Drain Plug Size?

[bigmarc66]

Hey guys, I was recently winterizing my 87' Force 125. I loosened the drain plug and oil started coming out, next thing I knew I couldn't find the drain plug.
This misplacement of the drain plug raised 2 questions:

1) Is it possible for the drain plug to drop into the lower unit? I ask this because I did not see it fall anywhere, I looked for a good time in the area. It seems silly but, I wasn't sure.

2). With the answer to 1 being no, Does anyone know what the exact size of the allen screw that makes up the drain plug? I put in a 5/16x24 in there temporary just to keep oil in, but it wasn't the exact threads. Can I buy one online?

Thanks in advance, Marcus

 

[gregmsr]

Re: Drain Plug Size?

Not possible for plug to fall "up" into gear housing. You probably dropped it maybe into the drain pan or something. Next, go here for replacment plug. Search your year (1987). http://www.mercruiserparts.com/Show.../33.png&inbr=1303&bnbr=130&bdesc=GEAR+HOUSING

 

[gregmsr]

Re: Drain Plug Size?

Careful not to mess up threads (if not already done) by using a makeship plug. Study the diagrams in the link. Part #'s 40/41. Always use a new gasket every time you remove/replace plug. You did remove the plug on the bottom to drain didn't you? If an 87 is the same as an 89, there should be two more plugs up on the side of the leg, one for fill, one for vent. They are all the same size. DO NOT remove the shift linkage screw. Find it and stay away from it. Study the diagrams and buy a Force repair manual (Clymer)

 

[bigmarc66]

Re: Drain Plug Size?

I have the manual, and I have the two top plugs, and the plug at the very bottom of the unit. I didn't take out the linkage adjustment, clymer makes that very clear. So it sounds like im good to go, order the new plug for the bottom plug and 2 new washers for the vent+fill plugs?

 

[gregmsr]

Re: Drain Plug Size?

Yep, but shipping will eat you up (get a shipping quote and see). Try a "Mercury Parts Express" search for a supplier nearest you. Give them the part numbers. Order several washers/gaskets and have them on hand, they are cheap. You need new washers every time you remove/install plugs. They will stuff them in envelope and mail em.

 

[bigmarc66]

Re: Drain Plug Size?

Thanks gregmsr, you were definetly right. Parts on ishopmarine were going to cost 8 bucks 30 bucks for shipping. Called a local shop and they had the plug washers on hand, but they could not recognize the force number. http://www.mercruiserparts.com/Show...1/28.png&inbr=1233&bnbr=10&bdesc=GEAR+HOUSING
thats the link to my motor and the part is number 44. The part number is FA523109 and the guy at the marina didn't know anything about it. Is there any solution to this besides ordering from an online site.

 

[Frank Acampora]

Re: Drain Plug Size?

Chrysler and Force used three different drain plugs in this lower unit; 5/16 socket head set screw, 1/4 NPTwith a straight screwdriver slot and 3/8 X 16 just like the fill and vent plugs. So. there is plenty of meat to work with there.

If the 5/16 doesn't fit properly, it is small enough that you can re-tap the hole to 1/4 NPT. But before you do this, be sure you can buy a Stainless Steel or brass plug--preferably with a hex socket head. Don't tap too deeply as NPT threads are tapered and if you go too far, the plug which is also tapered will not seal. Do it in stages to see where the best depth ends up--you want the plug to be flush to slightly above the gearcase surface. If you go with either 5/16 or NPT threads, be sure to use teflon tape on the plug.

You can re-thread to 3/8 X 16 to fit the fill and vent plugs but then you need to spot face the housing to provide a flat place for the gasket to seal. A machine shop can do it in 5 minutes; they have the special spotface and pilot tool but I don't know what they would charge. The tool is available at Graingers catalog and Fastenal might have it, but it probably costs around 45-50 bucks.

So, you have a whole bunch of choices.

 

[bigmarc66]

Re: Drain Plug Size?

