Camshaft is not turning

[payot]

120 HP Mercruiser (1980's circa)
I was cruising around in the water when suddenly the engine stopped with no warning, I made it in on my kicker. When I accessed the situation back at home I noticed that the distributor rotor was not turning. I pulled the distributor and the gears that connect to the cam looks great (no chips and not worn out at all). I looked in the hole when the distributor goes with a flashlight and got someone to turn the engine over for me, the camshaft did not appear to be turning. I then pulled off the water pump and flywheel (the pulley on the crankshaft) and then removed the timing cover. The gears on both the cam and crankshaft are in great condition (not worn out at all). I then cranked over the motor to see what's going on. I noticed that the gears were turning but the cam gear was not turning the camshaft itself (the middle of the big gear is not turning with it). Could somebody please advise me on what I should do now. I've never dealt with an issue like this before. Thanks in advance. Below is a picture of what I'm trying to explain, ALL of the middle part that is gold in color is not turning, I think the key is fine. If you think I just need to replace the gear could you advise me on how to remove it. Thanks.

 

[Don S]

Re: Camshaft is not turning

You need a new cam gear. The fiber gear came loose from the metal center section.

 

[payot]

Re: Camshaft is not turning

Thanks for the super quick reply Don, that's what I figured and hoped. Can I just pry it off with big flathead screwdriver or is there a technique to be used. Thanks.

 

[Don S]

Re: Camshaft is not turning

You have to remove the camshaft, and press the gear off and the new one back on.
The OEM service manual details the procedure.

 

[payot]

Re: Camshaft is not turning

Thanks again Don, I've been looking for my service manual for the past couple of days (I may end up getting another one), but would this require removing the engine? Just quickly wondering how much doo doo I'm in. Thanks.

 

[a70eliminator]

Re: Camshaft is not turning

Do you have enough room to slide the cam straight out? If so then all you have to do is loosen the rockers and remove pushrods and lifters and carefully pull it straight out being careful not to bang the bearing journals on the way out, there's probably a special lever tool to aid guiding it out. I've used a 3' long piece of all thread screwed into the bolt hole on the end of the cam. keep the lifters and pushrods oriented to put them back to the original positions, an egg carton works well.

 

[payot]

Re: Camshaft is not turning

The gear will get in the way of taking the cam straight out, I could pull the cam out about 1/2 to 2/3 the way. Is there a way to replace the gear taking it out just that far?

 

[fishrdan]

Re: Camshaft is not turning

What's stopping the cam from coming all the way out? You need to completely remove the cam from the engine and have the old/new gear pressed on/off.

 

[Don S]

Re: Camshaft is not turning

I could pull the cam out about 1/2 to 2/3 the way.

What's in the way from pulling it all the way out?

 

[payot]

Re: Camshaft is not turning

The floor is in the way, so if the cam needs to come all the way out to have the gear pressed off/on then either cutting out the floor or an engine removal would be required Either option sucks.

Albeit I think I would rather cut out the floor then an engine removal. Just really sucks because I redid the interior this summer including new flooring

If I removed the whole engine I could do a complete overhaul I guess at the same time. hmmm what do you think.