02 WRX Vacuum/Coolant Hose Install Guide

[freeman.matt]

Warning: This is going to be a lengthy guide with lots of pictures. If I get too verbose and you just want the photos, check out http://imgur.com/a/aqDJt.

Another Warning: I'm no expert, and much of what I've learned about my car has been from this website. I've been running these hoses for about a month now without issue, but something could be lurking under the hood. If you see anything that needs correction in either the writeup or photos, let me know.

Background: My 02 WRX had at least two leaks under the hood. I could smell the coolant leak, and I could hear a vacuum leak (which also made my heater lose heat at idle). Knowing the car is now 12 years old, I decided to go through and replace all of the hoses and hope I remedied the two issues.

Hose Source: I bought a kit off of eBay of silicon hoses from HPSI-Motorsports (their website) which shipped with most of the hoses that I needed. I did have to go back and order a few more, but I think I replaced some hoses that they did not intend or used a slightly different size. Regardless, I liked them and would recommend them to anyone. These are the final lengths/diameters of the hoses that I used.


Tools Needed: Nothing specialized. I relied heavily on a beefy pair of needle nose pliers and there are a few nuts that need to come out here and there, so a socket set or wrenches of some sort. Silicon grease was very helpful with getting the new hoses on, use it liberally.

Annotations: In all of the images I've circled the start and stop of the specific hose, labeled some nearby hoses for orientation help, and noted the hose length and diameter (ID) used. I've rounded up on all lengths, so expect to trim to fit. The hose label is alphabetical in the order I replaced them, but the rest of the writeup goes in a more logical sequence designed to minimize intercooler/coolant tank removals.

Begin Writeup

Were I to do this again, I'd pull the intercooler first and get it out of the way. There are numerous writeups on how to do this so I'll leave it to them for the details. I will say that with my brittle 12yo stock hoses, there was a lot of swearing and bloodied knuckles getting it out. This would be a good time to get a silicon IC hose kit and it really goes back in much more easily.

The two hoses below connect to the same fitting which goes into a short thick piece of hose. I did not replace it as it would have probably required pulling the turbo, but if you want to, it's 14mm hose. I believe these are crankcase breather hoses... I ended up having to cut Hose X at the elbow to pull it out as it was too rigid.

Hose E, Passenger Breather: 6" x 12mm


Hose X, Driver Breather: 6" x 12mm


With the IC still out, go ahead and replace the throttle body coolant hoses. The original Hose V ran through a mesh sleeve which I reused, I'm guessing it's for abrasion resistance or something.

Hose Y, Throttle Coolant Out: 10" x 6mm


Hose V, Throttle Coolant In: 12" x 6mm


Now you can put your IC back in... it shouldn't get in the way anymore. The next hoses run from the blow off valve. I have the stock boost meter, which is where Hose W goes. It runs through the firewall to the gauge. I replaced the hose all the way to the gauge, but should have only replaced the portion in the engine compartment. The hose in the cabin was still quite supple and it was a pain snaking the new hose up the the gauge. If you don't have a gauge, then you won't have a T fitting in hose U and should just cut a single 12" piece.

Hose U, BOV: 12" x 6mm


Hose W, Turbo Gauge: 60" x 4mm


Also in this area is the hose running the the brake booster and a vacuum hose running to the gas tank. This hose actually has a check valve in it, so either salvage the one from the original hose (which I did), or get another one. Basically, you want to be able to blow through the hose from the brake booster end into the engine, but not suck anything from it. The tank vacuum hose is in a group of three and it's the one with the simple pinch clamps on it, not the more powerful screw clamps required to contain fuel pressure.

Check valve in original hose


Hose F, Brake Booster: 16" x 9mm


Hose Z, Tank Vacuum: 15" x 6mm


More in next post...

[freeman.matt]

Now to the other side of the car and some coolant hoses. Do the next three hoses as a stack (ie remove A, C, D; install D, C, A). There are two 12mm bolts on top of the coolant tank you need to remove and one 12mm nut on the side that needs to loosen. Also, to get at the bottom of Hose D, remove the top half of the air filter box.

Hose A, Turbo Coolant: 8" x 12mm


Hose C, Bottom Coolant: 5" x 12mm


Hose D, Back IC Coolant Pipe: 13" x 12mm


Go ahead and reinstall the coolant tank, then go for the two coolant hoses which run to the pipes on the front of the IC.

Hose B, Front IC Coolant Pipe: 13" x 12mm


Hose G, IC Coolant Pipe In: 7" x 12mm


Now pull off the cold air scoop (it's 2 bolts of unknown size) and swap the two hoses running to the radiator.

Hose H, Left Coolant: 27" x 6mm


Hose I, Right Coolant: 22" x 6mm


These two hoses may vary on your car. I had to replace the radiator last year and there were some adapter parts required to fit newer radiators into the 02 WRX. The overflow hose is probably similar, but you'll likely not have the Uturn hose unless you've done a similar replacement.

Hose J, Coolant Overflow: 19" x 6mm


Hose K, Coolant Uturn: 7" x 6mm
http://i.imgur.com/EI4lKUV.jpg

Before replacing the air scoop, go to the next post and do the rat's nest. Once those 6 hoses are done, replace your air scoop and go replace some hoses in the turbo control circuit. Hose L is made of two hoses joined together by a coupler.

Hose L, Turbo Relay 1: 3" x 6mm & 17" x 4mm


Hose M, Turbo Relay 2: 11" x 4mm


More in next post...

[freeman.matt]

The last part of the turbo control circuit is made of three pieces around a T fitting. The hose you're replacing also has a restrictor pill in it which needs to be reused.

