The best way to take the crank
front pulley nut off:
Put an impact socket of appropriate size over the nut, if you
have an AC car you may have to grind the O.D. of the socket to
get it to fit inside the pulley. Use a 1/2 drive breaker bar
with the socket. Turn the breaker bar/engine all the way over
to the driver's side and rest the breaker bar on the inner
fender, put rags under the end of the bar. Disable the fuel
pump (pull fuse or disconnect relay) go in the cockpit and hit
the starter. This will spin that nut right off!
Engine overhaul
When lifting the engine, please note that the engine is
leaning to the left. This is my Spider with the head off. The
cam chain is secured by a wire and the support for the
carburetors is still there. It's OK to adjust the valve
clearance with the head off.
Since my Spider is a 1967 with
floor-mounted pedals, the servo booster is what you see far
right, green dot. You may also notice, that the liners have
been removed, dots and so has the battery, blue dot. The red
dot is the oil filter support. No spin-on filters 1967.
Cylinder Head
Clean the alloy head, but watch out for sharp tools. It's
easily damaged when treated hard. This is the 1967 model up
side down. Check the valve clearance. If incorrect, you may
use any shim from an Alfa. They will fit any Alfa engine
between 1965 to the 1990 I believe. Never throw away a shim,
it might turn out to be useful later. I have noticed that
Alfas hardly burn valves. The reason might be the fact that
they are sodium cooled. The exhaust valves have natrium and
sodium inside, so never ever try to brake one. This might be
dangerous if the sodium is in contact with water or any other
liquid or even air.
Camshafts
The twin overhead camshafts act directly on the valves. Thus
high revs are no problem, no pushrods or rocker arms there,
no, no. I have however had some trouble with oil consumption
due to old engines. The engines pre 1970 approx. had no seal
on the exhaust valve guides, only on the intake guides. With
new guides with seals on the exhaust side too, the oil
consumption goes down so check your engines. My real nightmare
was my Alfa 75 who was drinking oil like hell. I overhauled
the engine three times, liners rings, valve guides and all.
The combustion chambers were all clean and nice every time I
dismantled the engine. However, it turned out to be the head.
There was this little leak in the
exhaust hole on cylinder #3. The hole expanded when hot and
the oil was disappearing and my money too. A new head solved
that problem.
Pistons and rings and liners!
I have made rebuilds on some pre 1972 1750 engines. This is
what I always do: Step one is to certify that the pistons are
the problem. Have the compression ratio checked when the
engine is hot. The ratio should be the same on all four
cylinders. Pour some engine oil in the spark plug hole and
check the compression ratio again. If the ratio is increasing,
the rings may be leaking. If the ratio is almost the same, the
valves and the head need attention Remove the head and the
sump.
No need to remove the engine for this
kind of operation. Place a hydraulic jack and use a piece of
wood under the oil sump so you do not damage the alloy fins.
Loosen the engine supports. Raise the entire engine as much as
possible. Normally it's enough when the gearbox hits the body,
so you may place something between the engine supports and the
engine bay. The dots on the photo show how I do it. The green
dot shows the oil filter support.
Then raise the entire car and use
supporting jacks for safety. Never ever work under the car if
it's not secured by jacks. If you haven't already drained the
engine oil, this is the time to do so. Otherwise you will need
to wash your hair in kerosene. Undo the bolts and nuts
securing the sump to the engine block. The image shows
the wooden distances to raise and support the engine.
Gently draw the sump forward to get
access to the crankshaft. From underneath the engine, remove
the bearing caps and mark them. They are already stamped with
the number of the cylinder, but just to be sure ... Start with
the bearing caps on the second and third cylinders. They are
at their bottom dead point if you have done the right thing.
Slowly turn the crankshaft 180 degrees until the first and
fourth bearing cap is at their bottom dead point and remove
these too. On the Alfetta and 75/Milano overhauling is even
more easy. Just raise the car and remove the sump. Note the
spin-on filter, yellow dot.
Be careful so you do not damage the
bearing surfaces of the crank-shaft and gently press the
pistons upwards. Cover the crank-shaft bearings one by one
while working. Mark the pistons so you know which is # one
etc. Check if the pistons are of the offset kind. If so, there
is an arrow on top of the piston. The arrow shows the
direction from intake to exhaust, so be careful not to turn it
the opposite way. If your engine is so old that it has the non
offset pistons, I would replace them with newer ones. The
Alfetta 1,8 pistons are excellent and easy to find. Both
liners and pistons will fit your engine like new. The next
photo shows the Milano engine with the liners removed, dots.
As usual, the engine is still in the bay.
Be careful not to damage the surface
when you remove and change the rings. There are several tools
for this purpose, but you own hands might be OK too. The rings
are marked "TOP" etc. Have a look in a workshop
manual if in doubt. Remember to keep the openings of the rings
away from each other, i.e. 120 degrees. To remove the liners
you may try just to press and draw them upwards. There are
special tools for this purpose, however some are expensive. I
use an old piston with the top ring on. Put it up side down in
the liner until the top ring is expanding and then use a soft
hammer and a piece of wood to remove them both. Remember to
use an old piston, not the new one. The next photo might give
you the idea.
Liner in block
- inspect the liners for scratches etc. Replace all if
necessary. Use your fingertips to check them.
- Clean the bottom of the liners as well as the engine
block, but remember the bearings!
- Replace the O-rings with new ones. Do not use more than
one per liner though.
- There are steel shims available for diesel engines if
your liners are too short. Once, I used a set from an
IVECO diesel engine. That car is still running, BTW.
- The liners normally do not need any sealant, but since
it is not that fun to open the engine again if it is
leaking, I use a little bit of sealant. It is very
important to keep the engine absolutely clean.
- Check that the liners are about 0,05 mm higher than the
engine block, every one of them. This is what I have
learned the hard way, believe me. Have a look in the Alfa
Owners Bible or any workshop manual.
- I do the operation with the engine in the bay, it is not
that tricky.
- Finally, have the head overhauled at the same time.
Valves, guides etc. may need some attention too.
- Clean the pistons. Then take them to your local grocery
shop and check their weight one by one.
- Unless you have a weighing-machine of your own.
- There should not be any difference between them. If so,
see your local Alfa Service station.
While you're at it, remember to grease
the prop shaft at least once a year.
Use the proper grease for the prop shaft splines. The nipple is
at the yellow arrow. This will make your Alfa Romeo very, very
happy for many years.