PRACTICAL
by poking around with screwdrivers and
stiff spiral brushes.
When the ‘blow’ side of a vacuum
cleaner was applied to the anode orifice,
all manner of debris was ejected from
other water jacket openings.
The jacket drain tap and fitting were
completely blocked, which almost
certainly meant the engine had been
running with very limited cooling.
Major repairs
The major items that needed repair were:
a broken exhaust elbow, a badly scarred
piston, some heavy corrosion on the
exhaust port in the cylinder head and a
small burn pit in the engine block face.
SUMP PLUG WARNINGMuch has been written about the
‘sump drain plug’ on the 1GM10.
Remove this at your peril because
the plug’s primary purpose appears
to be, with the aid of a spring, to hold
the strainer for the oil pump in place.
Remove the sump plug and the
strainer will spring out of line.A simple rig was set up to test whether
the exhaust elbow had any leaks
Pinhole corrosion in the internal tube of the exhaust elbow meant it had to be replaced
New stainless steel exhaust elbow was
bought from America for £111Steel-reinforced epoxy was applied to the
exhaust port face...... and resulted in a solid, gas-tight face
when flatted offSump showing oil pump strainer and
retaining spring arrangementGASKET FLAME RINGThe head gasket consists of
Halite-type material with a steel shim
plate covering the whole upper
surface of the gasket. The edges of
the plate are folded back on
themselves, effectively forming a
‘tube’ which seals the cylinder and
protects the gasket material from the
combustion flame.The scarred piston had to be replaced at a
cost of £133, but we managed to repair
most of the other damage.Exhaust elbow
The broken elbow was re-welded by a
local engineering workshop for £25,
though it did need another ‘flash’ to cure a
slight weep revealed by a simple test rig
we set up. However, a further test then
indicated that the inner pipe was actually
perforated, so in the end we bit the bullet
and ordered a stainless steel replacement
from America, at a cost of £111.
In fact, the failure of this elbow led me to
remove the elbow on the 1GM10 in my
own Leisure 23SL. Although the face of
the exhaust port was not as badly
corroded as that on Northern Light, the
test rig showed pin-holing of the inner
pipe, so another £111 winged its way to
the US.Exhaust port
The scarring on the exhaust port face was
degreased and thoroughly cleaned up
using a small cutter in a Dremel. Since this
joint does not have to withstand high
pressures it was filled using JBWeld Steel
Reinforced Epoxy. This product is claimed
to withstand a temperature of 285°C, and
there is extensive evidence on the internet
of its successful use in automotive repairs.
When cured it was flatted, revealing an
apparently effective repair.Engine block
The next item for consideration was the
small pit on the top of the engine block.
This had been caused by the gasketprotection flame ring (see panel, above)
splitting on its internal circumference,
allowing the combustion flame to pass
through the split and to burn both the
gasket material and the engine block as it
exited into the water gallery.
The conventional approach would be to
have the block skimmed to remove the
indentation – and the piston shaved to
prevent it hitting the now-lowered cylinder
head. This would have meant stripping the
engine down to the bare block, two round
trips to a distant engineering workshop,
and more new gaskets.
But cleaning out the pit with a cutter in a
Dremel revealed there was actually some
metal left between the water jacket and
cylinder bore, that the deepest part of the
pit was away from the bore, and that the
register for the flame ring was only slightly
marked. In the light of these findings, we
considered that JBWeld epoxy should
once again prove to be a permanent and
cost-effective solution.
This approach could provoke the
comment ‘What a bodge up!’, but the
decision was not made lightly. Not onlyOil pump
strainerSump
plug
spring