Vacuum pump gone bad?

[IDIBRONCO]

Now to update this older thread. Yesterday afternoon, I pulled up to my garage to unload a ladder and my ATV ramps from the bed. Then I headed over to some friends' house to pick up the siding for my garage addition. As I backed out into the street from my garage, I had nothing but a hard brake pedal. I glanced at my vacuum gauge and it was reading 0. When I got into their driveway, I popped the hood to look. I saw oil that had been flung all the way back to the heater box and the firewall. I new for sure that the vacuum pump had gone bad so I shut the hood again and went on doing my business. This morning, I went outside to change the pump and put the old, barely functioning pump that I carry as a spare back on the truck. I found that the back of the drive unit had disappeared like so many others in this thread had. Since there is nothing to connect the drive shaft to the pump part that works the pod, I'm assuming that the pod itself is still good. I have a couple of old vacuum pumps that are still good so I'm going to change this pod over to one of the old drive units. Since it's going to be below freezing for the next couple of days, that sounds like a good project to do inside my house. I won't get the new combination put on my truck until Sunday or Monday when it warms back up a little bit.
My thinking for doing this is that it seems like it's the drive units themselves that are going bad in this thread and not the vacuum pods themselves. Maybe my way is a solution for keeping the vacuum brakes in the future?

 

[Rdnck84_03]

Looking at that I'm going to guess that it had some sort of an eccentric on the shaft. Probably wouldn't be too hard to turn something out on a lathe and cap the back with a freeze plug.

That's for someone that doesn't have spare pumps laying around to use for parts.

James

 

[IDIBRONCO]

This is the first time that I've seen the inside of one personally. It sounds like you're right. I don't know what actually failed inside it, but the oil is a silvery metallic color like there's a lot of metal shaving in it. The main vacuum hose looks like someone smeared silver anti seize on it. And it's almost as pleasant to get off of yourself.

 

[Rdnck84_03]

Since the shaft is threaded I'm guessing that whatever was in there has probably been loose and wearing for a while before finally coming completely apart and pushing the back cover off.

Kinda makes me think that this is how most of the recent failures I have seen were like this, it may be a good idea to figure out what it takes to disassembled the new ones and apply some red loctite before installation.

James

 

[IDIBRONCO]

I can report that the spare did wonderfully. At least it makes enough vacuum for me to stop.