Yamaha Oil Pan Removal

Anyone ever remove an oil pan from a mid size Yamaha four stroke? My F80 is getting a little water in the oil and due to a previous water intrusion issue that I fought with on another outboard I'm trying to figure out how the oil pan is mounted.... in case I need to inspect/change it out. The bottom of the oil pan is lowest spot that I could have a leak right?

I am going to try to figure out a way to pressure test the lube system or the cooling system to see if I can audibly locate a leak before I disassemble. Then I'm going to start taking it apart and checking the cylinder head, cooling passages, gasket surfaces, and oil pan. Any suggestions or cautions regarding this?

There are no external oil leaks visible.... either in or out of the water. Any info, tips, or suggestions would be appreciated.

Already changed thermostats and pressure control valves and checked fuel pumps for leaks.

Re: Yamaha Oil Pan Removal

I would certainly investigate other reasons for water in the oil before removing the oil pan. Head gasket leaks, exhaust leaks, are just two. A crack in the head is a possibility if the engine was ever overheated.

Re: Yamaha Oil Pan Removal

Total PIA bigtime...check into anything else possible prior to that job if at all possible

Re: Yamaha Oil Pan Removal

I am certainly going to check other potential sources first. The motor is pretty much corrosion-free.... I'm afraid I might have a crack that could be hard to find.

I figured that the oil pan is a major PITA..... I wound up swapping out midsections for the last motor that I fixed with this problem.

As far as head gaskets...... has anyone ever seen a simple head gasket replacement fix an issue with a mid-size Yamaha four stroke? I haven't even heard of it, there are always other issues.

Re: Yamaha Oil Pan Removal

Are you talking a significant amount of water? is it visible on the dipstick? when i changed the oil on my f80, i remember seeing a small amount of water come out when draining it....I am willing to bet a small amount of condensate is in the oil pan in most OB's, simply due to the service that they operate in.

Re: Yamaha Oil Pan Removal

Yes, I can see the milkshake on the dipstick now. The oil level doubled on the dipstick in about two hours of running so my leak has gotten worse than when I was just seeing condensation and froth inside the crank case and valve cover.

As far as a small amount of water normally being in the sump.... this should not be the case. The engine should get warm enough to evaporate condensation out. Guess what will likely fail first if you are mixing water in your lube system...... main/crank bearings. They are sleeve type bearings and very susceptible to excessive wear and spinning if they lose proper lubrication or are over-loaded by too-steep of a prop.

I am done running this engine until something is corrected and all evidence of water intrusion has ceased. I've played this game before.

As far as culprits: has anyone ever seen an "easy" fix for this problem such as a bad head gasket or seal? I haven't; it is usually a result of corrosion or a crack. I haven't known of any cracks in these mid-size Yamaha four strokes either. Somebody set me straight. On a 12 year old motor I am expecting to find corrosion, especially since what started as barely-noticeable water intrusion has turned into a major leak after I installed a new pressure control valve and thermostat.

Re: Yamaha Oil Pan Removal

Wow, thats definately bad...good choice not running it, never noticed a murky color oil in my F80, however I distinctly remember there being some water in the oil when I drained it after lunching my Main bearing's...The oil had about 10 hours of runtime on it. there is a powerhead gasket where it mates to the lower cowling/midsection...way out of the water though. It would be smokin white and running hot if the HG's were bad or leaking enough to froth up the oil. Be carefull pressure testing anything...

Re: Yamaha Oil Pan Removal

Ok.... I blocked off the breather hose and applied about 20 psi of air to the lube system through the dipstick tube. It held the pressure well and the only air I could hear getting by was in the cylinders, I couldn't hear a leak anywhere else.

With the oil drained and the oil plug out I hooked up the garden hose to the flush fitting and taped off the exhaust ports water tube, and tell tale. No water was running out through the crankcase drain.

Since I heard the air leak in the cylinder area I decided to remove the cylinder head and see what I could find. It was pristine with absolutely no corrosion and I did not see any cracks. I taped off the oil passages on the long block and again pressurized the crank case and only had a small amount of air passing by the rings.... I assume this is normal since there is no oil to seal them up now.

My next step is to seal up the cylinder head while it is removed to pressurize it and see if there is a leak near one of the valves. And I will also make sure that the surfaces where the cylinder head gasket mates are level..... I don't suspect any warpage though

The only other thing that I can think of is a bad seal, maybe on the suction side of the oil pump, that is allowing water to get in but not leak oil (or air pressure) out. But I doubt that there is really enough water up around the oil pump for the amount of intrusion that I suspect....

Who thinks what?

Re: Yamaha Oil Pan Removal

Removed and replaced oil pump, power head gasket, cylinder head gasket and accidentally broke the cam shaft by dropping it....... replaced that too. Put it all back together and took it for a run. Oil is clear and water-free after six hours of run time. Engine is running very strong.