Deteriorating Vacuum Harness Elbow

Fulton_Hogan

Fulton_Hogan

TJ Enthusiast
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Nov 11, 2020
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528
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Florida
I had the hood open today, adding a secondary return spring to my throttle (it's a 2005 4.0L and only had the onboard/inline spring) as a short term experiment. I was poking around, looking at the vacuum lines just to understand where everything connects. I've never really paid attention to them, but I'm glad I did today.

While lightly tracing the line that runs from the speed control back towards the engine I got to where the main harness plugs into the block and the rubber elbow was loose. I thought that's not good and I when I touched the elbow it was soft. Like, it would crumble to dust if I tried messing with it more than I did.

I circled the part I'm talking about and you can see the flake of rubber that fell off below the elbow.

Inked20210626_114712_LI.jpg


So I came right in, fired up this forum and searched for help on what the heck I needed. A Mopar 55037637AB vacuum harness is now on order.

I'm assuming this will be a detach and replace procedure? Meaning, unplug old and plug in new; just taking time to not crack, break, or tear any of the other connections in the process? Any other tips from those who have done this swap? Thanks in advance.
 
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I didnt realize how cheap the vac line is, I need this elbow too. ive done a few other rubber fittings when I could find them $$ but figured the price on this would have been way out of line. thanks for bringing this up, ill be placing a order as well.

as for any tips.. I usually have pretty good luck with patience and a firm grip of the rubber fitting and slight twist when removing vac lines off barbed fittings.
 
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Thanks all.

It sounds like I don't necessarily need to swap the whole harness. Once I get the replacement part, I could just remove the new elbow and replace the old one, leaving the rest in place?

I've not been having any noticeable problems up to now, so couldn't the rest of it fall under the "if it ain't broke don't fix it" rule?
 
P man said:
Wish I had known you needed this I would have shipped you a brand new mopar harness for the cost of shipping
Click to expand...
No worries, although I appreciate it!

I bought 2 just in case I mess something up on the one. They weren't expensive, under $20 each.

At any rate, I'll have a spare plus extra parts.
 
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Most of the rubber hoses and fittings on my ‘02 are in good shape except the ones coming out of the intake manifold for the smog junk. I think it’s the heat of the engine that gets ‘em.

I replaced the 90 degree elbow 6 months ago with a Dorman and it’s already failing. So I wouldn’t recommend them.

Gonna look for some silicone ones, I think they’ll hold up much better.
 
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I have been having some high idle issues the last few days and thought it was a vacuum leak so I just went out and checked this on my 03 and it's loose as can be. I guess I will take it off and hit Oreilly's and Autozone tomorrow and see if I can find a replacement.
 
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Fulton_Hogan said:
I had the hood open today, adding a secondary return spring to my throttle (it's a 2005 4.0L and only had the onboard/inline spring) as a short term experiment. I was poking around, looking at the vacuum lines just to understand where everything connects. I've never really paid attention to them, but I'm glad I did today.

While lightly tracing the line that runs from the speed control back towards the engine I got to where the main harness plugs into the block and the rubber elbow was loose. I thought that's not good and I when I touched the elbow it was soft. Like, it would crumble to dust if I tried messing with it more than I did.

I circled the part I'm talking about and you can see the flake of rubber that fell off below the elbow.

View attachment 261564

So I came right in, fired up this forum and searched for help on what the heck I needed. A Mopar 55037637AB vacuum harness is now on order.

I'm assuming this will be a detach and replace procedure? Meaning, unplug old and plug in new; just taking time to not crack, break, or tear any of the other connections in the process? Any other tips from those who have done this swap? Thanks in advance.
Click to expand...
Lots of vacuum line connections are available at your local auto parts store. Just pull, plug, and play.
 
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Found reinforced silicone elbows at HPS performance. They’re expensive, but I’m tired of replacing stuff like that with the cheap crap you get at the auto parts store.

Around $25 an elbow, comparable to OEM cost, but will last the life of the Jeep.
You can’t beat that IMHO. 😸
 
Modoc Guy said:
Found reinforced silicone elbows at HPS performance. They’re expensive, but I’m tired of replacing stuff like that with the cheap crap you get at the auto parts store.

Around $25 an elbow, comparable to OEM cost, but will last the life of the Jeep.
You can’t beat that IMHO. 😸
Click to expand...
Just for the sake of conversation, and saving follow-on readers the headache of guessing, what size elbow did you buy?
 
Fulton_Hogan said:
Just for the sake of conversation, and saving follow-on readers the headache of guessing, what size elbow did you buy?
Click to expand...
Haven’t bought it yet, been on the road. But they have 1/4” and 3/8”. 5/16” too, if I remember correctly.

Those sizes will do for our Jeeps.

Planning on ordering once I get home and confirm the sizes. I’ll post what I get. 😸
 
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Modoc Guy said:
Haven’t bought it yet, been on the road. But they have 1/4” and 3/8”. 5/16” too, if I remember correctly.

Those sizes will do for our Jeeps.

Planning on ordering once I get home and confirm the sizes. I’ll post what I get. 😸
Click to expand...

Totally understand, and thank you very much!

Hopefully it'll help someone else in the future.
 
freebo86 said:
What’s this secondary return spring you speak of and primary?
Click to expand...

The spring I called the "primary" return spring is the one integral to the throttle body housing. It is what snaps the throttle closed when you press it open via the external throttle arm.

The spring I called the "secondary" return spring is one I added. It is a generic throttle return spring that I connected to the hole in the throttle arm and the accelerator cable bracket.

Basically, like this: http://www.tmar.net/throttle_spring.htm

I did not build up an end piece attached to the throttle arm, nor drill anything as in the above link. There is an existing hole in the accelerator cable bracket which could be used. Ultimately I just bent the ends of the "secondary" return spring to take up slack and went with it.

The goal was to smooth out throttle sensitivity at low speed. It's probably extraneous, but in the limited driving I've done since, it seems like it did accomplish what it was intended to do.
 
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Fulton_Hogan said:
The spring I called the "primary" return spring is the one integral to the throttle body housing. It is what snaps the throttle closed when you press it open via the external throttle arm.

The spring I called the "secondary" return spring is one I added. It is a generic throttle return spring that I connected to the hole in the throttle arm and the accelerator cable bracket.

Basically, like this: http://www.tmar.net/throttle_spring.htm

I did not build up an end piece attached to the throttle arm, nor drill anything as in the above link. There is an existing hole in the accelerator cable bracket which could be used. Ultimately I just bent the ends of the "secondary" return spring to take up slack and went with it.

The goal was to smooth out throttle sensitivity at low speed. It's probably extraneous, but in the limited driving I've done since, it seems like it did accomplish what it was intended to do.
Click to expand...

Gotcha. Yah I did the same MOD on my 05 LJ. I purchased the OEM one and added it, helped a bit but not much, I added a second spring in addition to it and now it really feels like my old TJ did.
 
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The first place I ordered the vacuum lines cancelled my order, so I had a slight delay in completing this.

The second place I used (moparfactoryparts.com) should have been the first place I used. Normally they are, but I tried another place and hit the snag. Lesson learned.

Anyway, I received my lines on Saturday. On Sunday I pulled an elbow and valve off a new harness to swap with the old. It took zero effort to pull the old, deteriorating elbow off the engine; I honestly don't know how it hadn't fallen off on its own. It was basically hanging on the manifold stem. I plugged in the valve on the harness first and then the elbow to the stud. Looking good now.

Out with the old.

20210718_135453[1].jpg


In with the new.

20210718_135538[1].jpg


I have not have a chance to drive the Jeep since, but I'm not anticipating anything going crazy.
 
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