I took a 1989 Dodge Cummins diesel engine out of a pickup truck and I’m using the engine as a stationary power source. The combined power steering + vacuum pump has developed an engine oil leak, and since I don’t need power steering or vacuum, I want to delete the pump from the engine entirely instead of repairing it.

Rather than a timing chain, this engine has a timing gear train inside a housing in front of the engine block. The gears are supplied with engine oil that gets flung around inside the housing. I planned to replace the pump with a cover plate and gasket to contain the splashing oil. While taking the pump off the engine, I noticed that the gear, shaft, bearing and housing are built much more robustly than any power steering pump really needs to be, and I got curious why this might be. Timing gear train Diagram credit: Chrysler Motors 1989 Diesel Supplement Service Manual

The crank shaft gear rotates clockwise, turning the camshaft gear which turns the fuel injector pump gear and the power steering / vacuum pump gear, which is not shown in this diagram. The power steering / vacuum pump gear engages only with the camshaft gear.

I think the force from the crank shaft gear on the camshaft gear and the heavy resistance from the fuel injector pump makes the camshaft gear want to move toward the right. It won’t actually move to the right, of course, but the radial force on the camshaft within its journal will be heavily biased toward the right. I’m guessing that the power steering pump gear mount might be so heavily constructed in order to help resist that rightward force on the camshaft gear and minimize stress and wear on the camshaft journal. The camshaft journal is 2-1/8” diameter (~54mm).

Question: Will operating the engine without the power steering pump in place cause rapid wear on the camshaft journal and premature failure? Or are camshaft journals so strong that any off-axis forces from these gears are trivial and no cause for concern? I’m not a professional mechanic so I’m looking for advice from someone with practical experience in gear trains and engine journals.

If deleting the power steering pump might endanger the camshaft journal, I’ll just repair the power steering / vacuum pump and reinstall it, as useless as it is for the engine’s current role. I’ve figured out why it was leaking engine oil and the fix is not easy, but it’s doable.

  • 1
    Have you thought about checking if Cummins used that engine in a stationary format at all? That would tell you...
    – Solar Mike
    Commented Jul 29, 2019 at 16:22
  • @solarmike Good thought. This is a Cummins 6BT engine, which was also used in agricultural equipment such as Case tractors and in some stationary equipment. I've seen this engine with a large hydraulic pump in the same location as my power steering pump. In stationary use, I don't know if it was equipped with a blanking plate or with an idler gear where my PS pump is.
    – MTA
    Commented Jul 29, 2019 at 17:01

1 Answer 1


There's no "bearing load" problem. It will be fine as long as you are not losing oil due to a leaky cover plate.

The bearings on the cam are designed to handle the loads necessary, regardless of the position of the camshaft and/or pumps on the "clock face" of the driving gear.

The radial "bias" of forces on camshaft bearings will be negligible, and removing driven loads will only reduce these forces.

There are plenty of pictures online of fire pumps, gensets, and other stationary 6BT applications with nothing in this space.

Solar Mike's suggestion is a great one; you might even be able to purchase the blanking plate and gasket ready-to-go without fabrication:

Pure Diesel Power

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