lower unit leaking oil 90a

[tannerpace]

Help!

I noticed a puddle of oil under my lower unit a day after I took it out, so I changed the lower unit oil. After changing it I noticed it is still leaking but not from any plug. It appears to have a hair line crack right in the casing of the lower unit. It is on the port side. Is it possibe to replace the case of the lower unit only? DO I need to change all the gears into the new one? Could I just jb weld the small crack? any one ever had this problem before? The motor is only a few years old. I think its a 96.

 

[pvanv]

Re: lower unit leaking oil 90a

What color was the puddle? Most 2-strokes will drip some unburned fuel/oil residue. If it was black and stinky, it's probably not LU lube. If you do indeed have a cracked LU housing (possibly caused by salt accumulation between the prop shaft housing and the LU case), there is a distinct possibility that you will need a replacement. What is your exact model/serial? BTW... A 1996 model year is 16 years old -- almost old enough to vote.

 

[tannerpace]

Re: lower unit leaking oil 90a

It is not black it is lower unit lube for sure. I replaced it and it has water in it. I patched the crack with some epoxy weld and it is holding oil. I took it out twice and after yesterday it is leaking again but now it is coming from one of the water holes, on the left hand side where fresh water comes from The info you asked for is, a year 2001
model is a tohatsu m90a 3b7
serial number 27144.

what do you think ?

 

[Sea Rider]

Re: lower unit leaking oil 90a

Time for a new lower leg kit....

Happy Boating

 

[tannerpace]

Re: lower unit leaking oil 90a

What is a lower leg kit? I am mechanically inclined I have built two stroke motors before, I also participated in swapping a lower unit before. However I have never worked on this motor. Is a lower leg kit just another word for lower unit? where can i find one? Please be more specific.

 

[pvanv]

Re: lower unit leaking oil 90a

What is a lower leg kit? I am mechanically inclined I have built two stroke motors before, I also participated in swapping a lower unit before. However I have never worked on this motor. Is a lower leg kit just another word for lower unit? where can i find one? Please be more specific.

Assuming your LU casting is sound, or at least the epoxy job is holding...

You need to replace the seals in the LU. Get 3B7873212M LOWER UNIT GASKET SET $50.68, and using your Factory service manual, Part# 003-21036-1 $45.00, as a guide, replace the seals. Don't forget the shifter cam bushing o-rings, which are often overlooked. Due to the labor involved (you will need to drop and disassemble the LU), if it has been a couple of years since the water pump was serviced, also install a new 3B7652310M WATER PUMP KIT $94.64. These parts are available from any dealer, including me.

If your crack repair is not holding, you will need 3B7S600004 GEAR CASE $685.63. The motor may not be worth that cost. If you do change gear cases, you will need a dial indicator and a few other machine shop bits and jigs to properly shim the backlash of the gears. Or, you may be able to scrounge a used LU from a salvage yard. If you do, be sure to install new seals and a wp kit in that unit. You probably don't want to buy a new 3B7Q873028 LOWER UNIT ***'Y L at a cost of $2,149.88 (which is painted the newer "almost black" color).

 

[tannerpace]

Re: lower unit leaking oil 90a

The case repair is holding now, I removed the puddy with a stripping disk then champfered the crank and layed up seven layers of cloth with epoxy. only problem is after I run it some oil comes out of the holes in the bottom of the lower unit. I guess i do need a new lower leg kit before I mess something up?

 

[pvanv]

Re: lower unit leaking oil 90a

What holes in the bottom of the LU?

 

[TOHATSU GURU]

Re: lower unit leaking oil 90a

Probably the water drain holes. Chances are the gear case was ruined due to ice or impact damage and there was/is/will be leakage.

 

[tannerpace]

Re: lower unit leaking oil 90a

Probably the water drain holes. Chances are the gear case was ruined due to ice or impact damage and there was/is/will be leakage.

I think this is probley the most likely senario the boat sat for two years on a lift down in jacksonville florida. It started right up after that and I used it half a dozen times it was fine for a while. It does leak a mix of lowerunit oil and water from the water drain holes, now what do you supposed that I do? Would a new lower leg kit fix this? I already repaired the crack. It was on the port side in the middle on the prop bulb thing. I am not sure how the crack got there. Could have been a impact but I did not feel any thing.

 

[TOHATSU GURU]

Re: lower unit leaking oil 90a

There isn't a lower leg kit has there really isn't anything called a lower leg. Chances are you have a leaking seal or o-ring in the lower unit. That can be found by pressuring testing the lower unit and forcing the leak. Or, you can simply replace all of the gaskets, o-rings and seals in a shotgun approach. You can make a case to do it either way as it's not unusual to reseal a lower unit for fun and giggles. But, you may have a gear case that has a crack or void where it is not easily visible. In that case, the pressure test will force the leak at that point and it should be visible.

