Pro-Max Lower Unit Problems Pro-Max Lower Unit Problems
Bass Fishing Home PageTM    Boats and Motors  


Boating Equip.
Tackle Shops
Fishing Acc.


Fishing Reports
BFHP Articles
Fishing News
Fishing Tactics
Places to Fish
Boat Ramp Stories
Other Topics
Other Fishing Topics
Swap/Sell (no boats)
Props 4 Sale

Boats 4 Sale
Saltwater Fishing
Striped Bass
Lure Making
OBX Wildlife Photos
More Politics

Boats and Motors

    Pro-Max Lower Unit Problems
from Bill (  
1/3/2002 9:57:00 AM


 Hi..Noticed lube on the floor when i walked around the engine....97 Pro-Max 225.Unscrewed drain plug and nada fluid...also noticed small hole just forward of the drain plug about 2 inches that appeared to be blown out...1/4 in dia.There were 2 of the holes...looked like stamped in ???One above the other.One was blown out, and the other OK.What are those holes, and how do you re-plug the one blown out??Assuming seals went bad, and need a seal kit??? TKS for your help...

Rate this message:
1 Star

2 Star

3 Star

4 Star

5 Star

   Is it a SM or a TM lower uni? from Basswipe  1/3/2002 10:15:00 AM
 Sounds like a TM lower unit, and sounds like the holes may be "weep" holes. But I'm not sure. I don't know much about TM units at all. My SM has a weep hole just forward of the upper drain hole that allows fliud to leak out in case of over filling, or pressure from foaming and stuff of that natue. If it's not leaking from the prop shaft seal, or anywhere else, I'd refill it, and run it once and check it again. Make sure the gears are rotating fine without any abnormal noise or binding of course. When did you last change the lower unit oil? Good luck

   You probably have a shift shaft seal problem from Bob (  1/3/2002 12:40:00 PM

I have a 2000 ProMax with the Sportmaster lower unit. I started to have oil coming out of a small hole just in front of the upper drain hole. When I removed the lower unit, I found that the shift shaft seal had popped out of were it was suppose to be pressed in. It is about a $10 part and a new one can be pressed in if done carefully.

I received a lot of incorrect information about what that weep hole is for. It is for water that can get down into a pocket in the upper part of the lower unit. The weep hole is to let the water out so it does not freeze.

I recommend that you remove the lower unit and check out the seals before you run your engine again. To me, if you are leaking lower unit oil, you have a problem. In taking mine apart it was obvious that there is no overflow in case of over filling or pressure from foaming.

Hope this helps.

   ok Bob from Basswipe  1/3/2002 1:50:00 PM
 Riddle me this Batman, when would oil ever come out of that hole if it's only purpose was for an overflow of water that is collected then?? I can tell you one thing, if one of your seals breaks on your drain plugs, you will get water and oil mixture to come from that hole. That means that somehow oil, water, or a mixture of both will make it's way from the gearcase, to the weephole. That does not come from a collection of water. Not trying to start a pissing contest, but I have never(not never, but not alot) had water come from my weep hole, butI have had oil come from it.

   oil leakage from champ (  1/3/2002 7:01:00 PM
 bill, anytime you have a gear oil leakage there is a problem. do not run motor utill you find the leak. i would recomend removing the unit from the motor, remove prop and waterpump housing upper only and pressure test the unit. this will show you your leak. it should hold 8 to 10 psi before you get air passing out the shift shaft seal. this seal is put in upside down to be able to relieve any xcess pressure in the unit under normal use.the unit has to purge off somehow.locate problem and replace faulty part. retest unit to be sure. install new impeller and refill with gear oil and reinstall on motor. if any doubt have a pro look at it. take it to a qualified tec. beter to spend a few bucks now instead of a lot later. you should be able to get a complete reseal job for $150-$200. good luck and happy boating. also to basswipe, the weep holes in the gear case are only for water to drain out. if there is gear oil coming out the upper drain in the shift shaft cavity you have a week shift seal.

   It's not always weak from Basswipe  1/3/2002 7:53:00 PM
 and I know several others who have had oil come out there too. But, if you say so. Learn something new everyday I guess.

   weep hole from fast_glass (  1/4/2002 2:53:00 PM

I am not sure I understand your question, but I will try to provide what information I know and hope that it helps.

The weep hole is a 1/16-diameter hole that is about 4 inches in front of the top lower unit oil fill hole.

The only way oil can get to the weep hole is by leaking past the shift shaft seal. To me, if oil is getting past the seal, the seal needs to be replaced.

With mine, the seal had completely popped out and I had water in the lower unit.

After replacing the seal, I have had no problems. The reason the seal may have failed was due to over filling the lower unit. I now fill until I get oil coming out of the top fill hole. Then I let the oil continue to drain out the top-hole unit it stops. Then I seal it up. Mercury Racing even suggested letting about an ounce drain out before sealing it up.

I have included my email address if you would like to continue talking about this issue.


   Weep hole from Basswipe  1/4/2002 4:02:00 PM
 Ok, I'll just tell you what I know. I read one time on here where someone had some oil coming out of thier weep hole, and a few explnations were given for this, one being the over filling one. One time after filling my lower unit, I had some dribbling out after my first run, but never after that. I know of someone who had a rubber seal go bad, and the white milky substance came out of the weep hole. This person refilled the lower unit, replaced the rubber seal, no problem after that. I just changed my lower unit oil and I had no water in it, so I assume my shift shaft seal is keeping water out. I just know what I've read basically, never discussed this with a dealer, or MERC rep. All I can think is that possibly when the lower unit has too much oil, or has pressure from foaming from water and oil mixing, maybe the fluid leaks past the seal, and the seal seals itself back up to a degree. I really don't know. But I'll keep all this info in mind, and keep a close eye on the old weep hole. Thanks guys

Now none of this has helped the guy with the origanl question. I hope he gets his situation cleared up. Maybe someone emailed him.



Can't remember your password? Click here!
Email Address:

Users with subscriptions can attach pictures to their comments by using the form at"




Advertising/Sponsor Information

Register to post messages and reports


Subscribers don't receive these ads

Fishing Reports
BFHP Articles
Fishing News
Upcoming Events
Rally Page
BFHP Surveys
Fishing Tactics
Places to Fish
Other Topics
Product Evaluations

Boat Ramp Stories
Trailers & Towing
Boats For Sale
Tournament Tactics
Striped Bass

Fly Fishing
Saltwater Fishing
Non-Fishing 2
Political Hook
Tall Tales, Fiction & Legend
Complete Listing of Boards
Copyright © WMI, Inc. 1995-2017. All rights reserved.
This message board created and maintained by: WebMasters International, Inc. (WMI) address mail to

WMI disclaimer
Privacy Statement