1987 50 hp lower unit oozing gear oil from mystery hole

I recently bought a jon boat that came with this motor (507F7C). I will be selling the motor, as it is too large for the 14 ft boat. It runs very well and has compression of 132 on the top and 126 on the bottom. I changed the foot grease, installed a new impeller, and added a tell tale. I ran it in my barrel for 10 minutes or so before taking the boat to the lake for its maiden voyage. When I got to the ramp and was preparing the boat for launch, I noticed gear oil seeping out of the hole in the pictures below. There are 3 pictures which get progressively closer to the hole. It is located about 2 or 3 inches above the pointy part of the gearcase, then to the left an inch or two. I had bought the Clymer manual, but the lower unit in the manual is not exactly like my lower unit. Either the manual is wrong or a different lower has been put on this motor. The hole was machined, but I can't tell if it's threaded. So, my questions are:

1. Is there supposed to be something threaded into this hole, and if so, why is it here?
2. If there is no factory plug for it, could I fill it with JB Weld?

When I changed the gear oil, there was some water in there unfortunately. I know this hole will let water in if it's letting gear oil out, so I need suggestions on how to handle this. I can't, in good conscience, sell this motor to someone knowing that the lower unit has an issue that will lead to a catastrophic failure.

Thanks,

Bob B.

That is a drain hole for water.----Meant to prevent freezing of the casting in cold / freezing weather.----Do not plug it.----Install a seal kit on the gearcase.

racerone said:

That is a drain hole for water.----Meant to prevent freezing of the casting in cold / freezing weather.----Do not plug it.----Install a seal kit on the gearcase.

Click to expand...

Thank you, that makes sense. I forgot to mention that I did install a new top seal when I did the impeller. So the seal you're referencing must be past the bearing carrier? Sounds like a big job?

Resealing a gearcase is not considered to be a big job here.

The leak??? could be the seal around the drain/fill screws???

Do a pressure test and find the leak.

The reason your lower doesn't look like the one in the
parts diagrams??? It's not, it's from a much older unit.
The only difference is the old one came with a pointed
gear housing. Not a problem.

Do the pressure test, change the seals that leak and run it.
The drain hole: it's beacuse the older units actually
dumped unburned gas/oil right into the water.
The motor still has unburned gas/oil just not as much.
Every time you tilt the motor forward the carb dribbles a bit
of gas into the cover and it drains down and out the drain
holes, normal.

Jerryjerry05 said:

The leak??? could be the seal around the drain/fill screws???

Do a pressure test and find the leak.

The reason your lower doesn't look like the one in the
parts diagrams??? It's not, it's from a much older unit.
The only difference is the old one came with a pointed
gear housing. Not a problem.

Do the pressure test, change the seals that leak and run it.
The drain hole: it's beacuse the older units actually
dumped unburned gas/oil right into the water.
The motor still has unburned gas/oil just not as much.
Every time you tilt the motor forward the carb dribbles a bit
of gas into the cover and it drains down and out the drain
holes, normal.

Click to expand...

Thank you Jerryjerry05. You are a pro. I bought a seal kit when I bought the impeller, and I changed the drain/fill screw seals, and the one under the impeller (the easy ones to get to). So the bad seal must be further in. I guess the only question I have now is where to find a cheap puller for the bearing cage? Does Harbor Freight make one that will work? I don't want to buy expensive tools for a motor I'll be selling. The other option is to pull the LU off and take it to a mechanic, which might actually be the best option. Thanks again for your thorough and thoughtful response.

Shouldn't be real hard getting the carrier out.

Harbor Freight tools:
About the only thing I've found any good from
Harbor Freight is the battery load tester I got from them.
Their compression tester gives real poor results.

Was selling a 2002 225 EFI Mercury.
The customer brings his NEW tester from HF
The add said 150# all 6 cyl.

He starts testing and gets 80# 90# 80# 50# 80# 80#

I say wait 1 minute, get my GOOD tester and show him
his is a piece of crud.
150 across all 6

Jerryjerry05 said:

Shouldn't be real hard getting the carrier out.

Harbor Freight tools:
About the only thing I've found any good from
Harbor Freight is the battery load tester I got from them.
Their compression tester gives real poor results.

Was selling a 2002 225 EFI Mercury.
The customer brings his NEW tester from HF
The add said 150# all 6 cyl.

He starts testing and gets 80# 90# 80# 50# 80# 80#

I say wait 1 minute, get my GOOD tester and show him
his is a piece of crud.
150 across all 6

Click to expand...

Hi Jerry, I agree. There are very few things that I would buy from HF, but sometimes they have things that work if you don't use them too much. Ironically, I also had a bad experience with a Harbor Freight compression tester, except that it was reading about 20# low. I took it back and bought a good compression tester. Then, I rented one from autozone to make sure my new was was calibrated correctly.

I think I'm going to try to rig something up to a harmonic balancer puller. By the way, after getting your first response, I was able to determine that my lower is from a 1974 ish Chrysler 50hp. That helped a lot, but I can't find a parts diagram for the one I have. I should be able to stumble through it from here. I am very appreciative that there are guys like you out there, who give their time and expertise when there is absolutely no possibility of personal gain. Regards, Bob

This mean your not gonna send me a check???

I enjoy helping, I too use these forums for repairs
on other brands of outboards and Chrysler/Force
I have a local traveling repair business and these forums
really come in handy.

Compression tester: Yea HF sucks and the one from AZ isn't
much better.
I spent 160$ in 1987 for my tester.
Still works great.
Bought a tester for diesel motors, Snap On 50$ ebay.
Guy said it works GREAT!! NOPE!!
His pants are still a burnin
Managed to fix it with an o-ring.