Restrictor Pill


Hose N, Turbo Relay 3: (3" x 4mm) x 3


With that done, the last set of hoses is up near the alternator colloquially known as the rat's nest. This should actually be done when you're doing the long coolant hoses (H and I) since the air scoop needs to come out. It consists of 6 hoses. I was able to remove the relay that Hoses P and Q attach to simply pulling one bolt using a ratchet w/ a 3" extender. Go slow and try not to lose your place.

Hose O, Rat's Nest 1: 1" x 4mm


Hose P, Rat's Nest 2: 9" x 6mm


Hose Q and R, Rat's Nest 3 & 4: (3" x 6mm & 2" x 4mm) & (3" x 6mm)


Hose S, Rat's Nest 5: 5" x 6mm


Hose T, Rat's Nest 6: 9" x 6mm


And that's all. I ended up having coolant leaks at Hose A and the radiator o-ring, and the vacuum leak was in hose U. Good luck, it's not hard, just somewhat time consuming.

[oc2md]

Maybe it's obvious but how do you get the restrictor pill inside of the tubing? I just ordered the same hose kit as you suggested and they look awesome. Can't wait to put them in this weekend.

[02WRX84]

Great write up man! Great stuff! Where does the hose just below the IACV and to the right of it go?

I’m looking around and notice that there isn’t a hose connected there or on the throttle body under the inter cooler. I’m thinking the hose popped off and that they should have a hose connected to each other. What do you guys think?

[02WRX84]

Great write up man! Great stuff! Where does the hose just below the IACV and to the right of it go?

I’m looking around and notice that there isn’t a hose connected there or on the throttle body under the inter cooler. I’m thinking the hose popped off and that they should have a hose connected to each other. What do you guys think?

[Valarius Starchaser]

Originally Posted by 02WRX84

Great write up man! Great stuff! Where does the hose just below the IACV and to the right of it go?



I’m looking around and notice that there isn’t a hose connected there or on the throttle body under the inter cooler. I’m thinking the hose popped off and that they should have a hose connected to each other. What do you guys think?

That’s a coolant line

A lot of guys remove it never understood why no matter what climate your in what the gain is to doing it

To my recollection it’s a cold start/emissions type system

[benders]

Originally Posted by Valarius Starchaser

That’s a coolant line

A lot of guys remove it never understood why no matter what climate your in what the gain is to doing it

To my recollection it’s a cold start/emissions type system

I believe it's also to prevent the throttle from icing up in cold. Otherwise the pressure/temperature drop after the throttle plate could form ice and a sticking throttle.

[evo_nahh]

How are you guys clamping the hoses?

[Psychoreo]

That's a lot of words for "unplug the old hose, match up to the new hose, plug in the new hose"

[freeman.matt]

Indeed it is. The high yield stuff here is the table showing overall lengths and diameters required. The rest is just for thoroughness.

[silverstreak02]

Looks really good, was doing some work under the hood this weekend and was going to order a few small hoses to replace, but now I see there's a full kit I can buy..great post

[rdieder]

What are the closest sizes in non metric? The AutoZone near me has nearly all bulk hose in standard measurements.

[big_dog35]

Great write up man, gettin at this real soon! Been waitin for a DIY like this for a while. It's nice to be able to see and plan it all out before gettin at.

[CJ12]

I for one appreciate write ups just like this. Plenty of useful information and colorful pictures that show relevant detail. Thanks!

I'm a couple of steps away from buying an ancillary hose kit and will reference this when I do the install.

[lamby]

Thank you so much for this. I was looking everywhere. Kind of lost on hose T though. Could you post a better picture?

[Garo]

Nice upgrade to get ride of the old ones and ensure no leaks.

[bleuquila]

Amazing post and very timely for me - someone else took all my hoses off, and it's been a real headache getting everything reconnected from the bucket of hoses n' bolts. Like a really expensive 3d jigsaw puzzle. I knew I was going to need to replace your "hose b" to the IC, I trimmed my stock one too short when putting in a new inlet and now it doesn't route the way it should. So now I'm sort of fired up to replace all the hoses while I'm at it!

[taylor_90]

Very helpful thanks. Nice write up

[mathiasddr]

I've been thinking about replacing the hoses under the hood for a while now, still not having any issues related to the work you did? Also, thanks for the great write-up, it looks like something I would make.

Since we both have older model bugeyes, I feel I should mention that you should check your trunk seal for rust, if you remove it just get some silicone RTV adhesive for a quick reinstall. If your dashboard clock goes out it's a quick solder job with removal of the clock from the dash being the hardest part, and take care to wash down your engine every once in a while as well as cleaning your MAF sensor (both sides and inside where you can't easily see) to keep a smooth idle. Just some stuff I've had to take care of over time.

[kaminaricelica07]

I just order this same set today after seeing your post. Might be ordering more by the foot as I see fit. Thanks for the write-up!

[Dn41387]

Thanks, great post,will be very helpful pretty soon for me.

[kabz]

Awesome write-up. This'll help when I put my blobeye back together, though I did take pics and save and label all hoses and anything that would fit in a ziploc.

Hoses D and G (I'm fairly sure) are the head breathers that are Y'd together by the IC hard-line, and routed to the turbo inlet via Hose B. I guess they get routed like that so they don't end up heating the inlet air any more than they have to. [You have them labeled as IC coolant lines]

[Luuuuukebradley]

Hey I was wondering if you had to drain the coolant in order to change Hose A: turbo coolant hose.

Thanks,
Lucas

[Brother EddieJ.]

Originally Posted by Luuuuukebradley

Hey I was wondering if you had to drain the coolant in order to change Hose A: turbo coolant hose.

Thanks,
Lucas

Nope just suck some out with a turkey baster.