How to Repair Cummins 5.9L Vacuum Pump Oil Leak Photo Gallery
Bruce W. Smith –
Oct 6, 2017
Photo 1/22 | Cummins Vac Pump Rebuild Lead
Photo 2/22 | 001 Cummins Vac Pump Rebuild Lead | “Diesel Bob” Marinos leans over a 5.9L Cummins engine while removing its vacuum pump.
Photo 3/22 | 003 Cummins Vac Pump Rebuild Lead | Here is a look at the vacuum pump and Cummins reseal kit.
Photo 4/22 | 004 Cummins Vac Pump Rebuild Remove Intake | The first step in reaching the vacuum pump is removing the intake manifold. Diesel Bob’s ’98 Dodge Ram 3500’s pump seeped oil for a couple of months before he decided it was time to reseal it.
Photo 5/22 | 005 Cummins Vac Pump Rebuild Horseshoe Wrench | One of the best tools for removing the four 15mm nuts that hold the 5.9L engine’s power-steering pump to the back of the vacuum pump is a half-moon wrench. The nuts are in an awkward, tight location, and it’s hard to see in that space, so this makes the job a lot easier.
Photo 6/22 | 006 Cummins Vac Pump Rebuild Oily Pump | Cummins vacuum pumps tend to leak oil where the power-steering shaft enters the rear of the housing (arrow). The typical cause for the leak is a failed shaft seal inside the vacuum pump’s bearing housing.
Photo 7/22 | 007 Cummins Vac Pump Rebuild Wrench Oil Line | A 9/16-inch wrench is used to loosen the engine-oil feed line that provides the pump’s lubrication. There will be a little oil dripping out when the line is removed, so have a rag or pan underneath to minimize the mess.
Photo 8/22 | 008a Cummins Vac Pump Rebuild Kit | The vacuum-pump rebuild kit is very simple. It consists of two O-rings, the shaft seal, and the gasket that goes between the power-steering pump and the vacuum pump. Be sure to check the kit to make sure all four are present before removing the pump.
Photo 9/22 | 009 Cummins Vac Pump Rebuild Cleaning Parts | When rebuilding a part with new seals and O-rings, it’s prudent to give it a good cleaning to prevent dirt or debris from getting on the delicate sealing surfaces.
Photo 10/22 | 010 Cummins Vac Pump Rebuild Hammer Case | The vacuum pump is actually made up of two parts: The pump assembly and vacuum-pump bearing housing. Once the two 13mm bolts that hold the two elements together are removed, a light tap with a hammer will separate them. The pump section is set aside and not touched.
Photo 11/22 | 011 Cummins Vac Pump Rebuild Drive Seal | Here’s the culprit that caused our pump’s leak. The shaft seal is worn just enough to let oil seep past the power-steering pump’s driveshaft.
Photo 12/22 | 012 Cummins Vac Pump Rebuild Hammer Housing | Pro tip: Diesel Bob places a 15/16-inch wrench under the case’s ears to keep it level on the workbench then uses a 7/8-inch deep socket and hammer to carefully drive the seal retainer out of the housing. It only takes a couple of light taps.
Photo 13/22 | 013 Cummins Vac Pump Rebuild Pump Drive Install | Invert the bearing housing and place the cross-shaped coupling plate back in the bottom of the bore. It doesn’t matter which side of the cross plate is facing up.
Photo 14/22 | 014 Cummins Vac Pump Rebuild Socket Seal Removal | Once the O-ring is removed, a 1¼-inch socket is used to carefully drive the old seal out of the housing and reinstall the new one. Pro tip: Clean the retainer before installing the new seal—and leave a little solvent on the inside to help the seal slide into place. The solvent dries, leaving the seal firmly locked in place. (Don’t use oil, as the seal could work itself free, creating huge oil-leak problems).
Photo 15/22 | 015 Cummins Vac Pump Rebuild Oil Oring | The new O-ring “snaps” into place. Bob uses new engine oil to lubricate the seal and bearing retainer before reinstalling them.
Photo 16/22 | 016 Cummins Vac Pump Rebuild Seal Housing Install Thumbs | Thumbs are perfect tools for initially setting the seal retainer back into positon (O-ring-end first) in the housing. Doing it this way facilitates aligning it squarely and without damage to the aluminum piece.
Photo 17/22 | 017 Cummins Vac Pump Rebuild Hammer Retainer Install | After the retainer is partially in the bore, Bob lightly taps it into the housing until it seats firmly against the lip ridge. He also uses a special drive tool, but a 36mm deep socket (or equivalent size) works just as well.
Photo 18/22 | 018 Cummins Vac Pump Rebuild Retainer Installed Close | Once the retainer is in place, the cross-coupling plate must turn freely, and the O-ring shouldn’t be twisted or pinched.
Photo 19/22 | 019 Cummins Vac Pump Rebuild Drive Adapter Oring | The O-ring that seals the two case halves together rarely fails. But it’s good to replace it with the one included in the reseal kit, using fresh engine oil as a light lubricant.
Photo 20/22 | 020 Cummins Vac Pump Rebuild Bearing Housing Position | The bearing and pump housings are aligned with a dowel pin that must seat in the hole or the two halves will not seal. The drive must also be aligned with the cross coupling before cinching down the two bolts.
Photo 21/22 | 021 Cummins Vac Pump Rebuild Reassembly Air Wrench | Cummins specifications call for 22 ft-lb of torque for the bolts that hold the two sections together.
Photo 22/22 | 022 Cummins Vac Pump Rebuild Reinstalled | After the power steering’s drive is cleaned of any old residue, the resealed vacuum pump is bolted back into the timing cover housing (the pump shaft is turned until it aligns with the cam gear). Then the gasket is set in place and the power steering pump-drive’s dog rings are aligned so they slide into the slots of the vacuum pump’s cross plate. Cummins requires 18 ft-lb of torque on the nuts that join the pumps together and 57 ft-lb for the two bolts that secure the assembly to the block.