What year is my Merc Force?

Faedy

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Hi Everyone, Im a total newbie to boating but have a good mechanical head on my shoulders, and have acquired a 90hp Mercury Force engine that needs bottom end work, I am trying to sort out manuals and parts but need to accurately figure out which year my motor is first. I have attached some pics and have heaps more and pics of various numbers on casings heads etc. Any info would be greatly appreciated. Then I can start the questions about the bottom end :)
 

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jerryjerry05

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Pics need to be of the head or the lower unit.
The decals were a bunch of different colors.
The 90 was first made in 1990.
Then in94/5 they started with the Mercury lowers.

Under the electronics on the stbd. side of the head is a foundry stamp.
Remove the panel and see if there is a stamp.

A few more pcs will help.
 

Faedy

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Was hoping not to have to remove the electronics I guess I will have to do it now :) will post pics later of what I find. but here's more of the power head and lower unit
 

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pnwboat

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Looks like it's somewhere in the 1991 - 1992 range. It has the Mercury Switch Box ignition. Has the mechanical type choke. Has a Rectifier/Regulator instead of the older style Rectifier. Also has the figure 8 shaped fuel pump. There should be a sticker/label on the transom mount that has a serial and or a model number on it. Although, many times the numbers are faded.
 

Faedy

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Hi guys, thanks for the info, I found the first pic behind the electronics, thanks for the location Jerry, wouldn't have tried that without your recommendation. I had a look on the transom for a sticker pnwboat, but I think its long since gone but the second pic is of a casting number on the main leg behind the cowling. Cheers for your help so far guys its great.
 

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jerryjerry05

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It says 92 but the electrics say 93?
Is there a silver freeze plug anywhere on the motor?
It'll have a number stamped in it.
They used 3 different ignitions on that year 92/93.
 

jerryjerry05

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IF????? There is one????? Then it should be on the ignition side somewhere.
The drive is a 92-3 C /D is there a #4 stamped above the fill hole?

Closer pics of the fill/vent and the top of the drive???
 

Faedy

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Hi Guys, Ive had a good look for a frost plug with no joy but have discovered other casting numbers and what looks like whats left of the id sticker, which from further searching online points to it maybe being a 93 when they changed locations from the port side transom bracket to this starboard side. So any way, if you guys can have a look and confirm my thoughts that I'm looking at a 93 with what I pick is a 'D' gear case then I can get down to ordering seals,, water pumps, bearings and all such fun things to rebuild the gear case :) Thanks heaps for your help so far
 

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jerryjerry05

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First pic is a part#
Second is on the mid section.It could be used on any year after it was cast92
That's where the sticker was.
More part #s
 

Faedy

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lol cheers Jerry, so if I aim for ordering parts from 93 onwards, from what I can tell up to 91 -94 they were all the same build, they just had a heap less model numbers 93 onwards. Thanks for your help Jerry.
 

roscoe

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91-92 were transition years, from Chrysler Force, to Mercury. They were using up old inventory to clear the warehouses.

They literally had countless different combinations for dozens of model numbers.

You will just need to order parts that match the specific component you are working on.

You can look through a few dozen model specific parts lists and diagrams to narrow it down, or just deal with each component as the need arises.


Your has:
mechanical choke
thunderbolt switchbox ignition WITH terminal block connections, and "candy bar" box.
old style oval fuel pump
transom mount and bolt pattern is from Chrysler era
But tilt and trim has Mercury wiring harness with automotive relays
And trim pump is Mercury, 2 wire.
Lower units were the last part to transition to Mercury parts.

Jerry has id's the gearcase in post #8.



Carb kits will need to be matched to the specific carb part number.
They are not the same.
I would recommend getting carb kits from a Mercury dealer, where you will get the kit for the specific carb.

The generic kits available from aftermarket, will have a whole bunch of extra "universal" parts in the bag.
 

Faedy

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Cheers Roscoe, great Info. Sorry Jerry, I missed that bit in post 8, it doesn't have a 4 stamped above the fill hole. So that makes it a 'C' if I understand correctly.
Which is the key info I need so I can rebuild this sucker and get it going properly. The last guy looked like he enjoyed changing to reverse with the engine still spinning with good revs :) dog clutch and gear lobes are a bit rounded and it wont stay in reverse. Talked to an engineer and I recon I have that sorted with some brazing and machining :) bit of kiwi give it a go repair :) got to be cheaper than the $800 odd for replacement parts :) All the other info means I can make sure I get the right bits when I need to work on it :) then I can start on the boat, now theres more fun lol
 

jerryjerry05

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The dog and gears can be machined to work again.
Unless they are really worn down, you just need to cut down and not add to.
Have seen a guy use a dremmel to resurface and it worked great.

What parts are you looing for?

Most times you rally don't need to replace anything except spark plugs.
The carbs, unless they are REALLLLY bad usually only need cleaning.
I use Dawn dish detergent and fresh water and an air hose to do most carb cleanings.
In 1990 they started using the primer and did away with the mechanical choke.
 

pnwboat

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I wouldn't attempt to braze any material to the gear. The gears are probably heat treated. Brazing will possibly take the temper out of the gears making them soft.
Brazing generally heats up a larger area of the piece than ARC welding.

I would also be a little afraid of arc welding with MIG, TIG or Stick too. These methods won't put as much heat into the piece but anytime you're dealing with heat treated parts, you have to be careful.

Like Jerry suggested, just re-machining the rounded edges will suffice and you should be good to go.
 

Faedy

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Thanks guys sounds like some wise advice :) I will focus on squaring up the faces of the dog clutch and gears. I have included pics co you can see what I'm talking about, also the vertical drive shaft is blued, I'm assuming its been heated up at some stage , should I be concerned about that?
 

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pnwboat

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The clutch dog teeth on both the gears and the dog itself don't look too bad so they should clean up nicely.

I would look to see if there is a bearing that sits in the case in the area of the drive shaft that is blued. Off hand though, I don't remember a bearing that rides on that area of the drive shaft. There is one that sits lower on the drive shaft just above the pinion gear but that area of the drive shaft looks normal. If there is a bearing, take a close look at it to see if it has any damage. If there is no bearing, then I wouldn't worry about it. Replacing the drive shaft is not cheap and you would probably be better off finding a good used lower unit in the long run. That chip in the pinion gear would be a bit of a concern. You might want to keep your eye out for a good used lower unit "just in case" if concerns you.

TIP: The drive shaft bearing in the case just above the pinion has about 10 needle rollers. They will sometimes fall out of place if you tilt the case. Make sure they are all there and none are missing. Use some thick bearing grease to hold them in place, or use a short piece of cardboard tube (or anything similar) close to the same diameter as the drive shaft and insert it into the bearing to temporarily hold them in place.
 

jerryjerry05

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Use bearing assembly grease. Regular grease is too thi​ck.
Bearing assembly grease will dissolve quickly and mix with the oil.
 
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