GT-40 / 1.23:1 gear box / is there a 'typical' location for oil leaks?

[SilentSeven]

Boat's a 1997 Ski with 1500 some hours. I have evidence of oil in the bilge but can't see any obvious location where it may be coming from. To the best I can see, it's not from the front main seal or the pan gasket (sides). So...I suspect it got to be from maybe the rear main or possibly one of the tranny seals.

Is there a typical location that fails?

Is there a good way to determine if it's tranny fluid or oil in the bilge?

Boat needs no oil between changes in either the motor or the gearbox.

Appreciate any suggestions from hands on experience.....

[gary s]

If it's trans oil it will be red or pink when mixed with bilge water,engine oil will be dark colored. Valve cover leaks are common.

[SilentSeven]

Yeah...ok, that makes some sense. I'd say it's more pink than brown. So that would suggest a transmission seal. I'll look more carefully around the trans.... Any idea if the trans can be pulled without removing the motor? Putting in new seals is pretty straightforward if you can get the sucker out.

99% sure it's not the valve cover gaskets. Engine's all clean and tight on top.

[functionoverfashion]

I have pulled transmissions without pulling the engine. The catch is that the rear mounts are on the transmission, so you have to support the engine another way while getting the transmission out. I can be more detailed if you like, but it's pretty straightforward, really. Something like:

- disconnect water hose, throttle cable, neutral safety switch wires
- unbolt transmission from driveshaft coupler
- unbolt rear motor mounts from stringers (those attached to transmission)
- lift engine and transmission until transmission will clear driveshaft coupler to come out
- support engine because the rear end is only supported by its attachment to the transmission
- now you can unbolt the transmission from the bell housing and lift it (not by hand!) out, away from engine

That's an oversimplification but you get the idea. You could just disconnect the water hoses, fuel lines, throttle cable, wire harnesses and battery cables and lift the whole thing out together.

I did this when I replaced the rear seal on my 1.23:1 transmission in my old Supra. I had a tractor to use for lifting, but overall I was back in the water in about 3 hours start to finish, without a helper. Also: the direction of the seal does matter.

[SilentSeven]

Nice! Thank you....

Also quite a bit of discussion on correct craft fan on tranny leaks and repairs. After a bit of reading on that site, I'm thinking my front seal is weeping and should be replaced.

http://www.correctcraftfan.com/forum...replace-damper

http://www.correctcraftfan.com/forum...mission-remove

http://www.correctcraftfan.com/forum...nsmission-leak

Also looks like Skidim has the parts...I'm going to assume it's a 40 series.

https://www.skidim.com/products.asp?dept=1181

None of this looks too bad.

[functionoverfashion]

Now that I think about it, it was definitely the front seal on mine that was leaking - the side facing the engine.

edit: I was the one who started one of those threads - http://www.correctcraftfan.com/forum...nsmission-leak

So yeah, also don't remove that little hose on top of the transmission.

[SilentSeven]

Hey, did you do anything with your damper while in there? Outside of the seals, that looks like the most common 'while you're in the neighborhood' part.

[functionoverfashion]

I didn't change the damper plate but that's only because I'd already done that. The welds failed on mine where the splined shaft receiver is connected to the plate, but they looked like poor welds upon inspection - not by design, but like a Friday afternoon kind of job. But it lasted over 20 years and hundreds of hours, so it wasn't THAT bad.

I think they're around $100 so compared to the trouble of getting in there, yeah, it's easy to do while the transmission is out. But they're not a real weak point... that's your call.

Speaking of "while you're in the neighborhood" I suppose you should do an alignment after putting it all back together. That's free if you've got some tools, just a little tedious.

[SilentSeven]

Yes...the ever expanding job. Did you use the genuine PCM damper or did you use the Sachs version? Seems like lots of kudos for the Sachs version and it's $80-ish vs $225-ish.

I think the project list is shaping up like this:

- fix the front tranny seal
- replace the rudder packing
- replace the shaft packing
- check the muffler for any holes (been a few years since i did that)
- clean the aft bilge out

Maybe do the damper plate. Prolly will if I can do the Sachs plate...cheap enough to toss in.

Re-assemble and align.

[functionoverfashion]

Sounds like a good list of "while you're in there" stuff.

The marina where I was working at the time was a PCM dealer, so I'm sure I just got one from them. Looking at Skidim, it seems like they've updated the part, maybe that's why it's more expensive now?

[SilentSeven]

OK - completed the job. Thank you functionoverfashion for the removal tips - they were spot on. The front tranny seal was clearly weeping. Rear main seal was tight. Here's a few quick takeaways.

- You don't need a hoist to do this job. I undid the aft mounts and rotated the motor up by hand. My son put a custom cut block of wood under the exhaust manifold as I had the motor up to keep the aft tipped up. The transmission can be removed by hand, maybe weighs 60 or 70 lbs. Really wasn't that heavy.
- My damper was fine so didn't replace it. The transmission shaft just slid back in to the damper without any problems.
- The most difficult part of the job was the engine alignment. Basically, you need to use the front mounts to raise/lower on my 97. The rear mount nuts are not really accessible to loosen without some huge crowfoot type tool or similar. Next time, I would loosen the rear mount nuts on the aft mounts when the mount is out of the boat. My front mounts were really stiff (however not rusted) and there isn't much room to work. Had to buy a 1 1/8th inch 6 point socket from Harbor freight and use a breaker bar to crack the front mounts loose. From there, it wasn't initially obvious that you need to put a wrench on the bottom number to change the height. Just turning the top adjuster doesn't change the height unless you have the bottom nut locked. On the port side, had to remove all the shower pump hardware to get access. If I ever have an excuse to pull the front mounts I plan to grease the pivots and shaft.
- I forgot to protect the new tranny seal with a shaft protector when I first re-installed (doh!) the transmission front plate. I was concerned I nicked it and didn't want to take the chance. Discovered that the front seal is a 42mm OD, 25mm ID 7 mm deep seal. Standard size. Was able to get one the local parts store for $3 once I knew the size. Skidim sells the same seal for like $20 (I still recommend buying from them but I needed one fast)
- I think I do have a very small weeping leak on the back of the valve cover gaskets and so that will be next on the fix list. When I do that job, I'll likely replace all the vacuum hoses, EGR value and the ERG valve block seal at the same time. They are all looking a little crispy from age.

For the record, boat has 1550 hours and runs great. Hoping this solves most of my oily bilge issues.

[functionoverfashion]

Glad it went well! Alignment can be a real treat, but it's worth getting right. I bought a set of crow's foot wrenches and a few other tools years ago specifically for alignments. I also use a crow's foot on the manifold plugs, they work great! Whatever I spent on the tools is far less than I would have spent paying someone else to do the work, for how many times I've done it since. That said, when it comes to aligning my v-drive, I'm totally dreading that job because of the access to everything.

[SilentSeven]

Yes, I could see a v-drive being no fun. This job was mostly easy due to the access. Any quick tips on how to work the alignment bolts from when you did it? Here's a few questions.

- Any tips on prepping the mounts? I sprayed PB Blaster and let them sit a day. It clearly helped but didn't solve everything. The shaft/nut combo just has some built up corrosion and it's all just really stiff to work.

- Rear adjuster - need to loose the upper and lower nuts but not reasonable tool fits. A big (really big) crowfoot might work. How did you get these loose? Or did you do what I did and just work the front adjuster?

Anything else helpful you remember?