PCM 40a Transmission Leak

So it happened...

We had been blissfully enjoying our spring boating season when one morning I noticed a small red spot in the bilge, fast forward a week later this spot had grown to a strawberry milkshake... Never had any slipping or excessive heat or any other symptoms than the leak. I kept the fluid levels healthy and pulled the boat out recently.

I am at the point now where the transmission is removed and am trying to decide how to approach this repair. From what I can see, the leak is coming from the rear main seal on the transmission, there was a small puddle in the bell housing under the fly wheel.

Here's the details on the boat:
- 1989 Martinique (351 W)
- 450 hours
- 1.23/1 Model 40a PCM Velvet Drive Transmission

Here's my initial questions:
- From my research I believe I am a STD rotation, can someone confirm?
- Is the repair manual for the 70/71C the same for the 40A?
- Does it make sense to replace w/ new, have rebuilt, or only replace the rear main seal, on this 450 hour transmission?

I am more than happy to provide photos, share my journey (with photos, I hear how you guys love these) and provide any information you need...

Here are some answers

If the leak is from the bellhousing, it's the front seal on the transmission that's leaking. The rear will leak directly into the bilge

Sounds good as far as LH engine RH prop being an 89 Correct Craft, but you say PCM velvet drive

A PCM transmission and a Velvet Drive are 2 different animals If your label says PCM 40A 1.23 to 1 then that's what you have

Since they're 2 different animals a Borg Warner manual isn't useful at all for your PCM transmission.

Is it a strawberry milkshake inside the transmission? That would mean you got water in it

Or is it just strawberry looking in the bilge water

A transmission cooler with an internal leak would be a likely culprit.if it's milky strawberry colored in the transmission itself

All kinds of people will have an opinion on what you should do, I'll let them chime in on that but I'm cheap and seals are cheap

The condition of the shaft in the seal area may tell you something too.

And make sure you get a damper plate compatible with the PCM transmission input shaft splines splines

Hey KENO! Thanks so much for getting back to me so soon, you guys here are amazing!

The leak is from the bellhousing, so looking at the manual link you sent yes, from the front seal into the bilge. The bilge turned strawberry milkshake...

Went out to look at the engine some more and my tag states firing order is 1-3-7-2-6-5-4-8, I assume that will prove that it is LH?

I will attach some more photos of the problem and transmission.

I would like to go the cheap route too, but want to make sure if I am only going to replace the rear seal that I wont be pulling out in a few months for another seal - how are replacing a few of the other seals? If the rear and front are easy enough maybe I just do those? or if I have it out what kind of job am I looking at for the rest of the seals? Can a seal replacement be done separate from a overhaul/rebuild?

Speaking to the condition of the shaft in the seal, should I be looking for wear grooves on the shaft, what could that be telling me?

As for the operation of the transmission when I was in the water, in neutral at a low idle the shaft would spin... but barely, and I could stop it very easily with my hand, once the idle was up in neutral it wouldn't spin - and, I've never had it slip out or make any noises.

Sadly, while taking apart the drive line, the shaft was never out more than 0.002/3, there was no resistance in the spin of the prop, the strut bearings were evenly worn and the coupler sat perfectly aligned at the coupler face --- so if it wasn't for the leak it was running beautifully.

I was able to get the coupler off with some real delicate work so thankfully the put-it-back-together steps should be less costly.

Is this the correct damper plate? http://www.skidim.com/DAMPER-DRIVE-PLATE-PCM-40-TRANS/productinfo/R140016A/

Your firing order is for a LH engine. Makes perfect sense for a CC with a 1.23 to 1 transmission.

As far as shaft condition I'd be looking for grooves, pitting etc. Basically anything that would prevent the seal from working. You'll probably see a shiny spot where the seal lips ride on the shaft. Just don't want them too deep.

The slight shaft movement you describe is nothing to worry about. If it was at the point where the boat wanted to move forward, then you should worry and you don't want to try stopping the shaft with your hands. That's a dirty neutral due to warped fwd clutch plates.

I'd highly suggest that you reach out to Art and tell him what you have found so far. I had a pretty bad leak in my transmission and Art was able to walk me through how to fix it myself. Fortunately, my PCM 40A only had a bad front cover gasket. I documented my journey here:
Kevin's blog about a leaky PCM 40A