Well I fired up the F100 today. Even with the new oil, I got that ticking in the top end once it warmed up. It ran fine on some CAM2 I had lying around (no ethanol).

Oil pressure is fine, as far as I can tell. Not sure what I can do. I think the motor has 800 hours on it. But it came off a rental boat, so it could have 2800 hours. No ECU, so I can't tell.

The outboard cost me about $1000, so I am not sure I want to tear into it unless it sounds worse. It *IS* a solid lifter motor.

Any chance it needs a valve lash adjustment? Not an easy job if it's got bucket tappets with shims, but I understand that's required on the newer 4-strokes after about 400 hours! Makes Terry's "water cooled chainsaw motors" look pretty attractive! Excessive valve lash reduces lift and duration which will reduce max hp a bit, but it typically increases mid-range torque slightly, so if you don't mind the extra noise, it might not be worth fooling with, especially if a compression check says the exhaust valves & seats are still ok, since they're typically the weakest link in a 4-stroke!

I don't understand why they don't run full synthetic oil in the new 4-strokes, or all marine engines for that matter, as it really reduces wear. A little more expensive, but lubrication properties are so much better that it's the best thing you can do for any IC engine!

I checked the valve lash as best I could. But I am slow. So a hot engine becomes a cold one. But they seemed to be in spec. The noses of the cams looked like the flat tappet shim *over* bucket VW engines I used to have at 100,000 miles. And they would easily go 200K on the valvetrain. These are direct acting shim under bucket, but otherwise quite similar.

I really don't know. I will do a leakdown, although it seems to run fine. After that, I will just keep an ear out. And an eye on the pressure warning light. And I should check that to make sure it is working correctly.

I am a big Rotella T fan as it was recommended to me by my Suzuki mechanic as the next best over the factory marine grade. He stated the only thing the marine grade carried was an encapsulement component for moisture like the lower unit oil. In any case I am approaching 1800 hours on my big 4 stroke with no valve train issues nor any needed adjustments in 10 years.

The only "valve" issue so to speak I ever had came from exaust valve carbon build up from ethanol fuel use. I had a light tick and failed a leak down test on the bottom 2 cylinders. A combination of Ring Free and SeaFoam in a 6 gal can "cocktail" took care of that issue quickly and resolved the sticky valves. I still run cheap gas but add lucas treatment to every other fill and have not had an issue in 5 years. You could have the same issue starting to happen. Maybe a cleansing "cocktail" would be worth a try as it certainly would'nt hurt to de-carbon the motor anyway.

Thanks very much for the tip. I bought some aerosol Yamaha decarb spray. I haven't tried it. I am going to try to source non E10 gas for my vacation. I can probably hold 50-60 gallons in jerry cans and the 20 gallon tank, which goes a ways on a small 4 stroke. Like I said, it runs GREAT on CAM 2 110 octane leaded, but I want to find whatever the local equivalent of REC 90 is. Nothing is super local on puregas.org.

I ran Startron and the local marina E10 89 octane last year. I have used Seafoam before and it seemed to work well. I will give that a shot with ringfree after I aerosol decarb.

Thanks for the help!

The RingFree shock treatment ratio of 2oz for every ten gallons is the prescribed amount but many feel that is too week for a really bad case. I used a 3 gallon tank of 93 plus 2 16oz cans of SeaFoam and 6 oz of Ring Free with no issue. Make sure you can run the entire 3 gallons on a single run at crusing speeds. The back of the motor will be sooted up as well as the exaust dumps.

Either a compression or leakdown test should pick up a valve seating problem, but the leakdown is a static test is done at TDC, so it might not pick up a sticky valve since that's basically a transient problem. However if a valve is sticking, that could cause the clearance between valve/tappet/cam to temporarily increase more than normal as the cam lobe moves away from the tappet, so it might click just like it would if the valve lash/clearance was too large. Hard to imagine that a valve spring couldn't overcome a sticky valve, but they probably use pretty light springs on those OHC motors since there isn't much intertia in that valve train, so that ticking you hear might indeed be the symptom of a sticky valve! There is so much mass/intertia in an old pushrod/rocker arm system that very heavy valve springs are needed to keep all the gaps tight at high rpm, which may explain why sticky valves are pretty rare on older engines!