K 3500 Truck 4WD V8-5.7L VIN R (1998)
12.4. Go to Step 13 Connecting Rod Bearing Service.
13.
Connecting Rod Bearing Service
Important:
Do not disassemble connecting rod bearing caps for bearing clearance measurement.
The design of the connecting rods in these engines does not permit accurate bearing clearance measurements when the connecting rod caps are
disassembled from the connecting rods. Conventional methods of measuring bearing clearance, such as Plastigauge, cannot accurately be performed on
these engines.
GM Powertrain has developed a new, accurate and time-efficient means for measuring connecting rod bearing clearance without disassembly of the
connecting rods. In early 1999, SPX/Kent-Moore Tool will be releasing a new essential tool to dealers in the United States to facilitate this new
procedure.
Until this new, essential tool is released -
Contact:
SPX/Kent-Moore Tool at 1(810) 345-2233 who will then arrange for dealers to borrow a special connecting rod bearing clearance measuring tool and
associated instruction sheet and video.
Using this methodology, measure and refit connecting rod bearing inserts in each of the connecting rods. Use undersize connecting rod bearing inserts
(listed in the table below) to selectively fit each connecting rod bearing for a clearance of 0.001-0.002 in.
13.1. Center the connecting rod journal to be worked on in the 6 o'clock position. Using screw jacks, lock the crankshaft in position as close to the
bearing being worked on as possible. Tighten the screw jack sufficiently to displace the oil film from the upper main bearings. To avoid
damage to the crankshaft, use a cushioning material, such as a block of wood, between the crankshaft and jack.
13.2. Check rod bearing clearance using a bearing loading and unloading tool and test indicator capable of measuring 0.0001 inch increments.
Important:
A test indicator is required for this procedure, do not substitute a dial indicator. A dial indicator uses a plunger and will not provide repeatable
results. Likewise, Plastigauge is not effective in this repair and should not be used for this procedure. To ensure this analysis technique will be
accurate, do not disassemble the rod assembly.
13.3. With the rod bearing to be worked on in the 6 o'clock position, install the test indicator. Tighten the thumb screw until snug. Install the base
bracket to the oil pan rail and center it so that the handle can move freely in the slot provided. The link pin on the connecting rod bearing
clearance measuring tool should line up with the centerline of the connecting rod, and have a push/pull action in line with the connecting
rod. This alignment is crucial for accurate and repeatable measurements.
13.4. Screw the attaching stud of the flexible dial indicator support into a convenient oil pan rail bolt hole. Position the dial indicator so that the
stylus is centered on the connecting rod cap and lock the flexible dial indicator support into position.
13.5. Using the fine adjustment feature on the flexible dial indicator support (knob near dial indicator), adjust so that the dial indicator needle has
sufficient travel in both directions to take an accurate measurement.
13.6. Load the connecting rod in the upward direction of piston travel and zero the test indicator. Load the connecting rod in the reverse direction,
and record the reading off the indicator. Repeat this process 2-3 times, applying consistent pressure in each direction to ensure the oil film is
pushed out of the journal. Record these readings.
13.7. In order to accurately determine which rod or rods is causing the knock, perform this procedure on all eight rod assemblies.
13.8. Analyze the measurements from all eight rods. Select bearings that will put the total clearance for each rod at 0.001-.002 inch clearance.
Install new upper and lower bearing inserts as required, being sure to lubricate liberally with clean engine oil.
Tighten
13.8.1. Tighten the rod bearing caps on the first pass to 27 N.m (20 lb ft).
13.8.2. Tighten the rod bearing caps on the final pass to 55 degrees.
13.9. Reinstall the oil pump to the crankshaft rear bearing cap.
Tighten
