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This summer I bought a 440 chassis with a built 840 motor in it. The sled is clutched (tra rollers I was told?), has thunder jets, all new crank seals etc, dmax twin pipes fitted to stock can, mach 1000 heat exchanger for better cooling, carbon tech reed spacers, EGT and temp guages, and more. I list these add-ons, because I'm not sure what has contributed to the problem i'm having.

I never added any of these things, I bought it this way, and was also told that "Big John" on Doo-Talk here built the motor? It seems like it should have more power than it does for an 840, I can only do like 90 mph or so. Also, the VIN number of the sled brings the chassis back as a 700, but Ski-Doo never had a 700 in 06 did they? and there is a race tank and stock stickers on the sled saying "warning, for use on race courses only," so I'm a little confused whether it's actually a 440 chassis or not.

As far as the problem I'm having, I have put about 500 miles on the sled or so this year, and went out the other night for a ride. At the beginning, it looked like it was smoking a little more than normal, but wasn't sure, so kept going. 8-10 miles into the trip, the clutch seemed really loud, much louder than normal, I pulled over and tried the RER reverse to back up and it wldnt idle down to engage, the clutch just kept howling. Finally it sort of idled down, and went into reverse, but the clutch never really quited down. I shut the sled off and opened the hood and coolant was everywhereeee! On top of my computer, on both sides of engine, on hoses etc. The hose running from the coolant tank to the water pump housing on top of the engine looks to be good.

What could be the problem here?? any ideas or things I should check. I see a topic below this people may have had problems with the impeller stripping out, but I wouldn't think that would be my problem causing coolant everywhere, right??

I'm not really familiar with these water pumps at all, and never dug into one, any help would be greatly appreciated. Thanks so much!
 

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Sounds like an o-ring for the head let go if you had AF all over. Does that sled have a temp gauge?

Clutch noise was belt howling after it got wet.
 

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Discussion Starter · #3 ·
I do have a temp guage on the sled, and it never was flashing. It only flashes when im doing 80 or so and the rpms are high after 40 miles of riding hard. and what do you mean by o-ring for the head? like head gasket? thanks!
 

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Not a temp warning light-a digital temp gauge. With that modded motor you NEED one.

The heads on these motors don't have head gaskets, they have special O-rings to make the seal. If they fail just a little you'll get the mess you have. The smoking you notice could be due to burning AF also.
 

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Discussion Starter · #5 ·
Yeah, it digitally reads also. usually says "low" but then will read numbers too, that one doesnt blink red though, it is blue in color. The EGT guage is what usally blinks. What should I look for to see if I have a blown o-ring?
 

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You haven't locked up yet, so the first thing would be to wipe it all down and get it dry. Fire it up on a stand and let it warm up while you are looking the whole motor over and see where it is weeping AF. If it is weeping from around the head you will know its an O-ring. Then pull the head.
 

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Discussion Starter · #7 ·
okay, I just got off the phone with a local mechanic who runs ski-doos. He said that usually if the head o-ring goes, it will leak into the cylinder rather than all over, so it sounds more like a hose issue. At least now I know I can start the sled and look around for a hose spraying coolant.
 

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well not to state the obvious but check all connect tions for the cooling system if every thing checks out then chec that little bleeder screw under t-stat if didnt blow then it would b o-rings! surprising the the thing didnt melt down
 

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okay, I just got off the phone with a local mechanic who runs ski-doos. He said that usually if the head o-ring goes, it will leak into the cylinder rather than all over, so it sounds more like a hose issue. At least now I know I can start the sled and look around for a hose spraying coolant.
ya if its the inner and then it would of blown or atleast smoked like a mo fo its probrably the outer oring so tell that dealer to check himself!!

i would change all the o-rings and not just that one and can all b done in the sled
 

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Discussion Starter · #10 ·
First look for a hose issue though, right? could i squeeze the hose running from tank to waterpump and maybe notice something seep out somewhere?
 

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do this

well not to state the obvious but check all connect tions for the cooling system if every thing checks out then chec that little bleeder screw under t-stat if didnt blow then it would b o-rings! surprising the the thing didnt melt down
and then do this

You haven't locked up yet, so the first thing would be to wipe it all down and get it dry. Fire it up on a stand and let it warm up while you are looking the whole motor over and see where it is weeping AF. If it is weeping from around the head you will know its an O-ring. Then pull the head.
you will find the leak
 

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Discussion Starter · #12 ·
I pulled the lid off the coolant tub tonight and filled it with coolant to the cold level. Put the 13 psi lid back on and started the sled. It ran for maybe 2-3 seconds before the coolant starting just spraying everywhere from around the lid. I immediately killed the sled and it still sprayed out for another couple seconds.

Now I was thinking, great. My cap just lost pressure, but I pulled a 13 psi cap off my other sled that works great, and repeated the process. But.. Again, coolant started spraying everywhere from around the cap.

The coolant container top so more of an oval instead of a circle, and I've had to squeeze the top of the container to a circle to get the lid on, but do you think this could be causing the leakage? It's never happened before? Just randomly started leaking I guess..

If it helps, I took a couple pics of the top of coolant container, which I can attach if it helps. Thanks!
 

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It could be the cap. I take a vicegrip and bend the tabs so it seals better. There shouldn't be pressure unless it is hot. I think the inner orings are shot, the cylinder pressure will push the antifreeze out.
 

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Discussion Starter · #16 ·
Inner o-rings of the head? Also. I only let it run for 4-5 seconds or so and after it was off for a couple minutes. I took the cap off and it still popped and more anti-freeze came out?
 

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You say this is a 440-800 conversion, I have to ask, is it possible that the 440 Race choke is in the top hose PLUS you have the T stat in the 800 motor? Seems you don't really know what you have your hands on. This can be a problem when you pick up a Frankensled.

Do you know what the race choke is?
 

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Inner o-rings of what? And I tried two caps?
Where the head seals to the cylinder there are 2 o-rings, one to seal the cooling jacket from the atmosphere, and one to seal the cooling jacket from the cylinder. if the inner o-ring has gone bad there is a lack of seal between the cooling jacket and cylinder, pressure from the cylinder can over-pressure the cooling system causing the cap to leak.

also i never touch my coolant cap and have a spare at home, both me and my brother have noticed that when you remove the cap due to the oval shape there is an oval indentation in the rubber sealing surface. when you try to put it back on if you don't line up the indent perfectly id wont seal right, any time i take mine off i just put a brand new cap on. costs a bit but saves me having to worry about it. though with that issue its a very slow leak and not a "spray everywhere" situation.
 

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Looking at the parts fiche it says the 06 440 Race has no top hose choke. It still has the T stat. That kind of rules that out.

What do you have for a heat exchanger under the tunnel? Is it still that small stock 440 exchanger towards the back of the tunnel? No way is that going to cool an 840 big bore.
 

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If your cooling system is being pressurized that quickly, I would guess combustion gasses are leaking into the cooling system. This usually results from an internally leaking head gasket. Could be other locations, but that is a common leaking area.
 
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