Mercury Lower Unit Drain Plug Size & All The Details
The Mercury lower unit drain plug is located near the bottom on the engine’s side, and it’s a crucial outboard part. While purchasing this plug, there are plenty of factors to consider, like price, compatibility, brand, applications etc. But the drain plug size is the most crucial factor to consider.
However, the Mercury lower unit drain plug comes in 3/8 -16 size and is 0.25″ long. Drain plugs include the gasket or O-ring. During the lower unit’s oil changing, the mechanics recommend changing the O-rings or plug gaskets so that the drain plug remains in good condition for a long.
So, now in today’s article, we will cover the following aspects:
- Drain plug size details
- How does the drain plug work
- The use/advantages of drain plugs and
- When and how to replace the plug
So, let’s directly jump into the discussion now:
What Is the Mercury Lower Unit Drain Plug Size?
3/8 – 16 is the lower unit drain plug size. This plug is used in all the Mariner and Mercury outboards except the Verado series.
However, the proper seating of the lower unit drain plug depends on the seal significantly. Therefore you must use the seal. Also remember that, this plug screw’s version is non-magnetic.
How Does Mercury Lower Unit Drain Plug Work?
All Merc’s use the lower unit drain plug of 3/8 x 16 and the vent plug. On your lower unit, the use of the top plug is called the vent plug. You need to pump in the oil from the bottom plug as long as it doesn’t come to the top plug. Then tightly screw the top plug. Afterward, to minimize the oil loss, screw the bottom plug quickly.
What Does This Drain Plug Do? Is It Really Necessary?
This Mercury lower unit drain plug is mainly produced to meet the manufacturer specifications of Mercury Marine’s original equipment.
The lower drain plug’s non-magnetic screw version helps to prevent the leaking out of gear lube. Also, the plug prevents the gear case’s severe damage by preventing water from seeping into the gear. Furthermore, it helps to stop the boat part’s moistening and leaking. In short, the major purposes of a Mercury lower drain plug are:
- The plug lets the oil drain from the engine
- It keeps dust or foreign object away from entering the engine
- The lower drain plug helps to prolong the engine’s life
- It lets you change the oil quickly and easily
When To Replace The Mercury Lower Unit Drain Plug
The simple answer is every time you change the engine oil; you should replace the Mercury lower drain plug. However, along with this general rule of thumb, we strongly recommend you replace this plug when it becomes old, stripped, or worn out.
Over the years, due to the poorly fitting flathead screwdrivers, your oil drain plugs can get pretty ragged. Using the damaged or old drain plug increases the risk of leaking out of the gear lube and seeping the water into the gear case. Therefore you need to replace the drain plug to keep water out of your boat’s lower unit.
Firstly check the drain plug and make sure it is in good condition. If its condition is poor, we strongly recommend you replace it.
However, professional mechanics recommend changing the plug’s O-ring or oil plug gaskets also while changing the lower unit oil.
How To Replace The Lower Drain Plug on Mercury Outboard?
To replace the plug, follow the quick and simple steps below:
- First, detect the plug’s position and unscrew the plug itself
- The nuts hold the plug in place. So, loosen the nuts using the wrench.
- Once the nut becomes loose, now using your hand, you can remove the lower drain plug
- Finally install a new lower drain plug in place of the previous one.
Frequently Asked Questions (FAQs)
The lower unit on a boat makes up the outboard motor’s bottom-most part. It helps rotate the propeller shaft by using the outboard motor’s energy power.
The best lower unit drain plug gasket must be durable, good fit, and, most importantly it should, prevent leaks. Above all, make sure it fits your motor. Also, other considering features are installing and removing it should be easy.
Once the boat operates for one-hundred hours, you should change the lower unit oil in Mercury outboard. And this rule of changing oil is applicable for every 100 hours of running.
Wrap Up
Mercury lower unit drain plug helps to prevent the boat parts from leaking by sealing the boat hull’s bottom where the waterline meets. Therefore using the appropriate size plug is crucial. Optimistically, by going through our above comprehensive article, you now know the Mercury lower unit drain plug size and its other details.
However, you can comment to let us know your thoughts on the Mercury lower unit drain plug. Soon we will reach you.
You Can Also Read: