Using the 1U-8860 Large Engine Blowby Pickup Group{0781, 0785} Caterpillar

Introduction

The 1U-8860 Large Engine Blowby Pickup Group is an optional pickup for use with the 8T-2701 Blowby/Air Flow Indicator.

It contains a large 38 mm (1.5 in) I.D. pickup which allows it to be used on large engines without increasing the crankcase pressure.

It is designed to monitor the blowby volume on Caterpillar 3500 and 3600 series engines and the larger D300 series engines as well as competitive large engines.

The range of this pickup is 94 to 1888 Liters Per Min. (L/min), (200 to 4000 Cubic Feet Per Hour [cfh]).

Due to its all metal construction and large size, it is suitable for permanent installation on engines so blowby can be continuously monitored, making it useful for dynamometer rooms or marine or gen set installations.

The pickup group can also be used to measure air velocity such as radiator cooling air flow. When connected to the 8T-2701 Blowby/Air Flow Indicator, it provides a digital display of the blowby value (the volume of exhaust gas escaping to the crankcase). This blowby value can be used as an indication of engine condition.

However, it should not be used as a stand alone "good/bad" indicator for engine overhaul. It can be used as a signal that other engine condition indicators such as oil consumption, low power, hard starting, and excessive fuel consumption should be checked to determine if an engine is in need of maintenance.

The large blowby meter has no moving parts. An ultrasonic sound vortex shedding principle is used to measure the air flow. This principle makes the pickup reliable and virtually maintenance free.

This unit will be used to replace the smaller 8T-2685 Pickup for the measurement of 3500 series engine blowby. The 8T-2685 Pickup can be used on these engines, but only for a short duration test since the 50.8 mm (2 in) engine breather tube is reduced to 15.7 mm (.63 in) during the test. The 8T-2701 Blowby/Air Flow Indicator will be used with the larger probe, however a 1U-8863 Conversion Group must be installed to make it accurate. Refer to Installation of the 1U-8863 Conversion Group.

Refer to Special Instruction SEHS8712 for additional information on the Blowby/Air Flow Indicator.

Adaptability

When used with the 8T-2701 Indicator, the 1U-8860 Pickup can be used to measure the blowby on any engine within the blowby range of 94 to 1888 L/min (200 to 4000 cfh). This includes the larger Caterpillar D300 Engines, the 3500 and 3600 series engines.

Smaller D300 and 3500 engines may not have enough blowby at idle or partial load to give a reading when they are in good condition. Therefore, the indicator display will read zero until the engine is loaded.

1U-8860 Large Engine Blowby Pickup Group

(1) 6V-7145 Case NEEG2332 Decal (1U-8860 Group)

(2) 1U-8861 Pickup - Large Engine Blowby NEEG2331 Decal (1U-8861)

(3) 1U-8863 Conversion Group - Large Pickup

(4) 9M-0164 Hose Clamp - Worm Drive 12.7 mm × 63.5 mm Dia. (.50 in × 2.50 in Dia.) 2 Required.

(5) 1U-8868 Hose, Rubber - 57 mm ID. × 305 mm (2.3 in ID. × 12.0 in) (Goodyear Part No. 56036).

(6) SEHS8984 Special Instruction (not shown).

Optional Items

(1) 8T-2701 Blowby / Airflow Indicator

(2) 8T-5297 Cable - Blowby Pickup 915 mm (3.0 ft)

(3) 6V-2198 Cable - Blowby Pickup 5486 mm (18.0 ft)

(4) 5P-7366 Cable - Indicator Power 5486 mm (18.0 ft)

(5) 8T-5268 Converter, 110/220 Volts AC, 50/60 Hz for powering 8T-2701 Indicator. Supplies 11 to 20 Volts DC at 0.3 Amp. (Max. Current).

(6) 8T-2700 Blowby / Airflow Indicator Group for Small Engines, Complete (not shown).

