I recently developed an upper fuel leak on the front Primary Injector so I'll be sending both off for O-Ring replacement, flow testing and thorough cleaning. I might as well do a vacuum line replacement while the Rat's Nest is out.

Are there any known problems associated with the replacement of the OEM 3.5mm [petrified lines] with 4mm silicone lines?? Of course, ..I'll be using zip ties on all the new lines??

 

You would be ok, but why don't you just use 3.5mm silicone?

 

Baker Precision:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/baker-precision-high-temp-silicone-vacuum-hoses-330365/

As you can see, quite a few members use them.

 

I can't locate 3.5mm silicone hoses in any local auto parts stores. Plus,...A'Zone sells a silicone hose kit that consists of 4mm, 6mm, 8mm and 10mm lines in various lengths. Not bad for 15 bucks and they're available in three different colors.

 

Thanks Mahjik. I'll go back to A'Zone to look at the Kit a little closer. If the Specs are way off compared to Baker hoses,..it'll be a no brainer!!

 

I was able to get 3.5mm lines at Autozone, I dunno what ur talkin' about.

 

I couldn't find any 3.5mm over here, but I used 4mm, and it's been holding up for the past 2 years.

 

They were not available in my venue.

 

You get what you pay for!

I tried using one of those kits and changed only a few lines. The test run was fine for a couple of miles then at the end of a five mile run, my car was running like crap. The hoses had collapsed and got sucked closed from the vacuum and the heat. These cheap hoses did not have anywhere near the structural integrity nor wall thickness of the quality silicone lines (hose techniques).

They did give me my money back though.

chuck.

 

Read some of the old posts by HighTempSilicone. He made a very good argument that all silicone lines are not the same. I personally wouldn't use anything cheaper than his stuff or baker precision.

Dave

 

Hightemp silicone have a kit for fd car but I think is expensive

http://www.hightempsilicone.com/product/RX7VITONKIT

but why we need 6-8mm hoses?
and also why 3,5mm and 4mm? if we have 3.5mm i think that we dont need 4mm.

 

3.5mm is what I recommend. The 4mm fits, but it's not as snug. A proper vacuum line will fit nice and snug, and won't need any help to stay on properly.

DO NOT buy any vacuum line from a local auto parts store. You will waste your money and have to do the job over again. Buy QUALITY silicone vacuum line from either HighTempSilicone or Hose Techniques. They're thick-wall, proper fitting line that will last damn near forever, fit right, and not give you problems.

Quality line is nice and thick-walled, and will not kink on a tight radius bend. Also, it won't suck shut under vacuum, and with a proper fit it won't pop off under boost.

Do it once, do it right.

Also, proper fitting vacuum line does NOT need zip-ties or glue to help hold it on. Many of the early vacuum hose writeups were done by people who had line that didn't fit super tight and they had to compromise for that.

Dale

 

Dale, when you say do not buy from a local auto parts store, are you referring to the silicone hoses only, or to rubber also? I picked up some GATES 4mm heavy walled rubber vacuum line the other day with the intention of replacing my rat's nest lines (I am not completely sold on the idea of silicone yet) but I defer to those with more experience in the matter. I bent a 6" long piece into a a pretzel and it didn't collapse when I applied either vacuum or pressure.......

 

Thanks guys. Good solid information and advise. Sometimes a little slap of reality is all it takes!!

I'll get online and order the hoses. I'm thinking about 20ft of 3.5mm and 5ft each of 6mm and 8mm??

I'll post a few photos of the Nest once it's completed.

Q1)- What do y'all recommend I use to clean the Solenoids and electrical connections with?? I was thinking of spraying a little engine degreaser on a small cotton towl and wiping everything down??

Q2)- Who on the Forum can I contact for parts polishing. I'd like to get my alternator done.

 

Were you need the 6mm or 8mm hoses?
Why the high temp silicon kit suggest 3.5mm and 4mm hoses for rx7?

 

There is a 6mm line at the purge control lines, one from the vertical hardpipes to the rats nest, and the wastegate/precontrol actuator lines are also 6mm.

IIRC I only used 8mm at the PCV.

Dave

 

I just wish Baker or HTS had yellow 3.5mm available.....

 

FYI,

Baker does not sell 3.5mm silicone hoses. They only sell 4mm at $1.20 p/f.

And you're right, Baker and HTS do not offer the color Yellow.

 

You don't want yellow, trust me. Unless you are very meticulous (read ****), you'll get those dirty just installing them. And they don't look that good once they do get dirty.

 

Hey Mahjik, what color did you go with when you did your Vacuum lines??

 

The silicone vacuum line from the rice aisle is what I'm referring to. If you're planning on doing a total vacuum line job, I wouldn't use the rubber line - it will get hard and cause problems in not too terribly long of a time. It's OK if you have to replace a few lines in a pinch when pulling an upper intake manifold or something, but I would replace it with proper silicone when you can.

BTW, I'm using black vacuum lines. Most all of the colors simply look dirty over time. Also, I like the "stock enhanced" look with the black, but glossy, vacuum lines.

Dale

 

A purist. There's so few of us left!!

 

Red, but I wish I just stuck with black.

 

I'll throw in another $0.02 worth just to give you something to think about.

I did my vacuum hoses with 4mm I.D. instead of 3.5mm like everyone suggests. I had originally ordered the hoses from hosetechniques. They used to advertise 4mm and actually ship you 3.5mm. Anyway, so I sent it back and bought OBX silicone hose from a local speed shop. The quality is the same as the hosetechniques or baker precision. I also bought a crap load (about 30-35, I think) of the OEM spring clamps @ ~$1.00 per clamp. I personally like this method better than the 3.5mm and tie-wrap method because:

If you're not replacing the solenoids, they are probably very brittle from the heat and age. Ask me how I know? I broke about half of mine trying to very carefully install the 3.5mm hose from hose techniques. I think the 3.5 is just too tight. If you ever have to go back to repair any of the lines, chances are that you're gonna have to cut the lines to remove them because they are so tight, to avoid damaging anymore of the solenoids. And those solenoids aren't cheap. ~$50 a pop for the ones under the intake manifold and ~$200 for the unit (wastegate and precontrol) bolted to the front of the intake manifold. The OEM spring clamps hold the hoses on tight and they don't ever loose their tension. So, you get the benefits of:

a.) ease of installation
b.) ease of removal
c.) less likely to damage a solenoid during the process
d.) more cost effective - long term
e.) no difference in effectiveness or performance vs. 3.5mm

The only disadvantage that I can see is that the hose wall thickness is less with the 4mm. So, you cannot bend the hose as tightly as the 3.5mm, which means that you just have to extend the hose length just a little to correct this.

 

what are the length's from all the hoses you need to replace them all ?