My lower vacuum pump fell off. Looks like 2 of 3 bolts are gone and one is in there and broken. They look like m6 or m8, I'll get that easy enough I think. But it seems the actuator rod fell out that rides on the little cam in there and pushes on the pump itself.

Anything special about this rod? Can I make one out of stainless or something? What's the length? or, does anyone know where I can source one?

Put on new booster and mastercylinder today. Need help to bleed it, but seems the "low vacuum light" (antilock and brake light on at same time) is still on. All lines seem supple and non cracked. When pushing on the brake I can almost feel the individial strokes of the vacuum pump. Any ideas? Is this just cause there is one pump and not 2? I heard you can run them on 1 pump, I know my old Ford diesel did. Thanks guys.

-Luke

 

You need to plug/cap/remove or whatever it takes to bypass that lower pod. Then, life will be swell.

 

IIRC the lower pod is just going along for the ride and dosen't actually create any vacuum in our applications. You can just put the cap back on to seal it and go your way.

Search Bearkillers posts and you will find LOTS of info on the vacuum pods and how they work.

 

i still have my old pod and push rod. i can get you a length and diameter. however, i would tell you to just block it off. i still have 20in Hg. running the single pod.

 

I would put it back on. Even if it is only a failsafe.

 

As long as it's still good, I would use it too. Add in some check valves to the lines too, so that when one fails, the other can take up the slack without the vacuum leak.

 

with it dangling on the hose, would I be LOOSING vacuum as is? WIth my new brake booster and master cylinder, she really STOPS now! But the "low vacuum" lights are still on. I havn't hooked up a vac gauge yet, guess I could easy enough, but just got a hand a few hours ago to bleed the system then I went straight to Sunday dinner with the ol lady so I havn't looked yet.

If someone had a rod they would sell, find a source from, or just tell me I can make my own I'd appreciate it. I got plenty of stainless steel tubing from 1/4", 3/8", and 1/2" I could use with plugs on the end welded on. Lemme know if anyone thinks that would not work for some reason. Also if someone had a length I could work I'd use that, even though I would assume it's the distance from the high lobe of the cam subtract the length of the pod stoked.

Thanks for the help fellah's

 

Why on Earth would the lower vacuum canister even be there if were doing nothing? It is pumping every time the eccentric goes around, same as the upper canister.

I suggest you remove the whole vacuum pump assembly and see what all is missing. And then replace the o-rings while you have it off there. There are several in there and they are cheap.

There are a combination of bolts and studs with nuts holding the pods on, the bolt size listed as m6-1.00x20mm if you didn't get that info yet, studs and nuts are m6-1.00.

Cummins p/n for the Push Rod is 3914937

Accessory drive gasket 3938655
Vacuum Pump to vacuum pump bracket and vacuum pump to accessory drive support o-rings (2) needed 3910260
Power steering pump to accessory drive support o-ring 3911805
Lower vacuum pump bracket to accessory drive support o-ring 3912822

 

If your still using the truck your oiling the ground. The vac pump assy does get oil, slinger fed off the the front geartrain. If your going to run with one pod, don't know why you would, but if you are, you better cap off that vacuum pump bracket where the push rod fell out from.

 

Your system may still be sealed as far as vacuum goes. ?But like sdstriper, you should be losing lots of oil if you have not blocked off the dangling pod from the moto.

 

if you're still considering making your own push rod, i'll get you some dimensions tomorrow morning.

 

OK, I did a bit of searching and apparently QC was a bit of an issue at certian times. It appears that several people have found out that the actuator rod was MIA from the factory........... The lower pod SHOULD be doing something not just riding along.......

 

Mine definately was. When it fell out, I felt my already hard brakes got harder and the truck couldn't recover it's vacuum so the lights would go out like it used to.

Thanks for the part number sdstriper. I'll bring them to my rip off cummins dealership and see what they want for them!

ODDLY, I"m not "puking" oil. maybe a small leak, but not much. ALways a little oil there since the pod was loose, but my oil level hasn't changed when I checked yesterday when I got to work?? It's just splashing in there form the timing casing right?

 

I wouldn't expect it to run you out of oil but I am surprised it's just a dripper... I guess I shouldn't be all that surprised, it doesn't get pressure oil feed like the newer designed vacuum pumps do.

Whatever oil comes off the gears in the gearcase. Thats how it gets lubed. Or not...

 

I"m suprised too. When I had my timing pin out it made more of a mess. THis is dripping maybe.

Anyone know if making my own rod would be foolish? Does it need to be made of anything special, or have any special shape to the end that rides on the cam?