Priming a Clutch Pump System

DewEze Hydraulics

Engine-driven hydraulic systems have become a staple among truck upfitters. One of the things that most upfitters don’t think about is having to bleed the clutch pump system. Without priming, the risk of cavitation increases, reducing the longevity of your pump.

Why Do I Have to Prime the Clutch Pump System?

A primed clutch pump system is full of hydraulic oil and void of air, required by all hydraulic pumps to perform correctly. There are two types of hydraulic systems: flooded and non-flooded. A flooded hydraulic system is one in which oil flows directly into the pump by gravity, filling the system with oil. A non-flooded system starts with the pump empty of hydraulic oil, requiring suction to pull hydraulic oil through the pump. Below we will discuss a non-flooded hydraulic system.

Our testing shows that running a pump for as little as 30 seconds without oil can shorten the pump’s lifespan. Deweze has two recommended ways to prime your clutch pump system to prevent pump damage and cavitation. One method involves using pressurized air and a bleeder valve; the other requires filling the suction hose with hydraulic oil.

Steps To Priming Your Clutch Pump System with Pressurized Air and Bleeder Valve

Below are the basics of what you need to know to prime the clutch pump system with pressurized air and a bleeder valve. Please note: you will need an additional person to assist with this process.

Equipment and Tools

• Hydraulic Fluid
  • Use the DewEze Hydraulic Oil Recommendation Chart to find the best oil for your clutch pump system
• Wrench
• Compressed Air
• Shop Rag

Steps

1. Fill your hydraulic fluid reservoir up to the fill line.
2. Unscrew the nut on the bleeder valve.
3. Pressurize the reservoir: remove the lid on the top of the tank, wrap a shop rag around the air gun, fill the tank with air.
4. Have your assistant start the vehicle, engaging the pump and allowing hydraulic fluid to flow through the system.
5. With the bleeder valve open, wait for the excess air in the system to flow out until there is only hydraulic fluid flowing out of the valve and no air.
6. At this point, you have primed the pump. Close the bleeder valve, allowing the system to maintain a pressurized fluid level within the lines.

It is important to note that you should never drain the fluid completely during this process. The goal is to bleed the clutch pump system, not to drain the system. Priming the system with pressurized air and a bleeder valve should be completed; anytime there is air introduced into the clutch pump system. Examples would be the initial installation, reservoir or pump is replaced, or changing the hydraulic fluid. Pumps may need to be reprimed if they make loud noises or you experience delayed movement of hydraulic components.

Steps To Priming Your Clutch Pump System by Filling the Suction Hose

Below are the basics of what you need to know to prime the system by filling the suction hose on the clutch pump system.

Equipment and Tools

• Hydraulic Fluid
  • Use the DewEze Hydraulic Oil Recommendation Chart to find the best oil for your clutch pump system
• Wrench
• Funnel or fill container
• Shop Rag

Steps

1. Fill your hydraulic fluid reservoir up to the fill line and install a pressurized cap on the reservoir.
2. With the suction hose connected to the tank and routed to the pump, disconnect the suction hose from the barbed fitting on the pump.
3. Fill the suction hose with hydraulic oil until filled. Carefully, without spilling the oil, reinstall the suction hose on the barb fitting and tighten the clamp. At this point, you have primed the pump.

Priming the clutch pump by filling the suction hose should be completed; anytime there is air introduced into the clutch pump system. Examples would be the initial installation, reservoir or pump being replaced, or changing the hydraulic fluid. Pumps may need to be reprimed if they make loud noises or you experience delayed movement of hydraulic components.

Trust DewEze Hydraulics

With 27 years of experience, trust DewEze Hydraulics with your hydraulics needs. DewEze Hydraulics offers a Find-A-Kit feature, allowing you to narrow down the DewEze clutch pump system you need by inputting the make, year, and engine of your truck. Need help finding your closest DewEze Hydraulics Dealer? Use our Dealer Locator to find your nearest DewEze dealer.