The saga continues on my oil guzzling 51 MGTD MII. The machine shop that
just rebuilt my XPAG head (incidentally, they did an absolutely
beautiful job, looks NEW throughout), said I MUST hone my cylinders and
put in new rings. They listened to my symptoms, had me run a test in
which I put transmission fluid in the top of the pistons to measure
seepage overnight (rate was 1/32 to 1/16 inch per hour) and concluded
that the rings, although only used 11,000 miles, are not seated and/or
are bad. They said a common cause is fuel flushing the cylinders when
running the carburetors too rich. Never heard of this before, but then,
what do I know about cars - that's changing FAST.
I am looking for any advice on honing. Never done before so interested
in any cautions, lubricants, how to tell when to stop honing, etc. I
purchased a device yesterday from my local auto parts store. It has
three narrow vertical grinding stones which are on three spring loaded
arms. The package said it is a "deglazer" but the shop said this is what
I needed (apparently there are two different types of honing - one that
is done after a cylinder is bored and one for just seating new rings).
This unit is to be driven by a drill motor. At what preferable speed?
Following is what I have heard locally, but some of it is conflicting so
need to ask for advice. Also, perhaps some steps has been left out. What
is correct?
I was told to run the drill at low speed, and to zip to the bottom of
the cylinder in about 1.5 seconds with the honing stones, then without
holding at the bottom, bring it back up in 1.5 seconds. That should do
it. If there is any evidence of a ridge, to hold it at the top for "a
little while". I have heard to use oil on the stones. However, the parts
shop said to use brake fluid. Another source said to use kerosene or
gas. When asked why use a solvent instead of oil, was told to use a
solvent to keep metallic particles from being embedded in the walls and
keep it clean. Oil would do the opposite. Which is correct?
Because of the difficulty of getting pistons out when the crank is still
in place, the machine shop said it would be much easier to accomplish
the task from the top while the head is off. They said to disconnect the
connecting rods, push the piston as far down as possible but not out.
Cover the gap around the top of the piston with grease to keep debris
from falling down around the side, and then hone (I'm afraid gas or
brake fluid will wash away the grease, but perhaps not).
Then clean the walls with solvent, bring the piston up half way and lay
each new ring level on the top of the piston, to check the gap with a
feeler gauge. Any advice here?
Then bring the piston up as far as it will go, exposing all rings (my
pistions have just 3 rings). The old rings should carry up any debris
that might have fallen down the side, pass the grease. Remove the old
rings, clean the piston, oil piston and groves and install the new
rings. Stagger the gaps. Push the pistons back down into the cylinder
and reconnect the connecting rod. Job done.
Having never done this before and not having any manual to follow, I
would appreciate any advice, comments, warnings, etc.
Thanks, as always, for all the help.
Stu Keen
51 MGTD MkII
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