BREATHER AS 2908568 - Caterpillar

3406B And 3408 Truck EnginesSUPPLEMENT: 08/00/93Truck Engine News; October 1991; Page 5; "No Gaskets Used With Aluminum Flywheel Housings" on 3406B and 3408 Truck Engines.Add the following information before the subheading, "Procedure For Applying 1U8846 Gasket Maker".
In addition, there is a possibility of contact between certain gears of the rear gear train and the housing on non-current machines/engines when using 1U8846 Gasket Maker with the former (non-current) flywheel housings. If contact exists, one of the following options must be used:
1. Service the former gasket with itself.2. Replace the former housing with the new housing where possible.3. Mill out the flywheel housing where contact occurs.--------------- END SUPPLEMENT ---------------Reference: Truck Engine News, April 1991, Page 4, "Procedure For Applying 1U8846 Gasket Maker ".Description of Change: The flywheel housing gasket has been removed from truck engines with aluminum flywheel housings. The gasket has been replaced with 1U8846 Gasket Maker. The flywheel housings have also been changed to compensate for the removed gasket. An additional 0.7 mm (.028 in) has been left on the mating face of the flywheel housing in order for the bolt holes in the rear flange of the oil pan to align with the threaded holes in the bottom of the flywheel housing.Adaptable To: Chart A lists the new and former flywheel housings. Chart B identifies when 1 U8846 Gasket Maker and the new flywheel housings are in effect. The Reference Articleprovides complete information of the use of 1 U8846 Gasket Maker. 1 U8846 Gasket Maker can be use to replace the flywheel housing gasket on engines with former flywheel housings if the oil pan holes which are used with the flywheel housing are modified. Enlarge those oil pan holes to a 12.7 mm (.50 in) diameter. This will prevent possible side loading of the oil pan.
Procedure For Applying 1U8846 Gasket Maker
1. Be sure the contact surfaces of the flywheel housing and the block are clean and free of any foreign material.2. Clean the contact surfaces with 8T901 1 or 4C4079 Component Cleaner.3. It is recommended that the 1 U8846 Gasket Maker be applied to the contact surface of the flywheel housing. Apply a 1.5 mm (1/16 in) bead of 1U8846 Gasket Maker down the middle of the contact surface and around each bolt hole. This will provide a continuous bead of gasket maker around the contact surface.4. Use a roller, similar to the one shown in the illustration, to spread the 1.5 mm (1/16 in) bead of gasket maker into a thin even thickness over the contact surface.
This roller has a hard plastic roller and is available in discount or wallpaper/paint stores. This specific roller is used for smoothing inside corners when hanging wallpaper. Applying a larger bead of gasket maker is a waste of material. The larger bead will also make it more difficult to spread a thin even layer of gasket maker over the contact surface. Excess gasket maker will be squeezed out of the block to flywheel housing joint when the bolts are tightened.5.