Specifications (When used with the 8T-2701 Indicator)

Blowby Measuring Range:

Liters Per Minute (L/min) ... 94 to 1888

Cubic Feet Per Hour (cfh) ... 200 to 4000

Air Flow Measuring Range: (With Blowby V1.20 PROGRAM installed in 8T-2700 Indicator:

Meters Per Minute (M/min) ... 83 to 1656

Feet Per Minute (f/m) ... 272 to 5436

Accuracy:

The system accuracy is ± 10% of reading.

Resolution:

Blowby: 1 L/min (1 ft³/m)

Airflow: 1 M/min (1 ft/m)

Operating Temperature:

Pickup: -18 to 121°C (0 to 250°F)

Storage Temperature:

Pickup: -40 to 232°C (-40 to 450°F)

Probe Size:

Length: 382 mm (15.0 in)

Outside Dia.: 50.8 mm (2.00 in)

Inside Dia.: 38.1 mm (1.50 in)

Width: 113 mm (4.5 in)

Height: 130 mm (5.2 in)

1U-8860 Group Case Size:

432 × 330 × 114 mm (17.0 × 13.0 × 4.5 in)

Weight:

1U-8860 Group: 6.1 kg (13.50 lb)

1U-8861 Pickup only: 3.0 kg (6.60 lb)

Power:

Provided by the PICKUP connector on the 8T-2701

Blowby/Air Flow Indicator.

Installation of the 1U-8863 Conversion Group

A 1U-8863 Blowby V1.20 Conversion Group integrated circuit (1) is packaged with the 1U-8860 Large Engine Blowby Pickup Group. This integrated circuit contains the program which makes the large pickup readings accurate.

The integrated circuit must be installed in the 8T-2701 Blowby/Air Flow indicator you will be using. Once this is completed, the 8T-2701 indicator will be accurate for both the Large Blowby Pickup and the Small Blowby Pickup.

The 1U-8863 Conversion Group (1) is the small plastic box packed in the front storage area of the large pickup case. Open the small plastic case to identify the conversion group integrated circuit memory, but DO NOT remove it at this time. It should be marked "1U-8863 Blowby Gp. V1.20".

Use the following instructions to install the integrated circuit in the 8T-2701 Indicator which will be used with the large blowby probe.

Installation Instructions

1. Remove six screws (2) from the rear cover and remove cover (3).

2. Remove battery (4) from the holder. Use a small screwdriver to pry the old Blowby V1.19 integrated circuit memory from its socket and remove.

NOTE: This part is to be replaced and is no longer needed.

3. Remove the 1U-8863 Blowby Group V1.20 integrated circuit (1) from its protective plastic case and very carefully install it into the socket next to the battery holder (5) as shown above.

NOTE: The notch in the end of item (1) must be at the battery holder end of the socket.

NOTE: Check to make sure all of the pins are in the socket and are not bent over or under.

NOTE: The integrated circuit may not have as many pins as the socket has holes. When this occurs, install the integrated circuit as far as it will go towards the edge of the printed circuit board so the empty socket holes are on the battery holder end of the socket.

4. Install a new 9 Volt battery in the battery holder.

NOTE: Be sure that the + (positive) terminal on the battery is on the + (positive) red terminal on the holder.

5. Install rear cover (2) and six screws(3).

6. Check the operation of the 8T-2701 Indicator with the large blowby probe as described later. If a small 8T-2685 Pickup is available, also check the indicator with it by using the procedure in Special Instruction SEHS8712, "Using the 8T-2700 Blowby/Air Flow Indicator Group".

7. If the indicator works properly it is ready for use.

Blowby Test Procedure

1. Locate the crankcase breather(s) (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 them 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 they are not already connected together, 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.

2. The 1U-8861 Large Engine Blowby Pickup (4) can be installed directly into the breather flexible fitting (5) used on some Caterpillar 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.

3. 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 in) diameter. Secure the hose with clamps (7).

