1988/06/20 Caterpillar

D397, D398, D399 Engines;
3500, 3600 Families of Engines

Reference: Service Magazine; October 27, 1986; Page 4; "New Indicator Instrument Group Available To Measure Crankcase Blowby And Radiator Air Velocity".

A 1U8860 Large Engine Blowby Pickup Group is available for making blowby and air velocity measurements on the above engines. It is used with the 8T2700 Blowby/Air Flow Indicator Group for the smaller bore engines announced in the reference article.

The 1U8860 Pickup Group for large engines contains a large 38 mm (1.5") inside diameter pickup meter (not individually serviced) allowing it to be used on the above large bore engines without increasing crankcase pressure. It can also be used on large competitive engines. This pickup has a range of 94 to 1888 L/min (200 to 4000 cfhr). Air velocity through the radiator can also be measured (83 to 1656 meters/min or 272 to 5436 ft/min). Because of its all metal construction and large size, this pickup can be installed permanently on engines so blowby can be continuously monitored, making it useful for dynamometer testing, or for marine and generator set installations.

The standard items included in the pickup group are shown in Illustration 1. The large blowby meter has no moving parts. This makes the pickup reliable and virtually maintenance free.

Illustration 1. Items included in the 1U8860 Pickup Group for large bore engines.

Use the data obtained by the blowby meter only as additional information concerning engine condition and NOT as a stand-alone good/bad indicator of engine condition. Do NOT use such data alone to determine if the engine should be rebuilt. Other indicators such as high oil consumption, low power, hard starting, and excessive fuel consumption must be considered.

Read the blowby rate at full engine rpm, either at no load or full load. On some engines, the no load blowby may vary as much as 100% from the full load blowby. Use the highest reading for the actual blowby value. System accuracy is ±10% of the reading.

NOTE: On some D397, D398, 3508 and 3512 Engines, the blowby indicator may read zero until the engine is loaded because the blowby is below the minimum rating of the pickup.

Optional Items Available

There are five optional items that can be used with the large engine pickup meter in the new pickup group. See Illustration 2 for Item numbers. Item numbers 3, 4, and 5 are also optional items for use with the 8T2700 Indicator Group for small engines, and may already be in your shop.

...(1) -8T2701 Blowby/Airflow Indicator (part of 8T2700 Indicator Group).

...(2) -8T5297 Blowby Pickup Cable, 915 mm (36").

...(3) -6V2198 Blowby Pickup Cable, 5500 mm (216").

...(4) -5P7366 Indicator Power Cable, 5500 mm (216").

...(5) -8T5268 Converter. Converts 110/220 Volts AC, 50/60 Hz power supply to 11 to 20 Volts DC at .3 Amp maximum for powering the indicator.

Illustration 2. Optional items available. See text for description and specifications.

Using The Large Engine Pickup Group

Special Instruction SEHS8984 comes packaged with the pickup group. Before using the 8T2701 Indicator with the large pickup, install the 1U8863 Blowby V1.20 Conversion Group (Illustration 1) in the indicator. This makes the indicator accurate for both the large pickup and small pickup. The Special Instruction also covers this conversion. Special Instruction SEHS8712 gives more information on the 8T2701 Indicator.