405
Replacement
plain rubber cooling hoses - a caution
Recently the original
style of string reinforced rubber cooling hoses has been resourced
and hoses are now available individually or as complete replacement
hose sets at reasonable prices. Over recent years, when supplies
of string reinforced rubber hoses were not so easy to come by,
plain rubber hoses were available and have been bought and fitted
to MGBGTV8s and V8 Roadsters by members carrying out routine
replacements. In the last ten days or so one of our members
experienced a failure with a main cooling hose and it's worth
relating how the failure occurred. Editor.
(Jul 09)
A
plain rubber top hose, which had been on the car for a quite
a few years and looked sound if a little "mature",
swelled on the side nearest the fan belt pulley to such an extent
that it made contact with the edge of the pulley. This resulted
in a small groove in the outer face of the hose wall which eventually
developed to such an extent that the wall of the hose weakened
and burst, releasing the hot coolant. At that time the V8 was
crawling in very slow stop-go-stop traffic conditions near the
M42/M40 junction so without the ram cooling effect, the engine
was getting hot and the twin cooling fans were working overtime!
The high temperature of the coolant contributed to the pressure
in the hoses.
So
all members with an MGBGTV8 or V8 Roadster are |
urged
to check, or have checked, their top cooling hose - first
to check the clearance between the top hose and the pulley,
second to check the condition of the wall of the hose, third
to run the engine up until it is hot when the cooling fans
kick in and see if there is any sign of swelling in the walls
of the hose, fourth to check the service records to see how
old each of the hoses is and finally to check to see whether
the hose is an original style string reinforced or plain rubber
hose. You can identify a string reinforced hose by checking
the ends of the hose where the ends of the string can be seen
around the face of the circular section. When checking the
clearance between the top hose and pulley, the curve of the
plain rubber hose seems to be less generous than the original
style of the string reinforced rubber hoses, so that may also
be a factor in reducing the clearance.
It's
worth replacing the complete set of hoses on a preventative
basis - the temptation is to replace only the top and bottom
hoses as they are easy to get to and deal with, and feel the
smaller hoses can last a little longer. Take care adopting
that approach as the small hose beneath the carburettors can
burst unexpectedly as it did with me - fortunately I was moving
at slow speed on my drive and not on the motorway at speed.
See V8NOTE386 on replacing hose
BHH1083.
If
you prefer and do not mind the slightly black shiny finish,
replacement hose sets are also available in silicone.
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