Jasper Engines & Transmissions is aware of several aftermarket relocation and heat exchanging devices being marketed with claims that they decrease the operating temperature of the Stanadyne DS Pump Mounted Driver (PMD), improving its reliability.

These devices often involve modifications to be made to the wiring harness between the engine and the injection pump. The PMD is located on the side of the injection pump in an effort to dissipate the tremendous amount of heat it creates during operation. The fuel passing through the injection pump helps to dissipate that heat efficiently and consistently during all engine conditions. Other methods of cooling cannot maintain this consistency throughout all conditions that may be encountered.

Another issue that arises from the relocation of the PMD concerns the wiring harness. By moving the PMD, the harness may be extended, spliced into, or stretched to make the necessary connections. This causes numerous problems from added circuit resistance, poor connections, and voltage drops across splices. These can cause symptoms that lead technicians to replace the injection pump, or the PMD, unnecessarily. Symptoms like hot stall, no start, and fuel control solenoid DTC’s are all commonly diagnosed as a failed PMD or Injection Pump, and in many cases are simply circuit-related issues.

Each diesel injection pump JASPER sells is coated with a sealing lacquer in the critical areas, including the PMD and the harness. JASPER has spent several years monitoring DS injection pumps that have been returned from the field after being diagnosed as defective. We have determined that relocation and aftermarket heat exchangers are not beneficial to the life of the PMD, or the reliability of the injection pump, as a whole.

(Above left) Relocating the PMD could cause circuit-related issues as the wiring harness is extended,spliced into or stretched. (Above right) Aftermarket heat exchangers are not beneficial to the life of the PMD or the reliability of the injection pump as a whole.

Friddle: Which automaker builds the Panamera, a four-seat luxury sedan with a coupe profile?

Check our blog next Friday for the answer and another Friddle.

Last Week’s Friddle: Which “microcar” company is headquartered in Boblingen, Germany?

Last Week’s Friddle Answer: Smart

Last Week’s Friddle Contest Winner: Kevin Haik - Springfield, MO