Volvo Maintenance Hints for 7xx/9xx - Bill Garland's Nuclear ...

advantage is it's supposed to be proof against corrosion. But you're not a marine environment,
so I'd go with stock steel studs. Helicoil the heads if you must, but you'll get higher clamping
forces with the stock studs.
Exhaust Manifold Cracks and Repairs. See the FAQ file in "Exhaust" for more information. In
a word, replace, don't repair.
Cylinder Head Replacement. [Inquiry] If the cylinder head in my turbo engine fails, can I
substitute a non-turbo head? [Fitz Fitzgerald] Tthe heads from a Turbo and non-Turbo B230
engine can directly swap, but note the differences first and then you judge if you want to
proceed on that route:
1. Valves: Both the turbo and non-turbo heads have Stellite-flashed exhaust valves to resist
burning (can not be machined). Also, the valve stems in the turbo valves are hollow and are
partially filled with elemental Sodium. The Sodium is solid at room temperature, but once the
engine warms up it becomes liquid. The up & down movement of the valves causes the liquid
Sodium to be tossed up and down in the hollow valve stem, and helps to conduct heat away
from the valve face at a faster rate. While this isn't an absolutely critical requirement to have on
a turbo car, it does help to reduce valve face temperature.
2. Camshaft: The camshafts are different in the turbo and non-turbo engines. You'll need to
swap them, and then also re-shim the tappet clearances under the camshaft. This requires
having a large kit of spare shims (aka "Pucks") of various thicknesses to get the proper
clearances under each camshaft lobe. You can rent the tools and shim kit from IPD, and a
micrometer and feeler gauge set will also be required.
If this were my vehicle, I would probably just have the head machined flat and re-install it rather
than swapping the camshafts to a non-turbo head. I wouldn't hesistate to machine a bit beyond
the Volvo minimum thickness specs.
Turbo Rebuild and Replacement:
Turbo Failure Signs . [Inquiry:] Does anyone know what a turbo sounds like when it starts to
die? does death usually come slowly, or suddenly. will the car run without it, and if so, for how
long? [Response:] Some die slowly, losing output gradually as the engine ages. Others begin to
make noise (scraping or rattling), especially under load or when very hot, that may signal that
the impeller blades are touching the housing (or have been bent through the introduction of a
foreign object), or the bearing is about to go south. Others fail through seal failure, dumping oil