My Transmission Pan Adventure

I thought I would be proactive and change out my transmission pan bolts. Knowing that they typically get corroded and snap off when removing them if you live where they salt the roads. My truck only has 33,950 miles on it so I figured they shouldn't be too bad yet and I could take one out at a time and replace them. I did just that and cleaned them up with WD40 and put them back in until I could get some stainless ones to replace them with. The last one I tried to get off snapped. At that point I was kicking myself because i said I would always just do drain and fills and never drop the pan because I didn't want to snap a bolt but decided maybe I should atleast replace them incase I do want to drop the pan at some point.

Now I had to drop the pan to get the broken bolt out. What happens is the gasket for the pan is so thick that it leaves a good portion the threads exposed to any water that can get in there. I figured if I'm going to drop the pan I may as well replace the gasket, filter, clean the magnets, replace all the bolts and apply some anti-seize to them. I screwed up and ordered the filter for 1st gen Tundras part #3533034010. It looks identical to the correct part #3533060070 besides that the uptake hole has a piece of plastic over it making it half the size on the 2nd gen and the intake spout is longer on the 2nd gen. The 2nd gen filter is also about $30 cheaper than the 1st gen, both are made in Japan. Also might as well replace the filter O-ring while your at it part #9030131014. Oh and the gasket part # is 3516834020.


These are the the stainless bolts and washers I ordered from Amazon with the OEM bolts.
M6-1.0 x 25mm Socket Head Cap...

$9 M6-1.0 x 25mm Socket Head Cap Screws Metric, Allen Socket Drive, Stainless Steel 18-8 (304), Full Thread, Bright Finish, Machine Thread, 20 PCS

https://www.amazon.com/dp/B07D9P9KKH?ref=ppx_pop_mob_ap_share
X AUTOHAUX M6 x 10mm x 0.8mm... https://www.amazon.com/dp/B082Y676MW?ref=ppx_pop_mob_ap_share

After dropping the pan, I noticed not only is the bolt stuck but the metal piece from the gasket is also corroded onto the bolt. That came off pretty easily though. After that it was a couple hours of PB Blaster and a torch. Luckily was able to get it out without any damage to the threads. Heat was definitely a key factor in getting it free, my little Snap-On butane torch is awesome for this.


After celebrating my victory of getting the bolt out I replaced the filter which a decent amount of fluid comes out of when you drop it, so be prepared with the catch pan. There was some metal sludge on the magnets that I cleaned off. I also opened up the filter which kind if works similar to a vacuum bag. Its a fiber pocket that the fluid goes into and anything gets stuck in it and allows fluid to pass through. I had some small debris in it, little metal flakes and a small piece of the red sealant thats used between the tranny.


Got everything mounted up and replaced. The new bolts look like they belong there. What is nice about dropping the pan over doing a drain and fill is you get a little over 6qts out versus 4qts. If your truck is very new then maybe you can get away with swapping out the bolts no problem. Also if you live where they dont salt, you probably won't have an issue either. All said and done, I'm glad I did it but obviously bit off more than I wanted.

 

Excellent. Thanks for posting.
Did you use a screw extractor or vice grips and heat to remove broken bolt ??

 

Nice write up. Thanks for the details!

 

Thanks for the write up and pictures @Joe333x

I saved this thread and maybe this is a winter project I take on. I don’t live in salt state, but have nearly identical mileage and year truck.

 

Nice write up. I had to replace the pan on my 2002 and it was a long tedious job. Scraping off the old FIPG took forever. Even at 170,000 miles I didn't find any big debris in my old filter other than the normal stuff. Made me hopeful my transmission will last a while longer.

 

Seriously, I was happy everything was going smooth, every bolt came out rather easy, all the bolts on the sides you can hit with PB Blaster from the top and bottom but the end bolts the top threads are not exposed and thats surprisingly where the most corrosion was and the one that snapped.

