What are these two hoses for, 4.7 driver's side?

Gents,

Another pic from my '07 Sequoia.

What are these two hoses for? The smaller, upper hose seems to be quite old, but I haven't yet attempted to wipe it off to check its condition.

It appears there's a leak associated with the larger hose.

Any insight or advice would be greatly appreciated.

 

The larger hose is for your PCV and if you have no records of change, suggest you consider replacing the PCV.
Smaller hose is part of EVAP system.

 

FYI, per your picture, there's three lines you should probably refresh, and if you haven't done your PCV valve, which the fatter hose in your pic connects to, you should probably do that too.

Per @BubbaW 's diagram there, with links to Toyota's Parts system (don't get choked up by the MSRP, most dealers offer 10-30% off if you order through this website), the EVAP hose is 23829-50161, the fatter ventilation hose is 12261-50070, and the matching ventilation hose you'll find coming off the passenger valve cover is 12262-0F021. The PCV valve is 12204-50030. These part numbers should be correct for '05+ 1st gen Tundra and Sequoia. Most 05+ 1st gen owners should've probably replaced all four of these items at this point, at least once. I replaced my PCV hoses, as did a few others on here, and found the ends were dry-rotted/cracking to hell. Sorry non-VVTi / 2000-2004 folks, I can't say off the top of my head whether these part numbers work for you. PCV may be good for other years with screw-in valves, but likely not 00-02. Not sure on the other stuff.

Beyond that, there's also a lot of unformed 4mm vacuum hose throughout our engine bays. Toyota sells that in bulk, uncut, and the last digit of the part number changes based on what length you buy. The longest length is about 8½ft, the part number ending in 8 here, and runs around $40-50 if you buy it during a sale. This would be the exact same vacuum hose that's lasted 15-20 years on your current truck, so it's pretty compelling when compared to the mystery-brand silicone tubing you'll find all over the internet.

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Just a few follow-up questions there, Shifty. Is the 4 mm sized bulk vacuum hose the only size non-molded vacuum hose used on our trucks or are there other ID hoses used and or available from Toyota that we would need to replace as well. I seem to recall that Tundra 2 used different sizes when he dressed up one of his trucks using a silicone replacement hose kit.

I've been thinking about replacing my vacuum hoses as they are due at 21 yrs. I recently replaced the molded PCV hoses after changing out the valve itself last fall. I had to tape those hoses with split ends until I could install the replacements 2 weeks ago. I figure the unformed hoses are needing replacement based on what I saw there.

 

It's a tough question to answer.

Rather than answer it directly, I'm going to link some specific diagrams that cover about 80-90% of the fuel/evap/vac/water rubber lines in the engine bay, I believe, for molded and non-molded. Mousing over on any numbers in the pictures shown will give you the part name, and clicking on the number will give you the part. The unformed hose seems to mostly be that size pictured in the grid above, which is supposedly 4mm ID. But, like, I know the three hoses plugged into the square part of the OEM airbox, one (to fuel pressure regulator) is 4mm, the other (to power steering air control valve) is more like 8mm, and the third (PCV passenger hose) is probably like 15mm or something.

Note: these picture links are is for a 2006 AC, you shouldn't use them as a parts reference unless you have a 2006 AC. Whether it'll be pertinent to your 2004 is another story entirely. I know of vacuum differences in the earlier years, with hard lines running over the manifold, but not sure about '03-04.

tl;dr - I need to go thru the process before I can answer definitively. Even then, my '06 won't be the same as yours, fully.

Hose 1: https://toyota-usa.epc-data.com/tundra/uck40/3806/engine/1708/?full&picture=2
Hose 2: https://toyota-usa.epc-data.com/tundra/uck40/3806/engine/1201/?full
Hose 3: https://toyota-usa.epc-data.com/tundra/uck40/3806/engine/1706/?full
Hose 4: https://toyota-usa.epc-data.com/tundra/uck40/3806/engine/1603/?full
Hose 5: https://toyota-usa.epc-data.com/tundra/uck40/3806/electric/8716/?full
Hose 6: https://toyota-usa.epc-data.com/tundra/uck40/3806/engine/2211/?full

3rd link is obviously for VVTi trucks, for secondary air injection so no application for 2000-2004. 1st two are for vacuum/evap. The 4th link is for coolant hoses, 5th for the water lines to heater core, 6th for fuel lines on engine.

 

Thanks, Shifty for setting me in the right direction. I should be able to track most of what I need and get a better idea of what to look for (and where) using the info provided as a starting point. Pretty helpful info.