[starrynight2331]

Hey guys,

Last night I was removing my power steering reservoir to deep clean it (can’t afford replacement right now) and I didn’t realize I was putting weight on the world’s tiniest tube and broke it.

No fluid came out, I’m sure it’s an air-related thing, which is good. But I have no idea what it is. I do know it’s supposed to be soft and pliable, and mine is rigid and brittle, so it probably could have used replacing anyway in my defense. Guess I’ll tape it just for right now.

I found a picture online and have it marked.

My van is a 2004 Limited, 3.8L.

 

[Electrodude]

Hey guys,

Last night I was removing my power steering reservoir to deep clean it (can’t afford replacement right now) and I didn’t realize I was putting weight on the world’s tiniest tube and broke it.

No fluid came out, I’m sure it’s an air-related thing, which is good. But I have no idea what it is. I do know it’s supposed to be soft and pliable, and mine is rigid and brittle, so it probably could have used replacing anyway in my defense. Guess I’ll tape it just for right now.

I found a picture online and have it marked.

My van is a 2004 Limited, 3.8L.
View attachment 68720

I’m pretty sure you found the secret knee actuated “disable cruise control” switch. That’s a vacuum line for the speed control.

 

[Road Ripper]

Yup, those plastic vacuum lines can be easily spliced back together with a small section of rubber vacuum hose.

 

[starrynight2331]

Thank you both. That’s a HUGE relief, but my husband will be sad he might not be able to use cruise! Time to go use tape for now haha.

 

[Mopar-Mofun]

Thank you both. That’s a HUGE relief, but my husband will be sad he might not be able to use cruise! Time to go use tape for now haha.

I would advise not to use a rubber hose for that size. Rubber under vacuum collapses and the cruise may NOT turn off no matter how hard you pump or slam on the brakes.

Synthetic tubing like superthane (70 durometer) works in extreme low and hot temperatures under hood and will not collapse under vacuum.

If you mend the original tube, hold it together and bond with plastic safe epoxy. Once epoxy cures, wrap tightly with high temperature electrical tape rated for 80C (175F).

 

[LPete]

I would advise not to use a rubber hose for that size. Rubber under vacuum collapses and the cruise may NOT turn off no matter how hard you pump or slam on the brakes.

That’s just not true. You must not have been around cars in the 80s and earlier. They all used rubber hose for vacuum lines, and the lines never collapsed unless they got oil soaked. Brake boosters usually have a 3/8” vacuum hose and it doesn’t collapse. I think they probably went to nylon because it’s cheaper.

If it does somehow collapse, the cruise control won’t stay engaged. All the functions are built into the servo the line goes to. The hose is just a vacuum source, and the cruise would just stop working if the hose got plugged.

 

[Mopar-Mofun]

That’s just not true. You must not have been around cars in the 80s and earlier. They all used rubber hose for vacuum lines, and the lines never collapsed unless they got oil soaked. Brake boosters usually have a 3/8” vacuum hose and it doesn’t collapse. I think they probably went to nylon because it’s cheaper.

If it does somehow collapse, the cruise control won’t stay engaged. All the functions are built into the servo the line goes to. The hose is just a vacuum source, and the cruise would just stop working if the hose got plugged.

Eaton made the original cruise vacuum units from the K-car era up till early 2000s. Yes, one can get away with a rubber hose on the Eaton setup. The new system is not like that.

 

[LPete]

What does that have to do with it?

 

[Mopar-Mofun]

What does that have to do with it?

simple, different cruise control units from the old era to our era.

 

[Road Ripper]

I call bunk. I've used vacuum hose to splice plastic hose before, and it works fine. Why? Partly because mostly ALL vacuum hoses are made of rubber, with some even being made out of thick-walled silicone! Ever since cars had vacuum systems, rubber has been used for vacuum hoses.

