Stripped transmission drain plug

[cptnsolo77]

Hey all looking for some advice here. Long story short I stripped out the trans drain plug. I picked another one BUT the threads on the pan looked a bit worn so was EXTREMELY careful tightening it down. The plug did feel snug as if I had a good bite on the threads. Unfortunately it leaks a bit but its drivable and I can get to work. I dont want to risk stripping out the pan so I left it alone....and yes Im using a crush washer. Im going to give it another shot and try tightening it down again BUT in case I strip out the threads in the pan I want to be prepared for a possible repair so Im not stranded. I have one car and im basically preparing for the worst case scenario. Unfortunately I cannot find a oversized M10 plug and I looked high and low. I cant find a piggyback plug in M10 either. Looks like the next step is to tap to the next size up. My question :

Current bolt size is M10 X 1.5 Is the next size up M12 X 1.25 ?

I have never tapped a new thread before but Im confident I can do it. Will I need to drill out a larger hole for the next size up or can I just run the tap through for the new threads going from M10 to M12 ? Im worried about shavings in the pan so if I dont have to drill....I wont. Thanks in advance !!!

 

[Vitamin Yoda]

Is the pan replaceable?

 

[cptnsolo77]

Is the pan replaceable?

Yes it is.

 

[Kira]

1) new pan
2) I've heard that some pans have deeper threads such that if you strip out the threads 20mm in, the tapped hole has threads continuing to, say, 30mm. All you'd need was a longer drain plug or bolt. When the fast-lube goons stripped my neighbor's Honda oil pan I found this "advice". Alas, even the best 'nut 'n bolt' source I have didn't have long ones.
3) Try Permatex Ultra Black sealer. It worked on a stripped oil pan a Fumoto had a weak grip on.

 

[racer12306]

When tapping a hole, you need to start with the right size hole. Unless you have a tap that has a drill on the end of it (honestly not sure if that's a thing), you need to drill the hole with the tap drill size and then cut the threads. Taps only cut threads, not holes.

I believe the correct tap drill for a M12x1.25 is 10.8mm (but this can also vary depending on what kind of material your cutting into). Once you have a 10.8mm hole, you run your tap through.

There are sources online for determining the correct tap drill size for what your doing. Almost all of these are considering that the hole will be a load bearing hole and this certainly isn't, so you probably don't have to be as exact.

 

[Vitamin Yoda]

Yes it is.

I'd replace it then. You might spend more time and resources trying to fix the broken one than it's worth.

 

[Astro14]

What make/model car is this?

 

[JavierH19]

How hard is it to remove the pan? my first instinct would be to replace it instead of tapping it.

 

[zzyzzx]

3) Try Permatex Ultra Black sealer. It worked on a stripped oil pan a Fumoto had a weak grip on.

This would be my first choice, even if only used as a temporary fix if I only had one vehicle.

 

[Astro14]

Three options:
1. Helicoil
2. Time-sert
3. New pan

There is no goop that takes the place of threads. The above three offer a proper repair.

Of those three, helicoil offers the lowest cost. About $20. Get a new drain plug, so the threads are clean, and undamaged. Get a proper sized helicoil, use a bit of grease on the drill and the tap to capture the chips. Go slow, keep it square.

 

[cptnsolo77]

What make/model car is this?

03 Pontiac vibe. Same as Toyota Corolla and matrix.

 

[Astro14]

03 Pontiac vibe. Same as Toyota Corolla and matrix.

In that case, I would pull the pan, do the helicoil on the bench, just to ensure the pan is clean and no chips enter the transmission.

A helicoil is a permanent, proper, repair, and will last the life of the vehicle, while allowing you to remove the plug/drain the fluid again.

 

[D60]

Three options:
1. Helicoil
2. Time-sert
3. New pan

There is no goop that takes the place of threads. The above three offer a proper repair.

Of those three, helicoil offers the lowest cost. About $20. Get a new drain plug, so the threads are clean, and undamaged. Get a proper sized helicoil, use a bit of grease on the drill and the tap to capture the chips. Go slow, keep it square.

Was it TTC's (??) thread repair test which also used JB Weld might say otherwise. That said, I probably wouldn't use JB Weld on a trans pan -- if for no other reason it's not really meant for the fastener to be repeatedly removed

 

[Soft Cars]

Self tapping drain plug at NAPA

Dorman 090-192

 

[D60]

{snip}

I have never tapped a new thread before but Im confident I can do it. Will I need to drill out a larger hole for the next size up or can I just run the tap through for the new threads going from M10 to M12 ? Im worried about shavings in the pan so if I dont have to drill....I wont. Thanks in advance !!!

A 7/16-20 calls out almost exactly a 10mm drill size.

A coarse thread M12 calls out basically the same at ~.401"

A fine thread calls out .425" but if the depth of tapped area is minimal-- such as most trans pans -- the tap will probably feed through fine.

Bottom line, you probably don't need to drill but it might be wise to drill ~27/64. Be VERY careful if using a twist drill on the car as a 2-flute drill will feed in and hit your valve body.

Don't necessarily expect a hand tap to cut straight through. Go until moderate resistance, back out to break the chip, and repeat. Fortunately an M12 or 7/16 is strong enough to be relatively durable. I've hand tapped #2-56 on model engines and that's a gamble

 

[widman]

When they changed my transmission oil in Bolivia before shipping my Corvair to me, they tightened the cast iron fill plug so much into the aluminum transmission case that when it got here it did not go into third gear, as the plug was hitting it. After pulling the power pack and discovering this, I put gasket shellac on the male and female threads and inserted the plug to a normal position, watching the inside of the transmission and testing the shift. After letting it set up, I filled the transmission from the top, put the cover on, and reassembled everything.

So depending on how snug the plug is, this might be a solution. But there's have offered several good solutions.

 

[Urshurak776]

At work, we have a 19XR Compressor (Carrier HVAC Centrifugal chiller.) The transmission bolts up to the compressor casing with two 3/4" capscrews. Then, the overhung motor and stator assembly bolts up over the top of that to make a strong assembly, but until the stator/rotor assembly bolts up, it's a lot of weight on those two capscrews....

It's only used in my training classes, and one of the holes stripped out. Used a heli-coil to repair (never done one before either.) Went well and has held up over the last 4 years of repeated assembly and dissassembly.

Should work great for you!

 

[The Critic]

Three options:
1. Helicoil
2. Time-sert
3. New pan

There is no goop that takes the place of threads. The above three offer a proper repair.

Of those three, helicoil offers the lowest cost. About $20. Get a new drain plug, so the threads are clean, and undamaged. Get a proper sized helicoil, use a bit of grease on the drill and the tap to capture the chips. Go slow, keep it square.

Only #3 is an option. Like many steel oil pans, there is a welded nut on the interior of the pan. Generally speaking, you cannot enlarge those holes to install a thread insert - there just isn't enough material to support a thread insert. Thread inserts are best reserved for aluminum pans.

Timesert does make two kits that are specific to metal oil pans (#0765 and #1485), but neither are applicable to this application.

 

[KrisZ]

Over sized plug would be my choice, next would be a teflon tape. It's a 20 year old beater and that drain bolt is not used often. OP will probably never have to touch it again.

People were truly trained not to repair anymore. It's just replace.

 

[BHopkins]

It looks like a new transmission pan can be had for under $30. A new gasket is about $10 - $12. As @Astro14 says, a Helicoil kit can be picked up for half that, and it will have everything you need, including several Helicoils. If you have experience with installing a Helicoil, it isn't hard. But if this would be your first time, you may likely mess up your first one or two. No big deal. You just pull it out and insert a new one.