Oil pressure relief valve

[SouthernSailor]

Hello

My T9.9GPXR (2009) ALERT system kicked in after running at WOT for about 2 hours. I checked the oil before running it and it was good but after 2 hours the level barely read on the dip stick.

I did find oil dribbling down the front side of the Upper Case Assembly (behind the tilt mechanism).

Since topping it up I have run it for more than an hour at 3000 RPM and the oil level has not dropped at all. The engine has less than 250 hours on it and I find it hard to imagine a seal letting go but of course that could be the problem.

I am wondering if the Oil Pressure Relief Valve might have activated?

Does the relief valve reset automatically once the oil pressure goes back down?

What would cause high oil pressure if the relief valve did blow off?

I am reluctant to pull the power head off at this point but equally reluctant to run with a possible oil leak.

Not sure how to proceed, any thoughts would be most appreciated.

[boscoe99]

Hello

My T9.9GPXR (2009) ALERT system kicked in after running at WOT for about 2 hours. I checked the oil before running it and it was good but after 2 hours the level barely read on the dip stick.

I did find oil dribbling down the front side of the Upper Case Assembly (behind the tilt mechanism). Try and find the source of the oil.

Since topping it up I have run it for more than an hour at 3000 RPM and the oil level has not dropped at all. The engine has less than 250 hours on it and I find it hard to imagine a seal letting go but of course that could be the problem.

I am wondering if the Oil Pressure Relief Valve might have activated? The valve normally activates most of the time the motor is running.

Does the relief valve reset automatically once the oil pressure goes back down? It should. But, it can stick open which might result in low oil pressure, particularly at low RPM.

What would cause high oil pressure if the relief valve did blow off? High oil pressure might result if the relief valve did not do its job. That is, if the valve gets stuck closed.

I am reluctant to pull the power head off at this point but equally reluctant to run with a possible oil leak.

Not sure how to proceed, any thoughts would be most appreciated.

An oil pressure relief valve is typically comprised of a poppet or a ball that is held onto its seat by spring pressure. Once oil pressure rises to the point that it is higher than the spring pressure the ball is forced off of its seat. Oil then flows around the ball and the pressure is more or less maintained at the pressure that causes the ball to unseat.

Here is a link to a fairly good read on the subject of pressure relief valves.
Pressure-control valves | Hydraulic Valves content from Hydraulics & Pneumatics

Let Google be your friend and you can learn all that you want, and more, about pressure relief valves.

Hopefully you can find the source of the oil leak. Clean the motor up as best you can and run it again to see if oil leaks out or not. Maybe, just maybe, the pressure relief valve stuck closed, there was excessive oil pressure, and a leak ensued. Maybe the valve sticking closed was a one time event and it is now working properly. Who knows. 99% of a repair job can consist of finding out what is causing, or caused, a problem. The other 1% might be to actually fix the problem.

[boscoe99]

Hello

My T9.9GPXR (2009) ALERT system kicked in after running at WOT for about 2 hours. I checked the oil before running it and it was good but after 2 hours the level barely read on the dip stick.

I did find oil dribbling down the front side of the Upper Case Assembly (behind the tilt mechanism). Try and find the source of the oil.

Since topping it up I have run it for more than an hour at 3000 RPM and the oil level has not dropped at all. The engine has less than 250 hours on it and I find it hard to imagine a seal letting go but of course that could be the problem.

I am wondering if the Oil Pressure Relief Valve might have activated? The valve normally activates most of the time the motor is running.

Does the relief valve reset automatically once the oil pressure goes back down? It should. But, it can stick open which might result in low oil pressure, particularly at low RPM.

What would cause high oil pressure if the relief valve did blow off? High oil pressure might result if the relief valve did not do its job. That is, if the valve gets stuck closed.

I am reluctant to pull the power head off at this point but equally reluctant to run with a possible oil leak.

Not sure how to proceed, any thoughts would be most appreciated.

An oil pressure relief valve is typically comprised of a poppet or a ball that is held onto its seat by spring pressure. Once oil pressure rises to the point that it is higher than the spring pressure the ball is forced off of its seat. Oil then flows around the ball and the pressure is more or less maintained at the pressure that causes the ball to unseat.

Let Google be your friend and you can learn all that you want, and more, about pressure relief valves. I tried to post a link to a good article but the system rejected me.

Hopefully you can find the source of the oil leak. Clean the motor up as best you can and run it again to see if oil leaks out or not. Maybe, just maybe, the pressure relief valve stuck closed, there was excessive oil pressure, and a leak ensued. Maybe the valve sticking closed was a one time event and it is now working properly. Who knows. 99% of a repair job can consist of finding out what is causing, or caused, a problem. The other 1% might be to actually fix the problem.

[boscoe99]

A picture is worth a million of my words

[ASkipper]

SothernSailor, did you find the source of your oil leak?
I have a similar problem on my F9.9 dinghy motor - oil leak, which I see on the water around the engine when I start it up.

[renns_99]

I created an account just to bring this thread back from the dead. I purchased an F9.9 from an older gentleman who said he had attempted a repair to fix an oil leak. He replaced oil sump, and the plate between engine and sump, along with associated gaskets, and it still leaked oil. Upon disassembly and inspection, I found the relief valve was seized in the closed position. I'm presuming this pushed oil out places it wasn't supposed to go, and ended up in the cooling system, and out to the lake.
With some penetrating oil I've freed up the sliding spool inside the relief valve, and it opens and closes like it should now. I'm wondering if those familiar with this motor might be able to recommend what else I should be inspecting before reassembling and testing.
Attached is a picture of what it looked like below the powerhead on dissassembly.
IMG_0247.JPG

[panasonic]

I wonder if that motor was sunk at some point in time. Water got in the oil and was not removed properly causing the relief valve to rust and stick closed.

Other than disassembly of the whole block for cleaning I would buy some cheap oil and couple of filters and run the engine gently first, change oil and filter then do it all again. Closely monitor oil for signs of water and look for oil leaks.

[renns_99]

Thanks for the reply. I was wondering the same thing regarding being sunk. The guy I bought it from was the first owner, and he was quite honest in his descriptions of the work he'd done, including packaging and receipts for all the parts he'd purchased. He indicated the problems started when the sump started to leak oil due to a crack. He did the replacement himself, and apparently after that, he's had nothing but trouble with it.

I've finished the clean-up and reassembly. I'll stick it in the barrel tomorrow, and see how it runs. Here's the relief valve in question. It is threaded into the plate that's between the sump and the powerhead, hanging down into the sump. This is my first time working on Yamaha, and am very impressed with the build quality and ease of the repair.
IMG_0252.JPG

[renns_99]

OK, it's all reassembled, and I've test run, and flushed oil system a couple times. The oil is nice and clean now, and it starts and runs nicely, but it does smoke at lot at idle at least. I haven't been able to run it under load yet, but will do that soon to see if it clears up. I did a compression check, and found 150psi/155psi in top and bottom cylinder. Any thoughts?