Yamaha MR1 Blown Valve Cover Gasket, Oil Leak

[chamilton89]

II need an MR1 expert. I am working on a 2014 Yamaha VX Deluxe for a friend. I have worked on a ton of Sea-Doos but have less experience on these MR1 engines. My friend said they were riding and suddenly lost power and started smoking really bad. Pulled the seat and cylinder 4 spark plug well was full of oil and had blown the coil pack out spraying oil everywhere. This also melted that coil pack.

This is how I got it, after it sat for a year like this. Since I got it, I have replaced all the plugs, got a new coil pack, and replaced the damaged valve cover gasket that had let go letting oil into #4 spark plug well. Topped off the oil as well and it runs fine.

Ran it on the water for around a half hour and had zero issues, full RPM, no smoke. Got it back on the trailer and pulled the seat to find more oil in the bilge (fair amount, not a drip). Traced the oil leak back to the valve cover gasket that I had just replaced. Had blown right on the semicircle part of the gasket that covers the end of the cam, so that can be fixed easily.

My question is this. Originally I thought the gasket just let go and created all of the original issues that parked the ski. Now im really not sure. One second look, my friend told me it smoked like crazy when it dropped a cylinder and had the big oil leak. Now that the gasket has blown a second time, I am thinking I have a pressure issue inside that valve cover. Now I don’t know the dry sump oil system that well because normally I would just look for a clogged PCV. Why would excess pressure be trapped in the valvetrain causing that gasket to blow? I know there is a return that feeds back to the intake to burn that excess oil. So where do I start? Clogged hose? Too much oil? Any help would be greatly appreciated!

 

[WREKS]

There is a breather tube going up into the air box where it terminates in a filter. If that filter gets saturated from overfilling with oil, it may cause a pressure buildup in the crankcase and under the valve cover. I would try to determine if the filter is saturated. Disconnecting the breather hose where it connects under the airbox to that filter may help diagnose the problem. The filter is located under the throttle bodies.

 

[chamilton89]

Thank you for the insight. I actually have the older style (I believe) side intake setup that does not seem to include that filter. I did get my hands on a oil flow diagram and it looks like the breather goes to the tank and the tank blows to an oil separator that then vents back into the intake. Going to try blowing some air through each line and make sure everything is vented properly. If that checks outI think Ill just chalk it up to a bad gasket and then me not getting enough silicone one there for it to make a good seal.

 

[Slabby]

This one?
So you could see that the rubber seal on that spark plug well that seals the cover was shot?

Strange one... does sound like the seal. Was the smoke coming out the exhaust or inside the engine bay?

These engines don't like being overfilled with oil and you have to check the level when it's at running temp. Couldn't tell you what the outcome of overfilling is but its definitely a common problem that as I remember has a worse outcome than you'd expect...

 

[scokill]

This one? View attachment 131289
So you could see that the rubber seal on that spark plug well that seals the cover was shot?

Strange one... does sound like the seal. Was the smoke coming out the exhaust or inside the engine bay?

These engines don't like being overfilled with oil and you have to check the level when it's at running temp. Couldn't tell you what the outcome of overfilling is but its definitely a common problem that as I remember has a worse outcome than you'd expect...

Overfill usually only causes the oil filter to become saturated thereby starving the engine of air. I haven't heard of anything like the OP's situation because of overfilling. Overfilling stories are very frequent and no damage....other than to the air filter.

 

[chamilton89]

This one? View attachment 131289
So you could see that the rubber seal on that spark plug well that seals the cover was shot?

Strange one... does sound like the seal. Was the smoke coming out the exhaust or inside the engine bay?

These engines don't like being overfilled with oil and you have to check the level when it's at running temp. Couldn't tell you what the outcome of overfilling is but its definitely a common problem that as I remember has a worse outcome than you'd expect...

So that is the hose that releases excess pressure to the oil tank. My original seal blow was actually with the #15 oil seal in the above picture for the valve cover gasket. It was ripped and releasing oil directly into the well. My second blow was with the same gasket, but right at the end where it says to use 120B gasket sealer. I used standard RTV silicone, maybe that was my issue? All of this being said, I haven't ruled out that my original issue was just a gasket that broke and my second issue was just a poor installation of that gasket when I replaced it. My concern is that this is the same issue being created by a buildup of too much pressure inside of the valve train. Going to make sure that upper breather hose releases pressure (eventually) back into the intake and then reseal that gasket and hope for the best.

 

[WREKS]

I think what happens is that overfilling with oil allows oil to be pumped into the breather and hose going into the valve cover at the same time, creating excessive pressure buildup in the crankcase. The breather system is only there to equalize pressure between the crankcase and intake air.
The oil pump is very strong and fills the oil tank quite quickly, but should only fill it so full. If there is too much oil, it fills up the breather and related hoses.

Most members run their MR-1s and check the oil. Sometimes, you cannot trust the dipstick because oil may drain back into the sump. You may have plenty of oil, but it appears like it is really low.

The valve cover o-ring is rubber and has a tendency to drop out of the grove when installing it. I spot adhere it to the valve cover with a sealant before securing the valve cover to the head.

 

[chamilton89]

I think what happens is that overfilling with oil allows oil to be pumped into the breather and hose going into the valve cover at the same time, creating excessive pressure buildup in the crankcase. The breather system is only there to equalize pressure between the crankcase and intake air.
The oil pump is very strong and fills the oil tank quite quickly, but should only fill it so full. If there is too much oil, it fills up the breather and related hoses.

Most members run their MR-1s and check the oil. Sometimes, you cannot trust the dipstick because oil may drain back into the sump. You may have plenty of oil, but it appears like it is really low.

The valve cover o-ring is rubber and has a tendency to drop out of the grove when installing it. I spot adhere it to the valve cover with a sealant before securing the valve cover to the head.

You could have something here. With the way that pressure loop works on this dry sump system, I could just have too much oil and its actually blocking some of those pressure equalization hoses between the top case, oil tank and outside pressure. I am going to make sure those hoses are still free to move air and pull some oil out of the tank just as insurance.

 

[WREKS]

My MR-1 2007 SX230HO takes 4.5 qts. max.

 

[chamilton89]

So, update. Got my hands on the ski yesterday and blew some air through the valve cover outlet hose and air escaped without issue through to the air intake. No blockages and works just fine. Also pulled some oil out as well. Oil (cold) level was at the top mark. Also siliconed the valve cover gasket back in place where it had blown out. Screwed it all back together and am ready for another check ride for oil leaks. Thanks to everyone for helping brainstorm potential issues.

 

[Slabby]

So, update. Got my hands on the ski yesterday and blew some air through the valve cover outlet hose and air escaped without issue through to the air intake. No blockages and works just fine. Also pulled some oil out as well. Oil (cold) level was at the top mark. Also siliconed the valve cover gasket back in place where it had blown out. Screwed it all back together and am ready for another check ride for oil leaks. Thanks to everyone for helping brainstorm potential issues.

Run it on the hose for 15 minutes on level ground then check it. You have to check it when it's at operating temp. Wipe it clean and then screw it all the way in to check it. This is from every manual I've read. It shouldn't be above the High line. If it is above pull it out til it's correct .

Im still no expert on whether this affects your issue but I do know as others have said that you don't want to overfill on mr1s so for something so simple that you should do anyway, you may as well rule it out.

I'm rebuilding one of these atm and it's only really the dry sump thing that is totally foreign to me...