Thanks to the help received here I armed myself with a new 14mm spark plug thread chaser and fixed the problem I had with #3 cylinder's plug not seating.

It didn't take care of what I'm sure now is an exhaust manifold gasket leak. I'll be ordering the gaskets and other stuff and tackle that problem next.

Thanks for the help,
--
Erwin in Memphis, '88 745t 183,000 miles, '95 855t For Sale

When you have exhaust manifold off be sure and inspect side towards block for small hairline cracks. Common problem with these engines. Awhile ago I had a friend at a machine shop heat and weld one that I missed after having replaced gaskets the first time and it didn't see it!

good luck,

Joe

PS: you might want to replace the gasket for the oil filter extension while you have exhaust off.

Of course, with old manifold nuts, particularly on a turbo, the nuts are probably part of the stud by now. I wouldn't even try to get them off with a wrench, unless they look really good.

Apply PB Blaster each day for about a week before removal. IT will smoke a little when the engine's hot but that's ok. When you finally do go remove them, you *MIGHT* get lucky and find they're in good shape (recent work?). More likely they'er little rusted lumps. Buy the new Volvo lock nuts (copper exhaust nuts, actually a little expensive but there's nothing better) and Never-Seize.

Split those old nuts off with a sharp small chisel. This works really nicely. The nut will open up a little and spin right off. You don't need to split it in half, just partway through a side. Avoid hitting the stud threads. Should work quite well.
Good luck!
--
Rob Bareiss, New London CT ::: "Roterande Fläkt Och Drivremmar!"

Rob!
I note lots of problems with this area on the brickboard. I have never
encountered anything like it on any of my oldtimers over 35 years of driving
and working on them. I've always used standard 5/16"-18 UNC standard nuts on
my B18, B20 and B30 manifolds, RARELY replaced one unless it came off and
got lost, and never had one hard to remove, even when a stud was stretched.
The exhaust pipe flange nuts are special stainless steel items, 3/8"-16 UNC,
and likewise never gave problems other than occasionally coming off and
getting lost. So what is the problem with the newer models? I can see
some possibilities:

1. Finer #$%% metric threads
2. Smaller #$%% metric bolt sizes
3. Higher exhaust temperatures (which on an oldtimer would indicate
retarded ignition)
4. Inferior stud and/or nut metallurgy (I don't see how any copper alloy
would stand the required torque unless perhaps beryllium copper, which is
pretty rare these days)

I wonder if the same type of stainless nuts used on the old exhaust
flanges might be a good choice. I would imagine that they could be
found in #$%% metric sizes from some aircraft supplier, and if bought in
quantity, should not be very expensive.

I also wonder if the studs could be replaced with dual-thread studs to match
the threads in the head on one end and coarser threads on the other end
to reduce seizing opportunities.

Any comments you or others might have on this problem could potentially
be helpful to all those who use the newfangled OHC engines.

--
George Downs, The "original" Walrus3, Bartlesville, Oklahoma

Torque on the copper nuts isn't a problem because the torque spec is something very low, like 20-30 pounds I think. (Don't quote me. It's been a few months since I did mine.)

Jeff Pierce
--
'92 Mercedes 190E (my daily driver), '93 945 Turbo (a kickass family car), '53 Willys-Overland Pickup (my snow-plow truck/conversation piece)

Erwin,

I assume this is what you mean by "other stuff", but I thought I'd mention it (I was glad someone did for me when I did my manifold gaskets):

Since you're going to be removing the turbo, you're going to want a gasket (for the top) and an o-ring (for the bottom) of the oil return line.

And I think it was Confusious who said, "Spare the anti-sieze, spoil the job." (or was that Buddah?)

Jeff Pierce



--
'92 Mercedes 190E (my daily driver), '93 945 Turbo (a kickass family car), '53 Willys-Overland Pickup (my snow-plow truck/conversation piece)

My favorite independant Volvo shop says they have a better track record with Volvo exhaust gaskets than aftermarket. The same for crankshaft seals, but they also tell me the aftermarket cam/intermediate shaft seals are fine.

Be sure you use all NEW high quality locknuts on the manifold studs or you will be diong it again .

I've never heard of the "chisel method for removing the nuts......anyone want to comment on it?

That is what you do when the wrench won't grip them any more and you
can't get in with a vise grip or a pipe wrench. There are actually a
couple chisel methods. The first involves using the chisel to turn
the nut by hammering it in a tangential direction. If that doesn't
work you use the chisel to split the nut by hammering it axially.
Usually you only have to split it on one side to get it off but
sometimes you have to do it on both sides.

Note that injudicious use of a chisel, either sharp or dull, can increase
problems rather than eliminate them. A bigger hammer works better but
can also cause more consequential damage. Chisel work is the responsibility
of the person with the hammer in hand. NO responsibility is assumed by
others, regardless of any assumptions made by the chiseler.
--
George Downs, The "original" Walrus3, Bartlesville, Oklahoma