NO: 373AR2 SERVICE BULLETIN DATE: April 5, 2005 SUPERSEDES: S.B. 373AR1 dated 2/26/99 SUBJECT: COLD START ADVANCE MECHANISMS Diesel engines have a tendency of producing white exhaust smoke during startup when ambient temperatures are cold. The white smoke, which is produced by unburned fuel due to poor combustion, clears as the engine reaches normal operating temperature. Advancing the injection timing during cold startup conditions minimizes white smoke generation. One method of accomplishing this is by using a cold start advance mechanism on the injection pump. Stanadyne currently uses two types of cold start advance mechanisms on its D Series pumps - a mechanically actuated type and an electrically actuated type. Both types are designed to advance the timing a specified number of degrees during cold startup conditions. They are also designed to be de-activated after the engine reaches a specific operating temperature to permit normal advance functions. The mechanical type is manually activated and de-activated, were the electrically actuated type is activated and de-activated in response to electrical signals received from a temperature sensor in the engine coolant system. Mechanical Cold Start The mechanical cold start advance, pictured in Figures 1 and 2, uses a lever to rotate a face cam which in turn mechanically moves the advance piston thus moving the cam ring to advance injection timing. An exploded view of a typical mechanical cold start advance is shown in Figure 1. Please note that there are two different piston styles and lever orientations as shown in figures 2a and 2b. The stepped advance piston and the downwards lever orientation (Figure 2a) are used on Perkins applications. The advance piston with a pin and the upwards lever orientation are used on Cummins A series (Onan L series) applications. Mechanical Cold Start Mechanisms Face Cam Shaft Lever Stop Retaining Nut 215-265 lbf.-inches (24.3-29.9 N m) Figure 1 Lever Retaining Screw 35-40 lbf.-inches (4.0-4.5 N m) Stanadyne Corporation 92 Deerfield Road, Windsor, CT 06095, U.S.A. Tel: (860) 525-0821; Fax: (860) 683-4581; www.stanadyne.com
- 2 - S.B. 373AR2 with Pin Mechanical Linkage connecting hole Stepped Figure 2a Figure 2b Solenoid Actuated Cold Start The Solenoid Actuated Cold Start (CSA) is electrically controlled and, hydraulically actuated. This feature provides a fixed amount of additional advance by using a separate cold start advance piston, actuated by transfer pump pressure, to move the advance piston when the engine coolant and ambient air temperatures are low. The CSA solenoid assembly is threaded into the pump housing where it intersects a passageway that feeds fuel under transfer pump pressure to the cold advance piston (Reference Figure 3). During normal warm engine operation the solenoid is de-energized. When the solenoid is de-energized, the spring loaded plunger is seated, preventing pressurized fuel from reaching the cold advance piston. During cold engine operation, the solenoid is energized and the plunger lifts off of the seat allowing fuel under transfer pump pressure to flow through the check valve and behind the cold advance piston. The fuel pressure moves the CSA piston inwards providing the desired timing advance. Cold Check Valve Ball and Spring Figure 3 Transfer Pump Pressure Cold Start Solenoid Assembly
- 3 - S.B. 373AR2 Some engines require retarded injection timing when starting but then need advanced injection timing once the engine is running to prevent white exhaust smoke. To meet this operating criteria, a CSA valve body with an actuation delay feature was introduced. The delay is accomplished by an increased spring preload on the check valve spring which prevents the ball from lifting off its seat until sufficient engine speed and transfer pump pressure is achieved. Rectangular Style CSA Solenoid Assembly Coil Assembly (12 or 24 Volts) Retaining Ring Cold End Plug Coil Lock Nut 45-50 lbf.-inches (5.1-5.6 N m) Valve Body 90-110 lbf.-inches (10.2-12.4 N m) Figure 4 O-Ring Seals Plug Screws 60-70 lbf.-inches (6.8-7.9 N m) Two different styles of CSA solenoid assemblies have been used on Stanadyne pump models - a rectangular style and a cylindrical style. Both mount in the same fashion and are functionally the same. However, the individual components of each style are not interchangeable. Figures 4 and 5 show the serviceable components and assembly torque specifications for each style. Cylindrical Style CSA Solenoid Assembly O-Ring Seals Valve Body Washer P/N 35276 Valve Body 90-110 lbf.-inches (10.2-12.4 N m) Flux Washer Coil Assembly (12 or 24 Volt) Coil Lock Nut 45-50 lbf.-inches (5.1-5.6 N m) * Note: Coil Housing is packaged with the coil assembly and is not available separately * Coil Housing Figure 5 Protective Sleeve
