Ho to fix a leaky transmission?

[Scott T-Bird]

Last summer I noticed oil in my bilge water (we always had bilgewater because the packing gland was leaking all summer). So I found the source of the oil leak back by the transmission where it was extremely hard to clean up and get access to.

It just so happens that I wanted to replace my engine mounts and install a PSS shaft seal so now I have the engine removed and can fix all kinds of things. The photo of the transmission shows the leak just over the stained rags. It appears that oil is dripping from the shifting linkage. The engine is a Yanmar 1GM circa 1984 (rebuilt by PO sometime around 2001).

When I found the oil level going down last summer, I added transmission oil instead of the regular diesel grade oil that is recommended by Yanmar. Is that a major no-no?

Another question, what is the purpose of the red tank that is in-line with the exhaust?

The shaft currently shows the rubber hose still attached to the stern tube (in case anybody was wondering). I can't wait to see how the new shaft seal performs - I'm tired of trying to adjust the packing nuts and getting in there to remove the packing would have been a nightmare. I hope to have a permanently dry bilge for a change!

Another thought I had was to replace the original 35A alternator with a new one that will charge just a little bit faster.

 

[Clark]

Transmission Oil

Scott, if the specs call for engine oil; the addition of ATF is not good because it is much thinner. The end result is determined by how much you had to add (ie. how much of the final 'mix' is ATF) and how long you ran it. If you just added a couple of ounces to top it off and haven't run it much I would suspect no problem. Just make sure to use what is spec'd for your tranny when you get it back together.

 

[Don S/V ILLusion]

Scott
The leak appears to be from the linkage seal. It isn't a difficult repair but it is beyond my ability to describe. If you don't already have the Yanmar service manual, get one - they are cheap on the internet and include good pictorial diagrams of what you need to do. Replacing the seals is easier done than described. You might also want to replace all the seals given what you put in the tranny... especially now that the engine is out and you'll hopefully never have easier access.

The tank to which you refer is the water lift muffler.

 

[Scott T-Bird]

Putting it back together??

I wasn't planning on pulling the transmission apart. It seemed to me that the transmission oil that I bought was a much heavier weight oil (90W?) than the diesel engine oil (40W), so I am confused by your statement (I thought the transmission oil would be thicker). If my comment makes you laugh, I can take it ... a gear head I have never been!

However, earlier in the past summer, I did notice some anomolies occuring when shifting into gear. Sometimes it would chunk a little before catching. After I added the oil, the anamolies seemed to disappear. Maybe it would be a good idea to pull it apart; but, I am not sure what I would be looking for or what to do if I find something that appears wrong.

We don't use our engine much, being on a small lake and we don't ever use it for a destination that is longer than a few miles at a time. The number of hours that we have put on the engine in 4 seasons is miniscule. I do check the oil level frequently and last summer was the first time I noticed a change enough to add anything to the transmission, so I only added a few ounces and have put on no more than a few hours since then.

I often think about the fuel and have to admit to never even changing the filters. Here is a picture of the primary Fram filter (I don't even know what filter size it is). I thought about exchanging for a Racor filter as that seems to be the prefered brand. I am not sure if it is even possible to get in and scrub the fuel tank as it is wedged under the cockpit floor way behind the engine. I have no idea how dirty the tank may be, except that we have not had any problem with clogged filters and the engine never has run rough. (but we never have any rough wave action to stir things up).

Hear is a picture of the filter (top) the water strainer (bottom) and you can see the tank wedged far back.

Don, I do have "Marine Diesel Engines" by Calder and a much thicker book put out by Yanmar which is specific to various Yanmar models (including mine - I don't have the title handy because it is on the boat). I think I bought these books on this site a few years ago.

I have heard the term "water lift muffler" and figured it was referring to that red tank. What does it do specifically? I thought it might serve as protection to keep water from backing up into the engine during following seas, as I've heard that has been a cause of flooded engines. The inboard engine on my ski boat has no such muffler. The pipes just run directly to the exhaust ports.