Impact damage is always felt and heard. But, the damage can occur months or even years before it reaches a noticible/visible point. So, by the time you know you have a problem, it would be very possible to have forgotten that day where things went bump in the night.

Side bar:

Motor leg or intermediate motor leg usually refers to that part of the engine below the power head and above the lower unit.

The lower unit is that part of the engine that contains the transmission parts.

Gear case is the housing that contains the gears, shafts, etc., that makes up the lower unit.

Depending on who you are talking to and how bored they are, you may hear those terms mixed or combined incorrectly causing a little confusion.

 

[pvanv]

Re: lower unit leaking oil 90a

Right. Hidden damage may show up much later. Pressure testing can reveal the specific location of the leak. That may point you to a housing that still has a flaw.

But... if you are SURE that you have a solid, non-leaking casting, you can replace the seals as a kit. You would order 3B7873212M, LOWER UNIT GASKET SET, $50.68, from any dealer, including me. The kit has everything you need to do the driveshaft, prop shaft, and shift rod seals and o-rings, as well as the fill/drain gaskets, and the exhaust pipe and exhaust housing gaskets.

In our shop, on a motor of that vintage, if we were going to repair a leaky seal in the LU, we would do the complete kit, rather than just a specific o-ring or seal.

 

[tannerpace]

Re: lower unit leaking oil 90a

Ok this is what I was thinking. Thank you for your detailed and informative responses. I believe the seals most likely dried out after sitting, the power head is still in great shape. How many hours should a shop charge me to replace all the seals? What if any special tools would I need? I like the satisfaction of doing things my self but I realize it is not worth the frustration some times. How hard is this going to be? Can I do it at home with out air tools, and other special tools?

 

[TOHATSU GURU]

Re: lower unit leaking oil 90a

Two hours for someone who knows what they are doing. Three if they don't. Four if they are stupid and crooked No "special" tools needed. But, the avearge houshold took kit isn't going to cut it. It's not rocket science, but there is a skill set needed. If you are comfortable working on things that go vroom you won't have a problem. If you are an engineer don't attempt it because engineers usually have a lot of problems working on things because they get caught up in the "why" of it. One major warning: Do not attempt without a factory service manual.

 

[tannerpace]

Re: lower unit leaking oil 90a

OK so I got a used lower unit of eBay. I got the shop manual. I have ordered a new impeller. Going to use the water pump housing off my old lower unit. The propeller shaft seal on the new lower unit is now leaking. I removed the lower water pump plate to inspect. I did not realize the seller had not drained to lower unit of oil. when I put the lower units water pump back on it caused the propeller shaft seal to begin leaking oil. Also seems to have a small tear. I have a lower unit seal kit. But I cannot find how to replace the bearing carrier drive shaft seal. I believe I already replaced it on my old Lower unit, can come one talk me through replacing this seal?

 

[tannerpace]

Re: lower unit leaking oil 90a

What size spring pin do i need for the shift linkage? The shop manuel does not give a part number, I know it is either 3 or 3.5 mm. Not sure if that is inner or outer diameter Also not sure of length. Thanks any help is greatly appreciated.

 

[pvanv]

Re: lower unit leaking oil 90a

The two seals (separated by a shim) below the water pump are replaced in the usual way: drive them out, and tap new ones in. In the kit, you may find that the 2 seals have been superceeded by a single, thicker seal.

After you extract the prop shaft from the prop shaft housing, you can remove the 3B7601110M seal by either pulling the old one with a seal puller, or by drivimg the old one out from inside, using a drift punch carefully located.

Never replace just an impeller; Always do the complete kit, which gives you a new cup and wear plate, as well as a few other goodies. Pumps better and lasts longer.

The shift linkage pin is 9514033516M, 3.5 x 16 mm. It must be ss.

 

[tannerpace]

Took It for a spin today, worked great. When I got home to flush motor...I noticed was not peeing water very strong. Also some was coming out at the bottom where the lower unit mounts to the mid section. I could tell it was being pumped by the engine. Is this normal? Does this motor have a thermostat? Or did the water pipe possibly become unseated?

 

[pvanv]

If running on muffs, you may not have enough water to really get it to pee well. The rest is normal. The stat does not stop water flow, it just regulates it through the head.

 

[tannerpace]

I'm concerned about my water pump, please watch this video and tell me if this looks normal. When I first installed the lower unit the water pipe did not mate to the pump and no water was getting to the power head. I took it off and reconnected it. I am worried it could of blown the top water pipe seal or become in seated. M90a testing: http://youtu.be/XHCirp6fhhk