Question: My mechanic said I should replace the radiator
and heater hoses on my engine for preventative maintenance. Is
this really necessary?
Answer: It is if you want to minimize the risk of a breakdown
caused by a hose failure. Coolant hoses are pretty rugged, but
after four years of service, the incidence of failure rises sharply.
That's why many mechanics recommend replacing the hoses every
four or five years. It isn't absolutely necessary, but it can
greatly reduce the risk of a hose breaking or leaking.
The whole idea behind preventative maintenance is to replace
things BEFORE they fail -- ideally just as the component is nearing
the end of its normal service. Unfortunately, it's difficult
to tell exactly when that point is reached. The original equipment
radiator and heater hoses on some vehicles may go eight or ten
years without a problem. Then again, they might not.
If your vehicle is more than eight years old and the hoses
have never been replaced, you're probably driving on borrowed
time. Replacing the hoses would be highly recommended if you're
at all concerned about reliable transportation.
UNDERSTANDING HOSE FAILURES
Regardless of how frequently (or infrequently, if ever) the
hoses are replaced, they should be inspected periodically to check
for problems. Any hose that is leaking, age cracked, hard, brittle,
mushy-feeling, bulging or otherwise damaged needs to be replaced.
Heat, vibration and internal corrosion are the factors that
age the rubber in hoses and eventually make them fail. In many
instances, a hose that looks good as new on the outside will be
rotten on the inside. This is caused by "electrochemical
degradation," and it occurs because the hose, coolant and
metal parts of the cooling system form a galvanic cell or battery.
The electrochemical reaction that results forms small micro cracks
inside the hoses. The cracks allow coolant to penetrate the rubber
and weaken the reinforcement. Heat and flexing accelerate the
process, and eventually the hose fails from the inside out. The
process may take years to occur, or it may happen in a relatively
short time (25,000 miles or less) depending on the conditions
that are present.
Upper radiator hoses and small diameter bypass hoses tend
to be much more vulnerable to this type of internal failure than
other hoses. One reason is because these hoses usually carry
the hottest coolant. The smaller inside diameter of bypass hoses
also seems to accelerate because the coolant is flowing through
it at a higher velocity.
Some hose manufacturers are offering a new type of long life
hose made of "EPDM" rubber that is highly resistant
to internal corrosion. This type of hose is more expensive, but
is well worth the extra cost when you consider how much longer
it lasts (up to 200,000 miles or more!).
