Why buy a catch can? Ideally, oil is to remain in the oil channels throughout the engine and in the oil pan. Modern cars use what is called a "positive crankcase ventilation (PCV) valve" to recirculate excess oil blow-by back into the intake system to be burned off during combustion. It's an effective emissions tool that often works silently. However, when the PCV valve is not operating optimally, or the engine is being worked really hard, it can allow for an excessive amount of oil blow-by to re-enter the intake stream, causing buildup on the intake valves and degrading engine performance. The catch can mounts between the PCV valve and intake manifold where it can capture oil drawn through the valve cover by intake vacuum. Vacuum is high here during engine idle and decelerating. A properly fabricated catch can will trap the oil in the can without reducing airflow.
Materials Needed
Another option is to make one yourself. You'll need an array of tools, however. A drill with assorted drill bits and a cut off wheel will be needed. Essentially, you can fabricate a catch can from any cylindrical piece of metal. Drill two ports at the top for your air inlet as well as outlet, and one at the bottom for oil draining. Not all catch cans are built alike. The higher quality kits are engineered to perform with integrated baffling systems. These help keep the oil in the can instead of moving into the air outlet.
Step 1 – Find a place to mount catch can
There are several ways to securely mount your catch can. Some catch cans come with a bracket that is bolted to metal inside your engine bay, such as the firewall or inner fender. You may need to drill holes for the bracket and secure it with a bolt/nut or self-tapping screw. You may be able to find a existing bolt or nut that the bracket can be attached to.
Another is with zip ties or metal clamps. The metal clamps wrap around the catch can and whatever object your clamping to (battery tray for example) for a secure fit. Whatever your bolting/clamping the catch can to, make sure it's not a source of significant heat. You want the area vibrating as little as possible, so mounting directly to the engine is not recommended.
Figure 1. This catch can was mounted to the intake manifold using an existing bolt.
Figure 2. A Moroso catch can.
Figure 3. A home made catch can.
Step 2 – Route catch can hoses
Next you will need to route the catch can hoses to the valve cover and intake manifold.
A kit bought from a website such as Jegs or Summit Racing may come with the hoses you need. These hoses need to be the same diameter as the ports on the catch can. What the kit may not come with is the correctly sized hoses to connect to the intake manifold and PCV valve. You'll need a 4" piece of 1" diameter hose for the PCV valve and a 4" piece of 5/8" diameter hose for the intake manifold. You'll also need need hose clamps to keep the hoses in place.
The long length of hoses will most likely not match the hoses connected to the intake manifold and PCV valve. You can buy double-sided barb fittings to connect the hoses together. It will be hard to find a 1" to 3/8" double barb fitting for the PCV valve. You may want to purchase two fittings to step down to your hose size. Alternatively, try using a 1" metal pipe cap that is long enough to clamp to the 1" hose. Drill a 3/8" (or the size your using) hole into the center of the cap and thread a barb fitting into it. This fitting must stay attached to the cap, otherwise it can end up inside your engine. You can tighten a nut with a washer onto the threaded end of the fitting to increase strength. In addition M.I.G. or T.I.G. welding the fitting to the cap will ensure it stays seated on the cap. If these methods are not available a cold welding technique (J.B. Weld) should work well if applied correctly. Apply the J.B. Weld to both sides of the fitting and let it dry for twenty-four hours.
Figure 4. The catch can hose routing.
Figure 5. Connections to intake manifold and PCV valve.
Step 3 – Check for leaks
Start the engine once the system is fully tightened and installed. Spray soapy water around all the hose connections. If bubbles develop, a leak is present.
Remember to periodically drain the catch can of oil. Otherwise, the oil will make its way back into the engine.
Featured Video: How Does a Catch Can Work?
Materials Needed
- Flat head screwdriver
- 8mm-16mm sockets
- Hose clamp pliers (optional)
- Needle nose pliers
- Cutters
- Catch can
- Hose clamps
- Fittings (refer to Step 2)
Another option is to make one yourself. You'll need an array of tools, however. A drill with assorted drill bits and a cut off wheel will be needed. Essentially, you can fabricate a catch can from any cylindrical piece of metal. Drill two ports at the top for your air inlet as well as outlet, and one at the bottom for oil draining. Not all catch cans are built alike. The higher quality kits are engineered to perform with integrated baffling systems. These help keep the oil in the can instead of moving into the air outlet.
Step 1 – Find a place to mount catch can
There are several ways to securely mount your catch can. Some catch cans come with a bracket that is bolted to metal inside your engine bay, such as the firewall or inner fender. You may need to drill holes for the bracket and secure it with a bolt/nut or self-tapping screw. You may be able to find a existing bolt or nut that the bracket can be attached to.
Another is with zip ties or metal clamps. The metal clamps wrap around the catch can and whatever object your clamping to (battery tray for example) for a secure fit. Whatever your bolting/clamping the catch can to, make sure it's not a source of significant heat. You want the area vibrating as little as possible, so mounting directly to the engine is not recommended.
Figure 1. This catch can was mounted to the intake manifold using an existing bolt.
Figure 2. A Moroso catch can.
Figure 3. A home made catch can.
Step 2 – Route catch can hoses
Next you will need to route the catch can hoses to the valve cover and intake manifold.
A kit bought from a website such as Jegs or Summit Racing may come with the hoses you need. These hoses need to be the same diameter as the ports on the catch can. What the kit may not come with is the correctly sized hoses to connect to the intake manifold and PCV valve. You'll need a 4" piece of 1" diameter hose for the PCV valve and a 4" piece of 5/8" diameter hose for the intake manifold. You'll also need need hose clamps to keep the hoses in place.
The long length of hoses will most likely not match the hoses connected to the intake manifold and PCV valve. You can buy double-sided barb fittings to connect the hoses together. It will be hard to find a 1" to 3/8" double barb fitting for the PCV valve. You may want to purchase two fittings to step down to your hose size. Alternatively, try using a 1" metal pipe cap that is long enough to clamp to the 1" hose. Drill a 3/8" (or the size your using) hole into the center of the cap and thread a barb fitting into it. This fitting must stay attached to the cap, otherwise it can end up inside your engine. You can tighten a nut with a washer onto the threaded end of the fitting to increase strength. In addition M.I.G. or T.I.G. welding the fitting to the cap will ensure it stays seated on the cap. If these methods are not available a cold welding technique (J.B. Weld) should work well if applied correctly. Apply the J.B. Weld to both sides of the fitting and let it dry for twenty-four hours.
Figure 4. The catch can hose routing.
Figure 5. Connections to intake manifold and PCV valve.
Step 3 – Check for leaks
Start the engine once the system is fully tightened and installed. Spray soapy water around all the hose connections. If bubbles develop, a leak is present.
Remember to periodically drain the catch can of oil. Otherwise, the oil will make its way back into the engine.
Featured Video: How Does a Catch Can Work?