Volvo Maintenance Hints for 7xx/9xx - Bill Garland's Nuclear ...

link.
● Heater hose fractured due to aging and internal crack; catastrophic loss of coolant
● Heater hose chaffed against block, rubbing through and failing; catastrophic loss of
coolant
● Heater hose was not secured by plastic clip and contacted EGR exhaust tube, melting it
and causing a sudden leak
● Water pump-to-heater tube corroded at welded support bracket and failed
● Radiator plastic side tank fractured; catastrophic loss of coolant
● Radiator hose split due to aging and internal crack. Upper: loss of coolant; lower:
catastrophic loss of coolant
● Top radiator hose clamp was over-tightened, cracking plastic neck outlet. Some coolant
was pumped out and the engine temp gauge showed overheating but no damage
occurred.
● Hose clamp failed; lower radiator hose parted from radiator outlet neck. All the coolant
suddenly drained out of the radiator, leaving only the coolant in the block. Engine
required a new headgasket.
● Turbo oil cooler coolant hose became oil-soaked and failed. Check these when you
change your oil filter: they are below and behind the oil filter assembly.
● Coolant reservoir hose became oil-soaked at the clamp and split. All coolant was
pumped out and the engine overheated.
● Coolant reservoir bottom nipple broke off, the tank fractured, or the cap leaked, causing
loss of coolant.
● Water pump seized due to a bearing failure around the pump shaft, shucking one of the
two drive belts. The remaining belt was sufficient to start the pump turning again, but this
resulted in the cast iron pump impeller coming into contact with the back of the pump
casing, smashing it and causing loss of coolant.
● Electric frost plug engine heater leaked due to corrosion of the anchoring device; slow
leak.
● Nobody mentioned a failed water pump shaft seal as a cause of catastrophic loss-ofcoolant,
merely resulting in slow leaks.
In almost every case, the lack of an "idiot light" caused drivers not to notice the loss until too
late. When the driver finally looked at the temperature gauge, it was invariably far into the red
zone, indicating serious overheating. In almost every case, drivers attempted to drive to a
convenient destination such as home, a gas station, or a freeway exit. This extended drive
usually led to further engine damage. The least damage noted (except in the last instance) was
head gasket; in many instances the engine required replacement.
Lessons learned:
1. Assume that your cooling system components have a limited lifespan. Replace them
according to an intelligent schedule. I replace hoses and water valve every eight years
and the radiator at year ten. I replace the water pump either at a convenient maintenance
interval or when it starts leaking at the seal. For turbo cars, assume that the higher
underhood temperatures will reduce component lifetimes, so that your radiator and water
valve will last only eight years. Brickboard consensus is that the strong points in the
cooling system are the OEM hoses; the weakest point is definitely the heater water valve;