Tohatsu 25hp Gear oil change

[Commando C2]

Hello all

I have a 25hp tohatsu 2000 model 2 stroke.
she makes quite a clanking noise going into gear. reverse worse than forward.
once in it is gear it is fine but the noise sounds like metal against metal.

I got the engine out today and it leaked some watery/oily gunge from the prop /skeg area so i suspect there is a gear oil leak unless it is an over rich mixture from the exhanust. Pic of the leak attached.

I undid the top oil screw when the engine was upright on its trolley.
No oil seeped out, should it have?

What is the best way to change it, lye the motor on its side or do it in the upright position?
I am going to measure how much comes out so i know if it was low or not.

I took off the prop and the spline nut was not very tight at all, the prop could move about 3-4 mm on the spline. What is the tolerance here?
Also the seal around where the spline shaft goes into the gearbox housing was rusty and corroded but didnt seem to be leaking when inspecting it ( i had just run it so it had been wet)

Can someone direct me to a site to get the exact part no for these seals and also the seal on the oil filler screws as these seem to be constantly oily

I suspect the oil level is low hence the clanking into gear noise.
If its not low then i have a more serious problem

 

[Sea Rider]

Re: Tohatsu 25hp Gear oil change

Usually no oil or very slight amount seen popping out when removing upper oil screw, remove lower screw and see if exiting oil is contaminated with water, light grey/white milky combination, if so, will need to replace gear case components.

Place engine in vertical position, place pan under tail and remove lower screw first, then upper, when all oil is out, add some new oil throught upper screw to drain gear dirt, metal fillings, spin prop untill gear case is completely empty, fill new oil through lower screw with bootle nozle or hand pump while spinning prop untill you see oil exiting upper screw, replace upper screw, take bottle noozle out and replace lower screw, tight well both. If you see metal fillings in drained oil larger than powder particles, you have gear wear due to bad lubrication, insufficient oil level.

The shaft front/ rear play is about right, is not tight as propeller as someone would think. The tail oil mess is normal on that model engine, comes from the exhaust system through the tail, anyway, check gas/oil ratio probably too much oil when mixing, if ok, give a 1 minute wot before reaching shore to help clean exhaust. You could buy parts in iboats.

Happy Boating

 

[pvanv]

Re: Tohatsu 25hp Gear oil change

Agree with Sea Rider, and would add that the prop nut tightens down to zero play. If the prop is loose on the shaft, that could contribute to your clank, as the prop slides back and forth on the splines. It's also hard on the prop hub. Recommend a new cotter when you torque the prop nut.

That black residue on the prop hub looks like unburned fuel/oil mix. Not unusual.

Any dealer has the drain screw seals, about 50 cents each. Don't over tighten the drain screws, or they can be difficult to get out next time.

If you find water or "milkshake" in the LU drain, consider doing all LU seals; The most overlooked items are the shift rod o-rings.

 

[Commando C2]

Re: Tohatsu 25hp Gear oil change

thanks again for the info

i drained the gear oil and it is a dark brown colour. no white in there or any filings from what i can see.
going to measure the amount of oil to see if it was too low.
here is a pic of it and also of the rusty seal round the prop shaft.
it looks like is some metal in amongst the seal there.

 

[Commando C2]

Re: Tohatsu 25hp Gear oil change

the gunge that it dropped yesterday was a greeny black but i cleaned it off the floor before thinking to take a picture.
the fuel that i got with the engine did look very oily compared to my normal 50:1 mix so i guess the previous owner thought more is better instead of the right amount.

i will torque up the prop or at least do it hand tight which will be tighter than it was before!!

gonna put some new gear oil in once i have made something to squeeze the oil in with.

thanks

 

[pvanv]

Re: Tohatsu 25hp Gear oil change

Lube looks normal; The corrosion looks typical for a saltwater application. I would carefully refill the LU (get all bubbles out, and the level FULL). Re-torque the prop to zero end-play, and install a new cotter, and you should be OK.

Remember, do not "ease" the shifter into gear. The shift should be firm, deliberate, and brisk. Easing into gear can cause unnecessary wear on the clutch dog and its mating areas on the A and C bevel gears, resulting in shift chatter.

If your idle is too high, the motor will slam into gear, so verify the idle (when warm) to make sure it's OK.

 

[Commando C2]

Re: Tohatsu 25hp Gear oil change

thanks paul

there was 350ml of oil in there which i think is enough as the specs online say280ml

i will put the oil back in if i can find a way of pumping it back in.
i might use a primer bulb and line that i wont be using for fuel. this should work??

i know to put it into gear quickly and will drop the idle too. other engines i have had, have a idle adjust without having to take the hood off, that would be nice on this motor!

thanks again

 

[pvanv]

Re: Tohatsu 25hp Gear oil change

The primer would work, but most marine retailers sell a cheap pump for the 1-quart bottles as well. Even gravity would do it, as long as your reservoir is above the upper "vent" hole.

I think that the old 2-stroke idle adjustment you're thinking of is a lean/rich low speed adjustment. The idle stop is typically an internal adjustment screw that limits the throttle tang of the carb.

 

[Sea Rider]

Re: Tohatsu 25hp Gear oil change

Clean well propeller shaft and surrounding area, if hard to remove gunge, use a thin metal sanding paper, coat with marine ball bearing grease specially the surrounding area of the exiting splinned shaft, install all components back, tight, torque as specified.

Change complete gear oil, it's unexpensive, squeeze bottle untill you see exiting oil in upper oil screw, that's the max level, to have more won't do any good. Will have to remove cowl for adjusting idle.

Stated that oil seen on pic was normal, correction, this issue was seen or commented by clients in engines that were having break in periods from new, perfectly normal in this case, probably previous owner was using to much oil in mixture, readjust new mixture to 50:1, check plugs are the correct ones and gapped to 1.00 mm tight. The idle screw is the vertical one located at the extreme carb pawl, the mixture screw is the horizontal one, can't go wrong with them

Happy Boating

 

[Commando C2]

Re: Tohatsu 25hp Gear oil change

so is it possible to use normal gear oil that one might use in the gearbox of a car?
or is it the spec of the oil that is important, ike API grade?

i would imagine they are the same but the outboard stuff is more expensive because its sold for outboards and thats a rich mans game obvioulsy so they sell it for more!!

 

[TOHATSU GURU]

Re: Tohatsu 25hp Gear oil change

Same oil as used in the rear end of most cars. Marine EP 90 may have a minor additive base, but not enough to make a difference...Unless you are racing.

 

[Commando C2]

Re: Tohatsu 25hp Gear oil change

so differential oil is the same as gearbox oil?
i think i will get some of that as its cheaper and i can change the oil more frequently.
i am not racing but want best protection for my bevel gears!

 

[TOHATSU GURU]

Re: Tohatsu 25hp Gear oil change

EP 90 or 85-90 or whatever is the same, regardless of what you buy it for.

 

[Commando C2]

Re: Tohatsu 25hp Gear oil change

Got a litre of car gear oil for ?7
and filled the gearcase by using the primer bulb and long pipe with gravity.

i filled it so that when i turned the prop the oil would then seep out the top hole.

She doesnt make such a noise with the idle right down low.

One thing i did notice , is that if i put it in reverse the prop can be moved sightly and then the engine compression makes it difficult to move any more, which is to be expected BUT if i put the engine in forward i can turn the prop CW without it turning the engine over but virtually no resistance just a light clicking noise.
is this normal as on my other engine it doesnt happen?

Also noticed that it wont fire unless i make a very ling pull stroke on the starter coil, i have to pull it right out to the max nearly!!