Howdy;
Inspection of the exterior condition of oil cooler hoses will not determine
the condition of the hose, as most of the hose deterioration takes place in
the inner lining of the hose that transfers the hot engine oil. Engine oil
temperatures will be 30 to 50 degrees above the engine coolant temperature,
even higher on hard pulls. On the 455 engines, steel oil lines came off of
the oil filter adapter and ran forward, under the right exhaust manifold,
to the front of the engine. The oil cooler hoses were fastened onto the end
of these steel lines and ran to the cooler in the right radiator tank.
These hoses have replaceable ends on them. The replacement ends are of the
Aeroquip style. The 403 engines, put in the coaches in mid ' 77 had a
different oil filter-oil cooler adapter, and the oil cooler lines were
routed over to the right frame rail, and then ran forward along the frame
rail to the oil cooler in the radiator tank. These oil cooler lines were a
combination of steel lines and flexible hose, and most of the hoses had
crimped ends, not the replaceable type. The steel lines in both of the
engine models are subject to corrosion, especially where they are clamped,
and have been known to develop pin-hole leaks.
Aeroquip makes an excellent replacement hose for use in the GMC. It is FC
350-08 AQP Truck hose. This hose has an elastomer inner tube with a
polyester textile braid cover. It has a minimum bend radius of less than
2", which means it is flexible enough to not put undue strain on the
radiator tank. This hose was designed for truck applications, is DOT rated
and has a -55 to + 300 F operating temperature rating. The "08" on the
number designates the hose size. This hose uses reuseable fittings, the
same fittings that came on the 455 engines. To find a supplier, Aeroquip
web address is www.aeroquip.com
When replacing hoses on the 455 engine, a good improvement can be made by
doing the following: #1: eliminate the steel lines under the exhaust
manifold, they transmit the manifold heat into the oil. #2: route the
cooler lines from the oil filter-cooler adapter to the right frame rail,
then forward to the radiator. Use hose for the entire run, eliminating the
steel lines and the numerous fittings needed. On the 455 engine, these
adapters and fittings will accomplish this, and are available from Aeroquip
with these numbers. Two pipe to 45* flare adapters, # 2007-8-8B ; two 45*
swivel hose fittings, #4401-8S ; two male inverted flare hose fittings, 90*
elbow, #190235-8S. These 90* elbows are the same as what was installed in
the radiator tank as original equipment, and use the originals if
serviceable. Clamp the hoses securely to the right frame rail to prevent
scuffing.
Aeroquip also makes a Firesleeve that is a braided fiberglass tubing
impregnated with flame resistant silicone rubber that can be slipped over
the cooler hoses before assembly to protect the hoses from the engine
compartment heat. The Aeroquip number for this Firesleeve is # 624-16.
Bob
Drewes
Inspection of the exterior condition of oil cooler hoses will not determine
the condition of the hose, as most of the hose deterioration takes place in
the inner lining of the hose that transfers the hot engine oil. Engine oil
temperatures will be 30 to 50 degrees above the engine coolant temperature,
even higher on hard pulls. On the 455 engines, steel oil lines came off of
the oil filter adapter and ran forward, under the right exhaust manifold,
to the front of the engine. The oil cooler hoses were fastened onto the end
of these steel lines and ran to the cooler in the right radiator tank.
These hoses have replaceable ends on them. The replacement ends are of the
Aeroquip style. The 403 engines, put in the coaches in mid ' 77 had a
different oil filter-oil cooler adapter, and the oil cooler lines were
routed over to the right frame rail, and then ran forward along the frame
rail to the oil cooler in the radiator tank. These oil cooler lines were a
combination of steel lines and flexible hose, and most of the hoses had
crimped ends, not the replaceable type. The steel lines in both of the
engine models are subject to corrosion, especially where they are clamped,
and have been known to develop pin-hole leaks.
Aeroquip makes an excellent replacement hose for use in the GMC. It is FC
350-08 AQP Truck hose. This hose has an elastomer inner tube with a
polyester textile braid cover. It has a minimum bend radius of less than
2", which means it is flexible enough to not put undue strain on the
radiator tank. This hose was designed for truck applications, is DOT rated
and has a -55 to + 300 F operating temperature rating. The "08" on the
number designates the hose size. This hose uses reuseable fittings, the
same fittings that came on the 455 engines. To find a supplier, Aeroquip
web address is www.aeroquip.com
When replacing hoses on the 455 engine, a good improvement can be made by
doing the following: #1: eliminate the steel lines under the exhaust
manifold, they transmit the manifold heat into the oil. #2: route the
cooler lines from the oil filter-cooler adapter to the right frame rail,
then forward to the radiator. Use hose for the entire run, eliminating the
steel lines and the numerous fittings needed. On the 455 engine, these
adapters and fittings will accomplish this, and are available from Aeroquip
with these numbers. Two pipe to 45* flare adapters, # 2007-8-8B ; two 45*
swivel hose fittings, #4401-8S ; two male inverted flare hose fittings, 90*
elbow, #190235-8S. These 90* elbows are the same as what was installed in
the radiator tank as original equipment, and use the originals if
serviceable. Clamp the hoses securely to the right frame rail to prevent
scuffing.
Aeroquip also makes a Firesleeve that is a braided fiberglass tubing
impregnated with flame resistant silicone rubber that can be slipped over
the cooler hoses before assembly to protect the hoses from the engine
compartment heat. The Aeroquip number for this Firesleeve is # 624-16.
Bob
Drewes
