How to Fix your Transfer Pump – Before you Replace it

PMC GHO, IPM OP series, Graco T2 Transfer Air motor performance

After use, the transfer pump air motor starts operating sluggish and leaks air. This is generally due to deforming (wear) of the upper reversing spring and the upper air valve gasket. You can notice the spring wear off in two ways. The first being the pump fails to return to the down stroke and secondly the pump will pause momentarily when reversing to the down stroke which appears as a cavitation type action. In this situation, hanging the spring is the best solution, but when in a pinch, stretching the spring to its near original length can get you through the day.

The upper air valve gasket is pressed between two plates and is smashed every time the pump reverses. You may notice the seal wearing off by the slight to severe leaking that starts when the pump is in the stall position or when stroking down.

To replace the upper air valve while the pump is in the drum, remove the air cap and cylinder, then loosen the three allen screws. Before completely removing the allen screws, wedge a rag or paper between the lower plate and the air piston housing. This will ensure the holes and tubes remain in position when the screws are removed. Lift off the upper air plate and the seal is located under the plate. Flip the plate over in a pinch or replace if available.

Recommended Spare Parts

IPM OP series 500005 500015
PMC GHO PU-04000-72 PU-04000-15
Graco T2 157630 15J539

*Call 330-587-41411 to order the above parts.

Upper Reversing Spring

STEP 1: Remove Upper Reversing Spring from Air Cap

loosen the Allen Screws

STEP 2: Slightly loosen the Allen Screws (do not remove the screws)

Air Piston Housing

STEP 3: Wedge a rag or paper between the Lower Plate and Air Piston Housing

Upper Air Valve

STEP 4: Location of Upper Air Valve

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John Davidson is the VP of Operations at SprayWorks Equipment Group and is an SPFA PCP Certified Roofing and Insulation Installer, Roofing and Insulation Project Manager, and Supplier Rep. With over 30 years of experience in the spray foam and polyurea industry, John brings a wealth of knowledge and hands-on experience. He has worked on commercial and residential buildings, bridges and infrastructure.