10M

I'll try to make this quick....I have TRSs and had the bellows/u-joints changed a few weeks ago because they were starting to dryrot and I didn't know how old they were. Was about to leave yesterday and noticed some oil residue inside the prop and leaking out of the housing behind the prop. I checked the fluid level in the reservoir and it was down a little, so i added about 1/4 quart, cleaned the oil out of the housing behind the prop, ran the boat for 5 mins or so (put it in and out of gear a few times with the prop off) didn't see the fluid level change. Couldn't see any leaks, drips, etc. After interrogating the guy who did the job (marine mechanic who has done these a bunch of times), we decided to take the boat for a ride and check the level frequently. So i checked it 5 minutes in, level was down a little. 5 minutes later checked it again after planing off, sure enough bubbles on the dipstick, water was getting in.

I drained the oil when i got back cuz I didn't want it to be sitting w/water in it. Today couldn't feel any oil residue anywhere near the gasket that was replaced when doing the bellows, and it held 10psi for 15 minutes, no bubbling from inside the housing behind the prop. Also did a vacuum test with the same results. Any ideas? It didnt leak before I had him do the bellows, but none of this really makes sense.

It took 3 weeks of the boat sitting (without being used or started) for the small amount of oil to leak out, but only about 15 minutes in the water to foam the oil. Should we try more pressure? As of right now we have some 30W gear oil in there to see if it leaks overnight.

?

Drive oil was fresh.

amazing1

i would suggest the rubber o-ring around the bearing carrier in the lower unit. i had the same issue with the oil leaking out at the bearing carrier.
my .02 hope it helps

Driveguy

Prop shaft seals, 1 faces in to hold oil in 1 faces out to hold water out.

jeff32

have not read the hole thing but might be oil cooler? water mixing with oil in the cooler even if your drive pressure test ok?

picklenjim

Drive oil don't go through the cooler. Cooler is for engine oil.

picklenjim

When you drained the drive was there water in it? It takes a long time for the oil to move into the drive from the reservoir so in 5 minutes you may not see much change at all in the level. When you added oil to the reservoir it may not been able to flow into the drive due to air in the top of the drive. Remove the upper vent plug on the drive and set the level on the dip stick. The full mark on the dipstick is at the same level as the vent plug. Due to the test you've done in my opinion you probably don't have any problem except not filling it correctly.

10M

There were water bubbles in the oil when i drained it. Both drives were filled correctly, from the bottom, with the same amount of fluid. The other drive was and still is full and clean. When I topped off the one that had leakage, it was at my house. I ran it, drove 1/2 hour to the launch, checked it again, then idled/ran it for another 15 minutes before it started to foam. And it was still @ the full level on the dipstick. It had a lot longer than 5 minutes (and a bumpy trailer ride) to flow into the drive from the reservoir.

rufusgrouse

trs 101: The tr/trs series are "vented systems" insofar as drive oil containment is concerned. All other Mercruiser drives are either pressurized or vaccum vented. The sole advantage with the vented trs system is avoidance of water being pulled in via the vaccum created within the drive after a long day on the water. The oil contraction is facilitated through the "vent" on the drive oil resevoir. The disadvantage is the lack of oil pressure within the drive while running. This allows on occasion some oil to escape through the propeller seals due to lack of internal seal expansion as a result of the "vented" system".....In short; oil resevoir levels can fluctuate, and should be carefully watched.
Oil leaking through the bearing carrier after a bellows change is most likely the result of the check valve leaking oil into the exhaust cavity while installing the drive. If a new seal (26-48443) was not installed during service; an error was probably made. New prop seals can easily be installed without pulling the bearing carrier. The updated seals are 26-821092 and 26-814242. The forward carrier o`ring has about a 2% chance of being the problem, and in closing; the very "first" place to look for a trs water intrusion issue, is the 3/8 tranfer hose in front of the bell housing. I have seen dozens of drive fatalities due to the lack of maintaining the transfer hose and the attaching clamps.

10M

Rufus...makes sense. I think I will change the shaft seals and check the hose. I'll keep you posted. Any further input is appreciated. Thanks.

rufusgrouse

The other less possible oil leakage issues would be the two internal oil passage orings. The aft driveshaft passage (on top of the lower gearcase) has a close proximity to the exhaust passage, on on rare occasions leaks oil down onto the bearing carrier. The other remote possibility is that the ujoint bellows perhaps did not seal against the flange, and the removal and repacement of the drive aggravated a very, very common problem. That would be the seal directly aft of the ujoints themselves. The drive gear directly aft of the said seal is supported by a bearing which loses preload at a much higher rate than any other bearings in the drive. A "loose" bearing allows the shaft (62782) to have excessive lateral movement against the seal (26-62818), and if that were the case, the very action of removal and replacement of the drive could have facilitated leakage. I will assume that your mechanic covered that one though....