Sheared transmission bolt

G

Garrett12

Joined
Jun 14, 2022
Messages
6
Hello,

While tightening my transmission pan on my 2007 Hyundai Tucson, one of the last bolts to be tightened head snapped off. Because of how little pressure it took, I'm wondering if the bolt was compromised before. The RTV sealant I used had already been applied and had set for 1 hour before I torqued the bolts down to spec.

My question is two fold -

1. Will the missing bolt cause a leak or should the RTV make up for it?
2. Can I easy out the sheared bolt and replace it without having to take the entire pan off and reapplying RTV?

I've attached a picture for reference. This pan is bolted onto the front of the transmission in a vertical position. The bolt that's sheared has been circled.

Thank you for any input you have as I've got myself into a hole now.
s-l400~2.jpg
 
I had the same thing happen to me when reinstalling the AT oil pan on our 99 Buick Century. It barely took any torque to snap the bolt head off. I just made sure that the bolts on either side of the sheared one were properly torqued, and it has not leaked a drop in almost 3 years.
 
I'd watch it for any leakage. Probably won't leak if you did a good RTV application. I'm assuming it's a blind bolt hole. Not worth messing with IMO unless it leaks. If you can back out the broken off bolt without removing the pan, then you could certainly install a new bolt.
 
A few years back I had my rear end fluid changed on my truck. After I got the car home I could see where they had cleaned everything, and saw the fresh RTV around the back plate. I opened the fill plug, and clean, fresh rear end lube oozed out. I never checked the torque on any of the bolts.

A few months later I was washing the truck and I noticed one of the bolts had backed out several turns. So I torqued down, and checked all the others. (They were all fine).

Point being nothing ever leaked around the area of that 1 loose bolt. What I would do is buy a left hand twist drill set, and try drilling out the broken stud. Chances are it will come right out, because there is no torque against the threads. I've had many small broken bolts come out this way. You don't have to spend a fortune either. This is all you need.

Just make sure you center punch the broken stud in the center as close as possible. You don't have to worry about contaminating the fluid because if nothing is leaking out, then nothing is going to get in.

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Left Hand Drill Bit Set, 13 Piece

Amazing deals on this 13Pc Left-Hand Drill Bit Set at Harbor Freight. Quality tools & low prices.
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Time will tell if it leaks. If it were me, I would use an extractor to remove broken stud, retap and install a slightly larger SAE bolt. You must have over tightened or cross threaded. They usually break upon removal.
 
As it broke installing it the broken piece will come out easily, if it broke removing it due to corrosion you are in for a bigger repair.
Depending on how it broke determines how you should remove it, if it is flush with the pan tapping it with a small prick punch will probably get it moving. If not drop the pan, if the bolt is proud vise grips may grap it if not center punch it and use a quality left hand drill bit (not that cheap HF crap), chances are it will spin right out with no need to re-tap, helicoil or anything else just a new bolt.

You need a very small torque wrench for this, I never use one just a 1/4 drive ratchet and snug them up and use a real gasket if one is available instead of RTV. If it isn't leaking forget it and put some RTV over the broken bolt so it doesnt corrode (making it more difficult to remove) and get it next time.

 
Depending on bolt location on the case, some bolt holes go completely through the case. That hole can be drilled and enlarged slightly to allow a longer bolt to go through and backed up with a nut on the other side.
 
I know you fellows are pros and do these kind of jobs often but I've learned two things from my meager experience.
1) Aluminum cases are different than steel. It's as if they produce crystals which act as doorstops which jam bolts. As a result, I run a tap gingerly through the holes before running the bolts in. Overkill? It stops those harsh crunches!

2) It appears more cheap assembly line hardware is coming down the pike. Bolts in the header panel/radiator support of my car crumbled away as if made from graham crackers and those aren't the only examples.
 
Trav said:
As it broke installing it the broken piece will come out easily, if it broke removing it due to corrosion you are in for a bigger repair.
Depending on how it broke determines how you should remove it, if it is flush with the pan tapping it with a small prick punch will probably get it moving. If not drop the pan, if the bolt is proud vise grips may grap it if not center punch it and use a quality left hand drill bit (not that cheap HF crap), chances are it will spin right out with no need to re-tap, helicoil or anything else just a new bolt.

You need a very small torque wrench for this, I never use one just a 1/4 drive ratchet and snug them up and use a real gasket if one is available instead of RTV. If it isn't leaking forget it and put some RTV over the broken bolt so it doesnt corrode (making it more difficult to remove) and get it next time.

Click to expand...
I did use a 1/4 drive torque wrench set to the proper torque, something was just wrong with this bolt. Not sure what. Unfortunately I cant find a gasket for this vehicle so I used RTV. Thank you for the tips
 
Lubener said:
Depending on bolt location on the case, some bolt holes go completely through the case. That hole can be drilled and enlarged slightly to allow a longer bolt to go through and backed up with a nut on the other side.
Click to expand...
Dont believe it goes all the way through on this location unfortunately
 
ZeeOSix said:
I'd watch it for any leakage. Probably won't leak if you did a good RTV application. I'm assuming it's a blind bolt hole. Not worth messing with IMO unless it leaks. If you can back out the broken off bolt without removing the pan, then you could certainly install a new bolt.
Click to expand...
Its in a rough spot, but not completely blind. Ive had to take off a lot of items to get to it and am just worried I wont be able to see its performance after I reassemble (Battery blocks the view). Because its at the top right of the pan, I doubt it will be under pressure during operation (I think the fluid is sucked up into the transmission during operation?) but am worried about a cold leak. Thank you for the advice
 
chemman said:
I had the same thing happen to me when reinstalling the AT oil pan on our 99 Buick Century. It barely took any torque to snap the bolt head off. I just made sure that the bolts on either side of the sheared one were properly torqued, and it has not leaked a drop in almost 3 years.
Click to expand...
Good to know thank you.
 
Kira said:
2) It appears more cheap assembly line hardware is coming down the pike. Bolts in the header panel/radiator support of my car crumbled away as if made from graham crackers and those aren't the only examples.
Click to expand...
Some of this may be counterfeit fasteners that don't really meet the specs finding their way into the factory or desperation from lack of supply. Either way, it's happening.
 
I'd do what I had to do to get the bolt out and replaced. You'll always be wondering, is it leaking yet...?

I agree, the bolt should come right out.
 
1. Maybe leak... maybe not. You will find out soon enough.
2. I would extract the screw, clean that thread, and torque a new pan bolt in. Maybe it won't leak and all will be well.

When servicing transmissions, thread chaser with plenty of penetrating or tap oil, and then parts cleaner should always be considered. Some transmissions even require new pan bolts at each service. A good bolt inspection, brushing/cleaning, and even a die run would help find bad bolts, or at least reduce problems. Bolts do rust.
 
I would wait to see if it leaks. With the two surrounding bolts in place the sealer may be enough to seal it.
While I don't suggest trying it I have seen the leaks stopped by using a 3/8 drive extension and lightly tapping, using a
hammer/mallet the area where the bolt is absent. The mild bend in the rim of the pan might help if, in fact, there
is a leak.
 
Kira said:
Oh yes, but my car is a 2007 Volvo V70. This didn't happen with the two prior V70's.
Click to expand...
Even before I retired (2008) we were seeing issues with counterfeit fasteners from China in all kinds of supply chains. Many of them were actually fine to use but some were really dirtbag.
 
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