PCP Compressor

PCP Compressor Review and Maintenance Tips

PCP Compressor Review and Tips.

Setting up your own PCP Compressor correctly will prolong the longevity of this great little High-Pressure Compressor that we take for granted to fill our PCP air rifles. This PCP Compressor has the words Yong Heng Air Pump printed on the blue and sometimes black electric motor housing and comes in 4 models.

We import this PCP Compressor and perform a series of modifications and tests prior to releasing it for sale. Price at the time of writing this is $635.00 including GST, ready to connect and pump air with everything assembled and tested.

Setting up the Compressor.

I am going to assume you have purchased your PCP Compressor from Gunroom in Brisbane and are about to connect it up. Firstly, the PCP Compressor has to be mounted LEVEL to the ground to ensure adequate lubrication from the ‘splash fed oil system’ they employ in the PCP Compressor.

Failure to do this may result in the Compressor overheating and possibly suffering piston or bearing damage from under lubrication. Check the oil level is correct.


PCP Compressor top view.

High-Pressure PCP Compressor

Overfilling the crankcase with oil may also result in the PCP Compressor dieseling: that is where oil bypasses the rings and ignites, causing the PCP Compressor to enter a ‘runaway mode’: this is where the Compressor actually runs on the bypass oil and the RPMs go through the roof until it breaks a con rod or something similar. Generally, the PCP Compressor disintegrates through over-revving.


Nulon Fully Synthetic Oil

Nulon Fully Synthetic Engine Oil 5 litres


Here is a note: I fill the oil in the PCP Compressor we sell with 5W-40W in Summer and 5W-30W in Winter, the oil is Fully Synthetic NULON. Do not mix it with mineral oil. Available at Repco and Cheap Auto Parts nationwide.

Next, you need to get a 30 or 40-litre container that has a lid, this stops bugs and what not drowning in the water and possibly blocking the small pump impellor (been there, done that). I recommend the clear plastic storage containers you get at BigW for around $12 when on special. Fit the pump by pressing it slightly on the bottom of the tank where the suction cups at each corner of the pump will hold it in place.

I then drill 2 x 10mm holes large enough to fit the 2 silicon hoses through them. You will need to remove the cable tie on the black plastic pipe fitting that goes into the pump outlet to get it through the 10mm hole. Then fit the silicone hose with the black plastic tube into the pump outlet socket after fitting a replacement cable tie.

The return hose has to stick through the lid by no more than 40mm, so it is clear of the water. On my tank lid I used Sikaflex to bond the silicone hoses in place on the plastic lid – silicone may work as well as Sika as it is 1/4 the price so I would try that first. Let the fittings and silicone cure overnight.

When you connect the power to the PCP Compressor, the pump should automatically start running providing you have plugged the pump cable into the compressor side. To help you see that water is circulating, I put a small bottle of food dye (red or blue) into the water. You can view the water circulating in the image below.


PCP Compressor water cooling tank with dye

Dyed Water cooling flowing through a PCP Compressor

Should the pump stop working while the High Pressure PCP Compressor is running, the water will run back providing the return pipe is above the water. That way, should you see clear silicon hoses (without the food dye running through them), you will immediately know the pump is not working and shut down the PCP Compressor. This is demonstrated in the following image.



Dyed water cooling system

Water cooling not running to the PCP Compressor.


The PCP Compressor will overheat very quickly without water cooling. Trust me here…


Heat pad on Mark IV Compressor pipe.

PCP Compressor Felt rubbing pad on hot pressure pipe.

Note: You will see I put felt with 3 cable ties on the top PCP Compressor air pipe, that is not for looks, it is to save you from burning your arm when you reach over to dump the air. You can thank me another day.

On a cool day the PCP Compressor will top up a Brocock Compatto PCP tank from 50 Bar to 200 Bar in 40 seconds, so don’t walk away and leave the unit running. While these PCP Compressors are reliable, they should not be left alone if you believe in Murphy’s law.

I am often asked if they can fill a Scuba tank. The answer is yes, providing you have adequate water in the reservoir, a MINIMUM of 40 litres. Any less and the water will quickly heat sending the PCP Compressor temperature into the red (by Red, I mean in excess of 80 degrees).

Should the temp get up close to 80 degrees, just shut the PCP Compressor down and leave the pump running to pull down the head temperature of the PCP Compressor. Make sure you close off the Scuba tank and drop the air in the filling hose.

Note: Do NOT put ice in the water as some clowns do. The sudden cooling in the water jacket may pinch the final stage piston that gets really hot, then you will have problems.

The Water Filter.

The filter supplied with the PCP Compressor, is in my opinion, too small for repeated fills, used in high humidity or left in place over repeated fills. It comes with small foam filters that are not really that efficient as they quickly fill with moisture. Further to that, they are expensive to buy if you can find a supplier.

The alternative? Meds, and I am not kidding you. These tampons are designed to trap moisture, they come with a string for removing them out of the filter housing (as well) and above all, they are plentiful and cheap. For those of you unfamiliar with tampons, Yes, you have to remove the plastic covers first…

The image below shows the replacement filters and the tampons for those of you who have lived under a rock for decades. Woolworths sell them for less than $5 for a pack of 8 with Chemists Warehouse selling a pack of 30 or more, for just a couple of bucks more.

Now at first glance, they may seem a bit thin, but don’t be fooled, they swell up with the first hint of moisture and you need the attached string to remove them. I use the Carefree SUPER (?) Tampons below and they work just fine for the heavy use my compressor gets.


Tampons used as compressor filter elements.

Filter inserts on above left of tampons used as filter inserts.


Water is the enemy of PCPs and the filter is the only thing between your rifle getting rust in the action and/or the regulator and this PCP compressor. I advocate using a larger filter such as the one depicted below that comes with an extension whip hose making it easy to use.

However, if you are budget wise and only have the small filter that came with the compressor, use the tampons, change them regularly and you will be OK. The key words here are, “change them regularly…”, which is a pittance in cost to the damage water can do to your PCP. If you had a Daystate PCP, would you risk getting water in it? Of course not, so change the filters regularly.


Large water filter

High-Pressure water trapping compressor filter and extension whip hose

We have 100 High Pressure Compressors on order that are fitted with the above filter as standard. The price for the complete package is anticipated to be under $600 due to bulk buying.

Tip: When draining the air from between the compressor and the PCP, dump the air FAST. This helps seat the non-return valve in the PCP cylinder due to a high-pressure differential. If you dribble about and let the air out slowly, occasionally you will get the valve being held open slightly by the through-passage of high-pressure air, draining your cylinder over a few minutes to a few hours.

Tip: Always leave both drain valves on the compressor OPEN when not in use. This allows any resident moisture to drain out or dry up.

Tip: You should dump air from the High-Pressure drain first and before the air is completely exhausted, then open the Low-Pressure drain next.

PCP Compressor Safety.

Not to put too much emphasis on safety guys, but this little compressor can pump to 4500psi (300 Bar) in no time at all, so ensure that any cylinders on PCP guns are within their ‘use by date’. 300 Bar cylinders mostly use a final date after which the cylinder must be thrown out and not be retested.

Having owned a Dive Shop in Port Hedland around 100 years ago, I am all too familiar with high-pressure air cylinders and resulting accidents due to complacency.

The compressor has a burst disc that goes off at around 4500+ psi but that won’t save you should you put 4500 psi (300 Bar) in a 200 Bar cylinder or a cylinder that is dodgy. I will be doing a full article on PCP Compressor safety shortly and it will include images designed to disturb you so as to let the realisation of high-pressure air danger sink in.


Ian McIntosh

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