I've been living with oil leaks from around the HP fuel pump and the timing cover for as long as I've owned the boat (~6.5 years). I finally had a window of time to make fixing the problem a priority. Everything went smoothly and the engine is back together and works. I came away with some observations and questions though. To start here are some pictures/video of the cover before reinstalling.
https://drive.google.com/folderview?id=1gNX3pjZrcabZ2LUE6rKQAm_M1jVfweR7 I didn't have power tools available and some tight tolerances on the engine block only allowed me to get the gasket seating area as clean as you see it in the pictures. No large or thick chunks and most of the remnants were feathered in. Anybody have experience getting a seal with this much residue? The old gasket was pretty clearly a paper type which had hardened. The new gasket was a lead/babit/graphite material. Smooth and semi-reflective. My only hesitation was weather or not to use a sealant. And the lingering question of, "Why did the OEM change the material?" What are the benefits of a graphite gasket? RTV sealant or not? I ended up using just enough RTV sealant on both sides to provide a light smooth coat. The ignition timing is set by the shims between the HP pump and the timing cover. There is a timing procedure which I did not perform. Instead, I simply replaced the shims that were there with new ones of the same thickness. Anything that messes up that thickness will change the timing so the use of a THIN sealant is required. Remnants of sealant and damage to the shims made measuring the thickness of each shim tricky. I tried to measure a combined thickness of the stack of old shims and compare it to the thickness of the stack of new shims, because of the combined effects of damage and sealant, the old stack measured about 50% thicker than the new. I measured and remeasured and I am extremely confident that I selected the exact same number and thickness of replacement shims as was installed by the OEM. I can't recall the source but Blue Locktite is evidently the recommend sealant. I realize that Locktite makes a number of different products in various colors, not just thread locker. There was an associated product number which I was also unable to recall. Instead of loosing sleep I just used the blue threadlocker which I had laying around. A light wet coat on both sides of each shim. While I was in the project I found one of the studs for the HP pump came out. The nut was seized mid-thread and it appeared that the stud may have been bottoming out in the timing cover, not providing the required pressure to that corner of the HP pump. Also contributing to the oil leak. So the moment of truth arrived and the engine started without a hitch. I immediately noticed that it seemed to idle a little faster. I let it run in gear at about 2k rpm for about 2 hours before having confidence to leave the dock. No oddities except slightly higher idle rpm. While running around on the water I tried full throttle/rpm to see if there was "more power". Throttle felt smooth and responsive. It seemed like a higher rpm was achievable. Typically, with a dirty prop and bottom 2800 or 3000 rpm is the most I would get before black smoke would develop. This time I got to about 3400 rpm with no black smoke and more throttle. This all seemed very positive. If I pushed the throttle just a tad further the engine would immediately lose significant power and blow black smoke. I realize that the tachs on these engines are notoriously inaccurate. Mine measures about 10% low. Without getting the laser tach out I would guess that my real instantaneous (and momentary) rpm peeked at 3750. The OEM instantaneous rating is 3600. Thoughts? Is my experience normal for an engine which exceeds its max RPM or is this more representative of an engine with too much timing advance? *Some final thoughts*. -I think the mechanic who worked on the engine for the PO during my purchase caused/failed to fix 3 things. First, in removing the HP pump he broke the seal and never re-sealed it. Second, he probably deformed/damaged the shims. Third, he failed to identify/correct the seized nut on the stud. All of these combined to cause the primary oil leak. They probably also contributed to a decrease in engine timing. -In years past I had made half attempts to fix the leak. This was punctuated by failing to successfully remove hp pump. As a result no sealant was able to be applied and the shims where likely to have been further damaged. I too failed to recognize/correct the seize nut on the stud. My efforts probably exasperated the existing problems. -As I recall, I have had to set the pitch on my max prop lower than that recommended by the OEM (based on the engine/power and boat/Hull combination). -I now believe that the combined effects have "lifted" the HP pump about 50% higher than set by the factory causing the timing to be retarded. As a result the engine has been chronicly under performing. Over the years I've tweeked other engine and boat parameters around the reduced power (raised idle speed, lowered prop pitch) and simply accepted it as normal. -In the spring, I'll disassemble the prop to compare current settings with OEM suggested settings. Regardless of the findings I'll probably increase the pitch 1 step = 2° ~= 200rpm reduction. Oh yeah, almost forgot. So far, no leaks. Josh Muckley S/V Sea Hawk 1989 C&C 37+ Solomons, MD
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