Hi all

as title says, when engine is cooling down the coolant hose on the right hand side "goes flat" i.e. there seems to be vaccum in the system. I suspect that overpressure valve is ok, but is it nor releiving the coolant/pressure back in the system from the overflow tank. Suspect a defect filler cap, as far is I can read there should be some over/under pressure valves in the cap, is that correct? Release pressure should be 1,5 bar.

Question is....can it be fixed, meaning can you just clean the cap/replace something or is it not worth the hazzle? Better to replace the cap completely?

Manual says that filler pipe and cap ,must be replaced as a unit

16V RS

Return valve is the one to the right of center.
Check the valve, and that it's free passage to the area behind the outer gasket.
Also check the hose between the filler cap and expansion tank for kinks.

thanks Inge, looks like it could be worth checking the small valves if they are accesible :-)

/Bjarne

Bjarne,

I once had this problem which was caused by a swollen rubber gasket in the filler cap preventing coolant flowing from the tank to the radiator. A good gasket should be about 36mm OD x 26mm ID.

Just a thought,

Paul.

Thinking a bit laterally one thing that would cause the rubber gasket to swell would be a trace of oil circulating attacking the rubber, could this be a warning of the dreaded oil pump seal failure?
Regards,
K-BIKE

Yes K-BIKE, that's what caused the swelling with my gasket.

Paul.

In the"how to"section there is a write up of a method to check your radiator cap heat sensor by putting it in water, heating it and seeing at what temp. if any the thermostat opens.
Wish I could post a link for you but not sure how to do that.
RT

About swelling gaskets....if that problem arises, it could also be a idea to check the gasket at the top of the cap.
If it gets to close to center, it would block the ports to the valve housing (it's three of them).

K-BIKE wrote:Thinking a bit laterally one thing that would cause the rubber gasket to swell would be a trace of oil circulating attacking the rubber, could this be a warning of the dreaded oil pump seal failure?
Regards,
K-BIKE

...hmmm, not sounding good thought they solved that issue on the 16V/k1100?

I´m crossing my fingers that filler cap is the issue, time will show.....

/Bjarne

bjarnek100 wrote:thanks Inge, looks like it could be worth checking the small valves if they are accesible

Shouldn't be any problem if you have the old type cap, the return valve should be fairly loose if you touch it with your fingertip.

On the subject of checking things by heating them up, many many years ago when I lived in the UK I used to subscribe to one of the car magazines for DIY car service. but nearly fell off my chair when they wrote an article describing how with a saucepan full of water and a thermometer that you could check that the thermostat starts to open around 102 degrees C and is fully open by 105 degrees C by heating the pan up on the stove. I guess their technical writer was asleep during that bit of the school science class when they covered the boiling point of water.

I also recall when my sister in law was going out with the then editor of a very prestigious photographic magazine in the UK and being interested in photography I asked what he thought of the new Agfa film that had just been released and he was a bit non-committal so I asked which was his favourite camera he said he didn't own a camera to which I was incredulous and he told me "I don't have a camera and I don't know anything about photography" I said "how can you be the editor of a photographic magazine and not know anything about photography" he replied 'I am a professional journalist I do not need to understand the subject I am writing about". I have always been suspicious of technical journalists since then.
Regards,
K-BIKE

Love it!

K-BIKE wrote:On the subject of checking things by heating them up, many many years ago when I lived in the UK I used to subscribe to one of the car magazines for DIY car service. but nearly fell off my chair when they wrote an article describing how with a saucepan full of water and a thermometer that you could check that the thermostat starts to open around 102 degrees C and is fully open by 105 degrees C by heating the pan up on the stove. I guess their technical writer was asleep during that bit of the school science class when they covered the boiling point of water.

I also recall when my sister in law was going out with the then editor of a very prestigious photographic magazine in the UK and being interested in photography I asked what he thought of the new Agfa film that had just been released and he was a bit non-committal so I asked which was his favourite camera he said he didn't own a camera to which I was incredulous and he told me "I don't have a camera and I don't know anything about photography" I said "how can you be the editor of a photographic magazine and not know anything about photography" he replied 'I am a professional journalist I do not need to understand the subject I am writing about". I have always been suspicious of technical journalists since then.
Regards,
K-BIKE

Good point and good laugh but I recently had to check the 103c point on a K100 thermo sensor and by adding salt got the temp to 106c so maybe and only just maybe they are right.

Put some coolant/antifreeze in the water and it will raise the boiling point. Thinking laterally natch ..........

I long ago gave up on motorcycle magazines when a test that included a K-1200RS criticized the K bike for having an "old fashioned suspension" (Telelever and Paralever are old fashioned by a conventional fork on a Japanese sport bike isn't?) and they criticized the K for having a "heavy flywheel". Shows you what they know about the K. They have their heads so far up their exhaust pipe that if they tried to pull it out they would get whiplash.

Rick G wrote:
Good point and good laugh but I recently had to check the 103c point on a K100 thermo sensor and by adding salt got the temp to 106c so maybe and only just maybe they are right.

That must have been very salty water....
From what I recall of my school chemistry it takes 58g of salt to raise the boiling point of a litre of water by half a degree C
106C would require nearly 700g of salt per litre

Yeah I won the Mr Popularity contest for using up a heap of SWMBOs salt but it was for a very important test, I think she understood, I think.
I also found I needed to be careful with the resistance readings because salty water is a great conductor DOH but I eventually figured out why the readings didn't make sense.

All those sorts of tests, use of the dishwasher, oven, blender etc. need to be done whilst she is out of the house The salty water can be used to de-ice the freezer - "look dear I de-iced the freezer while you were out" Then instead of a bollocking you get a gold star!
Regards,
K-BIKE

OK, an overnight cleaning in soapwater freed both over- and under pressure valves in the cap. Did a low-tech test (mouth-to-cap test) and seems ok . Gaskets seems OK. Only one little question short.

The expansion-tank is full at cold engine (since the underpressure didn´t work). Manual says fill cooling system up until overflow pipe but do I need to drain expansion-tank completely before i do that, in order to leave a spare expansion volume?

/Bjarne

The coolant level should preferably be at the max mark, measured with a cold engine.
Adjust as needed.