 

[Tim R.]

90W gear oil is typically used in manual transmissions not automatic(automobile transmissions). Unless your tranny and engine share an oil bath which it does not appear that they do based on the filler plug on top of the tranny, it will usually take a different type of oil than the ingine. Check your manual for which fluid should be used.

Replacing the seal should be very easy and fairly cheap. If you do not feel up to it, it is even easier to remove the tranny from the engine and take to a mechanic to do the seal. Have him do all the seals. Once apart it would also be good to change the damper plate inside the bell housing. Again very easy if you can use a socket wrench.

The red tank appears to be your water lift muffler. It looks like it has a leak which you should address. Could be as simple as tightening the hose clamp or replacing the hose.

A waterlift muffler has 2 chambers that are common at the bottom. The muffler must first fill with raw cooling water and then the gas must force itself down thru the water into the next chamber in order to exit the exhaust hose and thru hull. I am sure someone here can explain it better. Inboard and I/O ski boats usually have the exhaust exit the hull below the water which acts as a natural WL muffler.

I have not changed my filters in 3 seasons. I pump and clean my tank every year and I keep spares on board and know how to bleed the system if necessary. I usually find very little crud or moisture in my tank at the end of the season.

 

[Bill Roosa]

Tranny oil

Hi Scott
If you only put a few oz in the tranny you are probably OK. Just suck the oil out and add the manufactures recommended oil.

As for adding a new alternator, be sure your system can handle the new current flows and power. An alternator over 75 amps will be needing a 2 belt pulley and the wires need to be able to handle the current WO/ heating up.

 

[bobtigar]

Re: Tranny oil

Ref-increasing the alternator size...Usually if the alt is lager than 100 amp it should be double belted. I'ver used an 85 amp for 10 years sigle belted without a prob. But you arent going to gain much. You would be better off spending your money on a multi stage regulator to fully chage the battery with the amperage you are producing. The best approach is a lger alt, new voltage reg and heavier wiring. Bob

 

[Capn Dave]

Ahoy Scott

I cant figure out what red thingy you are talking about. The waterlift muffler is in the first picture from you. It is the biege or light brown thing. In the last group of pictures the red thing down low is a seawater strainer. The thing that has the red top up above, on the bulkhead looks to be a fuel filter.

Fair Winds

Dave

 

[Benny]

Transmission fluid and transmission oil are two different things. If you added 90W to your transmission it is heavier than the 30W or 40W recommended by manufacturer. The problem is it may not get in between close tolerance gears or bearings to reduce wear so drain it and replace it with the proper grade. Permit me to suggest a high grade synthetic oil which are more resistant to breakdown. Regarding the seal, if the leak is minor and you are not mechanically inclined to deal with the transmission do not remove the shifter cover as you have a shifting cam and fork that will require aligment. If the engine is used very little and the leak just amounts to a couple of ounces every three months or so you can just learn to live with it with the caveat that you should frequently check the level. I agree now that the engine is out it would be the time to get things fixed but I doubt that you would find a competent Yanmar mechanic in Lake Hopatcong (pardon my geographic ignorance) so your best bet like others have suggested would be to acquire the Service Manual and perhaps with the help of an experienced mechanic (they have the tools and practical knowhow) tackle the fixes yourself.

 

[Benny]

Regarding a larger alternator remeber that a 1GM basically has the equivalent of 8 hp which is not much to drive it and also the boat. I would not consider anything larger than a 55 Amp with that engine and only on a lake.

 

[Scott T-Bird]

Great input from many sources!

Tim, I did buy the 90W gear oil at an auto parts store. I knew the recommendation is for the regular engine oil (and I had it on-hand) even though the engine and transmission do not share the same source. See another view of the engine. I'm not sure what I was thinking at the time ... maybe I was thinking that it would be smart thing to do!

Anyway, I like your thought about removing the tranny and taking it home to work on in a nice warm basement with a workbench! I am handy with a socket wrench and have English & Metric! It won't make a huge mess inside the boat if I pull off the tranny will it?