I think the plastic is used for the vacuum line because it is a long run, needs to be flexible to move with engine movement and out of the way for repairs, and may be under longer time periods of high vacuum compared to other systems. Drawback is it gets brittle with engine bay heat. Splicing the ends together with a small section of hose, the hose will NOT collapse because the plastic line is INSIDE of the hose. All the hose is doing is holding the two ends together, butted together underneath the rubber hose. Nylon line would get too soft with engine bay heat and collapse, so that's why PVC is used. Cheap and gets the job done for a reasonable amount of time past warranty, but not forever.

 

[Baron]

would CC really be stuck on if the hose collapses from a vacuum being pulled?

that sounds like it would fail to actuate fully, not be stuck on, doesn't it use the vacuum pressure to pull on cables?

 

[LPete]

would CC really be stuck on if the hose collapses from a vacuum being pulled?

that sounds like it would fail to actuate fully, not be stuck on, doesn't it use the vacuum pressure to pull on cables?

No, it wouldn’t stick on. The servo that the hose is hooked to has solenoid valves inside. One applies vacuum from the source to the diaphragm that pulls on the throttle cable, and the other one vents that vacuum. By switching between the two the PCM controls throttle opening and vehicle speed.

Even if that hose got blocked while the cruise was turned on, the PCM would keep doing its thing until the vacuum in the reservoir in the servo ran out, then the cruise control would just stop working.

 

[LPete]

I call bunk. I've used vacuum hose to splice plastic hose before, and it works fine. Why? Partly because mostly ALL vacuum hoses are made of rubber, with some even being made out of thick-walled silicone! Ever since cars had vacuum systems, rubber has been used for vacuum hoses.

I think the plastic is used for the vacuum line because it is a long run, needs to be flexible to move with engine movement and out of the way for repairs, and may be under longer time periods of high vacuum compared to other systems. Drawback is it gets brittle with engine bay heat. Splicing the ends together with a small section of hose, the hose will NOT collapse because the plastic line is INSIDE of the hose. All the hose is doing is holding the two ends together, butted together underneath the rubber hose. Nylon line would get too soft with engine bay heat and collapse, so that's why PVC is used. Cheap and gets the job done for a reasonable amount of time past warranty, but not forever.

Probably beating a dead horse here, but I’m pretty sure the lines are nylon. I looked up specs, and nylon tubing is rated for 200 to 240 degrees. Both PVC and polyethylene are well below 200 degrees.

 

[Road Ripper]

Probably beating a dead horse here, but I’m pretty sure the lines are nylon. I looked up specs, and nylon tubing is rated for 200 to 240 degrees. Both PVC and polyethylene are well below 200 degrees.

Aw dang, I got mixed up. You're right of course. PVC is a fancy way of saying vinyl, which gets soft with heat. That wouldn't make sense to use. Thanks for the catch!

 

[Mopar-Mofun]

No, it wouldn’t stick on. The servo that the hose is hooked to has solenoid valves inside. One applies vacuum from the source to the diaphragm that pulls on the throttle cable, and the other one vents that vacuum. By switching between the two the PCM controls throttle opening and vehicle speed.

Even if that hose got blocked while the cruise was turned on, the PCM would keep doing its thing until the vacuum in the reservoir in the servo ran out, then the cruise control would just stop working.

The cruise control on the old 1978 T&C wagon with the 440cid collapsed hose caused the cruise to remain stuck ON. I had to turn the key off to kill the engine. Sat on the side of the road messing around with it till I found the dumb hose on the 4 barrel.

If it now fails SAFER with a collapsed hose, then someone became BRILLIANT.

Glad this went on for several more postings. Yes, having the right hose material really helps for under-hood applications with extreme temps.

 

[whereisthelift]

I have had three of those little tubes damaged by mice. I always use model airplane fuel tubing. just put a couple of inches of tubing as a splice. Works perfectly.

 

[Rolatnor]

I don't see a problem with a rubber hose if it is reinforced rubber hose