4. Attach an 8T-5297 Cable or a 6V2198 Cable to the connector on the pickup and the other end to the pickup connector on the 8T-2701 Indicator. This completes the installation.

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.

1. Refer to Special Instruction SEHS8712 for instructions on how to operate the 8T-2701 Indicator.

2. Start and run the engine until normal operating temperature is reached.

3. 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.

Approximate blowby rates for Caterpillar large engines are shown in the chart. The values listed are the typical maximum rates for an engine in new condition. These values are typical ONLY and not absolute.

NOTE: Additional valves can be found in the Technical Marketing Information.

It is recommended to always check the blowby by the same method for better comparison of future tests. Record the blowby rate and the load on the engine during the test for later reference.

It is suggested that new engines initially be checked for blowby and thereafter during all maintenance checks.

As the engine rings and cylinder walls wear, the blowby will gradually increase. The blowby on a worn engine will be considerably higher than for a new engine. By keeping a record of the results, a gradual increase in the amount of blowby will be noted until the amount of blowby has become excessive.

Usually, high oil consumption and other problems associated with high blowby will not be experienced until the blowby is considerably higher than the values shown in the chart. (Approximately two times or more.)

After a new engine is used for a short time, the blowby can decrease as the rings are seated. Also, a newly rebuilt engine can have a high blowby rate due to the rings not being properly seated, or worn parts which were not changed, ie. valve guides.

Checking the Operation of the Large Blowby Pickup

Obtain the 8T-2700 Blowby/Air Flow Group which will be used with the large probe. Perform the check out instructions per Special Instruction SEHS8712, to be sure the probe is working properly before proceeding.

If the 8T-2685 Pickup is not available, only perform the following tests.

The components required for the following test are the 8T-2701 Indicator, the 8T-5297 or 6V-2198 Cable and the 1U-8861 Pickup.

1. Connect the 1U-8861 Pickup to the indicator with the cable.

2. Press the ON switch, then the FT/MIN, ACTUAL, and the NORM RATE switches. An arrow should appear on the display and point to the same name as the switch pressed. The display should read zero.

3. Blow into the pickup in the direction of the arrow on the side. Observe the reading on the indicator display. It should read approximately 862 to 1439 FT/MIN, depending on how hard you blow.

4. Press the M/MIN switch and the arrow should point to M/MIN. Blow into the pickup again and the indicator should read approximately 262 to 438 M/MIN, depending on how hard you blow.

5. Press the FT3/HR switch and the arrow should point to the FT3/HR. Blow into the pickup again and the indicator should read approximately 635 to 1059 FT3/HR, depending on how hard you blow.

6. Press the L/MIN switch and the arrow should point to L/MIN. Blow into the pickup again and the indicator should read approximately 300 to 500 L/MIN depending on how hard you blow.

7. Press the OFF switch and the display should be blank.

This completes the test for the 1U-8863 pickup.

Checking Airflow with the Large Blowby Pickup

The 1U-8861 Pickup can be used to check air flow through the radiator core in the same manner as the 8T-2685 Pickup, however, the range of air flows it will measure is not as broad.

The large pickup will not read a low air flow. When checking a radiator with the large pickup, it will often read zero in areas which have low air flows.

This makes it harder to check for plugging.

Refer to Special Instruction SEHS8712, "Checking Air Flow", for details.

Repair Information

If the large blowby probe does not operate correctly, use the procedure, "Checking Operations of the Pickup", to determine if the problem is in the pickup or the indicator.

If the pickup is found to be faulty, contact Caterpillar Service Technology Group for service or warranty information.

Units less than one year old will be repaired under warranty (except for abuse). Cost of out of warranty repairs will be charged to the owner.

Phone - Toll Free Numbers

Outside Illinois ... 1-800-542-8665

Inside Illinois ... 1-800-541-8665

Canada ... 1-800-523-8665

U.S. Mail only:

UPS or Emery only: