Bendix Commercial Vehicle Systems BX2150 AIR COMP - Manual (Page 11)

11
CLEANING OF PARTS
GENERAL
All parts should be cleaned in a good commercial grade
solvent and dried prior to inspection.
CYLINDER HEAD
Remove carbon deposits from the discharge cavity and rust
and scale from the cooling cavities of the cylinder head body.
Scrape all foreign matter from the body surfaces and use
shop air pressure to blow the dirt particles from the cavities.
Clean carbon and dirt from the inlet and unloader passages.
Use shop air to blow the carbon and dirt deposits from the
unloader passages.
OIL PASSAGES
Thoroughly clean all oil passages through the crankshaft,
crankcase, end covers, and base plate or base adapter.
Inspect the passages with a wire to be sure they are clear.
Blow the loosened foreign matter out with shop air.
INSPECTION OF PARTS
CYLINDER HEAD BODY
Inspect the cylinder head for cracks and obvious physical
damage. Pay particular attention to the area around coolant
ports for cracks. Check for stripped or damaged threads.
Apply shop air pressure to one of the coolant ports with all
others plugged, and check for leakage by applying a soap
solution to the exterior of the body. If leakage is detected,
replace the head.
END COVERS
Check for cracks, stripped oil port threads and external
damage; and if noted, replace the end cover. If the crankshaft
main bearings are installed in the end cover, check for
excessive wear and flat spots and replace the end cover if
necessary.
CRANK CASE
Check all crankcase surfaces for cracks and damage. Pay
particular attention to cooling fins. On compressors where
ball bearing main bearings are used the difference between
the O.D. of the outer race and the I.D. of the crankcase hole
should be .0000 inch to .0015 inch loose. This is to maintain
the correct press fit. The crankcase must be replaced if the
fit is too loose.
On compressors fitted with precision, sleeve main bearings
the difference between the O.D. of the crankshaft journal
and the main bearing I.D. must not exceed .004 inch, or the
end cover and main bearing must be replaced.
The cylinder bore should be checked with inside micrometers
or calipers. Cylinder bores which are scored or out of round
by more than .0005 inch or tapered more than .0005 inch
should be rebored or honed oversize. Oversized pistons and
piston rings are available in .010 inch, .020 inch and .030
inch oversizes. The cylinder bore must be smooth, straight,
and round.
PISTONS
Check the piston for scores, cracks, or enlarged ring grooves;
replace the piston if any of these conditions are found.
Measure the diameter of the top of the piston and the top
two ring lands. (Compare to cylinder bore and piston
diameters to be sure the diametrical clearance is between
.0128 inch minimum and .0177 inch maximum.)
Check the fit of the wrist pin to the piston. The wrist pin
should be a light press fit in the piston. This clearance should
not exceed .0006 inch. If the wrist pin is a loose fit, the
piston and pin assembly should be replaced. Check the fit
of the wrist pin in the connecting rod by rocking the piston.
Conn rod wrist pin .0009 max. Replace the connecting rod if
excessive clearance is found. NOTE: Wrist pin bushing
replacement is not recommended for those connecting rods
which incorporate them.
Check the fit of the piston rings in the piston ring grooves.
Check the ring gap with the rings installed in the cylinder
bores. Refer to Figure 11 for correct gap and groove
clearances.
FIGURE 11 - CORRECT GROOVE CLEARANCE
PISTON
RING
OIL RING
.004
.012
CORRECT GAP CLEARANCE
WITH RINGS IN CYLINDER
.002
.004 .0015
.0035
OIL RING PISTON RING
CRANKSHAFT
Check the crankshaft threads, keyways, tapered ends and
all machined and ground surfaces for wear, scores, or
damage. Standard crankshaft connecting rod journals are
between 1.2500 inches and 1.249 inches in diameter. If the
crankshaft journals are excessively scored or worn or out of
round, the crankshaft must be replaced. Main bearing
journals must be maintained so the ball bearings are a snug
fit or so that no more than .004 inch clearance exists
between the precision sleeve main bearing and the main
bearing journals on the crankshaft. In crankshafts fitted with
oil seal rings, the oil seal ring groove or grooves must not be
worn. The ring groove walls must have a good finish and
they must be square. Using a wire or similar device, check
to be sure the oil passages are open through the crankshaft.