Replacing trigger on 1984 50hp Merc

[mattinspire]

Hi All,

I recently bought a boat with this motor and have been out on it twice, noticing a distinct lack of power (GPS registered a max speed of 10kph). The motor sounded smooth and idled well, so I was suprised to discover that the bottom two cylinders had no spark at all!

It looks like corroded wiring is the culprit and I narrowed it down to the trigger. I have removed the flywheel, but have struck a problem where I cannot pull the trigger assembly over the piece that remains attached to the crankshaft as the diameter is slightly larger. It seems obvious to me that this piece must be removed, but I'm reluctant to throw the harmonic balancer puller at it until I know that it should pop off like the flywheel does.

Hoping someone knows what I'm talking about without a picture, but will take one if required.

Cheers,
Matt.

 

[cannonford57]

Re: Replacing trigger on 1984 50hp Merc

hi matt,a dealer will have the tool to pull the hub off.they areb available aftermarket also.when u reinstall,make sure u properly index the flywheel to the hubthats the only way to do it.hope it helps

 

[mattinspire]

Re: Replacing trigger on 1984 50hp Merc

hi matt,a dealer will have the tool to pull the hub off.they areb available aftermarket also.when u reinstall,make sure u properly index the flywheel to the hubthats the only way to do it.hope it helps

Thanks mate, I managed to use the balancer puller to get the inner hub off (was on there really good!). I have now replaced the trigger and am ready to start putting it back together. For indexing the flywheel to the hub, do I just turn it to TDC on No.1 and make sure the flywheel lines up with the TDC mark?

Cheers,
Matt.

 

[emckelvy]

Re: Replacing trigger on 1984 50hp Merc

For indexing the flywheel to the hub, do I just turn it to TDC on No.1 and make sure the flywheel lines up with the TDC mark?
Cheers,Matt.

Yup you got it!

 

[mattinspire]

Re: Replacing trigger on 1984 50hp Merc

Yup you got it!

Ok, I've just replaced the stator and I'm hoping its position isn't too critical from a timing perspective. It seemed to only like going one way anyway due to the path the wires take (please correct me if I'm wrong!).

I've struck a wee problem with lining up the flywheel with TDC etc. Finding TDC via No.1 isn't a problem, but the only marks I can see are on the flywheel itself and there doesn't appear to be a stationary marker on the motor to reference these flywheel marks against.

All help appreciated!

Cheers,
Matt.

 

[emckelvy]

Re: Replacing trigger on 1984 50hp Merc

Matt, there is supposed to be a timing pointer. Perhaps it's been removed sometime in the past. It would have had to been taken off in order to remove the flywheel.

Here's a parts breakdown which shows the pointer.

http://www.mercruiserparts.com/Show...0&bdesc=CYLINDER+BLOCK+AND+CRANKCASE+ASSEMBLY

You should be able to find its mounting point on the motor and then there's only one position where the flywheel would correctly line up to the pointer. If you're one bolt off either way, it's going to be obviously out-of-whack.

HTH...........ed

 

[mattinspire]

Re: Replacing trigger on 1984 50hp Merc

Matt, there is supposed to be a timing pointer. Perhaps it's been removed sometime in the past. It would have had to been taken off in order to remove the flywheel.

Here's a parts breakdown which shows the pointer.

http://www.mercruiserparts.com/Show...0&bdesc=CYLINDER+BLOCK+AND+CRANKCASE+ASSEMBLY

You should be able to find its mounting point on the motor and then there's only one position where the flywheel would correctly line up to the pointer. If you're one bolt off either way, it's going to be obviously out-of-whack.

HTH...........ed

Thanks for that, I'd say your dead right there.

With reference to exploded diagrams I attempted to recreate a pointer at the area where the original should have been. With No.1 at TDC it appeared there was only one bolt position where the flywheel could go to have the timing marks sit anywhere near the makeshift pointer.