Vice grips, trick was to get them as tight and as far down into the teeth as possible with out touching the transmission. I really took my time to make sure I didn't allow the vice grips to spin on the bolt and take away anymore of the bolt material. Once I did get it locked on good enough I also didn't want to turn it too hard and snap the rest off since I seen that happen in some videos as well. This went on for a couple hours just heating it up, spraying it and trying until finally it turned.

Hopefully you'll be okay, I've seen guys post with 60,000 miles say theirs came out with no issues since they don't live where it snows.

Luckily no FIPG on these ones, just the big thick rubber gasket.

 

Nice post!

Now all you need is a new stainless drain bolt to match!

 

Lol yeah the drain and check bolt look like crap on the outside bit the threads are all perfect on the inside. I might replace them next drain and fill though.

 

Thanks for the great write up!

 

Everything is good except for one thing, your bolts. I would put back the OEM bots, especially if you live with salt on your roads. Aluminum and SS do not mix at all, even with anti-seize. There is a reason why outboard manuf use the same types of metal from you trans pan bolts on the outboard. I also happen to work in a water and sewer treatment plant next to the ocean. We use a LOT of anti-seize and I can tell you no amount of anti-seize will ever keep the aluminum from corrosion when in contact with SS. Eventually the SS bolts will start to corrode your trans.

 

These hits are back to back, seems like google is arguing with it's self on this question:

Can I use stainless steel bolts in aluminum?

https://www.google.com/search?q=sta...0i22i30l7.11260j0j15&sourceid=chrome&ie=UTF-8


While many people worry that stainless steel fasteners, such as screws, bolts, nuts, or host of other options, won't work with aluminum due to the risk of galvanic corrosion between the two very different metals, the truth is that stainless steel is the metal of choice for fasteners to secure your aluminum materials.Jun 3, 2021

What Type of Fastener is Best for Aluminum? - Brikksen!
https://www.brikksen.com › home › page › blog › p=wha...

Search for: Can I use stainless steel bolts in aluminum?




If you have an aluminium engine block and use stainless steel bolts, your engine could be at risk of bimetallic corrosion. The aluminum will be the anode and the stainless steel bolt the cathode. This will result in corrosion between the two materials especially in a marine environment.Jun 10, 2020

 

Nowadays I wouldn’t doubt that not even google can make up its mind, lol. I have had my fair share of galvanic corrosion on my aluminum trailers with SS hardware and on SS hardware on aluminum T-Tops and other aluminum parts on my boats. Personally, I wouldn’t use SS bolts on the trans pan, especially since they salt the roads where he is at. It just speeds up the process. Better off dealing with a broken bolt than with a corroded bolt hole that will most likely pit the gasket surface and have to tap a larger bolt in the future. It’s not to say it’s going to happen quickly or he might not even own the truck by the time it happens, who knows. Just sharing friendly advice for future reference.

 

I'm in Az, no salt. I have had the filter, gasket & Amsoil transmission fluid for a year. I have done 2 flush & fills and will be pulling the pan in October or November when it cools off and will r&r the filter & fluid, I just ordered these bolts & washers.

 

The OEM bolts are steel, not aluminum. The corrosion doesnt happen on the threads in the transmission, as you can see from the photo, the bolts corrode on the threads that are in-between the gasket.

 

Yes, it rust between the pan and gasket because it’s exposed to the elements more than the threaded part of the bolt. The OEM bolts come with a zinc coating, that’s why they are grey looking. Zinc and aluminum don’t react much to each other. Now SS and aluminum are totally different metals and the weaker one will always give way, being the aluminum. The galvanic corrosion will start as soon as the two metals contact. Like I said, take it as friendly advice. I have dealt with many, many SS bolts to aluminum parts living here in Miami and salt water. The SS will always win. Me personally, I prefer to deal with a broken bolt than with a corroded trans housing. It’s the lesser of two evils. And by the way, don’t think that because the bolt doesn’t break doesn’t mean that the bolt won’t get welded in, sorta speaking, to the trans threads.

 

I appreciate your concern I'm guessing you've never dealt with getting a broken bolt out of the transmission. I am going to do an experiment with some aluminum foil wrapped around an OEM trans bolt and one of these stainless steel ones coated with anti-seize and soak them with some corrosion solution and I will post the results in this thread. If the aluminum foil rusts onto the stainless steel worse than the oem does, then i will purchase new OEM bolts instead.

