Rear Main Seal + Thermostat Parts questions. [5VZ-FE]

I have a 2003 V6 AC Tundra 2wd with the 5vz fe engine A340E automatic transmission. I'm buying some parts for upcoming work I plan on having done to it eventually.

I've been looking at the toyota EPC using my VIN to find the correct parts.

Question 1: In the parts diagram for the rear main seal, it gives me part #

90311-A0027

However, when I look at the rear main seals on Rockauto, they usually come in a kit with a piece that looks like the above part PLUS a flat U shaped gasket for a total of 2 gaskets. But nowhere in the EPC diagram does it show me that U shaped gasket. Do I still need it? How do I find the toyota part number for it?

Question 2:
For the thermostat, the EPC shows a part number for the thermostat itself (90916-03075), AND it's gasket separately (16325-62010 the one that wraps around the wide circle part of the thermostat). But when I look up the part number for the thermostat, half the pics show it preinstalled with the gasket, half show it uninstalled. Do toyota OEM thermostats normally come preinstalled with the gasket or do I need to buy it separately?

Or, should I just go with an Aisin one from Rockauto that has it preinstalled? (I don't know if Aisin is the OEM manufacturer or not.)

Thanks!

 

https://youtu.be/Yw40zyjMmv4?si=m2F6MWAuNSpmuTKA

 

Thank you!

Hmm I wonder what the odds would be of that U shaped felt gasket leaking in the future if I were to only replace the main seal with an OEM one. Seems like the only way to do both would be to either use the Fel Pro kit or use an OEM, then order the fel pro kit, throw away the fel pro main seal, and use the "U" gasket in the kit.

 

Nah, I'd blow that one off

 

I hate to be the one to ask, but are you 100% sure it's an RMS leak?

Asking, for reasons, you wouldn't be the first to change out the RMS, which rarely ever leaks, and go through all that pain for nothing. Paging @The Black Mamba who is one such victim, but there are a couple more on here.

Also, have you tried a non-invasive, not-a-fix-in-a-bottle-though-it-comes-in-a-bottle solution, like

$22 AT-205 Re-Seal Stops Leaks, 8 Ounce Bottle

AT-205, which is a basic seal reconditioner, similar to what major oil brands use as their additive package in high-mileage oils?

 

I'm going to have some transmission work done to the truck soon so I was just going to have the shop replace it while the transmission was out.

I have a P0741, truck has 250k miles approx, shifts smoothly, doesn't slip, but makes intermittent/sporadic ticking noises from the transmission area while the car is in drive or reverse at a stop, and I get a whirring noise like an alien spaceship that increases with the RPM after the truck is really warmed up after driving on the freeway. But it goes away when its cold and I only drive it around town.

The front of the transmission is soaked in tranny oil and grime so I can't tell if there's engine oil mixed in with it too. Rear cam plugs are seeping too so I plan on doing the whole valve cover gasket job too eventually.

As for the thermostat, I still probably have 20k safe miles left on the timing belt, but was just going to buy the part early for when the time comes to do the job as I want to replace the thermostat with the other stuff.

 

Maybe a stupid question from me, but have you already inspected your flex plate to make sure it's not cracked, which is another not-so-common-but-it-does-happen thing?

And sorry if I already suggested this or asked, it's sometimes hard to keep track with the sheer volume of posts on this place from newer members.

 

No I have not yet. And thanks for the suggestion. I was under the truck a few days ago but didn't look to see if I could see the flex plate. Do I need to remove anything to inspect it? Or is there a hole somewhere I can stick my snake camera in and look at it?

I'm sure the transmission shop will tell me but that would be a good idea to get the part ordered beforehand if it is bad.

 

A couple of things. Because this is one of the things in the community info megathread.

Yes, there's a black inspection cover at the base of the bellhousing that will let you see some of it, to a degree. But it'd probably help substantially if it was up on a lift.

That said, understand the sounds may not be identical to yours, but pulling from the megathread:

• Strange rattle noises at back of engine, like marbles rolling around: Several people here and at other forums have found this issue where they describe the sound as loose marbles banging around. Then found their flex plate was cracked, sometimes in multiple places. Ticking timebomb. Check it out and another one with videos.

We actually just had another new member pop up out of the blue and theirs was cracked, this was sometime in the last 1-2 months. Another recently came on saying theirs completely grenaded, and the truck had sat for like a year or more, and they were just getting it running?

It happens. I don't necessarily think it's what your situation is, but I'd toss it out there to at least have it on your radar, in case you've got two things going on at once.

 

This is the inspection cover. You remove it to access the bolts that hold the torque converter to the flex plate. These must be removed before you can separate the transmission from the engine.