Broken vacuum pump

[CumminsPower98]

Last Wednesday I started out on a cold morning in Beach, ND heading back east to get another trailer in Indiana. I stopped at a rest area and before I got back in the truck I took a quick look underneath to check for leaks and was shocked to see everything under there, front to back, completely soaked in motor oil and dripping off of everything. Usually this 309k mile truck is nearly spotless under there so this really got my attention in a hurry. I found it was leaking from the rear vacuum pump seal and that the power steering pump was slightly shaking. Right away I knew that one of the driven tangs had broken off of the PS pump coupler but this didn't explain why the pump was shaking because even with a bad drive there is no way for the pump to move with four solid mounting points to the vacuum pump. I topped off the oil and drove on. I made it to Fargo, ND where I would be most likely to find parts. I went through 4 quarts of oil in 250-300 miles (not sure when it let go). I jumped on the net to locate parts stores and the first one I called had both pumps in stock. I also went over to the Cummins dealer and got the vacuum pump seal kit in case the pump was ok.

Now I had all the parts, tools and supplies needed to do the job but no place to do it as it was cold and windy out with night coming on soon so I pulled out the latest addition of the TDR Travel Companion to see if there was anyone listed near by and sure enough there was Dave, who offered an indoor heated place to work, in Moorhead just 6-8 miles from where I was parked. He was listed for emergencies only so I wasn't sure if this constituted an emergency or not but I went ahead and gave him a call. He was happy to help and made room for me in his garage and then came over to where I was parked at the Flying J and led me back to his place.

I pulled in there and got to work, he also helped me out some. Well I got it all apart and sure enough one of the PS pump coupler tangs was broke clean off but what surprised me the most was that somehow it caused one side of the rear of the vacuum pump to break off so this explains why the PS pump was shaking slightly and why it was dumping oil past the seal. This really is a weak point. My cousin's '97 broke one off and caused three teeth of the vacuum pump gear to break (I still don't understand what can bind up in there so bad to cause these other breakages though). Both tangs broke off on my uncles '98 only on the vacuum pump side with way fewer miles then mine. I knew mine were worn on the PS pump and should have changed it last time I had it out but it wasn't leaking at all so I put it back. I had done a vacuum pump seal a long time ago and it was holding fine until this happened.

Anyway we got it all back together and Dave and his wife invited me in for some snacks before I took off. What a great guy, I can't say enough good things. This was such a life saver. I was not looking forward to doing this job out in the freezing cold.

Someone tell my why on earth a rebuilt vacuum pump is so pricey (maybe because people return ones with broken housings?) I paid $539.20 plus a core charge of $47.50 at Carquest. You know the rebuild parts can't cost near that much. I went ahead and kept the core because between this pump the one I have at home with the broken gear and the seal kit I got from Cummins (p/n 4089742) I can build another good pump for cheap. It's strange, the drive tangs on the vacuum pump were hardly worn at all but the PS pump driven tangs were pretty bad at 308k on the original pump. So guys if you have high miles on these parts, be aware of what can happen. I figured worst case they would both break and I would loose power steering/break assist.

Sorry, I didn't get a picture of the broken PS pump coupler.