Grizzly G470 User Manual
Page 20
 
Model G0464/G0465/G0467/G0468/G0470 Air Compressors
-
18
-
Symptom
Possible Cause
Possible Solution
Loud repetitious noise 
coming from machine.
1. Pulley setscrews or keys
are missing or loose.
2. Motor fan is hitting the
cover.
1. Inspect keys and set-
screws. Replace or 
tighten if necessary.
2. Adjust fan cover mounting
position, tighten fan, or 
shim fan cover.
Low pressure at the 
tool.
1. Pressure regulator.
2. Air leaks in hoses.
3. Pressure gauge bad.
4. Pressure switch turns the
motor
OFF too soon.
1. Adjust pressure regulator,
if no improvement, inspect 
regulator for leaks or 
replace.
2. Check air hoses and all
connections for leaks (see 
Page 20).
3. Replace the pressure
gauge.
4. Adjust the pressure switch
(see
Page 21).
Low pressure at the 
tanks, or tank pressure 
drops after compressor 
is turned 
OFF.
1. Air leaks in tanks or deliv-
ery pipes.
2. Drain valve open.
3. Air filter clogged.
4. Leaking check valve.
5. Pressure relief valve
releasing below 120 PSI.
6. Gaskets leaking.
7. Worn rings.
8. Pressure switch turns the
motor
OFF too soon.
1. Check air tanks, pipes and
all connections for leaks 
(see 
Page 20).
2. Close drain valve.
3. Inspect and clean air filter.
4. Repair the check valve 
(see
Page 19).
5. Replace pressure relief
valve.
6. Check gaskets on cylinder
head assembly, repair or 
replace as needed.
7. Inspect and replace pump
piston rings.
8. Adjust the pressure switch
(see
Page 21).
Compressor knocking.
1. Improper oil level.
2. Air filter clogged.
3. Piston assembly loose.
1. Check oil level and add oil
(see
Page 9).
2. Inspect and clean air filter.
3. Inspect and repair piston 
and connecting rod.
Pressure relief valve 
stays open and motor 
won’t stop running.
1. Pressure switch adjusted
too high.
2. Faulty pressure switch,
unit is trying to overpres-
sure the tank.
3. Faulty pressure relief
valve.
1. Adjust the pressure switch
(see
Page 21)
2. Turn compressor
OFF,
unplug from power sup-
ply, and empty tank. 
DO NOT USE until switch 
is replaced.
3. Relief valve is reliev-
ing pressure too early. 
Replace pressure relief 
valve.