I'll try running it again and maybe try topping up the radiator with the engine running. 

Might try bleeding it again with the front up, not sure I can get to the bleed screws on the cylinders now everything's back in place, I'll take a look.

But it probably needs to get out for a run to get it properly working, a number of owners have suggested that's the case.

better get the wheels back in properly then!