NEW STYLE HOSE CLAMP SERVICE INFORMATION

SUBJECT: NEW STYLE HOSE CLAMP (SERVICE PROCEDURE)

VEHICLES AFFECTED: ALL C/K AND R/V TRUCKS ALL YEARS WITH 7.4L, 6.2L, 5.7L, 5.0L OR 4.3L ENGINE

A new design hose clamp will be used in production starting with the 1992 model year on C/K trucks. Usage of this clamp will expand to include other models in the 1993 model year. The Mubea constant tension hose clamp was designed to reduce the amount of coolant leakage from radiator and heater hoses.

With the previous design, screw type clamps, it is difficult to maintain a constant load on the hose connection. Some of the load is lost under certain temperature changes. The Mubea clamp exerts a relatively even and constant pressure that is maintained under varying temperature conditions.

SERVICE PROCEDURE:

+ The Mubea clamp must be installed on a hose which will be put on to a clean, dry, paint free surface. If lubrication is necessary for assembly, only GM lubricant P/N 1051717 may be used.

+ Production of trucks with the clamp began 02/91, starting with the water pump and radiator connections. The heater hoses will follow in some applications.

+ If the vehicle was originally built with Mubea clamps, the clamp should be replaced with the same P/N Mubea clamp and not a screw type hose clamp.

+ Also if the vehicle was originally built with screw/worm type clamps, the clamps should be replaced with screw/worm clamps.

Note: Standard pliers or hose clamp pliers will not work well on the new style clamp. Various tool companies have developed special pliers to install and remove these hose clamps. Some companies may have a plier available that is effective in removing the larger size clamps but may not open wide enough to accommodate the clamp once it is off the hose and relaxed. Do not compress the clamp (permanently) to make the tool fit it, since this will decrease the effectiveness of the clamp. GMC does not endorse any specific tool or company. Check with local sources to determine availability.

PARTS INFORMATION:

Mubea clamps will be used in the following applications:

Size Part Number Application ------ ----------- ------------- 27mm 10108255 Heater Hoses 24mm 10146975 Heater Hoses

42mm 15671833 Radiator/Water Pump Hoses 50mm 10108249 Radiator/Water Pump Hoses 55mm 15671832 Radiator/Water Pump Hoses

Note: The clamp's size is stamped on the tab of the clamp.

Parts are currently available from CANSPO.

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.