excessive coolant pressure.

[moto5151]

I have a 12 pro, turbo. I was tinkering tonight, making sure things are good for the weekend. I noticed that the coolant bottle waspretty much empty. A couple weeks ago on my first test ride I also noticed that my coolant was low. I was told by the guy who tuned my sled this summer that it got hot and bubbled over a little and would need a top up. When I cracked the coolant cap the level rose quickly and bubbled over. A good sign that its hot.
Any way, tonight when I cracked it open, it quickly came up and started to bubble over. To the point where I can't fully open it.
This happened with a cold eng, that's been sitting for 2 weeks.
I know it supposed to be pressurized, but seems excessive. Any ideas?
Bad "rad" cap? Or normal? Can't remember it being that pressurized with stock eng...

 

[gm3d]

Run it withthe rad cap off. If it bubbles, you have a compression leak into the coolant. Not good! Find the leak! (Head gasket o ring maybe) Better have a look.

 

[Bnorth]

Run it withthe rad cap off. If it bubbles, you have a compression leak into the coolant. Not good! Find the leak! (Head gasket o ring maybe) Better have a look.

This.

 

[moto5151]

Well it hasn't been started in 2 weeks, any built up "compression" pressure would have been bled off by now. I think.

 

[Barnes]

Sometimes air bubbles can become trapped in the system, running with the rad cap off allows them to escape. And yes even after sitting for 2 weeks, the air bubble can still be trapped.

 

[moto5151]

Ok, but will trapped air cause a pressure build up?

 

[cs5]

gm3d is right, there is only one place pressure can come from and thats compression from your cyl. Having air in the system is one thing but if it sat for 2 weeks and you can't take the cap off you have a lot of pressure. Check it out, better safe than sorry.

 

[Riverjet]

I don't think you really have any issues except maybe you don't know how to remove the cap properly? When you turn the cap counter clockwise and it comes to a stop, you need to put some down force on it to continue undoing it all the way.

 

[007sevens]

On the top of you thermostat housing on the head is a little screw. Loose it and fill with coolant till coolant comes out of the screw then tighten it, finish filling with coolant to full line on bottle.

Sorry for sounding like a school teacher just that somebody new or young could read this as well.

A leaking head will press coolant out will you ride but I'm not sure what would cause a vacuum and then release when pressure is released at the coolant bottle other than air in the system.

I might try setting this up in your garage. Take your shop vac and place the suction in a 10L can with a small hose such as fuel line (just make sure it fits into you coolant bottle) to make a suction pump and suck all your coolant out just loosen the little screw so that air can move into and out of the system. Then replace the coolant while the little screw is loose to let air out will it fills. This procedure has work for me many times and never had a air lock.

Just my thoughts hope you figure it out.

 

[High Velocity]

On the top of you thermostat housing on the head is a little screw. Loose it and fill with coolant till coolant comes out of the screw then tighten it, finish filling with coolant to full line on bottle.

One more note to add to this. To properly and easily bleed the cooling system, raise the front end of your sled 2-3 feet above the end of the tunnel. This will ensure any air trapped in the coolers is purged as well.




Sent from my iPhone when I should be fishing.

 

[moto5151]

Thanks riverjet, but I know how to take the cap off. Here's the thing, when its running, the coolant naturally lowers in the bottle. When hott expands, this is why you xcant take the cap off. I understand the theory of air lock. My other thought, is that the turbo is somewhat causing the coolant flow, and air to move differently then stock. Ill just have to release the pressure, start it and let the air work itself out. And double check for buubles while running with the cap off.

 

[High Velocity]

Definitely check for bubbles while it's running, but first, do the bleeding procedure that 007sevens and I mentioned just to ensure there's no trapped air. Just make sure the front of the sled is elevated at least 2-3 feet. Any air trapped in the rear of the cooler will not come out unless you elevate the front end. Good luck !


Done fishing. Let's go sledding !!

 

[lilduke]

Cracked Cylinder maybe?

 

[moto5151]

I bled the system this morning. I couldn't get the front end very high, but I did manage the get it to take a few gulps of coolant. I did notice bigger bubbles coming up when running, just before the gulp. Everytime I shut it off the coolant level rose, less and less each time. I'm gonna let it sit for an hour and let it cool off, then recheck it.
If it was a cracked cyl, wouldn't it run bad? If its a head gasket or o-ring, wouldn't the bubbles be constant? Which they are not. I'm gonna go with trapped air, just gonna run it how it is. Lol
Also, the air explains the reason for the coolant to drop in the bottlw when running, and return when pressure is rreleased. Its a lot more stable now. I just can't explain why the bottlw is still at a good level, even with air gone from the system. Overfull from the last time I thought it was low and added?

 

[lilduke]

I had one with a craked cylinder that ran mint,,, only think was when riding it would over heat really fast,, Took me awhile to figure what it was cause i had just replaced a cooler and thought it was air locked or something..turns out i had a cracked cylinder

 

[go green]

Pressure test the coolant system , if it holds pressure then you have a air lock , if it looses pressure you have a leak . That will determine you next course of action .

Test don't guess.

 

[moto5151]

I let it sit for an hour or so now. Coolant level has dropped below add mark on the bottle. I can take the cap off without pressure release. Pretty sure it was air. Ill take a look while riding, and monitor it. I hate second guessing myself. Thanks all for the info and help.

 

[moto5151]

So I'm second guessing myself again. If the head gasket and or o-ring is pinched, or leaking, would the pressure from the bottle bleed back into the cylinder when not running? Should I see coolant on the top side of the piston if I take my plugs out?
Shouldn't the compression build enough pressure in the bottle to make it overflow from the cap when running?

 

[Beels]

Shouldn't the compression build enough pressure in the bottle to make it overflow from the cap when running?

Yes it should.

 

[moto5151]

Checked my plugs, pistons had coolant on them. Took head off and both compression o-rings were gone. I couldn't find them anywhere. Pistons and cylinders look fine. Put it back together, no more pressure or bubbles. Glad I second guessed myself this time.