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-   -   1.8 Bar Rad Cap? (http://husaberg.org/cooling-systems/22679-1-8-bar-rad-cap.html)

KentJ August 9th, 2016 01:11 PM

1.8 Bar Rad Cap?
 
Hi All,

I noticed my rad cap was not sealing well and letting coolant out through the overflow. I figured it was just boiling over often and even installed a Motion Pro coolant reservoir, but a home-made pressure tester showed that the cap was not holding pressure.

The only rad cap my local Husky or KTM dealers had was a 1.8 (26psi) bar cap instead of the stock 1.4 bar. Do you think the extra pressure will cause any problems? ie pushing past the water pump seals?

Thanks

-Kent

pollo August 9th, 2016 01:27 PM

I think there's not a problem with it. I can remember my dealer saying the same. I believe my 06 650 has the 1.8 cap and also may have had it on my 05 650.
I pretty sure im not the only one doing this.

KentJ August 9th, 2016 01:50 PM

Thanks, I'll give it a go and see what happens. I'll post back with my results...

-Kent

Taffy August 9th, 2016 02:42 PM

i can't see the point? it can only end in tears....

just coz your local dealer doesn't hold it doesn't mean you shouldn't chase the correct cap?

I don't get it.

Taffy

pollo August 9th, 2016 03:41 PM

I checked my 650. It has the 1.4.
But im pretty sure I went with the 1.8 at one point on my 05 because of some reason I dont remember and had no problems with it.
And that bike is gone now anyway.
Taffys advice is better than mine here.
Stick with the 1.4 if possible.

pollo August 9th, 2016 03:51 PM

I do recall now that with my current 06 650 I had the cap spew out and lost a lot of coolant one time.
The caps do wear out or become faulty. So i just put a new 1.4 on and it took care of that.

Taffy August 9th, 2016 11:23 PM

the rubber seal folds over and people don't take the time and care to see it and get it flat again.

also, as you put the cap on, the edge of the rubber seal cacthes the overflow entrance (to the exit!!!) and this tips the cap over just as you press it down.

regards

taffy

FE350 August 10th, 2016 01:15 AM

Now coolant boils at different temperatures as per what your altitude is. So for instance if you are at sea level your 1.4 bar cap will work different than when you are at 5000feet.

Increasing pressure raises the boiling point of the coolant. So if your engine runs "hot" you can raise the pressure and keep the coolant from puking out due to boiling. Raising the pressure won't "fix" a severe over heating problem though. Horsepower 'causes' heat. So, more horsepower, more heat. More radiator and air movement are required when you increase the power level. Just mixing in antifreeze will raise the boiling point about 10 to 20 degrees, add pressure of 15 lbs and you add another 20 to 30 degrees to the boiling point.

So for the answer:
What altitude are you at?
Is your machine running hot?
How is your coolant to water mixture?
Is your bike stock or tuned?

Allot of factors relate to the pressure of the cap. Changing this cap from 1.4 bar to 1.8 bar is only about 6 psi different and this will not hurt your machine at all. If anything it will keep it from boiling and boiling is more of a worry than the pressure is, unless you are running cheap Chinese rads.

You are also at sea level or close so you should not have anything to worry about.

On another note: Boiling coolant is bad for a number of reasons which I won't get too into here, but, steam/bubbles in coolant actually insulate coolant from the combustion chamber and would render the coolant useless at cooling the hot engine. It can also cause water pump failures and other damage via a process called cavitation. Thus the reason a higher pressure cap would be used. Allot of pro's vs con's as we know temperature is a bad thing but boiling can be worse in some cases, so we keep the coolant from boiling and run a little hotter?

KentJ August 10th, 2016 09:07 AM

The bike had been boiling over on me previously, but only in the really nasty stuff.

I added small fan earlier in the season and was really impressed that I didn't have any boil-overs on a couple rides in some really gnarly, steep, clutch-slipping, uphill rock garden single track (McNutt). A weekend or two ago it was boiling over in some much tamer single track which came as a bit of a surprise to me.

I tested the rad cap and found it wasn't holding pressure, so that's probably a big factor.

I did grab the 1.8 cap because it was the only one available locally and I'm heading out of town for 2 loooong days of riding tomorrow. The parts guy convinced me that all the cool kids are running 1.8s too. The correct part will be in after I get back.

In the meantime I managed to steal a 1.4 cap from my brothers KTM EXC so I think I'll just return the 1.8 in exchange for a 1.4 when I'm back.

Thanks all.

FE350 August 10th, 2016 09:11 AM

Quote:

Originally Posted by KentJ (Post 173527)
The bike had been boiling over on me previously, but only in the really nasty stuff.

I added small fan earlier in the season and was really impressed that I didn't have any boil-overs on a couple rides in some really gnarly, steep, clutch-slipping, uphill rock garden single track (McNutt). A weekend or two ago it was boiling over in some much tamer single track which came as a bit of a surprise to me.

I tested the rad cap and found it wasn't holding pressure, so that's probably a big factor.

I did grab the 1.8 cap because it was the only one available locally and I'm heading out of town for 2 loooong days of riding tomorrow. The parts guy convinced me that all the cool kids are running 1.8s too. The correct part will be in after I get back.

In the meantime I managed to steal a 1.4 cap from my brothers KTM EXC so I think I'll just return the 1.8 in exchange for a 1.4 when I'm back.

Thanks all.

Have a great ride on your trip. I do miss Mcnutt as I lived in Maple Ridge for years and rode it allot. I now am in Kamloops, so lots of riding to do :)


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