Oil Pressure Relief Valve – 1967 H0-xxx-xxx Engine 1500 series – Part II

PRACTICALITY: Oil Pressure Relief Valve Part II

What does an examination of the Oil Pressure Relief Valve mean for us as we drive our 1967 Beetles?

First, we must recognize that the Volkswagen Engineers carefully planned these engines with Oil in mind. They were planning an Engine which not only would use that Oil as the Lubricating Agent but also as the Cooling Agent. Just as one must monitor the coolant in a water-cooled vehicle—we must monitor the Oil in our Air-cooled Engines. This translates as follows:

Change the Engine Oil regularly. I once talked with the owner of a Beetle who told me that he had trouble removing the Oil Drain Plug and Plate. So, he just added Oil as needed. Unfortunately, he was ignoring the fact that such inaction was costing his Engine its life. Pollutants such as moisture and carbon from the combustion process deny the Oil its properties to properly lubricate the Bearing Surfaces. Eventually, these pollutants act as corrosives/abrasives and create an active environment for damaging susceptible Bearing Surfaces.

For those of us who put few miles on our Beetles, experts recommend an Oil Change at least once yearly. This is a non-invasive way to prolong Engine Life and to obtain many more miles of enjoyment!

Carefully choose an Oil which is suited not only for our Engines but for the Climate in which we will drive our Beetles. Consult local authorities for the best Oil for your Climate. Oil for someone driving in Gulf Coastal areas will not necessarily be correct for someone who drives in northern climes.

When changing or adding Oil to your Engine, make certain that the car is parked on a level surface. Otherwise, it will be impossible to determine the level on the Dip Stick. To get the most accurate reading, check the Oil only after the Engine is turned off and the car has been sitting for a while. Pull the Stick, wipe it clean and replace it. Wait a few seconds, then remove and check the level. Dip Sticks are clearly marked for determining the Oil Level.

Do not allow the Oil Level to go low. Remember: these Engines do not hold much Oil—5.3 US Pints (2.65 Quarts) or 2.5 Liters (4.4 Imperial Pints).

When the Engine is running, it is consuming some Oil during the combustion process. The older the Engine, the more the Consumption Rate. Just because there is no “smoke” coming from the tail pipes is not an indicator that there is no Oil Consumption. Oil always is being consumed.

A person wrote in saying that suddenly the engine of his Beetle quit. He was able to coast to the roadside. Upon examination, it was found that the engine contained NO Measurable Oil. As a result of lack of lubricant and heat from lack of cooling ability, the Engine simply had stopped.

The driver told us that since he had been checking beneath the car for drips and never had seen any, he assumed that the Engine wasn’t losing any Oil. Fortunately, in this case, the Engine could be saved and was successfully rebuilt.

Check your car’s Engine Oil regularly!

When you turn the Key to the “On Position”, the Green Oil Light will show at the bottom of the Speedometer. When you turn the Key to the Start Position, and start the Engine, the Oil Light may continue to show momentarily. It should go off quickly once the Engine starts. If it continues to glow, turn off the Engine—the continued burning of the Green Warning Light may reveal a serious Oil Pressure problem.

If, when the Key is turned to the On Position and the Green Warning Light does not glow, go to the Engine Compartment to make certain that the Wire to the Oil Sender Switch is connected. If it has fallen off, reconnect it and repeat the Starting Procedure to make certain that the operation is good.

The local VW Engine Builder mentioned checking the Oil Sending Switch for defects. Cheap versions sometimes leak and fail. Purchase the best one available if there is the need. ATE (German) produces a reliable Switch.

Rarely, the Bulb to the Green Oil Warning Light may burn out. Secure a replacement for the bad Bulb. Or, a wire connection at the Back of the Speedometer may have loosened. At any rate—do not drive the car without finding the cause of the Green Light failure to show.

If, while driving, the Green Light comes on—do NOT continue to drive. Immediately find a place to park to investigate the cause of the Warning. Depending upon the cause, continued driving generally results in Engine Failure.

Maintain a healthy Fan Belt. A slipping Belt will result in uneven turning of the Cooling Fan, over-heating the Engine due to lack of airflow through the Oil Cooler. When the Oil does not cool, the Engine will over-heat and failure will result. If the Belt is slipping because it is loose, properly adjust it.

If the Belt is old and cracked, replace it at once.

If the Belt breaks during driving, the Red Speedometer Generator Warning Light will light. Immediately find a safe place to park and switch off the Engine. Lack of Cooling Air/Cooled Oil shortly will result in Engine failure. Do NOT continue to drive because you think that it’s only a short distance to your destination. Engine failure is almost certain to happen.

Carry a Spare Belt and learn how to install it. With two tools and a little knowledge and practice, you can become a Belt removal and installer expert.

Another possible cause for the Green Light to come on, and to stay on, is Debris, such as a shop rag, which may have gotten sucked into the Fan Shroud. A blocked Fan cannot efficiently cool the Oil as it is pumped through the Oil Cooler. As a result, the Engine becomes hotter and hotter. The hotter the Engine, the less viscous the Oil–severely reducing Oil Pressure. Engine failure will happen fairly quickly. Again—the thing to do is to immediately park the car and investigate. (it follows that when checking for debris in the Fan Shroud, be sure to have the Engine switched off) Remove the Debris and, after allowing the Engine to cool, attempt a restart to see if the Green Warning Light goes out. Drive carefully in order to assess for damage to the Engine.

