LU Replaced Seals Still Leaking

[cebra]

I bought a Ranger that had milky gear lube in the lower unit. I pulled the carrier, water pump, and shaft seals and replaced all of the seals (including those below the water pump on the driveshaft). I replaced the water pump as well. I checked the boat after having it out a few times and have milky gear lube again and more metal shavings than I would like to see on the new drain plug. Any thoughts on what to I should look into? I did have to beat the heck out of the prop shaft seals to get them out but I was fairly careful not to mar the lip inside the carrier. Thanks.

[leonreno]

I don’t know the specifics of changing the seals, so problems with installation I’m not sure. But first thing I would check is prop shaft run out. You should also pressure test to find the leaking seal.

[lpugh]

^^^^^^ + 1

[EuropeanAM]

Drain gearcase and perform pressure test while checking for leaks with soapy water (or kiddie-bubble mix).

If you would, please take a moment to review the Announcements at the top of the Forum, and be sure to provide the Required Info (serial number) when posting. Thanks!

[cebra]

The serial number is OD239534, I can't see anything on the page for Announcements. I did a pressure test and it held 10PSI for about 30 minutes, I left it on overnight and it had dropped to 8PSI by the morning. No bubbles when checking for leaks with soapy water. It had a fair amount of milky oil after only 3 trips out to not have a leak. I think I may try to submerge it and see if there are any bubbles. Is there an "oil port" o-ring that is supposed to be on the top of these lower units (hole near the water pump)? The schematic says no but some similar Mercury lower units do have this o-ring.

[cebra]

Found it:
1. OD239534
2. 1994 Ranger 372V
3. HiFive (pitch unknown)
4. Max RPM unknown
5. Idle WP = 5, Full Throttle = 15
6. Analog Instruments
7. Stock Engine

[JOE54]

that o ring is for mercruiser not outboard , i test um at 20 psi then pull a vacuum on it

[cebra]

Thanks Joe, I will up the pressure on it this evening and see if I get any air escaping. It is still sitting in the bathtub at the moment to see if there is water ingress.

[cebra]

I believe I have figured out the issue. I tested the pressure many times using the vent hole, I noticed at 20PSI I had bubbles coming from around the tester in the vent hole as I needed to tighten a bit and thought I should test the vent plug too. I moved the tester to the drain hole and it bubbled from the vent plug at 10PSI. I replaced the seals multiple times (I have black ones, light blue ones, and yellow ones) and still it bubbled. I put the original vent plug in as I had put in new ones and no bubbles. I checked with all the seals I had an no bubbles, tested the new plug again and bubbles started again. The only thing I can come up with is the new plug I purchased is defective (such as warped) and will not seal no matter how tight it is. Lesson learned, I will always test from both vent and drain holes.

[leonreno]

Always check the mating surface also, many times the old gasket will stick or partially stick to the aluminum housing and you won’t notice it but makes it hard for the new gasket to properly seal.

[JOE54]

I believe I have figured out the issue. I tested the pressure many times using the vent hole, I noticed at 20PSI I had bubbles coming from around the tester in the vent hole as I needed to tighten a bit and thought I should test the vent plug too. I moved the tester to the drain hole and it bubbled from the vent plug at 10PSI. I replaced the seals multiple times (I have black ones, light blue ones, and yellow ones) and still it bubbled. I put the original vent plug in as I had put in new ones and no bubbles. I checked with all the seals I had an no bubbles, tested the new plug again and bubbles started again. The only thing I can come up with is the new plug I purchased is defective (such as warped) and will not seal no matter how tight it is. Lesson learned, I will always test from both vent and drain holes.

always every point of contact with any seal

[EuropeanAM]

One other suggestion: DON'T exceed 14.5 psi on your gearcase when testing. Seal damage can result.