Usage:
3400 Family Of Engines
Reference: Service Magazine; September 14, 1987; Page 8; "New Piston Cooling Jets Used" for 3400 and 3400B Families Of Engines. Service Magazine; March 26, 1990; Page 15; "Caterpillar Announces 460 hp 3406B (5YG) Heavy-Duty Diesel Truck Engine".
Damage to the piston cooling jets on 3400 Engines during repair continues to be a field problem for dealers and customers. The following suggestions will help to minimize the occurrence of cooling jet failures.
Removal And Installation
To eliminate the possibility of damaging piston cooling jets during removal of the connecting rod cap and rod bearing, the piston cooling jet assembly should always be removed and kept clean. The wider connecting rod of the 3406B 460 Hp Truck Engine (5YG) and 3406B Vehicular Engine (11N) in the 245 Excavator, cannot be removed without contacting (and damaging) the "double tube" cooling jet design.
Inspect The Jets On The Bench
1. Lay the jets side-by-side and look for visual differences in the position of the tubes.
2. Check the inner radius of the cooling jet tube for possible contact with the piston skirt. Some distortion of the nozzle tip is a normal result of the tube manufacture and will not reduce jet performance.
3. Check the tube-to-body braze joint for possible cracking.
4. (Optional) Check nozzle alignment with 5P8709 Tool Group (does not currently accommodate the double tube jet design).
After assembly of the cooling jets with the correct torque of 25 ± 7 N·m (18 + 5 lb ft), the clearance between the cooling jet and the piston [at bottom dead center (BDC)] should be at least 0.64 mm (.025"). This can be checked by looping a (measured) shipping tag wire between the jet and piston while the piston is at BDC. Replace any jets that have contact or damage.
Engines listed in Chart A (built during fourth quarter of 1988) were suspect of having possible piston contact with the cooling jet tube.
New Cooling Jet Bolt Used
A new 7E6479 Bolt is now used on both the standard 7W4990 (single tube), and the new 7E3632 (double tube) Piston Cooling Jet to replace the former 4N9916 and 7C2478 Cooling Jet Bolts. The new bolt has a larger under-head washer face for reduced jet body scuffing and a larger flat for improved oil flow. This improved flow is needed for the double tube jet design which supplies oil to both a cooling gallery and the under-crown areas of the 7E0489 Piston. The new bolt is effective with the engines listed in Chart B.
New Connecting Rod Used
The 3406B 460 hp Truck Engine (5YG) and the 3406B Vehicular Engine (11N) for the 245 Excavator now use a new 9Y6400 Connecting Rod to accommodate the wider 9Y7735 Rod Bearing. The torque of the connecting rod (9Y6400 Rod, 9Y6053 Bolt, 9Y6051 Nut) is the same as the standard rod, 80 N·m (60 lb ft) + 120° turn. The larger bolt size used in these new rods will result in a greater "load".
NOTE: A future threaded rod design for the wide rod bearing will have a different torque/turn specification.
Rod Eye Bushing Wear
Recent field reports have noted measurable wear of the rod eye bushings on late model 3406B Truck Engines. This has been observed during head gasket repairs or routine rod bearing replacement. Wear of 0.25 to 0.38 mm (.010 to .015") have not led to engine failures up to this date. While the "reusability" limit is being evaluated by Caterpillar, parts with rod bushing-to-pin clearance of up to 0.25 mm (.010") at mid-life should continue in service until overhaul.
All engine fuel settings (including timing advance) should be checked for conformance to factory specifications.
The cooling jet bolts should be updated to the new bolt design to ensure optimum oil flow. (See Chart B.)
The 8T2822 Temperature Label (part of 8T2844 Temperature Label Kit) may be used on the oil filter to verify that oil temperature to the engine does not exceed 116°C (240°F).