Maybe the Green Warning Light flickers at Idle when you are sitting at a stop light. This can happen during hot weather, when the Oil is thin. But, it is best to check for the cause. Perhaps it’s only the result of a Low Idle Setting. Properly adjust the Idle at the Carburetor to see if this helps.

If adjustment does not help, discover the reason for the flickering Green Warning Light.

At the same time, check the Engine Oil Level! Replenish it, if it is low.

The Piston in the Oil Pressure Relief Valve may be sticking. This usually calls for taking the car to a qualified VW shop for an investigation of the problem.

The car must be placed onto a lift. Once the Plug to the Relief Valve has been loosened and removed, a small amount of Oil will drain in the process. The Spring and Piston now can be removed to check for a damaged or worn Spring and burrs on the Piston–or debris which has caused the Piston not to move properly.

If you are doing the job yourself, properly lift and secure the vehicle so that it is stable and will not fall. Then, remove the Plug and parts. If the Piston is stuck in the Chamber, it can be removed by using one of the following methods.

There is a professional Oil Relief Valve Piston Removal Tool

If the tool is not available, you can use a Wooden Dowel such as the ½ inch Dowel which I used. I whittled the end a bit smaller, testing until it would enter the bottom of the hollow Piston. Then, after jamming the Dowel into the Piston, I twisted the Dowel until the Piston was loosened and could be pulled from the Chamber.

Volkswagen suggests using a 10mm Bottoming Tap. Screw the Tap into the Piston and twist the Piston, pulling at the same time. The Piston should come free.

Clean the Piston to remove any burrs. I polished mine using 2000 wet/dry abrasive paper.

If the Piston appears to be damaged, locate and obtain a good used original one.

I also cut a piece of light scrubby cleaning pad and, using a pair of long forceps, I twisted the pad into the Chamber, turning it round and round, removing it from time to time to reposition the cleaning pad. In a few minutes, I had the Chamber polished nicely. Now, the Piston would fit and easily slide up and down within the Chamber.

What if all of the above are in good working order—but the Green Oil Warning Light continues to come on at operating temperature and at speed, when Oil Pressure normally should be good?

Remove the Oil Sender Switch and install, instead, an Oil Pressure Gauge. Check the Gauge for Oil Pressure when the Engine is Cold and when it is Hot. Start and run the Engine. At Cold, the Oil Pressure should be fairly high. As we have noted above, when the Oil is Cold, it is quite viscous and will help to raise Oil Pressure (above 55 psi). If the Oil Pressure is quite low at Cold Start, it can be an indication of worn Internals. If when running at Hot Engine and the Oil Pressure reading is very low, this also can be an indication of worn Engine Internals, making it impossible for Oil Pressure to rise. According to Volkswagen, “…once operating temperature has been achieved, at 2500 rpms (approximating 40 mph), Oil Pressure should be about 28psi.” This is sufficient to keep the Green Warning Light Off.

When finding low Oil Pressure (as in #9), it is time to check the Engine’s Mileage. If the mileage is high, it may be time for a major overhaul.

A qualified VW Mechanic should be able to check for “End Play. By grasping the Crankshaft Pulley, the Pulley can be pushed and pulled. A very small amount of “play” is “allowable” but major “play” is an indicator of tired Bearings and other worn surfaces.

Another indicator would be an examination of the Oil Pump. With the engine still in the Beetle, the Pump Cover can be removed and checked for Gear markings. See the photo below.

While the Cover is removed, the interior of the Pump Housing can be examined for Gear wear on the Aluminum Housing. If there is significant wear, probably the rest of the Engine also is in need of an overhaul.

If only the Cover shows Gear wear marks, turn the cover 90 degrees, use a fresh gasket and reinstall the Cover. (or have the Cover sanded smooth or purchase a new Pump Cover)

Adding higher viscosity Oils is NOT a cure. It may seem to delay an overhaul, but in the long run, such tactics and delays only put off the inevitable and may even result in destruction which can require a new Engine Case. (when I was growing up, people used to add “Motor Honey”, a VERY thick substance, to old engines to raise oil pressure)

A Compression Check is not immediately relative to Low Oil Pressure (Green Oil Light coming on). However, a Compression Check can indicate whether the Piston Rings are sound or whether they have worn, and how much. Do a Cylinder-by-Cylinder Compression Test.

With a Warm Engine and the Throttle held Open and all of the Spark Plugs Removed, crank the Engine by using the Starter.

As miles accumulate on the Engine, readings will drop. The “wear limit” is about 100 psi. Lower than 100 psi is an indicator of wear past good Engine Performance.

Poor Compression due to Worn Rings or Loose Cylinder Heads will cause the Engine to run hotter—thus affecting Oil Pressure readings.

There is much more which can be added to this Discussion. The Bottom Line is: Usual Care for our Engines results in Long Engine Life.