Benny, I bet I could work on that shifting cam and fork in a comfortable environment. Even so, Mack Boring is relatively local and they must have done the rebuild, since their sticker is on the engine. When we first brought the boat home back in 2004, I had their service man come out and take a look, just to give me a little tutorial and some assurance that it was running well. The guy was very friendly, he had a few good stories to tell about some boats he has worked on, and the bill wasn't even horrible!

About the alternator, I have been mulling it over in my mind whether or not it would be worth the expense to upgrade. Now, we have very little battery needs, but I'm thinking about the future when we want to spend some overnight time on the boat in a new location. Even then, I don't anticipate very much of an increased need for regenerating power, especially if/when we would be connected to shore power. I was thinking of upgrading only marginally, using the same footprint and not adding a belt. I think the max would be 60 or 75 Amp. It may not be worth the expense. So Bob, I think you are saying that a marginal upgrade is not worth the expense and an added multi-stage regulator is better?

Dave, the water lift muffler looks brown but I called it red because it was probably red plastic originally! Yes, the water strainer is at the bottom right with the water intake hose showing and the fuel filter is above. Is it worth exchanging the original Fram fuel filter with a new Racor filter?

 

[Tim R.]

Scott, you will not make a mess pulling the tranny. As for overnighting, spend your money on a good set of Trojan 6v golf cart batteries. You will get more than enough power for a couple of days. I don't think that one banger could handle a bigger alternator anyhow. I did a race last sep. that was 27 hours on my 220AH dual 6v batteries. I ran the chartplotter, instruments, VHF, radar(at night), nav lights, occasional water pump, occasional cabin lights with no problems. I got a slip at the end and recharged.

 

[kloudie1]

Quick note on oil viscosity.. Gear oil and motor oil do not use the same "weight" system.. The viscosity of 90W gear oil is about the same as SAE 40 motor oil, around 100 SSU at 210F (specification).. they are thicker at lower temps, but they thicken at the same rate, so at lower temp, they are still about the same viscosity.. You probably did not do any damage to the transmission by mixing in the 90 w .. If there is damage, it was not the tranny oil that caused it.. There is an O-ring and an oil seal on the gear selector. The whole assembly (along with the oil inside) comes out with 4 bolts.. but I think there are some little pieces that can slide out and get gone .. Better to keep adding oil if it isn't too much of a hassle .. or get a service guy to remove it and change teh seal and ring..

 

[sailaway78]

My .02

Hi Scott,
I doubt very seriously if you did any damage with the wrong oil As for the seal, like others have said it it a pretty easy change. But if it is like my 3GM, there is an adjustment on the shift mechanism, and you need a manual for that. Going any farther than this with the tranny will require some tools other than a set of sockets. You will have to pull the coupler of the it will be the biggest deal. Don't buy a seal at the Yanmar dealer, or any boating place for that matter. A seal is a seal, and all you need is the number off of it. A bearing supply place will sell you a seal for about 1/10 what the marine place will. As for the alternator, same deal. I took my old 35 amp to an alternator shop, and got a 70 amp to replace it. The mounting foot is a pretty standard size. Three point something inches between the ears. The larger alternator is suprisingly larger. It will work fine though if you replace it with one that has the tensioning ear about 45 degrees offset. It's pretty obvious when you look at it, but the tensioner arm will not clear the case it you have the tension ear directly opposite the mounting foot. Cost of the alternator was 70 bucks. On mine, I also increased the wire and fuse size on the alternator output. The stock wiring is maybe OK, but marginal when you double the output. Any other questions just post up.

 

[Ray T]

If it was me and I had as little mechanical experience as you do I would take my tranny and head for Mack Boring. There is some technique involved in removing and replacing seals. If you ding the seal while installing it you wouldn't know about it until you ran the engine, this would be very disheartening. Paying a pro to do this would be money well spent and it shouldn't cost a mint. Ray T