Im not looking to have to re tap anything. The threads are still fine, I am just looking for a replacement for the screw. If you know this exact size, then i would not have to order one from online. The drain screw on the very bottom of the unit was a hex screw, not a bolt or screw. The two plugs further up on the lower unit are much bigger and different than the bottom drain plug. My question was just whether or not I can get a replacement plug using the part number from a place other than online sites.
Thanks, Marcus

 

[gregmsr]

Re: Drain Plug Size?

Try these people: mccallemail@earthlink.net
304-269-6449
McCalls Marine, Jane Lew, WVA
They have tons of old Force stuff
Do a Google search on the name
Cheap shipping

 

[bigmarc66]

Re: Drain Plug Size?

Guys, definetly got a problem. Got the new drain plug as I thought I lost it, comes to find out the original plug must have dropped into lower unit. I went to put in the new plug and i was screwing it in and all of a sudden it was gone, fell right in, didnt stop setting. Where do I go from here? take off lower unit?

 

[Frank Acampora]

Re: Drain Plug Size?

Well, you have three choices: The right way, the wromg way, and my way! LOL

If the screw is definitely inside the lower unit: If the drain plug was located on the lower nose in front of the skeg, (where they usually are) it went into an area where there is nothing for it to interfere with. It can not get into the forward gear bearing because the gap in the races is too small. If you are a gambling man, just leave it.--That's the wrong way. The right way is to disassemble the lower unit and take out the plug or plugs.

If the drain plug was located midway on the lower unit torpedo (about midway along the skeg) then you have no choice: you must disassemble the unit because the screw will interfere with the gears and dog clutch causing major damage.

My way which I would try first: Since the 5/16 drain plug no longer will seal, you must now re-tap the hole. So, I would carefully--so as to not get aluminum chips inside the lower unit--re-tap to 1/4 NPT threads. The hole will now be large enough to pass the 5/16 plug so using a fine piece of wire try to fish out one or both of them. If you are lucky, with patience and persistence you will get them. If not, you will need to disassemble the lower unit to get them out--which you would have done anyway so there is nothing to lose and everything to gain.

 

[bigmarc66]

Re: Drain Plug Size?

Could an option be to, leave the plugs in there, and put a 5/16x24 bolt in there with thread lock. Instead of having a set screw just have a hex head on the outside of the unit. I am totally unsure of this idea, I dont want this to be a jerry rig, so would this lead to potential damage?

 

[Scaaty]

Re: Drain Plug Size?

Could an option be to, leave the plugs in there, and put a 5/16x24 bolt in there with thread lock. Instead of having a set screw just have a hex head on the outside of the unit. I am totally unsure of this idea, I dont want this to be a jerry rig, so would this lead to potential damage?

Well, go with Franks suggestion of just leave it if ya don't want to rip it all down, then need $100+ in gaskets, crush washer, etc. And a lot of work.
I have an (88 125) gear set right now on the bench going to ebay soon. Came out of a LU with busted off skeg, that I needed the driveshaft from. I just tossed out the LU shell, so I can't remember what it looked like up there. That said, the very forward drain/set screw, really has no where to go. Just took a good look at the manual. All in that area is the shift yoke, and doubt it could get caught in that. The bearing and race are behind that, and its too big to do any harm (also no churing of oil in that area...gears other side of bearing). Probably just lay down in the bottom in front of the bearing. Myself, I would do a drill out, re-tap a size up..(theres plenty of meat in that area), then while tilted up at 45 degrees, get a squirt bottle, and start flushing it out. Might just fall out. Get one of those thin flexible magnetic strips, cut to size, and stick it in the hole, and work it around. Good luck!

 

[bigmarc66]

Re: Drain Plug Size?

That seems to be what im gonna do, retap it bigger. Would it be okay to use some gasoline after I retap it and flush out the whole lower unit to flush out any possible shavings and possibly the plug. Or is that bad to put gas in the LU to flush it out. Would there be something better to use to flush out, or is flushing it out with a lesser dense liquid a bad idea altogether?

