Overflowing rad problem = head gasket failure????

[dirtbag]

1980 440 Invader. It's been running great and it was running great when all of a sudden coolant starts spewing from the rad cap, coming thru the grill and splashing inside the windshield. I shut it down. One plug was wet - but I have no air box just some velocity stacks. There was a lot coolant sprayed around and I think it injested a bit.

I put in new plugs and started it and within seconds it was spewing again.

Luckily I was close to a friends place so I fired it up and ran it the 1/4 mile there with the rad spewing, in a cloud of coolant steam. It seamed to run good despite the leaking fluid.

The temp gauge has never moved since I bought the sled so, no I don't know if it was getting hot. It was about -15C and the sled was running great right until the eruption.

My guess is either a head gasket failed allowing compression to pressurize the system (most likely) or something managed to block a coolant line and the pump or overheating built pressure (not too likely) - I doubt the water pump is that that powerful and there was no indication in performance that it was heating up.

Any thoughts? Is that how you would expect a head gasket to fail? One second it's perfect and the next it's a catastrophic failure causing a coolant overflow?

I attempted to check the first condition by bringing a cylinder up to TDC and pressurizing it with compressed air to see if I could replicated the rad cap breach. However I wasn't really thinking and the light grip I had on the clutch was nothing against 100psi spread over almost almost 6 square inches of cylinder surface. ( I don't think I'm going to lose the thumb nail )

I will attempt that test again today but with the clutch better secured and the air applied more gradually this time.

The weather is still perfect for sledding so any help with a speedy recovery is greatly appreciated.

I just thought of this could it simply be a bad rad cap? I did look at it and the spring was intact and it seamed to function good by hand.

[dirtbag]

I eased up the pressure to 50psi on the first cylinder and it held good but the second caused the rad to overflow just like on the trail.

Looks like I need to do a head gasket. Is it just common sense to do them as a pairs? Is it ok to do just the head gasket and leave the base one alone?

Any Canuks know if I they have these at Royal Distributing? or Snowline in London Ont?

Thanks

[Interceptor398]

Do the one acting up and see what happens.  Good Luck!

[Pmlecom1]

I purchased my Winderossa set from Winners Circle.  Their shop is in Markham.  Next day was at my door step!  Good price and great service.  www.winnerscirclecanada.com  Good luck!

[dirtbag]

Can I ask how much was the set?

[dirtbag]

Just ordered a complete engine overhaul gasket set (Winderossa) from Royal Dist. for $41.99 - $59 with taxes and shipping.
With any luck I could be putting it back together by the weekend.....

[Pmlecom1]

The Winners Circle site lists them at $40.21 for the full set.  Similar pricing.  The big difference is when you actualy talk to the sales guy.  He's graduated high school many years ago!  And wrenches on sleds and bikes himself.  IMO anyways!  Best of luck!