After 14 years, the vacuum hoses on my truck are dry, cracked and just plain wasted. So I started this project by purchasing 10ft of 5/32" vacuum hose to replace everything under the hood. 10ft is not enough, I need more, like 15ft more but for now the 10ft I did replace was well worth it. Everything I took off was cracked and/or brittle. Who knows how many small leaks I had going on in there...and worse...how many do I still have? With a vac gauge hooked up readings are excellent so I can only imagine it getting better once this project is completed. I replaced one hose at a time using the old hose to measure up the new hose. I have 10ft of 1/4" as well but I didn't get to that tonight. I am guessing 25 feet of 5/32" vac hose should be plenty to replace everything under the hood.

This is one inexpensive way to make your older KA/VG run better.

Modified by Reverend D at 7:34 PM 9/4/2009

Modified by Reverend D at 7:34 PM 9/4/2009

Modified by Reverend D at 7:36 PM 9/4/2009
Modified by Reverend D at 7:37 PM 9/4/2009

Hose it cheap and cracked dry rotted lines can kill performance and make truck run bad. get plenty and good luck. This is the one thing most people overlook as a tune up thing. Cheap easy and makes a world of difference.

this is why you delete them....

well i guess on the newer trucks it may mess with stuff... but yeah i only have one hose!!! and its only a little over a foot long

I am sure my mpg's would drop like a rock if I started deleting lines. I am rock steady at 26mpg's this year.
Modified by Reverend D at 12:21 AM 9/5/2009

oh god yes... they would

mine went from 22ish in city.... to only 18 on the damn highway!!!

I replaced the rest of the hoses tonight. Easy job, a couple tight spots but I don't think I had more than 30 minutes into the job tonight, including the test drive. I am now reading 21"hg at idle and it goes as high as 25" during decel. A couple of my EGR actuation hoses were in really bad shape when I got to them. I'd say that 20ft of 5/32 vac hose is plenty for the KA24E. I have lots left over now since I went for 30 ft total. I also replaced a couple questionable vac tees as well. 14 year old plastic really can't be trusted much.

It runs so nice now. Smooth, responsive and braking is once again noticeably better. An easy maintenance item that easily gets overlooked.

Tools needed:

Box Cutter- For removing old hoses.Side Cutters- For cutting new hose to length fast.Long Flathead Screwdriver- For the one of two pesky hoses that want to stay where they are.20ft: 5/32" vac hoseVacuum Tees

Skill Level: Intermediate (Hoses must not be mixed up)

Drove the truck 40 miles to work today and it was a really nice ride. The brake pedal is much more firm than before. Idle and take off are both smoother than before too. The engine just has a more confident feeling all through the RPM spectrum. I must have had a decent size vacuum leak at the EGR hoses because of the brake pedal improvement I am feeling.

Rev_D21 wrote:I replaced the rest of the hoses tonight. Easy job, a couple tight spots but I don't think I had more than 30 minutes into the job tonight, including the test drive. I am now reading 21"hg at idle and it goes as high as 25" during decel. A couple of my EGR actuation hoses were in really bad shape when I got to them. I'd say that 20ft of 5/32 vac hose is plenty for the KA24E. I have lots left over now since I went for 30 ft total. I also replaced a couple questionable vac tees as well. 14 year old plastic really can't be trusted much.

It runs so nice now. Smooth, responsive and braking is once again noticeably better. An easy maintenance item that easily gets overlooked.

Tools needed:

Box Cutter- For removing old hoses.
Side Cutters- For cutting new hose to length fast.
Long Flathead Screwdriver- For the one of two pesky hoses that want to stay where they are.
20ft: 5/32" vac hose
Vacuum Tees

Skill Level: Intermediate (Hoses must not be mixed up)

Rev_D21, thanks for all your help, but I have to revive this older thread because I can't PM yet.

You mention 1/4" hose in the first post but left it off the final parts list. Do you need 1/4" or just 5/32"?

Thanks man.

A little more info for my question...

I've search the forums a found two external parts websites recommended here for vacuum line references (both with the same diagram).

http://www.nissanpartszone.com/Page_Pro ... geID=21861

The last diagram on this page.
http://www.courtesyparts.com/hardbody-t ... _5421.html


It looks like there are three 'groups' of vacuum hoses.

1) the 22310B group (that kind of circles through the diagram from 7 o'clock to 1 o'clock and then around from 1 o'clock to 4 o'clock)
- I added up all the lengths (3400mm = 133.8" = 11' 2"). So is this the 5/32"??

2) the other 22310 group at the bottom (22310H, 22310HB, 22310HC, 22310HD, 22310HE)
- Are these 5/32"?

3) the 14912 group at the top left (14912M, 14912MA, & 14912MB)
- What are these? 1/4"?

Thanks in advance.

There is only a short length of 1/4" hose and that runs off the charcoal canister. The rest is 5/32nd hose. It's tough to go by the parts breakdown, it's best to replace the hose one section at a time. Buy an entire roll of 5/32 hose on a spool, it's better to have too much than too little.

I am going to replace all the vac lines on my 91 D21 with the 4cyl. When I pulled the vac line from the charcoal canister I found a small brass reducer inside the line, anyone know what this is for and if it has to be there? I checked the truck running and it seemed to run better after I removed it.