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2011 m8 coolant issues. Possibly o rings?

J
Nov 28, 2020
16
6
3
Have a new to me 2011 m8 with full slp exhaust and intake and pcv. Runs great sometimes but coolant keeps disappearing. Sometimes it comes out from overflow and other times it just appears on ground on clutch side usually. Temp light has come on a few times and I possibly overheated at least once. Today I noticed a tiny amount of oil in the overflow. After some research it seems o rings are the most likely problem. I don’t have access to a shop to do the work. From looking at it it seems it may be a relatively easy job that’s possible to do without removing the motor. I figure just remove exhaust and plug wires and pop off head. Change o rings and reinstall. Looks pretty straight forward unless I’m overlooking something. I’ve heard the o rings can be a nuisance to stay in place. Any tips or tricks to doing this job. Hoping to do it as soon as I can get the parts. Gonna do it outside if it’s doable.
 

kiliki

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Dec 27, 2008
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put sled on its coolant tank side down and pull the cap and drain then with it on the side pull one head bolt. this will let air into the motor and finish letting enough coolant out so you don't have it in the motor when you take the head off. pull head and with the new O rings you can gentility stretch them until they fit in the jugs. Then put the head just over the O rings and start 2 head bolts one on each side of the head, once they are started then lower the head onto the jugs and hold pressure until you can get the two head bolts snug.
you don't have to undo the hose in the back of the head. once done fill and put sled on can side for a few and then lay flat and fill again until it takes all the coolant you took out.
 
J
Nov 28, 2020
16
6
3
Hoping inner o ring is my problem. No coolant leaks when sitting. After a good hard run it spits most of coolant out of overflow. Noticed today for first time a oily residue in overflow tank. Sled runs well when coolant is topped up. I notice a lot of brown smoke when moving sled after it’s green parked for awhile. Thought it should be white smoke with coolant issues. Am I on right track with going after inner o ring. Guess I’ll know for sure once I can see in there. Any issues using the sled softly while waiting on parts. I live where it’s the only means of transportation out of town. I can use the wife’s little 550 if I’m risking killing a piston.
 

Old & slow

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Feb 18, 2017
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Make sure your rad cap is not the culprit. Sometimes the seal is bad or the tabs get worn and you can just bend them down for a tighter fit. I would also check the water pump and make sure the weep hole is not plugged or leaking. For the o rings you can use Vaseline to help keep them in place. If the inner o ring is failed you should get white smoke and be able to smell the coolant in the exhaust.
 
Last edited:
J
Nov 28, 2020
16
6
3
Rad cap is the plastic style without the bendable tabs. I haven’t smelled any coolant burning and plugs look a nice perfect tan colour. What made me suspect o rings was the cloudy coolant on the overflow. I can go a couple days but the coolant always ends up spraying from the overflow. Within a couple days it’s usually empty and full of air.
 

Old & slow

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Alberta
I guess you can change the head o rings but it sure is not a common failure but it could be who knows and it is a lot easier and faster than the water pump . Personally i would be looking hard at the water pump just to make sure it is not the issue.
 

kiliki

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if you get over pressure in the tank and a slight black film its an outer O ring. if you are always short on coolant and it has a lot of white smoke then its an inner O ring.
Make sure it is pushing it through the system as it warms put your hand on the cooler in the tunnel to make sure it is getting warm.
 
J
Nov 28, 2020
16
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Went for a good ride today. Didn’t lose any coolant at all, no over pressure. Rear exchanger was warm to the touch. Have a new cap ordered. Will try easiest fixes first and go from there. Next I’ll try inner and outer o rings. Machine ran top notch today in heavy snow , slob conditions. Just gonna run it with a bottle of coolant with me at all times for now.
 
J
Nov 28, 2020
16
6
3
As a update I replaced my coolant cap and it completely solved my problem. Old cap wouldn’t seal properly. New cap is much easier to remove and keeps the coolant level in the right area. Not quite up to the cold Line just a shade below it.
 
J
Nov 28, 2020
16
6
3
Coolant don’t stay at the cold level line, more lijj look Eva couple inches below it. Hasn’t lost any in last few weeks of riding. Rear coolers gets warm quickly and no temp light. Crazy how important a simple cap can be. No visual issues with old cap other than being tough to remove
 
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