CASE 7T2653 - Caterpillar

Blowby Test Procedure
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Locate the crankcase breathers (1) on the engine. The engine may have more than one crankcase breather. If there is more than one, the blowby coming from all of the crankcase breathers must be measured at the same time.Most engine installations will already have the breathers connected together with tubing (2). The pickup can then be installed after the point where they come together (3). If the breathers are not already connected, they may be connected with hoses or by temporarily plugging all but one breather for a short period during a temporary test.If the pickup installation is to be permanent, the breathers must be connected together with adequate sized tubing to prevent excessive crankcase pressure.
The 1U-8861 Large Engine Blowby Pickup (4) can be installed directly into the breather flexible fitting (5). The fitting is used on some Cat engines, provided the fitting is the correct size. This installation is suitable for a temporary check of blowby.Be sure to install the pickup with the arrow pointing away from the engine in the direction of blowby air flow. Secure the pickup with a hose clamp. Since the pickup is heavy, it may be necessary to secure the pickup to keep it from moving during the operation.
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For installation to the end of a metal blowby tube, a rubber hose (6) is included in the group. It will fit most tubes which have close to a 50 mm (2.0 inch) diameter. Secure the hose with clamps (7) .
Attach an 8T-5297 Cable or a 6V-2198 Cable to the connector on the pickup and the other end to the pickup connector on the 8T-2701 Indicator . The installation is complete.Measuring Blowby
Note: The large blowby pickup is sensitive to excessive high frequency noise and air currents entering the open end of the pickup. To prevent inaccurate readings, keep the pickup outlet as far away from the engine turbocharger as possible, and away from the fan or any wind blowing past the open end of the pickup.If the pickup must be placed close to the engine or in the air stream, use a length of rubber hose to extend the outlet away from the source of high frequency noise or air stream.
Start and run the engine until normal operating temperature is reached.
Blowby readings should be taken with the engine at full rpm. Readings may be taken at no load or full load, but the engine must be loaded to measure the maximum blowby output of the engine.On smaller 3500 engines, the indicator may show zero until the engine is loaded since the blowby is below the minimum rating of the pickup.Analyzing Results
Note: Blowby should be used as a guide only to indicate engine condition and not as an absolute good/bad indicator. DO NOT use the blowby data alone to determine if the engine should be rebuilt. If the blowby value is high, check the other indicators such as oil consumption, low power, etc.Cat recommends checking the blowby