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

$21 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.

 

Yeah, I was 100% convinced for years that my rear main seal was leaking. So much so that I removed the transmission only to discover that it looked awesome. I replaced it anyway since I was already there but I don’t recommend pulling the transmission just to check. I am now 100% convinced that it was the half moons that were leaking. Those were fixed as well when the valve cover gaskets were replaced.
https://www.tundras.com/threads/wha...-gen-tundra-today.2558/page-1929#post-3535095

 

Did you replace the U shaped gasket as well when you did replace it? Or just the rear main circular seal? And did you go with OEM toyota or aftermarket?

 

Looked at the flex plate this morning and pulled the cover off it. It looked good but I only was able to see half of it. Guess I'll find out at the transmission shop.

 

I only replaced the rear main circular gasket. OEM lasted 25 years and was still not leaking so that's why I put another OEM back in it. I thought I had a pic of the part number, but it looks like I didn't post it. Let me see if I can dig it up.

 

I mean, I don't doubt it. The oil leakage from up above would kinda support that, in fact, one of the two half moons at the back of each head was leaking. Someone probably didn't seal them correctly, or didn't uninstall/reinstall correctly the last time they had the valve covers off, or they just lost seal after so many years of ownership. Unless I'm mistaken, both of these spots with clearly wet oil coming down from above are directly below half moon plugs.

EDIT: Crap. I just noticed the starter bendix and realize this is a V6. I don't know where the 5VZ half moons are. The spots below, I'm thinking in V8/2UZ format.

​

 

Here's my parts list https://www.tundras.com/threads/1st-gen-lunch-table-general-discussion.60450/page-1984#post-3495496

No, you have it pretty close

 

IIRC the 3.4 has both 4 half moons and 4 cam caps that need to be sealed with FIPG

 

I believe its just two cam plugs and 2 half moons on the 5VZ-FE.

Guess I'll have the transmission shop replace the rear main seal anyways even though its probably okay. But considering the truck is 22 years old with 250k miles, I don't want to risk the original one deciding to start leaking next month. I'll leave the U gasket alone for now. (Or buy the felpro kit that comes with it from Oreily) and tell the transmission guy if he thinks it needs it, then feel free to open the package and use it, otherwise leave it alone and install the OEM rear main seal which I'll be supplying him with and then I'll return the fel-pro kit for a refund.

 

Why is it going to the trans shop?
It’s your money, but I wouldn’t pay eight hours labor to R&R the trans just to replace a seal that is more than likely not leaking

 

Usually the half moon cutouts are to assist with sliding the cams out did they put a cutout on both sides of the head so you can slide it out either way?

 

@shifty` - I stand corrected only 2 cam covers and half moons.