Help with busted transmission oil pan bolts?

Bought my TRD Tundra used. Last owner probably doesn't washes it after driving during winter and 5 of the transmission oil pan bolt busted off due to rust when I attempt to remove the bold to do a transmission oil/filter change. When I was able to get the pan off, I notice it doesn't have the straw/level check tube. I wonder if whoever serviced the truck before me even got it accurate because now, I feel like the shifter doesn't want to engaged to D normally.

 

This is a common problem and it’s why conventional wisdom of The forum is to leave the pan and the “filter” alone.

In addition most people on here have adopted the “drain and fill method”. They drain out what they can and put that amount back into the trans, a few times over a few miles, allowing the new fluid to mix with the old and thereby diluting the old fluid with new fluid effectively creating a change in the fluid.

 

I should have followed what the wise man do but if I do, I would have under filled my transmission because after I got the pan out, I don't see the overflow tube in the pan. But the disaster now is, when I attempted to weld a nut to the stud, it still didn't give up so I grind it down and drilled through. I used a bolt extractor and the corner of the transmission that holds the bolt broke off. Now I have another issue to deal with. I guess I'm going to have to try the aluminum welding rod to attach the two piece together and hope for the best.

 

oooh man I feel you there... I broke 2 off... Lived in Cali most of it's like with some treks to Oklahoma at the end of the winter season and Reno, NV for a full year and snow season cycle. Just to give you some context.. The back 2 corner bolts are seized in there, I tried extracting it via a nut and forcing it out and all it did was snap whatever was in and above what was left. I left it at that, and the rest of the bolts hold the pan up and gasket makes good contact with the transmission... I've dropped this pan twice and I've replaced bolts twice with anti-seize coatings.. I hope I never have to drop this pan ever again, but if I do, I'm replacing the bolts once again.

 

My guess is, the person who owned it before me take it to a service station and they never replaced the pan filter. Currently has 187K and that's why I decided to replace the filter. I did notice that the bolt head is rusty but didn't think it would be that bad. I guess he never washed his truck after driving during the winter. Lucky you, you only broke two. I believe I broke at least 5 lol

 

I watched some videos and they were able to do it that's why I decided to give it a try. I bust the corner off when I drilled a hole through the old bolt and used a bolt extractor. I think it might be ok without that corner bolt but I feel better if I can do the aluminum weld stick with a torch to help hold the bolt. Ordered some thread repair inserts for the rest.

 

Yes. Not but, but just a bit to where I need to weld it back on in order to put a new thread insert on to keep pressure on that side.

 

I went through this a couple weeks ago. Few options, assuming welding a nut on doesn't work. For the outside bolts that go all the way through, just drill it out oversized so it's a through hole and get a longer bolt with a nut. This is actually superior imo since the bolt can't seize up, and you get increased strength due to the steel nut. For the bolts that snapped into a blind hole (front and rear ones) just drill and tap them, if you're forced to oversize the drill bit then helicoil them.

 

The "filter" really isn't a filter, it's a 'screen' at best; which is why most of us don't mess w/replacing them...

I believe the biggest issue with why these bolts often snap is due to the use of dissimilar metals between the bolts and what they are being threaded into. This essentially makes it very easy for galvanic corrosion to occur by simply adding an electrolyte (road salt).