Jeepnick

Been plagued with low vacuum issues for a few years now. Pulling even a slight freeway grade will make me lose heat or AC until the road levels out and the engine develops more manifold vacuum. I have checked hoses under the hood and all look good. I think I'll pull the accumulator "football" under the right bumper. I casually looked at the area a while ago and it looked like I might need to remove some underbody or inner fender plastic panels held with single use plastic rivets.

Anyone know the easiest way to get to this? It's a '99 Classic.

94JeepCherokeeMan

My buddy slick761 rerouted the vac ball, you could ask him how to do things with it.

chadh92

I've got a 96, but mine came out just by getting underneath the front end and unbolting a little V-bracket (it's shaped like a V in my memory). That's the only thing that was actually preventing you from reaching it if i remember correctly.

If it's different for the newer models, at worst you'll just have to take the bumper off.

Jeepnick

got it! Remove the plastic bumper end cap. Drill out a pop rivet, remove two 6mm screws (10mm hex) and nuts, peel back rubber under cover, remove two 4mm screw (8mm hex) up high. Pull out to the right.

My ball accumulator is like new, holds vacuum fine, hose connection to it will stick to my finger with engine running, no appreciable vacuum loss that I can tell.

What's next?

Bodyguy

you should have so one way valves inline that comes from the motor to a T. That valve allows the engine to pull a vacuum in the system but not loose vacuum when the engines vacuum drops. Check that valve and make sure its operating properly.

Bodyguy

Jeepnick

I'll check them. thanks!

retread

check vacuum first make sure you need to if vacuum to it is low go from there

webb'scherokee

If you are a Motor Head (no offense intended) , or a M.H. wantabee, at some point you are going to want to have a vacuum gauge in your tool box.

If you don't already have that tool, now might be a good time to spring for one. They are very inexpensive and last forever, unless the buddy down the road who you loaned it too hasn't returned it yet. I say "yet' it's only been 2 1/2 years.

If your vacuum chamber is in the back, find the line leaving the engine bay and cut the line at that point. Of course, once you cut the vacuum line, you will need to cap both sides of the cut and tape it with red tape. That's so you can easily find the cut when it comes time to splice the 2 cut end together to restore the V. chamber back into the system.

Once you have isolated the V. chamber and capped the line going back to the bumber, does the vacuum restore itself. If so, then you've discovered that the V. leak is either in that line or it the V. chamber, or both.

webb'scherokee

If it's the V. chamber for sure, that would be the time to remove it from the bumper location for repair, instead of replace. Next get a section of vacuum hose and attach it to the ball's fitting . Next submerge the ball in a bucket/container of water and at the same time, blow air thru the hose and look for the escaping air bubbles in the water. Once the leak is located, dry the thing really well and patch it with a ample amount of epoxy cement of your choice.

Let us know how it all works out !

Jeepnick

The ball seems fine and the hose that goes to it from the tee seems ok as well. The hose that goes to the tee from the intake manifold looks good as well. I haven't checked the one that goes to the heater controls and I think that's where the problem lies.

Any help here?