- 4 - S.B. 373AR2 The cylindrical style CSA assemblies have been superseded to the rectangular style for both pump production and service. To aid in service replacement, several service kits containing complete rectangular CSA assemblies have been created and are identified on the service specification. The individual components for the cylindrical style will remain available until stocks are depleted. This is a running change and all stocks of cylindrical style CSA assemblies and individual components should be depleted prior to changing to a rectangular style CSA assembly. The service kits are identified in the table below. CSA Service Replacement Kits (Cylindrical style to Rectangular style) Rectangular Service Kit* Part Number Equivalent Cylindrical Type Components Valve Body Coil Assembly Coil Assembly Valve Body 37054 33191 32944 34268 34194 37055 33307 32944 34268 34195 37056 33307 33240 34269 34195 37057 33191 33283 34270 34194 37058 33307 36572 34195 37175 33191 36572 34194 * Includes: Valve Body, Coil Assembly, Coil Lock Nut (P/N 32955), O-ring Seal (P/N 32866) The valve body, coil assembly, and electrical connector variations for each type of CSA assembly are identified in the tables below. NOTE: Serviceable components are not interchangeable between the two styles. Reference the individual pump specification for the required part numbers. Cylindrical Type CSA Coil Assemblies Rectangular Type Coil Voltage Connect or Type Wire Lead Length 34268 32944 12 B Long 34269 33240 12 A Long 34270 33283 24 B Long 34271 33285 24 A Long 36572 12 B Short 36573 24 B Short 37074 12 C Short 37075 24 C Short CSA Electrical Connectors Type Description A B C CSA Valve Body Assemblies Actuation Feature Rectangular Type Cylindrical Type Delay 33191 34194 Non-Delay 33307 34195
- 5 - S.B. 373AR2 Cold Start Solenoid Assembly Installation When installing a CSA solenoid assembly, the valve body should be threaded into the pump housing and tightened to the recommended torque value prior to mounting the coil assembly. To properly mount the coil assembly observe the following procedures: Rectangular Style: (Reference Figure 4) 1 Place the coil assembly onto the valve body with the wire leads facing the 9 o'clock position, as viewed from the transfer pump end. Install the coil lock nut finger tight. 2 Rotate the coil assembly until it lightly contacts the hydraulic head assembly and tighten the coil lock nut to the torque value specified. Cylindrical Style: (Reference Figure 5) 1 Place the valve body washer, flux washer (with the stepped O.D. facing outwards), and coil assembly (including the coil housing) onto the valve body. Install the coil lock nut finger tight. 2 Position the protective sleeve on the coil assembly (with the step inwards and the flat towards the hydraulic head assembly) and slide the sleeve over the coil assembly until it bottoms against the pump. 3 Rotate the protective sleeve and coil assembly clockwise until the sleeve stops against the hydraulic head assembly (wire leads will be in the 9 o clock position as viewed from the transfer pump end). Tighten the coil lock nut to the torque value specified. Note: Use a screwdriver to hold the valve body assembly when loosening or tightening the coil lock nut. Calibration During the test following service calibration routine, the CSA solenoid is energized and de-energized to confirm proper operation. Pump models with delay type valve bodies may also have check points that required throttle adjustment to a specific fuel delivery in order to achieve an advance parameter. Certain of these pump models may also call for the use of an alternative CSA piston (slightly smaller diameter) in cases where the advance travel is insufficient at part load (adjusted throttle). Pump models that may require an alternative CSA advance piston have the alternative piston part numbers listed on the service specification. Compact Cold Start To address clearance issues on certain engine applications, a compact version of the CSA was introduced. The compact CSA operates in the same way as the standard CSA. However, the compact cold advance uses a cup shaped cold advance piston recessed in the pump housing and a low profile advance end plug. Some compact CSA equipped pump models use pump housing with the CSA solenoid mounted at an angle to address additional clearance issues.
