ENGINE OVERHEATS WHEN TOWING INSTALL LARGER COOLING SYSTEM
SUBJECT: ENGINE OVERHEAT WHEN TOWING OR DURING HEAVY USAGE (INSTALL LARGER COOLING SYSTEM)
VEHICLES AFFECTED: 1988-91 C/K WITH 5.7L VIN CODE K
THIS BULLETIN IS BEING REVISED TO CHANGE THE LABOUR OPERATION, LABOUR TIME, TO DELETE THE FIRST PARAGRAPH UNDER THE FIRST NOTE, CHANGE STEP 13 AND ADDED TWO NOTES UNDER STEP 27.
Some 1988-91 C/K trucks equipped with 5.7L engines may experience an engine overheat condition 118 - 126 C (245-260 F) while towing a trailer or under heavy usage, yet during normal operation, without heavy load or trailer, the engine operates at a normal temperature 100 -115 C (210 - 235 F) .
If this condition is encountered and cannot be repaired using procedures in the service manual, a larger capacity cooling system may be installed. This larger capacity cooling system typically reduces engine operating temperatures by 20-25 F while towing a trailer or under heavy usage.
IMPORTANT: This larger capacity cooling system is not intended for correcting engine overheats that occur while idling or under normal operating conditions.
NOTE: It will be necessary to install new engine oil cooler hoses on models equipped with an internal (inside radiator) engine oil cooler.
On models with an externally (outside radiator) mounted engine oil cooler, the installation will require the removal of the external oil cooler and hoses. They will be replaced by the internal (inside radiator) engine oil cooler, which this larger capacity radiator features, and the required oil cooler hoses.
SERVICE PARTS INFORMATION:
Quantity Part Number Description -------- ----------- ------------------------------ 1 52457632 Radiator (auto & manual trans) 1 15650248 Shroud (upper) 1 15650247 Shroud (lower) 2 15553981 Insulator (upper) 2 15591853 Insulator (lower) 1 15574276 Bracket (right) 1 15574275 Bracket (left) 1 15627103 Radiator Hose (upper) 1 15629092 Radiator Hose (lower) 1 12076298 Protector (lower radiator hose 1 15574167 Baffle 1 15552389 Deflector 3 11513687 Bolt (rad. support baffle) 2 11509363 Bolt (rad. mounting bracket) 1 15611492 Hose (outlet) "C" models 1 15623000 Hose (inlet) "C" models 1 15611493 Hose (outlet) "K" models 1 15622999 Hose (inlet) "K" models
INSTALLATION PROCEDURE:
1. Disconnect battery.
2. Drain cooling system.
3. Remove upper radiator shroud.
4. Remove upper and lower radiator hoses.
5. Remove heater hose and over flow tube.
6. Disconnect transmission oil cooler lines from radiator. (automatic transmission only).
7. Remove engine oil cooler lines (if equipped).
8. Remove external engine oil cooler (if equipped).
9. Remove radiator.
10. Remove lower radiator shroud.
11. Remove fan and clutch assembly
12. Remove lower radiator insulators (rubber mounts).
*13. To enlarge the radiator core support opening to the dimension shown in figure 1, mark the section of the core support to be removed and remove the sections, using a suitable tool (panel cutter, die grinder with cut-off wheel, panel knibler, etc.). The core support openings are stamped and can be used as a guide. When cutting the lower corners, it is important to leave a small triangle shaped section for proper radiator support rod attachment. The edge of the new opening must be painted to prevent corrosion. Use P/N 1052820 or equivalent.
14. Install new lower radiator insulators for larger radiator in outer slots (holes) of lower radiator support as shown in Fig. 3.
15. Install new radiator support baffle, refer to Fig.2.
16. Install new lower radiator shroud.
17. Install new radiator assembly.
18. Install fan and clutch assembly.
19. Install new upper radiator insulators and retaining brackets as shown in Fig. 3.
20. Connect transmission oil cooler lines to the radiator
NOTE: It may be necessary to slightly bend both transmission oil cooler lines in order to obtain proper alignment with the radiator.
21. Install new engine oil cooler lines (if equipped). Refer to Product Service Bulletin # 89-6-117 for proper installation.
22. Install new hose protector on new lower radiator hose and install new hose assembly.
IMPORTANT: When installing the new lower radiator hose assembly it is important that the hose protector be positioned correctly in order to avoid any direct contact of the hose with other components.
23. Install new upper radiator hose.
24. Install heater hose and over flow tube.
25. Install new upper radiator shroud.
26. Install new upper radiator air deflector (see Figure 2).
27. Transfer all labels from old upper shroud to new upper shroud.
*NOTE: If labels cannot be removed successfully, order replacement labels from CANSPO using the part number printed on the original label.
If replacement campaign labels are required, refer to current copy of "Dealer Follow-Up Campaign Bulletin" for information on blank campaign completion labels.
28. Refill cooling system and check for leaks.
29. Reconnect battery.
WARRANTY INFORMATION
For vehicles repaired under warranty use:
Labour Operation: T7221
Labour Time: 1.4 hr.
Add: 0.5 hr. (If necessary to replace engine oil cooler lines.)
NOTE: Labour Operation is coded to base vehicle coverage in the warranty system.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
