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Its a 85 mercruiser 140(3.0), we pulled the distributor out and the gear on it is fine. The gear down in the motor looks fine. Any suggestions as to what is wrong. Thought maybe the gears were bad but the rotor doesnt spin like its slipping.
Spin the motor over with the distributor out, look down in the dist hole and see if the cam is turning. If not, TIMING GEAR problem. Also be sure to check that the pin that holds the gear on the dist shaft is not sheared.
Sounds like you have more of a problem than you think. If the gear on the distributor is solid, and you can hold the gear and still can't turn the rotor, then the problem is in the engine itself. Possibly a broken cam or cam gear or crank gear. The 3.0L engines don't have timing chains, only 2 gears.
Don S. that is what I was scared of. At first I was thinking that the pin that holds the gear was sheared, I wish it were that easy. When we pulled the distributor and saw that the gear was fine I looked down the hole where the distributor goes and saw nothing but dollar signs. I called a mechanic friend of mine after I got home (the boat is at my lake house) and he said it could be the timing chain, but that is why I posted the question on here. Is there anyway of telling whats wrong without having to pull the motor.
If it is the timing gear on either the crankshaft or cam, can either be replaced without replacing the actual cam or crankshaft. The cam or gears arent that bad pricewise but the crankshaft is another story. Also, how does the distributor gear connect to the crankshaft/cam gears.
I don't have a clue how much room you have to work on it, but the front of the engine will have to be taken apart, and since that includes removing the motor mount, you might as well get it out of there.<br />When something like that breaks, there is usually metal in the pan also, so you are looking at more than can be done in the boat.
there is plenty of room to work on it, its a 19ft. sea ray seville. Old style runabout with two seats in the back instead of a bench. Almost as easy as an inboard type motor(mastercraft) to work on.
In other words, tow it to the mechanic. We dont have a trailer for the boat but there is a marina within a couple miles that has a full time mechanic. We could probably hoist the motor out of the boat in the boathouse if we really wanted to tackle it ourselves. Just trying to get an idea of what could be wrong so the mechanic doesnt gouge me. Which manual would you recommend for future problems.
the crank gear locates on a keyway, (sheared,Why?)from there goes to a gear bolted onto the nose of the cam,(sheared /fallen out bolts)the cam itself drives the dist. (broken cam)Like don says, broken parts = metal rolling around inside.
Don't know about a 3.0 but my old 2.5 has a fiber cam gear and the Mercruiser part numbers for the 2.5 and 3.0 cam gear are the same. If it is the fiber gear, which it most likely is, it should be an easy fix.
Looking down into the hole where the distributor goes the gear on the camshaft appeared to be in good shape. You could feel the distributor gear locking up when we placed it back in the hole. Hopefully its just one of the timing gears and it didnt do any damage to the valves, I know if a timing chain breaks you can bend valves.
I know the timing gear on the front of the camshaft does not turn the distributor but doesnt the gear that is a few inches back on the cam turn the distributor? And if the the gear on the cam that turns the distributor is in good shape, wouldnt that mean that more than likely its one of the timing gears or actual camshaft that is broken.
Yes you are correct, I would suspect the fiber timing gear on the cam as the most likely problem. It can be replaced without pulling the engine. Put a block of wood under the oil pan to support the front of the engine, remove the motor mount,crankshaft pully and water pump.You will need a puller to remove the pully hub from the crankshaft Remove the timming gear cover. You will have to align the timming marks on the cam and crankshaft gears when replacing the gear. The trickest part is reinstalling the rubber gasket on the bottom of the timming cover. I have done this before.
