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Possibly overtightened/stripped transmission t70 drain bolt

('06-'08) 
9K views 25 replies 9 participants last post by  Rudyjr 
#1 ·
I was in over my head today doing my trans/diff fluid changes. I managed to get the jobs done making a ton of stupid mistakes along the way (I wasn't well rested and I was cracked out on coffee). When I was finished I checked the forums to double check some stuff and people warned against over tightening the drain bolt so I broke the bolt and used my cheap torque wrench to tighten it to 33 ft lbs except my wrench was acting up and not clicking so i kept tightening it until the resistance started becoming less and I got that sinking feeling. Did I strip the bolt? If so what should I do?

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#2 ·
Transmission or differential?

I've repaired a differential a workshop used an impact wrench on the drain plug and stripped the thread. I drained the oil, put the plug back in and filled with naptha ( to wash and remove the gear oil) After draining the naptha and letting everything drain out over a few hours, I installed the plug again with a good amount of RTV gasket maker. From what I know it's done 28000 miles since the repair with no dramas.
 
#3 ·
If you were using say a 0 to 250 ft lb torque wrench then it would be easy to miss the "click". If you were using a 0 to 50 ft lb (which is what you should use) there should be a noticeable click. I am kind of surprised you might have stripped the plug. It is a very beefy setup and I would guess you would need well over 100 ft lbs to strip it.

You have options:
1. Insure the plug is "tight" by using either a torque wrench or if you have a mechanics "feel" (sounds like you might not have that though.) ... If it doesn’t move say at 25 lbs you are good (for now). Put a mark on the plug and housing and verify it is not moving. Additionally you could put a bead of good glue around the plug and housing.

2. You could go with link's suggestion. I don't see the need to totally wash out the pan with naptha though. You could use the hard set black "Forma-a-Gasket. As a practical matter if you put in a good syn oil it won't need drained for years.

3. Replace the plug or housing.. Replacing the housing is not practical IMHO.

Hopefully a lesson learned for you. Housiong plugs (if they are not loose) will never come out on their own. Checking the torque was not necessary. But if you insisted..know what you are doing. (not slamming you). I am 66 years old and have wrenched my whole life. For me "If it ain't broke..don't fix it.
 
#4 ·
Thanks for the replies. To confirm, its the transmission. I was using a 10-150 ft lb wrench. I'm going to buy the 0-50 wrench and test it. I'm curious, would the bolt threads or the housing threads strip first? Or are both most likely stripped? (if I did actually strip something)

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#7 ·
Oh and adc, trust me, I can't get, "if it ain't broke, don't fix it" out of my head now
Yea.....we all need to learn this the hard way.....Don't feel bad...its part of life. And you probably missed the click. But like I said just take a wrench and snug it up by hand..if it doesn't move you have it made. You didn't try to loosen it right? If you over-tightened it..it shouldn't hurt anything because the threads are not tapered (ie it won't split the housing). If threads are shot it will be the housing...probably...

0 to 50 is an ideal size..and on that size..the 'click' on it at say 15 ft. lbs will be very slight also. So be careful with it at lower ranges. Its the nature of click type wrenches. That's why Dial types are good.
 
#8 ·
Thanks so much again for the replies. I'm deciding not to stress over it. We'll just see how the next fluid change goes and I'm going to have that done at a shop to get their opinion. I bought a 0-80 ft lbs torque wrench (that measures in inches its confusing) I set it to 25 ft lbs and the bolt didn't budge. I'm going to mark the bolt position with my paint marker when the car cools and just monitor it occasionally. Thanks for the suggestions and info guys. Y'all are great.
 
#9 ·
I set it to 25 ft lbs and the bolt didn't budge. .
You are good to go. I can almost promise you it won't come loose. Don't bother taking it in when it needs done. You can look at the threads yourself.. Besides the front differential is pretty easy on oil. If you changed it its good for a good long while. Personally I would have liked to have seen you get a 0-50 torque wrench. It might get you in trouble on spark plugs where the torque value is pretty low (12 ft lbs lubricated). and its still too low for wheel lugs.

I doubt the other numbers are inch pounds. They are probably Newton-meters (metric)
 
#11 ·
I got under the car recently and noticed a little blue bead of redline gear oil on the trans plug. It may be leftover leakage from my torn axle seal a month ago. Regardless, it got me wondering if it would be possible to repair the drain hole with a repair kit like Timesert. How much would this run at a machine shop?
 
#13 ·
Yeah I'm 90% sure I stripped the housing threads based on how it felt when I was turning the plug. The thing is, until I see a drips of gear oil on the garage floor, I'm not touching that plug. All my gear oil changes are going in and out through the filler neck from now on. (Unless the 6-speed is in my future)

I was looking up repairs for this type of situation and I came across this thing called a Timesert. Its a threaded bushing insert that threads and locks into the damaged hole and allows a new bolt to thread in. I would want a shop to do this as I'm not going to mess this up twice.

If anyone is familiar, would this be a cost effective solution?

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#16 ·
New insight/perspectives

I've been thinking. There are only 1 or 2 oil changes left in this transmission. I'm due for a change in the next 4,000 miles. I want to make sure the plug never twists loose on me. Gear oil is already dripping out of the plug. For those who don't know, my trans. drain plug was over tightened and beginning to strip.

For the next oil change or two I see a few options:

1. Sealing it with RTF then a few beads of JB Weld (or another recommendation?) to secure it (given that I can break the plug loose without damage for the 2nd oil change)

2. Just JB Welding the plug permanently shut now (given that JB weld or something else can permanently secure it) and doing all future oil changes with a pump through the filler tube.

Any suggestions?
 
#22 ·
I changed the trans oil today, It was the first time I had touched the drain plug since I stripped it (though other shops have drained through it since). The trans housing is definitely stripped. Funny thing is though, one of the shops used teflon on the plug without telling me about it. I was able to confirm with a torque wrench the last time I tightened it that it was at least 25ft/lbs tight. Today, I don't even think it's 15ft/lbs. The dishonesty of that shop ruined my day today. I guess I should start looking for a machine shop to fix this.
 
#24 ·
I'm still trying to figure out why torque wrenches are being used on drain plugs. :huh:
They are used just as much for making sure you don't jover-tighten as to insure there is sufficient torque to seal or rather stay in place.

, I don't even think it's 15ft/lbs. The dishonesty of that shop ruined my day today. I guess I should start looking for a machine shop to fix this.
One thing you could do is just put a very very small bit of JB on there to insure it doesn't come lose. You could go with the quick setup stuff...its not as strong. You will easily be able to break a small amount you put on there off when you remove the plug in the future.
 
#25 · (Edited)
There's another method you might wish to try. While the Timesert fix is an excellent and permanent fix, there are thread forming compounds that may be of use.

Loctite Form a Thread is what I have in mind, they're kits that can be used to restore threads. I know John Deere uses these in a lot of cases where a proper fix would be inordinately expensive. Or the cleanup of the gear case of all shavings a royal pain and expense. They used the product on a friends tractor where a bolt hole in the hydraulic housing stripped. Doing that with an insert would have meant draining the hydraulic case, flushing it and then refilling it. You're talking 25-30 gallons of hydraulic fluid there.

You seem to hint at a rather limited life expectancy for the tranny-or your keeping the car. That being the case, you might want to try the Form a Thread first. Check the Loctite website to make sure the stuff is oil proof. It would seem to be, but better to check first.
 
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