Seal Packing on Oil Pan Bolts? Using Rubber Gasket

I have a 2005 Camry with the U250E automatic transmission. I’m looking at the instructions on how to drain and refill the transmission, remove the filter and replace with a new one.

The service manual says that thread packing is required on the bolts that go around the permitter of the oil pan to secure it to the block. I’m curious if this really required. I have seen videos of people on YouTube do this task, and not apply thread packing. Also I removed one of the bolts, and there doesn’t appear to be any thread packing on the bolts.

I’m also using a rubber gasket. I thought thread packing was required if you used a metal gasket or you made your own gasket with some gasket maker material or used a paper gasket.

If I’m using a rubber gasket, the thread packings seems kind of unnecessary?

Can anyone provide some clarification. I guess I should do it because it says to, I’m just wondering what the function of it is?

I thought you were taking some kind of auto mechanical class . It seems that this would be perfect for a class discussion .

Me would just use the proper gasket , snug the bolts and if it does not leak then all is good.

I’m only a backyard mechanic, so I’ll admit that I don’t even know what thread packing is. I’ll have to look it up.

I’ve dropped the pan several times on several vehicles and just used the rubber gasket with no leaks.

I noticed our 2013 highlander, Toyota didn’t use a regular gasket. It is just some silicone/gasket maker. Haven’t dropped the pan on it. Just drain and fill.

I happen to also have a 2005 Camry and I’ve done the automatic transmission fluid and filter service many times

I’ve never used that seal packing on the bolts

I’ve made sure the threads are clean and torqued the bolts to spec

Never had a leak from that area

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The Three Bond 2430 specs read as a sealer and a threadlocker. If the bolt holes on the trans case extend into the case itself… i.e. not blind holes, you must use some type of sealer or the trans WILL leak. The threadlocker part is less important but still…

I don’t see a direct replacement product from Loctite… but I’d bet PST 592 would work well.

The bolts don’t extend into the case itself

They thread into blind holes


Seal packing is a form of gasket.

Instead of using a gasket, Toyota used a sealant to seal oil pans, transmission pans, etc…

But since a gasket was supplied, the sealant isn’t required.


Thanks for all the help guys!

That’s what I assumed, but I just wanted to be sure. I also had never hear of thread packing before until I saw this.

I expect the only thing you’ll need is the gasket to get a leak-free job. If you want to do more use some spray adhesive (for gaskets) on the gasket to hold it in place, and spray a little on the bolt threads at the same time. I used this technique when bolting together both halves of a clamshell type water pump last year, totally leak free from the get-go. Be sure to torque the bolts to the specified amount when you install the bolts. Read the spec carefully, as the units may not be what you are expecting, e.g. inch pounds vs foot pounds. Generally these sorts of pan bolts are not installed super-tight.

No experience on a transmission service on your car, but on my truck (Ford C4 automatic) removing the filter is a little tricky. There’s a spring loaded valve behind the filter that can spring who-knows-where when the filter is removed.

Normally I would expect that… not having worked on a Toyota automatic… But the description of Three Bond 2430 confused me. 2430 is a sealer threadlocker not an RTV. Seems like the wrong stuff for the job.

Those transmission pan screws tend to loosen over the years, that is the purpose of the thread locker. The screws compress the gasket and can’t be tightened to the point they won’t loosen.

Pan bolts are much tighter when using RTV or FIPG and won’t loosen.

But why the sealer? Threadlocker I understand but sealer?

On the old Camry the pan seal looks like some paper thing and it doesn’t break when I remove it so I just reuse it. I have a rubber gasket and poor quality filter screen from an auto parts store. The “filter” screen mesh is so much larger than the OEM that I decided not to use it, and I now see why it is included as a kit with the new pan gasket. You have to really watch what you get at auto parts stores.

On some transmissions, the manufacturer used an RTV sealant, rather than a rubber or paper gasket. When you remove the pan to change the fluid and filter, you need to replace the sealant or rubber/paper gasket. The new filter will typically come with a rubber gasket, and you do not need to use any additional sealant with this gasket. If it comes with a paper gasket, I would coat both sides with black RTV sealant, but don’t use too much.

On some transmissions, the manufacturer used a rigid type gasket, made of rubber with an internal steel frame. This gasket is designed to be reusable, again with no additional sealant.

On any transmission, the most important thing when it comes to tightening the pan bolts is tight enough not to leak, but not too tight which will damage the gasket. It is best to use a torque wrench, and follow the manufacturer’s torque specs, however it is also possible to “guesstimate” the torque by remembering that the torque value is in inch-pounds, and using the little 1/4" ratchet handle and making it as tight as you can with only one or two fingers on the ratchet handle will be close enough.