Yamaha MR-1 High Output-MAJOR PROBLEM! WATER IN OIL!

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Found water in my oil. Damn. I began with a couple of easy fixes, to no avail. Still had water in the oil, just as bad as ever. Then suspected worst case scenario....the head or head gasket. So I tore into the engine to investigate. Turns out it was something else that wasn't nearly as complicated as taking half the engine apart. In hindsight...there was never a need to remove the cylinder head. You'll see why in this video.
But the bottom line is, I eliminated all possibilities and now THE PROBLEM IS SOLVED!
I hope this video will help anyone else with a similar issue. INSPECT THE HEADERS FIRST! Especially if you operate in salt water. If these surfaces have corrosion breaching, water will enter the cylinder head due to valve overlap and aggressive cam lift, and being in such close proximity to the head.
FYI: The first and ONLY point where cooling water should meet exhaust gases is at the end of the left side exhaust pipe where the rubber coupler connects it to the waterbox/muffler. Anywhere before that can lead to water being sucked back into the engine.
FINAL NOTE: If you ever have to remove the cylinder head, remove spark plugs, then valve cover to expose camshafts and timing chain.
Drop a long wooden dowel in front cylinder.
Rotate engine coupler CCW until no further upward movement of dowel is detected. This will bring it to TDC.
Make sure the front cam lobes on intake and exhaust cams are facing away from the engine. If not, continue to rotate coupler another turn or two until at TDC with cams oriented correctly. Pay attention to the dimple on the camshafts and be sure they line up with the index arrows on the camshaft caps.
Remove caps (refer to a manual for correct torque and un-torquing sequence) and keep the caps oriented correctly with the cams, do not mix them up. Then remove timing chain tensioner and this will loosen the chain, at this point, remove the camshafts.
At this point you can remove the head bolts and then the cylinder head.
Reassembly is the opposite order, BUT PAY PARTICULAR ATTENTION TO YOUR TIMING MARKS ON THE CAMSHAFTS AND CAPS, and make sure you are still at TDC.

[@moleisrich1]

Dude here we are in 2024 I’m having this sort of problem. Can you just clean out the ports?

[@HKPSG1Shooter]

The issue was corrosion holes through the inner wall of the exhaust manifold. Very difficult to try to weld that, or even get it clean enough to attempt to weld it. I’m not really sure why there was corrosion, as I flush my engine after every use. But, it has been in a lot of salt water over the years, and sometimes even your best efforts won’t defeat salt water electrolysis

[@AndTodaysProjectIs]

I build a lot, and I mean a lot of MR1 motors from the VX110 to the FXHO and I am so glad you posted this video. Excellent job figuring that out. This information will go a long way toward helping other people out who have the same question on the forums that I'm on in the future when all else has failed. I have to figure out a way to bookmark this video so I can send it to them later. Question for you though, during the sea trial it looks like you're running around 8000 RPMs. The MR1 FX140 and FXHO run at 10,000 RPMs... Or maybe it's 10,300 I can't remember exactly at this second... Was that sea trial at wide open throttle? If so, something is missing there. What prop and pump are you running? We have played around with different props and that always seems to be the source of RPM loss if it's not the stock pitch

[@HKPSG1Shooter]

Thanks! It was definitely perplexing trying to hunt down the source of the water infiltration. Thought for sure it was either the head gasket or an exhaust component. But it turned out to be corrosion holes through the cooling jackets of the exhaust manifold. During my sea trial after the rebuild I was running about 3/4 throttle, not wide open. At full throttle I’m getting about 9500 rpm. I’m using a 1998 Yamaha XL1200W 155 mm jet unit, and I’m running a 13/19 pitch impeller. I wish I could run with the larger pump like they use on the VX110, but none of those have a bolt in intake duct like the XL1200.

[@jemdost6724]

Hey Rob Since you build mr1s I need to replace the manifold gasket #36 on this diagram. Do I need to take off the cylinder head to get to the exhaust manifold? I took off every bolt I can see just about but there is no nudge whatsoever.

[@rickelrod3099]

Oh dam 😮

[@HKPSG1Shooter]

Yeah, I had a sick feeling in the pit of my stomach when I found water in my oil. It was an involved task, but I got it solved

[@olegodorodko]

ts not mr1

[@HKPSG1Shooter]

No, it’s an MR1