I should have posted this as a follow up on this thread, but I went through and pulled the engine and re-built it. Some pictures over here: Old Marine Engine: P60 Water in Oil & Stuck Valve - Bad exhaust design, bad exhaust manifold, or what?
and a full album over here: https://www.flickr.com/photos/kronic...57679586805264
All in all it was maybe 40-60 hours of work, a lot of which were spent disconnecting the wiring and hoses, and then grinding off all the old paint before re-painting. Very little technical skill required-- just a lot of elbow grease. I had the time and space to do it, and at about $500 of materials it was 100% worth it. Now I know the engine inside and out, should anything go wrong in the future. The engine runs strong again and I love the Islander 30 Mk II it's powering.
Things to check:
- Check the oil. If it's milky or gray at all, you're getting water in the crank case. This will definitely cause stuck valves. This could be because of a leak in the head gasket, or water backed up through the exhaust (due to over cranking with a water lift muffler or a faulty exhaust design.) If you have water in the oil and it's been sitting for years, I recommend you pull the engine, clean out all the emulsified oil, and rebuild it. That gunk sticks everywhere and won't be easy to flush out while the engine is in the boat (trust me-- I tried many times).
- Check if/how many valves are stuck-- pull the spark plugs (you'll need a non-standard 7/8" spark plug socket, or a 7/8" combination wrench. Then turn the flywheel (the big circular part facing foreward) while putting your thumb over each spark plug hole. If you don't feel pressure after 2 complete turns on each plug, you have a stuck valve.
- Take pictures of the exhaust. Very unlikely that it's original on a boat this age, and if you're unlucky like I was, the PO's repair may have made things worse. Not a lot of room to do a proper exhaust riser on this boat.
- If the exhaust checks out and there is no water in the oil, the problem could just be corrosion on the valve stems due to sitting too long in a marine atmosphere. In this case, you may be able to un-stick the valves by pushing them down through the spark plug hole and if the corrosion isn't too bad this might fix the problem for good. I used a tool shaped like this that worked well for a while: https://www.amazon.com/Great-Neck-TL...ds=tack+puller
Be careful not to hit them too hard this way or you might bend a valve stem (honestly I hit them pretty hard and didn't manage to bend anything, but consider this a standard disclaimer)
Those are the things you can check without tearing into the engine. Here are the next steps if the above doesn't work:
- If the valves are stuck solid, you will need to remove the head and try tapping them down that way. If the valves still stick after freeing them, you may need to do a valve job. This is a flathead engine with the valves in the block, so you will be doing this with very little space on the boat, but it is possible with this valve spring compressor tool: Sears.com
. You will also need a magnet on a stick and a mirror on a stick.
- If you have water in the oil, but the head and gasket look ok (no blown through spots) and the exhaust design checks out, you may have a hole in the exhaust manifold. You can check this by pulling the manifold and hooking a garden hose up to the water inlet and plugging all the normal water flow holes with your other fingers. No water should leak into the intake/exhaust passages.
- If you pull the head, you will need a new head gasket. If you're salt water cooled, you will need a new copper one from Gasketstogo.com -- not the regular steel ones. Order these 2 at a time as they take a few weeks for delivery.
- If you remove the engine to rebuild it, you will have to take the manifold and the head off to get it out of this boat. Then you can slide it up and out (see my pictures for how I did this). Take your time and it's less scary than it sounds.
Hope that helps and everything checks out-- depending on your ability to put time into this boat, it could be totally worth it-- as for me, it's a beautiful afternoon here on the San Francisco Bay and I'm about to head out for a sunset sail...!