So, I put everything back together and gave the motor a crank. It coughed a couple of times, but there's still no spark on the bottom two cylinders and I think I've messed up the timing by separating the flywheel from the hub, as prior to embarking on this mission the top two cylinders would run the motor just fine.

Does the problem sound more like the stator or the CDI?

How could I get the timing back on track given the situation I'm in?

Thanks once again!

Cheers,
Matt.

 

[kellyisu]

Re: Replacing trigger on 1984 50hp Merc

I would say probably the stator or switchbox. Find out how to test them by doing ohm readings on the wires so you are not just buying parts for nothing.
Someone on here should be able to help you out with getting the information, if you don't so already, on how to do that for your particular motor. I did for my motor when I lost fire to one of my cylinders on my 79' 40hp 2-stroke. It ended up being the stator in my case. Good luck

 

[mattinspire]

Re: Replacing trigger on 1984 50hp Merc

I would say probably the stator or switchbox. Find out how to test them by doing ohm readings on the wires so you are not just buying parts for nothing.
Someone on here should be able to help you out with getting the information, if you don't so already, on how to do that for your particular motor. I did for my motor when I lost fire to one of my cylinders on my 79' 40hp 2-stroke. It ended up being the stator in my case. Good luck

Thanks for that, I'll get out there and test tomorrow. I should have done that at the beginning, but the corroded wires seemed so obviously the problem, bah!

One thing that's baffled me a little is that even if the flywheel was stuck on the right way, how does the timing get adjusted? This motor has no distributor to rotate etc.. and the only adjustment (timing wise) that I could envisage would be winding the ends of the trigger linkage on their threads to make the linkage shorted or longer and/or adjusting the stop screws.

Cheers,
Matt.

 

[Riverman128]

Re: Replacing trigger on 1984 50hp Merc

Matt,
From reading your posts, it appears you don't have a service manual for your engine. A word of advice, get one before going any further. The timing is adjusted by the linkage rod. At this point, you need correct information. Get the manual. Google CDI Electronics or CDI Rapair and I think you can download the stator and switch box tests.

 

[mattinspire]

Re: Replacing trigger on 1984 50hp Merc

Matt,
From reading your posts, it appears you don't have a service manual for your engine. A word of advice, get one before going any further. The timing is adjusted by the linkage rod. At this point, you need correct information. Get the manual. Google CDI Electronics or CDI Rapair and I think you can download the stator and switch box tests.

Embarrassingly, I did have the Seloc manual for the engine but let (what I thought was) common sense prevail when it came to removing the flywheel, as in "How could it possibly come off with those 8 bolts still secured?" ... lesson learned.

I have since taken it into the shop where it has been diagnosed as a faulty stator from the DVA test, more worrying though is that they've said the top two motor mounts are broken and this could result in the gear linkage ceasing to operate and a possibly unsafe condition on the water. I've been quoted about $1500 NZD to repair as apparently the powerhead has to come off to do those top mounts? The shop doesn't really want to touch the motor, which is a shame because it's cosmetically in great shape and the compressions are all good and even.

Of course, the shop had a suggestion for a replacement motor. They have a 2007 Merc 30hp, elec start, man tilt with only 10hrs on it. They'll supply and fit for $3500 NZD (about $2500 USD). I was concerned at first with the drop in HP (30 vs 50) and it's effect on on my 15.1ft boat, but was assured that "Today's 30's are pretty much the same as old 50's in terms of real-world performance" and the motor would do just fine for me. The shop is a Merc dealer, so wouldn't/shouldn't lie about such things?? Can anyone give any cred to those claims?

I'm on a budget so buying a higher HP motor this new is out of the question. All other second-hand 50 - 60hp units I've seen advertised are around $3500+ and the newest are around 10 - 15 years!

Should I pay the same money for an old, higher HP motor, or run with the 2007 that's lower on HP but still has 4 years of warranty left?

Cheers,
Matt.