- 6 - S.B. 373AR2 Originally, the compact cold advance was designed with a thick sleeved housing assembly as shown in Figure 6a. For the purpose of standardization, a thin sleeved compact CSA was introduced after thin sleeved pump housings for Target featured servo speed light load advance equipped pump models began to be used exclusively (Ref. S.B. 373). Both the thick and thin sleeve designs are functionally the same but physically different as shown in Figures 6a and 6b. Thick Sleeve Design Bore Sleeve ( Thick ) Cold Bore Sleeve ( Thin ) Thin Sleeve Design Cold Plug CSA Solenoid* (Rectangular) Plug P/N 33395 O-ring Seal P/N 32948 CSA Solenoid** (Cylindrical) * Rectangular style only Figure 6a ** May be either cylindrical or rectangular Figure 6b Both designs use steel sleeved advance bores, the same CSA solenoid assemblies and light load advance components including common advance pistons. However, the housing assemblies, cold advance pistons, and the advance end plugs are unique to each design as shown in Figure 7. Thick Sleeve Design Cold O-Ring Seal Thin Sleeve Design Cold Plug (Install with recessed holes facing downwards) Bore End Plug 240 270 lbf. inches (27.1 30.5 N m) Figure 7 O-Ring Seal Plug Screws (4) 60 70 lbf. inches (6.8 7.9 N m)
-7- S.B. 373AR2 The thin sleeve design is now used on all compact CSA applications. All models that were originally specified with the thick sleeve design have been superseded as shown in the tables below. NOTE: Serviceable components for the thick sleeve design are only available until current stocks are depleted For service, the conversion from thick sleeve to thin sleeve should be performed only when housing replacement is required. When converting from a thick sleeved design to the thin sleeved design, the power side advance plug, cold advance piston, advance plug screws, and associated seals will also be required. Reference the individual service specification for required part numbers and quantities. Original Stanadyne Model No. (Thick Sleeve) John Deere Applications Superseded By Stanadyne Model No. (Thin Sleeve) John Deere Part No. DB4327-5359 Obsolete RE 501259 DB4327-5360 DB4327-5563 RE 500441 DB4327-5366 DB4327-5562 RE 500442 DB4327-5367 DB4327-5571 RE 500443 DB4327-5368 Obsolete RE 500444 DB4327-5396 DB4327-5572 RE 500382 DB4327-5400* DB4327-5583 RE 502217 DB4327-5406 DB4327-5574 RE 502218 DB4327-5407 DB4327-5576 RE 502238 DB4327-5425 DB4327-5573 RE 500867 DB4327-5476 DB4327-5580 RE 501983 DB4327-5477 DB4327-5581 RE 501986 DB4327-5478 DB4327-5582 RE 501985 DB4327-5484** DB4327-5584 RE 502509 DB4327-5488* DB4327-5583 RE 502217 DB4327-5502** DB4327-5584 RE 502509 * DB4-5400 (RE 501258) was superseded by DB4-5488 (RE 502217). ** DB4-5484 (RE 502182) was superseded by DB4-5502 (RE 502509). Original Stanadyne Model No. (Thick Sleeve) SISU (Valmet) Applications Superseded By Stanadyne Model No. (Thin Sleeve) SISU Part No. DB4629-5346 DB4629-5534 836854744 DB4629-5347 DB4629-5535 836854746 DB4629-5363 DB4629-5597 836854758 NOTE: Although the Stanadyne model numbers changed the John Deere and SISU (Valmet) customer part numbers remain the same.
- 8 - S.B. 373AR2 Cold Ready Pumps A number of pump models were released with all the cold start advance components except for the CSA solenoid assembly. In place of the CSA solenoid a plug (P/N 33131) was installed. These pumps are referred to as being cold advance ready. Figure 9 shows the components and torque specifications for the CSA solenoid plug. O-Ring Seal P/N 27268 O-Ring Seal P/N 32866 Figure 9 CSA Solenoid Plug P/N 33131 90-110 lbf.-inches (10.2-12.4 N m) There are a small number of pump models that were originally built as CSA ready that have since been changed to include the CSA solenoid. If you should receive a pump that specifies a solenoid but is not equipped with one, it should be serviced as is, without the solenoid. However, if a customer requests to have a solenoid fitted to a pump that specifies a CSA solenoid but did not have one originally, you may do so but all charges associated are to chargeable to the customer. Note: As part of a field program to address a white smoke issue, John Deere has added cold start advance solenoids to pump model DB4-5289 on an as needed basis (Reference S. B. 528). Technical Support Group Product Support Department Revision Date Changes 2 4/05 Added solenoid service, supersession and operation information. Added obsoleted thick sleeve model numbers.