How much gearcase lube do you Sportmaster guys remove after filling

[Mr. Demeanor]

I keep getting a little water in my lower unit. It pressure tests fine. My tuner actually sticks down into my lower unit and I have my cooling dry stacked. I think I am heating up the gearcase and pushing some oil out then when I stop I have a vacuum that is pulling a little water back in as it cools. I would like to try lowering the lube level a little to give it some room for expansion.

To give you an idea of how hot its getting, this is after the Suwanee River Run. The side of the gearcase that the prop throws water against is discolored. The tuner sticks down into the lower unit about an inch.

[Dave Strong]

Manuals say 1oz. Shift shaft seal is the weakest seal,

Dave

[Dave Strong]

Never could understand why prop and driveshaft seals are always double seals and shiftshaft is single. In your case a small remote reservoir may be the answer. Tony Reynolds makes a shiftshaft bushing that has double seals.

Dave

[mrcrsr]

Your drys tacking should have a water tube cooling the gear case when I drain mine it is still full up to the vent, and I never drain any out after filling it

[mrcrsr]

Here's how I drystack a 3 liter. http://www.screamandfly.com/showthre...r-the-21-trick

[Mr. Demeanor]

Here's how I drystack a 3 liter. http://www.screamandfly.com/showthre...r-the-21-trick

Whats the point of diverting the water if you going to direct it right back into the exhaust (on the propshaft carrier)? To me the point of diverting the water out of the mid/lower is to make more room for exhaust gasses to flow.

I still have a good but of water passing by the carrier with my setup. Looks like enough to keep the carrier cool to me.

[Sonik]

To answer your original question Chris, I had a problem with my sporty burping fluid out of the shifter shaft after long runs for almost 2 seasons on a fresh rebuild and it was frustrating because I knew I was following the factory fill procedures. I changed the shifter shaft seal twice but same result. My end-game solution?? As ridiculous as it sounds, I followed the manual procedures with the exception of adding 2-3 additional "burp" and settle sessions before screwing the vent plug in and draining 1 oz. of fluid out. Pump it full, let it sit for 5 min, one more pump, let it sit for another 5, one more pump, install vent plug, drain 1 oz. and cap it. Hasn't pulled any water in, leaked or pushed a drop through any of the seals since I did it this way. I can't explain why this solved my issue but it did.

[powerabout]

The shift shaft seal it used as a pressure relief valve
Dry stacking keeps the tuner hot which speeds up the gas flow and makes the return pulse stronger

F1's answer to hot gearbox, just vent it?

[Mr. Demeanor]

Any pics of a vent setup? I know mine is different being a Yamaha but interested to see how its done.

Sonik, I know some of the guys with fast center console tournament boats that made LONG fast runs were having the same problem and blowing gearcases due to the water. The did the same as you describe and it solved the problem. Ill give it a try.

[powerabout]

2 issues
Too hot and oil fails
Sucking water back in after pushing the oil out

[albypine]

Jacking to the moon along with long runs cooks the oil in my lower . I have to drain about 1 oz out after each fill or will be changing a pushed out shift shaft seal after each 80 mile run

[Mr. Demeanor]

I made some LONG high speed runs on the Suwanee. I am running Alisyn 80 weight and although it was a little milky after 315 miles of hard running my magnet look good. Just a little fuzz as usual. I change the gearcase fluid quite often. That was probably the most miles I ever put on without a change just because we ran so far in a few days. Cheap insurance IMO.

[myron]

make sure your driveshaft is not pitted where the seal area is

[milkdud]

Ive always thought it would be interesting to put a temp probe in a gearcase that is surfaced . Not sure how you would get it in the case? If you put a nose cone on you could probably put it in from the front and it would be under the nose cone.

Just a wild idea.... Id like to know how hot it gets in there.

[powerabout]

OMC its easy, down the shift cavity as the oil is pumped around