Overfilling transmission

My transmission got low on fluid a little while ago on my 2008 with the 5.7 and wouldn’t go past third gear. Drained and filled it and now it goes in all gears as usual. Problem is I couldn’t get the check bolt out (snapped my Allen head off inside of it) will it hurt the transmission to be overfilled? Or even effect performance in any way?

 

I would say that under filling OR overfilling is not good for a transmission. Theres a reason why they have procedures for filling to capacity. The question I’d want to know is how did it become low in the first place??

 

Can you spray some penetrating oil on it and get ahold of it with vice grips? If not, find a place that can weld a nut on it and get it out. Either way, you’ll probably need a new check bolt.

 

Word on the street is, these transmissions are pretty picky about their fluid levels and even type. But that fact that it's giving you all of your gears seems promising.

I would work slowly and carefully to remove the overflow...after sourcing a replacement along with new gasket.

A bolt extractor of correct size would be a good starting point. Since the head is rounded and protrudes from the pan, you could cut a slot across the head with a Dremel and use a flathead screwdriver to remove. Maybe even just vice grips on the head??

Just be careful not to drill or cut thru the bolt, it's only like 3/8" deep. Definitely don't want to introduce metal shavings into the system.

 

I'd be most worried about damaging the pan. Even if you drilled all the way through, the metal shavings will be trapped in the overflow tube and washed out with the fluid.

OP, you may have to plan on more fluid. You are supposed to pull that plug with the engine running and the fluid at a specific temperature. If you pull it with the engine off, you will drain off too much.

 

Always knew it needed a drain and fill, but we never got around to it (not mine at the time), but anyway it had something like 265k miles on it when it locked out 4-6th gear. It has 278k now, but it has an overfilled tranny and feels like it is somewhat slipping. This is not all of the time, but sometimes it can act up on a shift.

 

Yes, whenever I tried to extract the change bolt, the transmission was up to operating temp. Need to try again I guess.

 

Actually we broke our Allen head and managed to not strip the head on the bolt. I think I’m about to hit let it warm up and get some penetrating fluid on it with some vice grips. Wish me luck!

 

Yeah. Little heat and vice-grips is a great and pretty safe way to start.

Do a little research on the fluid leveling procedure for these tundras. You do not check the level at operating temp. But some in-between temp that Toyota has selected. There is a procedure using the OBD port and a paperclip where the truck will let you know when to crack the overflow.

 

This doesn't directly apply to the OP's situation but a tip worth remembering; when changing oil in say a rear axle or a transfer case, it's always good to make sure you can loosen the fill plug before removing the drain plug so you don't get in a situation where you have drained and can not refill which would leave you unable to drive the truck until it was resolved.
The same would be true for the transmission where you should check to see if both the fill plug and the level check plug can be loosened before draining.

 

Worst case what does a new or used pan cost?

 

Hear that the studs that hold the pan like to shear off as well. Maybe more harsh climate related; like salted roads area.
If issues with a plug, likely issues with those as well.

 

Forgot about that. Yeah, replacing a pan may involve multiple broken bolts.

 

I just had my 17 transmission flushed at 60,000 from the dealer.
They used BG and not Toyota WS. I was concerned at first but doing a little digging it seems Toyota WS is not regarded as top end fluid.
I did it at the dealer because it came with a lifetime warranty on the transmission if they performed the service.
A little off base to OP but thought I’d share.

 

Actually I just stuck some Allison transmission fluid in it

 

I got the check bolt loose with some vice grips and when I tell you that it drained for a minute I mean it. In fact, I stopped it after it trickled a little bit, but it went back to flowing before I got the bolt in lol. No lockout from a low fluid level though, so that’s good!

 

The truck was running when you drained it, right?

 

Uhhh... I assume you are referring to leveling plug overflow, and NOT the transmission drain.

If one were to pull the DRAIN with the motor running, all of your ATF would end up on the ground and the transmission would likey be irreparable.

 

Yes. This thread was about getting the check plug loose, not the drain plug. I was responding to the post above mine where he said he got the check plug loose and it drained for a minute. It’ll do that even if it’s filled correctly but not running.

 

I refer back to the video basically every time I perform a transmission drain and fill. It has really good info regarding the poor-mans/DIY leveling procedure using a paperclip, OBD port, and some fancy shifter work.

Toyota engineers seem pretty good at what they do, so I trust the systems they put in place AND the fluids they designate for the systems.

https://youtu.be/Ujx6BkbMGic

 

Gotcha.

I am hoping to prevent confusion to someone else who might stumble upon this thread.

 

Thanks. I see how my wording was off since I said drain. I was thinking of what the OP had said above.

 

Yes, the motor was running and it was the check plug.

 

Yes, it was the check plug.

 

Sooooo, did you ever perform the proper leveling procedure?

Any change in the amount of fluid, or improvement in the operation of the transmission?

 

I mean, I let some fluid out til it trickled just a bit lol. It does seem to feel a little lighter on its feet now. For instance I was going 20 just now and floored it and it broke one loose audibly. And also I was going probably 15 at a red light just before that and I’m pretty sure that it started to break both loose and get squirrely on me. Not to mention the sweet drift I did getting on the 4 lane highway the other night

 

The transmission fluid is supposed to be between 115*F and 130*F when you pull the leveling plug. This is why there is a procedure to notify you of the appropriate time (temperature) for leveling.

If at normal operating temp when you pulled the plug (much hotter than 130*F), your transmission will be low on fluid again.

Just want you to have to best chance of preserving your transmission.

Hopefully this helps.

 

get a small drill bit and set a stop on your drill and drill out the broken allen head. Have a new plug on hand too. From experience on other cars, its better to have it slightly overfilled so as to make sure the fluid is getting and covering everything its supposed to. I had problems with reverse one time when the fluid was a little low.

 

Just wondering why they changed the temp. I never noticed this before. It used to be 115-133, now it’s 99-111? Isn’t it the exact same trans and fluid?

 

To be honest I have no idea about the actual temperature range, which is why I use the correct procedure and just let the truck tell me when it's time to jump under and crack open the overflow.

I just found reference in another thread mentioning 113 to 130.