Hummer H1 Service Manual page 50

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PROBLEM
Excessive Oil 1. Prolonged high speed, high load, or overload
Consumption operation.
2. Incorrect oil grade used for high ambient
temperature operation.
3. Oil leaks at:
¥ Rocker covers
¥ Rear main seal
¥ Timing chain cover or seal
¥ Cooler hoses/lines
4. CDR valve or hose faulty.
5. Engine problem:
¥ Worn broken piston rings
¥ Worn valve seats or guides
Engine Vibration 1. Loose engine accessories:
¥ Alternator
NOTE : See road
¥ A/C compressor
test information
¥ Power steering pump
in this section.
¥ Mounting brackets
¥ Pulleys
¥ Belt tensioner
¥ Serpentine belt
¥ Drive pulleys
2. Torsional damper damaged or loose.
3. Flywheel (driveplate) cracked or loose.
4. Torque converter imbalance caused by inter-
nal damage or missing balance weight.
Overheating 1. Dirt, debris blocking air ßow through cool-
ers, condenser, and radiator.
2. Low coolant level.
3. Serpentine belt loose, worn, or tensioner
inoperative.
4. Prolonged idling/slow speed operation in
heavy trafÞc when ambient temperatures are
high.
05745159
Engine Diagnosis
POTENTIAL CAUSE
¥Oil pan
¥Oil Þlter
CORRECTION
1. Reduce overload, or speed as needed.
2. Switch to SG, SH-CD oil with SAE viscosity rat-
ing of 15W-40, 20W-50, or 30W.
3. Locate and correct leaks as needed.
4. Check valve and hose and replace if necessary.
5. Run compression test to verify ring problem.
Overhaul cylinder heads if guides, seals, valves are
worn. If wear is premature, check injectors and
injection pump. Excessive fuel will wash oil off
walls/guides causing ring and valve wear.
1. Check and repair as needed. Replace damaged
missing bolts and apply Loctite 242 to loose bolt
threads. Replace serpentine belt if damaged.
Replace bent, broken pulleys.
2. Replace damper if damaged, worn, loose.
3. Replace ßywheel and also check for ballooned or
damaged converter.
4. Replace converter.
1. Remove and clear Þns with compressed air, soft
bristle brush, or water stream.
2. Add coolant and check for leaks (hoses, surge
tank, hose connections, water pump, radiator).
3. Replace belt and/or tensioner if either part has
failed or is worn beyond limit.
4. If this type operation cannot be avoided, have
driver turn on heater and ÒrevÓ engine when
stopped in trafÞc. This will help dissipate some
heat and get more air through radiator (from fan).
Engine 2-13