1982/10/20 Caterpillar

3304 And 3306 Engines In All Applications

Reference: This article is to be used in place of the earlier article with the same title on Page 1 of the October 21, 1981 Engine News. Cancel the earlier article, and make a note to use this article as a reference. This article has all the information given in the earlier article, plus some new information which has become available since that time.

Description of Change: New rod and piston groups with new pistons and rings are used in the above engines. The new piston rings will give better control of engine slobbering, especially during operation under light load or no load conditions.

For engines that have lower kilowatt (horsepower) ratings (see Charts A, B and C), rectangular type rings are now used instead of the former keystone type rings. For engines that have higher kilowatt (horsepower) ratings (see Charts D and E), new keystone type top and intermediate rings are used.

In comparison with the former parts, the new keystone top ring is made of different material, and both new rings have design changes to improve ring performance in the engine. The top ring has a different shape, as shown in the illustration. The new intermediate ring has a keystone "twist" design, and is changed to increase the surface area in contact with the cylinder wall. These changes will decrease engine slobbering and increase the service life of the rings.

Adaptable As: The new parts are direct replacements for the former parts, as shown in Charts A and D. The new parts are in effect with the serial numbers shown in Charts B and E. Chart C shows some of the lower rated applications where the parts in Chart A can be used. See the topic "Troubleshooting". Chart F shows the replacement piston ring groups (or kits) which are available for the basic piston groups, and the rings in each group.

Troubleshooting

If engine slobbering becomes a problem, use the procedure that follows to find and correct the probable cause.

1. Inspect turbocharger seals for wear or damage. Install new seals if necessary.

2. Check valve guide clearances. See the "Specifications" section of the Service Manual for the correct clearance specifications.

3. Install a 6N7174 Oil Shield on each rotocoil assembly on the engine valves in the cylinder head.

If these steps do not correct the problem, go to Step 4.

4. Check the serial number and arrangement number of the engine with the numbers shown in Chart C.

a. If the numbers are in the range shown in Chart C, install the new parts shown in Chart A.

b. If the numbers are not in the range shown in Chart C, go to Step 5.

5. Check the Parts Book for the engine serial number and arrangement number to find the type of rings used in the specific engine.

a. If the engine uses rectangular type rings (9S3029 Top Ring, 5S6750 Intermediate Ring, and 9S7788 Oil Ring), the problem is possibly worn rings. Install new rings of the same part numbers.

b. If the engine uses keystone type rings (as shown in the "Former Part No." column of Chart D), and the serial number and/or arrangement number are not in the ranges shown in Charts B, C, or E, install the new top and intermediate rings shown in Chart D.

Comparison of top ring designs.