Torque Master Lower Unit Blockoff Plug Install W/Pics

[Yellow Jacket]

I was considering plugging a few of the top water intake holes on a Torque Master Gear Case. Is this recommended and what is the correct way of doing this?

[EuropeanAM]

On gearcases THAT INCLUDE LOW WATER PICKUPS, strictly for the purposes of preventing air introduction (in cases of high engine mounting height), yes.

UP TO four (upper) holes can be plugged. Two or three on each side is usually sufficient.

Utilize 1/16 x 27 NPT Stainless Steel Pipe plugs (allen head). Tap holes, install plugs with RED loctite, until flush with case. Be sure to clean any metal debris from water intake passages... you don't want aluminum filings in your water pump, block, thermostats, etc.

[Yellow Jacket]

Are those plugs 5/16-27?

[EuropeanAM]

NEGATIVE! They are 1/16" x 27 NPT (National Pipe Thread).

Available from Merc Dealers, or you can "order" them in bulk from some local hardware stores (this is how we keep them).

[Largemouthlou]

could ya post a pic of one when ya get a chance??

[EuropeanAM]

Here ya go..........



1/16" x 27 NPT Pipe tap included in the picture (this is the one I actually use in the shop). Keep in mind: this is a "NPT Size Plug" (National Pipe Thread, with a "tapered thread" to ensure a good seal). These sizes refer to the "inside diameter" of the pipe they are usually utilized with... and NOT the "outside diameter" of the threads. Hence (as I was recently asked), it indeed "sounds" like you are drilling a hole that's too large... but you're not as the actual outside diameter of the plug is NOT 1/16" (it's closer to 5/16" OD).

Holes should be "pre-drilled" to 17/64" prior to tapping them out.

Install plugs with red loctite until perfectly flush with trailing edge of the case. The plugs we use have a "slightly beveled" head on them... they seem to be "less prone" to cause gearcase blowout than a "blunt" plug.

[cowtrimmer]

Put some grease on your drill and tap and the filings will stick right to it.

[Yellow Jacket]

Don, thanks for your response on the correct way to install the plugs in the LU I want to buy the plugs from you. Should I just call your Parts Department?

[EuropeanAM]

Call or email. Email is listed in profile... click on "EuropeanAM" to the left of this post.

[Yellow Jacket]

I sent an email to your Parts Department
Thanks Again

[Largemouthlou]

Thanks Don!!

[Yellow Jacket]

Parts are ordered.
Thanks
Rich

[Eagle670]

If you dont want to ruin your paint/ corrosion protection u / can use BIG poprivet , i does it on my 3.0L EFI i had , and i find it was the simpliest way

Just my 2 cent

[Yellow Jacket]

It's been about three months and 20 fishing days since I plugged the top three holes of the 2005 225 ProXS Torque Master. I was able to raise the motor another 1/4" and gain a little speed and handling. The most noticeable improvement is maintaining good water pressure and engine temperature especially in turns.

[FishinMcNut]

I finally got around to installing the LU plugs I bought from Don. It is a very easy DIY that sounds more complicated than it actually is. The biggest challenge was finding a 1/16" NPT tap. Once it was located I picked up a pkg of red high-strength thread locker and a 17/64" drill bit.

Supplies:


First step was drill the top four holes (max recommended by Merc) with the 17/64" bit. I used a strong shop vac with the hose inlet just below the hole I was drilling (or, tapping) to keep the shavings from getting in the water passage area. Make sure to drill straight in, not at an angle. The bit does not remove much. I used very low drill speed with minimal pressure.

Holes drilled:


Next step was tapping the holes with a 1/16" NPT tap. Again, I kept the shop vac inlet positioned just below the hole I was tapping to keep it all clean. Make sure you tap all the way in until all of the tap threads have touched the LU. Otherwise, the plugs might not go in all the way (voice of experience).

Showing the tap at the correct depth:


Next step is to apply the red thread locker to one plug at a time and install it until the head is even with the LU surface to the rear (away from boat). This will keep the plugs from causing turbulence in front of the prop.

Installed:


Total time was less than an hour. Can't wait to see the difference it makes with my hydraulic jackplate raised over 4".

I have my fingers crossed that Don does not point out any errors with my install.

[Hardhead1]

nice job. looks like the drill bit got away from you a time or two.

[FishinMcNut]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hardhead1 &raquo;</TD></TR><TR><TD CLASS="quote">nice job. looks like the drill bit got away from you a time or two. </TD></TR></TABLE>
That was marring from the shop vac hose fitting rubbing on it. It cleaned off...

[EuropeanAM]

Nice job, Kevin! Thanks for contributing pictures... I've combined your thread with another, and pinned it to the top of the forum for future reference!.

[Yellow Jacket]

Good Job

[jaystein21x]

Can anyone say for sure at what point below the pad should the top water inlet holes be plugged? Thanks