Can't find coolant leak on M7- would it be OK to use radiator stop leak?

WYrider · Sep 5, 2008

It seems to only leak when the sled is running. About 3/4 cup a ride. I haven't seen any leaks on the snow when letting it idle for a while in one spot, so I thought it might be a head o-ring. Replaced them but it still leaks. Thinking of using vehical radiator stop leak. Think it would be OK to put this stuff in a sled? Any other spots I might need to look first?

harf69 · Sep 5, 2008

ck front cooler

I would check the front cooler where the hose and cooler meet they tend to leak there

RACINSTATION · Sep 5, 2008

Do not use stop leak. You need to find it. Check all hose clamps on coolers and heat exchangers as well as on the motor. I see the rear heat exchanger hoses leaking most of the time. If no leak there, then check the head orings and base gasket.

weekendracer728 · Sep 5, 2008

Yea Do Not Use Stop Leak!! That crap makes things worse on sleds...

sledhead699 · Sep 5, 2008

yea could be leaking in to the head and burning it check the o rings under the head .

mtn mike on boost · Sep 5, 2008

the L side hose clamp at the front heat exchanger fails alot.but considering the small amount its loosing, i would guess a head leak the orings pinch easy and could likely be your culprit

Luke The Drifter · Sep 5, 2008

I bet its the heat exchanger hose clamp. My M7 has the same problem, doesn't leak enough for me to bother fixing it for the amount of work involved to get at it. I just keep an eye on my coolant level and ride

WYrider · Sep 5, 2008

As stated in my original post I checked the head o-rings. There was nothing wrong with them and no rust around the groves where a leak may have been present. I replaced them anyways as I had already bought the o-rings. I was extra careful as I know how easy they are to pinch. After one ride, no change.

SLEDIOT · Sep 5, 2008

What ever U do don't use the leak stop. Worse case scenario U pack some coolant in a pop bottle I do!!. You put that leak stop in there and for sure you will pop a cylinder cuz it will cause a blockage. Replace all yer clamps it is cheap, then go from there. Do it on the stand in yer shop not out in the mountainswhere all the snow gets jammed in the tight spots. More than likely your leak iswhere the coolant line comesoff the top of yer heat exchanger thru the tunnel and across the front of yer fuel tank. Put the sled on a bunch of milk crates and check this spot while it is running/idling.

grabs10 · Sep 5, 2008

I kind of had the same problem at one point an time I think. If you are constantly pulling the cap off the coolant resievor to fill with coolant, your cap might not be seal very well or seat properly as the plastic bottle will wear. If it is not seating very well or you have a weak spring in the cap it will allow it to vent and boil out at lower temps than it should or steam out through the vent hose on the resievor through out the day with out much of a sign where it is going as it would only do it going down the trail when temps were up. I replaced bottle and cap with what comes on the M8/m1000 as it is a better design than what came on the M7 and no more coolant leak. May not be a problem for you but just something to check or watch.

graveler · Sep 5, 2008

grabs10 said:
I kind of had the same problem at one point an time I think. If you are constantly pulling the cap off the coolant resievor to fill with coolant, your cap might not be seal very well or seat properly as the plastic bottle will wear. If it is not seating very well or you have a weak spring in the cap it will allow it to vent and boil out at lower temps than it should or steam out through the vent hose on the resievor through out the day with out much of a sign where it is going as it would only do it going down the trail when temps were up. I replaced bottle and cap with what comes on the M8/m1000 as it is a better design than what came on the M7 and no more coolant leak. May not be a problem for you but just something to check or watch.

those older bottles warp really easy!!!!

DWHalverson · Sep 6, 2008

Mine was leaking from the hoses on the water pump. They are a pain to get at, even with skid plate pulled and the bottom of the belly pan. Mine were not very loose, but just enough. I changed to better clamps than the ones Cat uses.

Sparx · Sep 6, 2008

RACINSTATION said:
Do not use stop leak. You need to find it. Check all hose clamps on coolers and heat exchangers as well as on the motor. I see the rear heat exchanger hoses leaking most of the time. If no leak there, then check the head orings and base gasket.

I'm with Racinstation in regards to the base gasket. I had the exact same issue with my ProXR 800. I would use up to a litre of coolant every ride and never had a drop anywhere else. Check your plugs, mine was bad enough to show signs on the plug that one was burning fine and the other was washed clean from the coolant being burned. If you leak coolant anywhere, chances are the chasis is going to leave a drop or two for you to find wether in the belly pan or next to the leak source. Mine got worse on more WOT senarios and would burn more than if I was just trail riding taking it easy. Once I replaced the base gaskets and sealed them up good with some Loctite gasket maker my problems were solved. The plugs were the indicating factor even though it sounds like your burning a 1/3 less coolant than I was. I ended up riding around with a drink for me and the sled every trip until I replaced the base gaskets. When I took my cyl heads off the mag side cyl was spotless with no carbon signs and the PTO was normal. If your cyl and plugs are too clean to be true on either or both cyl, you know your burning coolant. Methanol injection baby! LOL

WYrider · Sep 6, 2008

Sparx said:
I'm with Racinstation in regards to the base gasket. I had the exact same issue with my ProXR 800. I would use up to a litre of coolant every ride and never had a drop anywhere else. Check your plugs, mine was bad enough to show signs on the plug that one was burning fine and the other was washed clean from the coolant being burned. If you leak coolant anywhere, chances are the chasis is going to leave a drop or two for you to find wether in the belly pan or next to the leak source. Mine got worse on more WOT senarios and would burn more than if I was just trail riding taking it easy. Once I replaced the base gaskets and sealed them up good with some Loctite gasket maker my problems were solved. The plugs were the indicating factor even though it sounds like your burning a 1/3 less coolant than I was. I ended up riding around with a drink for me and the sled every trip until I replaced the base gaskets. When I took my cyl heads off the mag side cyl was spotless with no carbon signs and the PTO was normal. If your cyl and plugs are too clean to be true on either or both cyl, you know your burning coolant. Methanol injection baby! LOL

I thought about that too. But when looking at the jugs on the M7, it didn't look like the water jackets went all the way through the jugs and into the crankcasing. Can anyone tell me if the jackets go through the crankcase on the M7's? If thats the case I will replace those gaskets as well.

I have ran the sled in the shop on a stand and checked it over well and did not see any leaks. However, I have not gone through and tightened all clamps to be sure. I think I will do that next. The coolant bottle might be something to look at too. Thanks for the inputs!

mountainguy · Sep 6, 2008

You could try pressuring your coolant sys and then looking for the leak or leave the pessure on and see if it drops and how long it takes. This may help you find it aslo if it drops and no leak found you could pull he spark plugs and pull her over and see if coolant comes out.This will tell if the base or head gasket is leaking internally. Hope this helps. Do not pressure the system over 20psi.

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Can't find coolant leak on M7- would it be OK to use radiator stop leak?

WYrider

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harf69

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mtn mike on boost

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