Second thing. After I retap the hole, should I put in another set screw or should I use a bolt with a head on it so I never need to worry about this stupid thing again.

Thank You all for your help, Marcus

 

[Frank Acampora]

Re: Drain Plug Size?

See my original reply to you: Go to sears and buy a 1/4 NPT tap, and brass plug--stainless if you can get it. ( National Pipe Thread) Less than 10 bucks. Most plugs have a square head, some have hex heads and some have recessed hex to drive them. The recessed hex is the plug of choice, next being the hex head. If you get the hex head, thin it for less drag and turbulence ahead of the prop.

NPT threads are designed for black iron pipe and fittings. Threads and plugs are tapered so they will seal with pipe dope or teflon tape.

Tap in stages so you do not go too deep. After each stage, test the plug to see its depth in the gearcase. Too deep and the plug will enter too far and will not seal. Too shallow and the plug will stick out too far. Just right and the plug will be about even with the surface of the gearcase.

Use teflon tape on the plug and screw it in relatively tight but don't kill it. It will seal more pressure than the gearcase would ever see and you will never have a problem with it.

Cleaning with gasoline is dangerous. It only takes a spark to light you up. And gasoline has damn near the explosive potential of dynamite. ---Yeah, I know!--- We have all done it a hundred times and we all are careful and had NO trouble. The problem is the hundred and first time when we are forgetful or someone else interferes. Not only that, but what about the unproven possible carcinogenic effects of breathing vapors?
Better choice would be diesel fuel or kerosene--or, spring for a couple of bucks more and buy a low volatility cleaning solvent.

 

[Scaaty]

Re: Drain Plug Size?

Yep, Frank has it nailed. Use gas for combustion, not a cleaner..(its the fumes that explode, gas itself don't burn in liquid form). I go through a LOT of Oderless Mineral Spirits here..'bout 8 bucks a gallon at Walmart...reuseable to a point too..

 

[bigmarc66]

Re: Drain Plug Size?

Finished the Job up today. Drilled out the hole with a 7/16 drill, made the hole nice and big. Then I fished around with some wire for about 4-5 mins. Whola, out the plug came. After I got the first plug I continued fishing around for about 10 minutes for a possible second, but couldn't feel anything. Retapped with a 1/4NPT as described, and put in a brass plug for now, gonna look into a stainless plug. Worked like a charm. Thanks guys for your help on this one, worked great.

 

[Scaaty]

Re: Drain Plug Size?

Great!...Ya aint the first one to enlage that puny original. The brass should work OK, just remember its soft, so just goop it with something (little marine bearing grease will work fine), and just snug it up. And yep, SS would be better. Glad to hear it..( ya will sleep a little better tonight!)

 

[gregmsr]

Re: Drain Plug Size?

Not possible for plug to fall "up" into gear housing. You probably dropped it maybe into the drain pan or something. Next, go here for replacment plug. Search your year (1987). http://www.mercruiserparts.com/Show.../33.png&inbr=1303&bnbr=130&bdesc=GEAR+HOUSING

WOW, I can't amagine my drain plug falling into the gearcase with as big a head as it is on the plug. Yours must be different plug size.
Anyway, glad your getting it worked out.

 

[Scaaty]

Re: Drain Plug Size?

WOW, I can't amagine my drain plug falling into the gearcase with as big a head as it is on the plug. Yours must be different plug size.
Anyway, glad your getting it worked out.

Those motors have a puny Allen head set screw..no head..way up under the gear case nose cone. Thats the reason for the many horror stories ya read of people yanking the shift yoke pivot screw, as it looks like that should be it, and on the side of the gearcase.
Also it is possible that while not thinking, and the threads a little wore out, to twist it the wrong way, and screw it into the case, instead of out. You are working on a upside down screw.