Sometimes you can overtighten things that aren't supposed to be overtightened... and then you have to fix it. Check out what we did so you don't make the same mistake!
So 2 weeks ago, I did my 4th drain and fill for my 2013 1.6L Eco SE...
When finishing up the process, I felt the level plug in the side of the transmission housing turn just a liiitttle bit too much, and my heart sank to my feet. I was using hardly any torque, even a tiny 1/4" socket driver with my hand at the ratchet for minimal leverage... it was still enough to cross thread and damage the aluminum as the level plug is steel...makes me wonder how many times it was cranked down before I bought it.
So 2 weeks ago, I did my 4th drain and fill for my 2013 1.6L Eco SE...
When finishing up the process, I felt the level plug in the side of the transmission housing turn just a liiitttle bit too much, and my heart sank to my feet. I was using hardly any torque, even a tiny 1/4" socket driver with my hand at the ratchet for minimal leverage... it was still enough to cross thread and damage the aluminum as the level plug is steel...
This left me thinking 3 big questions:
Did I destroy it completely? What does that mean? Even though it's just one hole, being able to remove this plug is vital to maintaining the vehicle at the proper service intervals, so just putting the plug back in with JB weld to be stuck in there forever is not an option... Also, talking in terms of "forever", our transmissions have a clamshell style aluminum housing with the main pieces stuck together and a "lifetime" trans fluid filter... which leads me to the next question:
How can I fix this without sending tons of metal chips into the transmission? Even though the trans housing is aluminum and the drivetrain is steel, and the high likelihood of 1 or 2 aluminum chips hurting the main gears is very low, these chips can still damage other areas of the transmissions such as oil pump inlets and outlets as well as sensors. We don't want foreign chips of ANYTHING in the transmission, so any means of thread repair should be done with the goal of metal chip management.
Should I try to fix this or have somebody else with more knowhow and precision for transmissions do the work???
I did research, browsed FordEscape.org, and talked to a few mechanic buddies of mine... in terms of the shops and dealers nearby, I was fairly underwhelmed by the trepidation to do the work... but I understood their responses:
Mechanic mom and pop shops are nervous to try and fix trans thread damage to risk a liability on the whole transmission housing.... they wouldn't touch it.
Machine shops would be able to handle it no problem, but they're not set up to do that kind of work- no car lifts, or anything like that...(guess they could use a fork lift lol)
Dealer said they wouldn't do it and they hire out machinists to come in and repair threads to our aluminum trans housings...they DID say they'd be happy to replace my transmission for me... not lying.
I then took it upon myself to do this repair for what I THOUGHT was a fully stripped hole as my plug was spinning in place for a good hot second...
I looked up the threading of the level plug and compared it to a thread gage.
Factory threading for our plug is M10x1.0
I write this in MASSIVE letters because... I couldn't find this thread info anywhere... This the threading at least for my '13 1.6L eco with the T30 torx socket head....my plug is to the left of the drive axle in the driver's wheelwell..
IF the thread is fully stripped out, the next option is to up size the thread, buy a new bolt for a plug, and add a rubber washer under the head.
The next FINE thread size up from M10x1.0 with a is a 7/16x20, which is obviously no longer metric, but standard. A 25/64 (0.391") drill bit will open up the hole just slightly to be the proper drill diameter for the 7/16x20 tap.
***NOTE: Drilling of any sort is of course a high speed tool and will likely send SOME chips into the trans housing, even if coated in grease. You MAY have decent luck with a 7/16-14, which is a coarse thread. The only risk here is less threads per inch of course, so perhaps more risk with backing out with vibration since the gasket will be a purchased/add-on item rather than the gasket attached to the underside of the OEM plug head.
Some notes for thread/ diameters assuming your M10x1.0 hole is stripped out:
M10x1.0 major diameter/ anticipated stripped hole diameter = 0.393" (....10mm)
7/16x14 COARSE THREAD drill diameter (hole to receive tap) = 0.368"
7/16x20 FINE THREAD drill diameter (hole to receive tap) = 0.391"
Finally, the last option would be to use a helicoil, but like everyone before in this thread says, that's a lot of material to remove to install the coil, so it would be up to you to be careful not to allow metal chips in the transmission as well as have good luck to find a good shop who could do it for you if you were uncomfortable. I had no such luck on any repair method in my local area as stated above :/
Link to machinist table of drill diameters and taps: Tap Drill Chart
Upon actually draining my trans fluid again and looking at the hole, it appears it's not completely stripped, but horribly cross threaded... kind of a hybrid. Since this is not under pressure and I'm just trying to seal the rubber gasket against the housing, I thought it safe to do a retap/ thread chase rather than try to drill and increase the thread size/ risk chips entering the trans... I of course used grease packed in the tap flutes just like @centex said here earlier. Worked great and went through a bunch of Q-tips and grease, but it was worth it.... really not as hard as I thought it would be- click the
it's not the best video I've done since it's recorded after I actually did most of the work, but I did my best to explain the content here and show how I threaded, removed, and regreased the tap.
Thanks and hope this is helpful to some!
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