Hi Listers,
I ask for advice from your wisdom. Here's the story
1976 TR6, stock engine (I think)
A couple of days ago, I was warming it up at idle when the engine began to run
poorly, like missing on a cylinder. No smoke anywhere. Must be electrical,
since it happened so fast and there's Lucas waiting in the wings....
A quick check, everything firing ok, gas feed ok, still runs low on power.
Compression test:
140 - 140 - 130 - 15 - 15 - 120
So lucas is not at fault for once. Must be a blown head gasket between cyls 4
and 5. No loss of coolant, no coolant in the oil, must be only between
cylinders.
So I took the head off, and there's no real obvious break in the gasket
between 4 - 5. There's a little more discoloration on the head between those
cylinders but not obvious to my untrained eye. A straightedge across the head
shows less than .002 difference, about the same as on the rest of the head.
It's pretty obvious that the head has been off before which is probably why it
wasn't too hard to do. The car has 105K miles and I've put 35K on it and the
PO didn't remove the head so it's been at least 45K miles since it was off. I
haven't removed the valves but there's not a lot of carbon in the combustion
chambers, so they may be ok as is.
The pistons are fairly tight in the bores, ascertained by rocking them at tdc.
No ridge to speak of. The block seems flat, or at least it's not much warped
if at all. This is the later block with the grooves cut into the deck. Since
it all seems ok, I'm willing to say the gasket itself went bad and replace it
and be done with it.
Do any of you know if this is a reasonable course of action? Any ideas on
what else could be at fault? Should the head be planed? I'm not thinking of
raising the compression ratio, just put it back as it was, but planing it to
make it absolutely flat. The head thickness is about 3.95 inches. I can't
find the emails that the list sent around about the correct head thickness,
and what CR you get for different thicknesses.
More questions, if I may: any recommendation on head gasket sets?
should the head studs be replaced?
should I use permatex on the head studs
into the block (3 came out when uncrewing the nuts)
even if they're not replaced, should the
studs be removed and re-permatexed?
no gasket cement on the head gasket
itself?
If I'm making any ridiculous errors please let me know. You folks have come
to my rescus many times. and I really appreciate the helpful wisdom of the
list.
George Loriot
1976 TR6
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