Yet Another “What is this part?” Thread

[Bluesky 07]

I must have seen this thing countless times under the hood but don’t know what it is. It’s on the driver’s side and doesn’t seem to have a p/n on it. I have a 1GR-FE V6.

 

[maxdef]

Vacuum res - 25719-50040

That is called the vacuum reservoir. I had replaced mine a little while ago. Interestingly, mine had a green evap port in-line just before it, but the new OEM replacement did not, but it's apparently only used with some Toyota tool anyway.

2005 Toyota 4Runner 4.0L 4WD SR-5 Vacuum Reservoir. Engine, SYSTEM - 2571950040 | Cobb County Toyota, Kennesaw GA

 

[Bluesky 07]

Thanks. So I've been Googling and YouTubing for 10+ minutes and still can't find a source that tells what this part does. Do you happen to know?

 

[maxdef]

That's the extent of my knowledge on this part unfortunately. I had looked into it before a while back and I think its part of the rear evap system, but I'm not entirely sure what the purpose is. My only guess is in regards to excess vapors/fumes being funneled back to the engine to burn off. In my situation, replacing the line with the reservoir on it help close a small leak I had from old rubber.

Someone more knowledgeable should be able to set us straight

 

[Bluesky 07]

[MENTION=66389]BlackWorksInc[/MENTION]

 

[maxdef]

Lol that is exactly who I was thinking of when I typed it.

As a follow up, here is something I came across that has a diagram to give a better idea.
The vacuum reservoir would be just after the test port before the engine.

Evaporative Emission Control (EVAP) System - P0441 Diagnostic Code - Trouble Code Diagnosis Guide | Toyota Parts Center

 

[BlackWorksInc]

If I remember right, it's main purpose is to just act as a dampener/buffer for vacuum pulses and changes in pressure.

Keep in mind that on older vehicles the EVAP test is performed with the vehicle running and using running engine vacuum which is actually pulsed if you used a pressure transducer to measure it. In later models (starting around the '06~'07 model year for most Toyota/Lexus vehicles IIRC) the EVAP Canister actually has it's own vacuum pump & reference orifices built into it, so it now has the capability to do Key Off/Engine Off self-tests. I imagine they probably don't actually need the vacuum reservoir/vacuum surge tank (I hate when Toyota does this... the parts fiche calls it a Vacuum Reservoir, the FSM calls it a Vacuum Surge Tank... Toyota isn't the only one who can't just be consistent with their terminology throughout their documentation... just annoys me when I need to order parts based on diagrams) since the EVAP Canister should be calibrated for way the pump operates, but perhaps it helps smooth whatever possible turbulence could occur when the Purge Valve opens? That last part is just a theory as you're getting into some engineering level of analysis at this point and this stuff will barely be mentioned if not outright not even mentioned in an FSM or training literature.

I do remember that old carburetors and vacuum based switching systems back in the 80's to 90's would have "modulators" on them to dampen the vacuum so that a valve/switch/device was operated smoothly when vacuum was used rather than sharply/jerkily. So likely similar function here, I could probably find you guys some more detail if I dug around in Toyota's literature for a while.

Anyways, sorry that I haven't really been around as much. Work's been busy and I've been managing with life related things and so I am just not as active as I used to be; might not be for a bit? But I'll make an effort to poke my head in here every now and then.

 

[inscarguy]

Here is the part number: 23820-31021

 

[Bluesky 07]

If I remember right, it's main purpose is to just act as a dampener/buffer for vacuum pulses and changes in pressure.

Keep in mind that on older vehicles the EVAP test is performed with the vehicle running and using running engine vacuum which is actually pulsed if you used a pressure transducer to measure it. In later models (starting around the '06~'07 model year for most Toyota/Lexus vehicles IIRC) the EVAP Canister actually has it's own vacuum pump & reference orifices built into it, so it now has the capability to do Key Off/Engine Off self-tests. I imagine they probably don't actually need the vacuum reservoir/vacuum surge tank (I hate when Toyota does this... the parts fiche calls it a Vacuum Reservoir, the FSM calls it a Vacuum Surge Tank... Toyota isn't the only one who can't just be consistent with their terminology throughout their documentation... just annoys me when I need to order parts based on diagrams) since the EVAP Canister should be calibrated for way the pump operates, but perhaps it helps smooth whatever possible turbulence could occur when the Purge Valve opens? That last part is just a theory as you're getting into some engineering level of analysis at this point and this stuff will barely be mentioned if not outright not even mentioned in an FSM or training literature.

I do remember that old carburetors and vacuum based switching systems back in the 80's to 90's would have "modulators" on them to dampen the vacuum so that a valve/switch/device was operated smoothly when vacuum was used rather than sharply/jerkily. So likely similar function here, I could probably find you guys some more detail if I dug around in Toyota's literature for a while.

Anyways, sorry that I haven't really been around as much. Work's been busy and I've been managing with life related things and so I am just not as active as I used to be; might not be for a bit? But I'll make an effort to poke my head in here every now and then.

Thanks, and totally understand about life keeping you busy. I appreciate it any time you chime in and no worries ever if you can’t.