How to change the timing belt/water pump on your 300ZX
It's not really hard to change the timing belt on a 300ZX, but make sure you
get it right. You also should consider replacing the water pump
at the same time because
if it goes bad, you'll have to do the job all over again.
Same for the tensioner, if it breaks you're out an engine.
I'd reccomend changing it every other
belt change. Also get the tensioner stud if you're changing the tensioner,
have to be ordered at most dealers. There's not much sense in
putting a new tensioner on with an old heat stressed stud is there?
belt dosen't turn the water pump, but if the pump leaks, the water will
leak into the timing belt cover and rapidly degrade the belt. Trust me, it's
cheap insurance. You also should replace the front main oil seal at the
same time, and both cam seals. If they starts leaking, it won't
hurt anything, it's just a pain
to disassemble everything just to change the oil seal later.
The passenger side cam seal for some reason has a tendancy to go
bad before the other one.
You will need this stuff:
Timing belt(~$30), and water pump($40 NEW at auto zone), Oil seal(~$5-$10),
and the crank timing spricket key($0.50), also consider changing the
a Nissan one, which is the only one you should use). Also make
sure you have all appropriate
gaskets, etc. The water pump should come with a gasket, the thermostat gasket
is a dollar or so.
This is all that is needed to change the timing belt/water pump on
an early 300ZX:
- Remove fan, radiator shroud, all engine belts, the
crank pulley, the A/C idler pulley, the timing belt cover,
the spark plugs, and anything else in the way.
- remove water pump and replace with a new one, do this first so you
don't spill coolant all over the new belt.
- Turn the engine over by hand until the marks on all three pulleys
are close to the marks on the rear timing belt covers.
May take a few minutes. The location of the marks on the old belt(If
you can still see them) is totally unimportant.
This is important: The purpose of setting the
engine in this position prior to removing the old belt is so that
the engine will be in the "alignment" position to accept the new belt.
Once the old belt is off, you can't rotate the engine. If you remove
the belt without putting the engine in this position you'll have no
way to verify that the timing is correct once the new belt is on.
- Loosen the tensioner and remove the belt.
- If replacing oil seals:
- Hold the cam sprockets still and unbolt them, remove the sprockets
the cam seals. natrally, replace the sprockets and torque to
It is easiest to place the car in 5th gear, with the old belt on
and simply unbolt the cam pulleys.
Only break the bolts lose, then remove the pulleys and belt at the same time.
When torqueing the pulley bolts, put the old belt on to avoid
stressing the new one.
If you have an automatic or if the engine is out of the car, you'd
better have air tools,
or do it this way: Cut the old belt into one long piece.
Wrap it around the cam
pulley and hold the pulley with a chain wrench, removing the bolt
with a wrench.
Do the same when reinstalling the cam pulleys.
There are no lips behind the cam seals, so if you tap them in too far,
they will just pop inside the heads, requiring lots of disassembly to remove.
Tap the right(passenger)) side seal until it is flush with the metal surface
or slightly below(no more than a couple mm), and the left(driver)
side seal until
it is flush with the smallest diameter of the taper, you'll know what I mean
when you take it apart and look at it.
- Pry the crank sprocket off the crank, it will be very tight, you will
probably have to destroy the thin metal guide plate behind the sprocket,
but you will replace it with the new one you special ordered from Nissan.
Replace the seal, and install the new metal plate, the NEW sprocket key, and
the sprocket with anti-sieze compound on the inside of it.
Do not, under any circumstances, hammer a prying device behind the
sprocket or you may break the oil pump housing, which is bad.
- Installing the new belt
with the marks on the belt directly adjacent to the marks on the pulleys, noting
that new belt has has a front and rear facing edge.
- Double check your installation. Now triple check it, and check a fourth time.
You must be absolutely sure you put the belt on right or
your engine will be destroyed when you start it, no second chances, get it right!!
- Check installation of belt again.
- Turn the engine over by hand a few times to ensure that nothing interferes.
(Note: After you turn the engine over, it takes a few thousand revolutions until the
marks on belt and pulleys line up again, do not worry if you are absolutely sure
of the timing. If you have any doubts at all, go back to step 3.)
- Adjust the belt tension according to the shop manual. This may take a
few tries, but take your time. The tension has a large impact on belt life.
- Replace all removed Items, and start engine.(replace the 2 inch water
hose between the thermostat housing and metal coolant pipe right behind
the fan now, they have a very, very bad habit of leaking)
Before you take off the timing belt, the engine must be in the correct
position to accept the new belt. Turn it with a wrench until the notch in the
oil pump housing is in line with the dot on the crankshaft belt sprocket.
The camshaft sprockets will align with two very small dots stamped into the
rear timing belt cover. The passenger side camshaft is very unstable in this
position, if it gets turned either direction even a small amount, it will snap
about 1/4 turn more, nothing will hit, just get a wrench on the sprocket bolt
and turn the camshaft back. It would be very advisable to change the crankshaft
oil seal now too. Get the small plate that goes between the crank sprocket and the
oil pump housing from the dealer before you begine, because it's very likely that
it'll get destroyed in trying to remove the crank sprocket. I'd also reccomend
that you change the timing belt tensioner at this time. I've heard horror stories
about it seizing up. Cheap insurance. Examine the water pump closely now too,
it's behind there and is a pain to replace just because it went 10k miles after
you changed the timing belt. Also take care of your fan clutch, they are
very, very expensive, like ~$200.
I would also reccomend clean the contacts on the cyclinder head temperature sensor, as
it is extremely easy to do with the timing belt covers off
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