Small hole in lining of rear wheel well (not bolt)

I was waxing my 21 4R today and noticed this small hole in drivers side rear well near where all the bolts stick out.

After waxing for winter was putting some fluid film on the lower wells and found it.

My buddy suggested some RTV. I have it parked now for winter in garage and has not seen rain all year so not super urgent.

Curious if others have had this and what they did to rectify?

Below is pic close up and a bit back.

The brown stuff in there is not rust it’s like a foam insulation

 

Might be a drain for the sunroof or some kind of a vent. Would not recommend plugging it. I’ll do some more research.

 

Wow drain for moonroof? That far back in rear wheel well.

I am in no rush to fill. Truck is parked in garage and covered for winter. So I don’t think I need an urgent fix since I don’t drive in winter or snow.

I definitely want to make sure I am doing the right thing. I am not a mechanic by any means here just want to keep this 20 plus years.

 

Looks like something could have been slung out from your tire and punctured the undercoating......
Not a drain!

 

I wondered if something hit it also but gosh I would think I would have heard something like that.

 

And here’s mine!



I would not close up any holes. Even if it’s not a drain, the body is made up of various panels, and that hole could be there because engineers determined that it was needed to avoid trapped moisture…who knows.

 

ReRunner/Mcspazatron,

Thanks for post. Are your holes in driver side rear wheel well?

If you are kneeling at that tire sort of on your left side underneath rear passenger seat ?

 

Another here with the same damn thing, I thought it happened when my wheel weights flung off but I guess it’s just a feature like said above lol

 

My 2022 has it also. Had not noticed it before. Definitely intentionally there. Anyone without a moonroof have it?

 

I seriously doubt they would put a sunroof drain there, where it has potential to clog the fastest. When clogged they usually soak the passenger side carpet I am pretty sure.

 

My 19 has the same hole

 

Sure seems odd that we all have this cut out in the same spot. I would think there was a drain there would be a tube? There is that yellowish/brownish insulation at least I think that what it is

 

It seems odd because we dont know why it looks like this, or what it’s purpose is. Every car has “odd” stuff underneath it, and most manufacturers dont worry at all about cosmetics for things in a vehicles nether regions. We see it on 4runners because it’s higher than most other vehicles and more likely to be seen when we’re cleaning and admiring them.

It would be more odd if we all didn't have exactly the same holes. The fact we do simply says “it’s on purpose”.

The stuff you think is insulation is actually the adhesive used between sheet-steel panels. When a body (or unibody) is made, you have a ton of different stampings that are spot welded together by robots. This adhesive is used to finish the joint (probably plays mostly protective, but maybe also a structural role). Watch a few car factory documentaries, and you’ll see the robots applying the adhesives too. Some might think that adhesives are a cheap way to finish joints between panels, but airplanes, exotic cars, and anything besides maybe a double hulled tanker ship, depends on adhesives for structural tasks.

Im willing to bet that the hole through the coating in the wheel well is made by hand, after the wheel wells are sprayed with then tar-like liner.

Someone asked if everyone with these holes has a moonroof…. i have the holes, but do not have a moonroof.

It’s not necessarily a drain. Could also be a gusseting panel to strengthen a 90 degree joint between panels. (A gusset would not need to be completely closed to strengthen a corner). In that case, they would have to make sure the tar would not close off what would have otherwise been open. There’s one thing worse than moisture when dealing with corrosion, and it's trapped moisture.

 

Might be venting for gas tank

 

Moonroof Drain Locations (Underside)

 

So, since I never recall seeing that “blemish” on my 14 SR5P or my 21 TRDORP I looked to make sure. Nothing but the infamous bolt that pushed the undercoating out.

See photo:




EDIT: I looked and it is definitely there....

 

Drove by dealer lot and an ORP parked for service had the hole also. It’s not as large as mine or others but definitely there. Not sure if model year but definitely Gen5

 

Look closer…it’s there. You just need to take the pic from a lower angle.

 

It’s probably just a manufacturing defect, why change that over the years if you don’t wanna fix your front differential or shimmy problems either!

 

You are correct Spaza!
I looked and it is definitely there...
Not as pronounced as other photos.

 

Haha, you know, with how big companies work, I suppose there is the chance some guy, long ago, decided to punch out the tar coating in that spot because maybe he thought it should be open. And then hundreds of apprentices have followed suit without question. Now nobody in toyota even knows anymore why it’s there or when it started haha.

I suppose even the Japanese arent immune from “we’ve always done it this way.” Lol. But damn, they sure are consistent!

 

Hey guys update on this.

The service manager and the master tech at my dealer have advised me not to fill in these holes.

As others suspected these are drain holes for the moonroof. Apparently there should be holes in each wheel well. I will have to inspect my passenger side more closely.

They had a new 4R delivered this morning and theee holes like mine on each side drivers and passenger wheel wells.

Just wanted to give a heads up so no body fills these in.

 

If they are right what in the hell kind of a design is that !?

 

Makes me want to dump water in the sunroof area and see if it comes out there

 

You know weird thing is I do not recall seeing any sort of tube up there in that hole. I would have suspected a tube to come out near that area. But I am not going to fill it that’s for sure.

 

i thought the link previously posted showed the drain tubes coming out behind the rear bumper cover, not in the wheel well.

 

I think that video is an example for a Cadillac Deville model year 2000. Unless I am reading something wrong in the title.

 

But I still wouldnt cover them. Especially since it’s clearly there by design. Being unsure of it’s purpose would make me even more leery of messing w it.

 

Not the cadillac vid…I meant the link in post 17 of this thread. These pics are from there:

passenger rear




driver rear inside. It exits at the body, not well

 

Gotcha Spazatron I misunderstood.

Does it seem like the pic with the red trim that you reposted has a slightly different “black wheel well liner”. Maybe they changed this. Just wondering if this is a 5th Gen?

It seems like the majority of the pics of our 5th Gens have a less smooth black surface for that wheel well liner?