Hi all,
Well, this is a bit embarrassing, but I had a similar problem to Mike's
and thought maybe coming clean to the list might in some way, some day,
save some one a bit of grief or shorten the problem solving procedure on
their 100.
A couple of weeks ago, I had similar problems with my newly restored
Austin Atlantic (A90 engine, same as the 100). I was going uphill
however, and with greatly reduced power (apparently running on 2
cylinders), I had to pull over. She was still idling roughly, and I saw
steam (white vapor) coming out of the tailpipe. Shut her off
immediately. The engine was still quite cool, so no overheating
involved. The problem was a VERY blown head gasket, if there is such a
thing. As Rich points out, a chunk of gasket was missing between # 3 &
4 cylinders.
Turns out the head was inadvertently torqued incorrectly (only 55 ft
lbs), when it should have been 70 to 75 ft lbs. The workshop manual I
had inherited from a previous owner had a handwritten note indicating
the 55 ft. lbs. for the head nuts, and the mechanic working on the car
did as it said. I don't know how this could have worked for the
previous owner, but that's what it said.
I have seen slightly leaking head gaskets, but never one that was
actually missing material between the cylinders. And of course, as
Mike's low compression readings suggest, it almost always occurs between
#'s 3 and 4 on this engine. I also have a BN2 Healey 100, and it seeps
ever so slightly along the head gasket line in the area of 3 and 4. My
Healey has been this way for years, and many miles in this condition, so
I don't worry about it. The Atlantic however, was another story.
Because of the missing gasket material (melted?), we re honed the
cylinders, re lapped the valves (some copper was found between one and
its seat), drained and replaced the oil, drained and flushed the cooling
system about 5 or 6 times, etc., etc. We wanted to be sure we didn't
have any additional problems from the missing copper section on this
go-around. Torqued, and later re torqued (hot) to 73 ft. lbs. My
mechanic, by the way, believes in re torquing iron heads hot, and
aluminium heads cold. He has a good bit of experience with both.
Regards,
Russ Staub
'50 Atlantic
'56 BN2
'67 BJ8
'60 Bugeye
Mesa, AZ
Rich C wrote:
> I'd bet you have a chunk of head hasket blown out between 3 and 4
> bores. When the head comes off, have both the head and the deck
> checked for truth. I've seen this problem on more than one Hundred,
> where the head had been made dead true, but nobody checked the deck of
> the block....equally important. A good friend replaced his head gasket
> and made sure the head was flat 3 times in 26000 miles. Then we pulled
> the engine down and checked the deck and found it to be .0035" thou
> dished.
>
> Rich Chrysler
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