Vacuum hose sizes in engine bay?

[Bob98SR5]

Hey guys,

Has anyone pulled and replaced vacuum hoses in their 3.4L V6 engines? As it seems I'm headed down the path to replacing or rebuilding the injectors again, might as well replace all the vac hoses on this old goat since everything is open kimono now. ID hose size preferred. And yes, I'm not at my truck at the moment.

[Bob98SR5]

Hope to tackle this one hose at a time w/ lengths per part and a pic diagram. End goal is to have size + total length of vac tubing needed. So far:

Smaller hoses: ID = 5/32" (4mm)
Longer one that connects to air box: ID = 5/16" (8mm); Wall thickness = 1/16" (1.6mm)

[Seanz0rz]

Looking forward to this. Many of mine are starting to crumble.

[Bob98SR5]

I have a feeling that the ID of all the hoses are in increments of 2mm starting from 4mm. The problem is that the SAE hoses I got from O'Reilly's for the larger hose has a wall thickness that's too big for the hose holder. So off to search because the Toyota replacement is nearly $30!

I just bought another digital caliper too to be more precise. Can't find my old one. I hate moving. I always lose shit.

[troyboy162]

Man I wish I could help on this, but I am also looking forward to your findings. I think all of us are due a few hose replacements by 2016.

[Bob98SR5]

After about 2 days research, most if not all sources online say either use silicone tubing, rubber, or Viton. I've had experience with Viton tubing for the Biodiesel Benz a few years ago. I'm going with Viton. The best source for Viton tubing is (you guessed it) McMaster. Here's the link and part numbers:

http://www.mcmaster.com/#viton-fluoroelastomer-tubing/=12jv7ou

Green, black and beige colors. Part numbers correspond to different sizes.

5102K41
5102K42
5102K43
5102K44
5102K45

While silicone is more better in terms of chemical/oil resistance, most if not all of the ones for automotive application are high gloss in appearance like you'd find in a riced out sports car.

[Seanz0rz]

I have a friend who failed visual on a SMOG test because of a red silicone vacuum line. Completely ridiculous, but it happens!

Thanks for the link!

[Bob98SR5]

I've read that happening in CA on several other car forums too, Sean. I'm going to do all the measurements on hose thickness tomorrow and place the order.

I read on another forum from one of the old members I used to know that the 96-97's have more vac hoses. How many more, I have not a clue.

[YotaFun]

Its not too many more, having both makes this fun hehehe...
Its mainly in the design of the throttle body and the placement of the Evap Canister.

[Bob98SR5]

So much to my disappointment, replacing all the hoses won't be as easy of a task as I presumed. The sizes, shape, thickness and the hardness of each tubing type is all over the map. I'll put a better table together with names of what each hose connects to (and a good pic or two), but for now this is what I have just for data points and I'm not done with all the vacuum hoses. See attachment.

As you can see, there's some uniformity around the ID sizes (8mm). The only one different is the longest hose that runs across the engine bay from the air box to the evap box (10mm). However the thickness of the hoses, shapes, and hardness are all over the map. Some hoses like the one on top of the evap box and the one that runs from it to the plenum (along the firewall) is formed medium hard plastic. What I am concerned though if I buy from McMaster is whether or not the 1mm tubing they sell in metric will collapse. I believe some of these hoses may be thicker to prevent vacuum-induced tubing collapse. I may be wrong here. Any guesses?

If not, my next task is to see if I can find a tubing supplier who has hoses with different diameter thicknesses.

[Seanz0rz]

Bob,

Did you ever complete this project? I have the dreaded EVAP P0446 CEL and suspect it is due to a split vacuum hose. I'll tear into it this weekend, but will probably start replacing hoses for fun. After 20 years, they look pretty janky.

[Bob98SR5]

Bob,

Did you ever complete this project?

Sean, et al:

Though I didn't capture all the hose lengths, here's the hoses that I bought that worked for my 98 4Runner. See attachment.

Of note, on our last outing (4 people in my truck w/ a full load inside and on top of the rack), my 4Runner got 19 mpg for the first time ever. I attribute this to driving at an avg speed of 55-60 mph. While it's ludicrous to say that the hoses had something to do with this, I can say that the performance and mileage *wasn't* compromised by these new hoses.