WR400 water "frothing" in Radiator ??

85 Husky WR400 (now 430cc), frothing water in Radiator and blowing a bit out overflow only sometimes usually under hard acceleration.......any ideas why? water is hot (normal) but not boiling after a run......is this common?? am I stressing over nothing?

New to old school husky Kettles so still learning...............

Thanks in advance

Hi NZHusky,

It should behave no differently to a car (without a header tank) with regard radiator issues.

When you say 'frothing' is a white froth when you open the rad cap? If it is white then you could have an oil leak into the water system or the water has become contaminated by other means.

With regard to blowing out water under hard acceleration. It could be that the rad cap has become weak and therefore the pressure build up forces the water out through the vent pipe (which is designed to do in the event of too much pressure) or it could be that too much pressure has built up due to gasket leak which happens under load. Normally this would manifest itself in loss of power though...

I'm not sure how you could test the Rad cap spring for it's pressure rating unless you had a spare right Rad which you could slowly build up the pressure until it vented....

Hope this helps.

Stu

Thanks Stu....the frothing is of a green colour probably due to the anti corrosion in the water, I did the ole finger dip in the water to see if there was any traces of oil,cant see any traces...I will change water and retorque head bolts and head screws when hot. Looks like the cap is its original Husky cap so could be weak....has anybody else experienced this?
If oil was leaking in, where would it be coming from?

Cheers
Phil

Hi Phil,

If you can't see any traces of oil in the water then chances are there are no leaks. The frothing could be the result of the venting.

Do you have a friend that has Husky you can borrow a Rad cap from to test? You might have to go down the 'process of elimination' route.

Stu

I thought re-torque should take place when engine is cooled off?
at least thats what I did on my '71 400 after the rebuild.
re-torqued 3 times

yip your right mike.....re-torque when cold . Had to remove pipe to get at half of them so hot is not a good option anyway. 29ft lbs on the nuts and 26ft lbs on the screws.........all needed torqueing !!
have to wait for the weekend now to see if its cured
Cheers
Phil