 

I am 47, been working on engines since god knows when. I am still a mechanic by trade, not automotive but industrial. I have dealt with just about everything imaginable. I have been dealing with SS and aluminum since my first dirt bike at age 10 and then the real issue when I started getting into jet skis and boats. So yes I have dealt with a few broken 10mm bolts. What solution do you plan to use, Nitric, Muriatic or Sulfuric? Each one of these can dissolve one of the 3 metals with out dissolving the other.

 

I'm referring to getting a broken one out a Tundra transmission while laying underneath the truck with just a nub to grab onto. Im going to use vinegar, salt and hydrogen peroxide. Which I already tested one of the stainless bolt vs a non stainless with before using these and the non stainless corroded and the stainless one did not. I wont being using any of the acids you mentioned since none of those resemble salted roads. A boat engine running in salt water exposed to a lot more salt than a vehicle in the winter. I also hose done my undercarriage frequently.

 

I'm almost scared to R&R the transmission bolts. Do not want to have to deal with a snapped bolt. I guess it's a deal with it now or deal with it later situation. Makes me wonder what other bolts I should remove now and put never seize on??

 

Yes, I have plenty of on my back experience wrenching on cars. I actually have had 1 bolt break on 1 of the 4 tundras I have owned while doing a valve body removal for modification. You think removing a broken bolt upside down is hard, try installing a valve body back, while on your back, by yourself. And obviously a metal bolt will rust over a SS bolt, buts that's not the issue I was referring too though.

 

Just depends where you live. If its a state that has vehicle rusting issues then I would do it. But in reality, these trucks don't need the pan to be messed with. If you just do regular trans oil changes there is no need to open up the trans pan. If it makes you sleep better at night, like me, do it. I just don't worry about it because there are no rust issue here S. Florida. If it brakes, depending on the amount of bolt let behind, its a simple vise grip and turn deal. If not, a left hand drill bit will work just as easy. Its a small bolt that is torque down very little, doesn't take much to get it out. And heat is always your friend.

 

Thanks, yeah I may do it just to calm the OCD down. I do plan to do regular drain and flushes. They do salt the roads where I currently live but it's few and far between.

 

And to answer your other question about anti-sieze, well since they salt your roads I wouldn't worry to much unless you want to remove every bolt and coat it. LOL I feel for you guys that have to deal with corrosion on your vehicles.

 

Yeah could go down a crazy rabbit hole here for sure.

 

What is the issue you are trying to scare people away from using stainless steel bolts then if it's not corrosion? I said I'd use aluminum foil to see if the aluminum would corrode onto stainless steel since it seemed like that's what you were referring would happen. I just did a quick little search and it doesn't really seem like it's going to be an issue, but I will do the experiment anyways to see what happens. Funny enough they make anti-seize with aluminum and it's safe for use on stainless steel...

https://www.garagejournal.com/forum/threads/stainless-bolts-in-aluminum.126549/

 

So on another note here, what did you use to fill the tranny with fluid, and transmission temperature ??

 

Its friendly and actual experience advice. Do with it as you please. It’s not to scare anyone. Just like lift spacers onto top of OEM coilovers can collapse the coil over and has happened doesn’t mean people don’t do it and still add them. If people didn’t give past experience with stuff they have done we would all be guessing and hoping for the best. Since your googling, go ahead and google pics of aluminum to SS galvanic corrosion and tell that’s not a concern.

 

Drivers side there is a 24mm plug. Run a hose from the engine bay to the hole and fill that way. Easiest way I have found to do it. Trans temp is around 99-113 if I am not mistaken. Lots of thread about it. Best to have scanner for the temp as it is also the easiest way to tell.

 

You have 16 so you also have to pin the thermostat open. Also discussed in the many threads. Or what some are doing. 4 quarts out, 4 quarts in. It’s plus or minus but not really an issue from what I have read.