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Low water light coming
on.
There appeared to be water coming from the rear head/block face. After removing
the heads (3 days to fabricate special tools) there where no signs of any blown
head gaskets (4 separate heads), so I removed the valves and made up some
fittings to pressurize the water jackets with compressed air (after
clamping rubber patches over the mating face water ports). Hey presto, the core
plugs were like sieves. After replacing the core plugs, I decided to toss the
heads in a bucket of water and perform the pressure test again aha, more bubbles
emitting from head no 3, this time from a pin hole within the inlet valve throat
in the dividing waterway, There is a small core plug at the manifold side of the
head through which the waterway was presumably bored during manufacture. After
having removed this plug I shone a torch into the valve throat and peered into
the waterway, where I could see the pinhole clearly. The solution was to bore
the waterway slightly bigger and press in a short length of stainless steel
tubing after having coated it with Loctite, and re-build the top end,
result----Perfect (it strikes me that some of these castings are a bit too thin
in the valve throat area).
Next: - the drive shafts
vibrated like hell whilst accelerating hard.
Turned out to be the inner
CV joints. They are like a tripod at the end of the inner assembly, each (horn) of
the tripod having a needle roller bearing mounted on it or supposedly so only my
offside one was minus a bearing, which caused the whole shaft to run eccentric
with the transmission of torque, and vibrate. A quick trip to my local bearing
stockists yielded some loose rollers with which I re-built the joint and the
problem was cured. During the course of inquiring with several propshaft
specialists re service- exchange items (which isn't available for the diesel), I
was enlightened about the common problem with 800s of the inboard splines
breaking off and falling into the diff when the driveshafts are jarred out,
Apparently a lot of these fast fit type of establishments get around this
potential problem by separating the c/v joint and leaving the inner splines
engaged in the diff to facilitate clutch /g-box removal. Methinks mine must have
been the victim of this rough practice, but it turns out that the diesel shafts
don't have the usual snap-ring arrangement and are free to be withdrawn easily.
Next: - the power steering
rack seals failed and I was loosing loads of ATF.
Enter the local breakers,
and one s/hand Mk 1 rack later (same fitting but looks slightly different in the
valve area) and that problem was cured although a complete bastard to fit and remove. I had always been curious as to how these racks worked so dismantled the
old one to find out, and basically, the column shaft does not connect to the
pinion directly as in manual steering, but connects to a valve spool via a
coupling (with a small amount of backlash built in to the Column-pinion, but a
direct transmission running through the centre of the pinion into which is built
a small hydraulic direction control valve), the idea being that when the
column is turned, for the first 1 deg the pinion does not move but the valve is
opened, which allows pressurized hydraulic fluid to force the piston and rack
in the desired direction i.e. - the rack actually pulls the pinion around as
opposed to a manual set-up which is vice-versa. Now as long as the column is
continually turned the valve stays open, but as soon as the column is held
steady, the movement of the rack continues for that one deg which in turn closes
off the hydraulic spool valve. (The steering stays where it is until a
further input is generated via the steering wheel). To put it another way,
the pinion is playing catch-up with the valve spool (by the amount of controlled
backlash between the pinion and the valve spool).
Next: - Two months later I
jumped into the car and fired it up, at the merest touch of the steering
wheel, it continued to rotate to full lock. My immediate thoughts where "I
wonder if the u.j. on the column has come loose and disconnected". I jumped
out of the car and looked at the front wheels as I gave the steering
wheel a quick nudge the wheels moved full lock, (the power steering had gone
super powerful). I drove the car to work and back and decided that it was
far too dangerous to use further without rectification. I rang a few rack
specialists who all offered no advice but wanted to liberate large amounts of my
wallets contents. With having examined the previous rack I decided that the only
way that my current problem could occur is via the controlled amount of backlash
increasing thereby opening the spool valve further and causing a faster flow of
hydraulic fluid. The backlash is determined by a hardened and ground steel
washer that has an opening in it i.e. an incomplete circle, one half of the
coupling is dogged onto this washer via a small rollpin that engages in the slot
and the other half is similar but engages from the underside. After going
through the tedious job of removing the rack again, I stripped the pinion
coupling down and found that the afore mentioned washer had actually broken in
two halves, thereby increasing backlash, it appears that the washer had been
over - hard and been made brittle, although the only possible cause that I can
think of for its breakage is the fact that any movement and torque through
the steering wheel, has to be transmitted via this washer. Now I'm 6ft 8 and
often used the steering wheel to lever myself in and out of the car when the
engine is, not running ... Fortunately I had kept the parts from the old rack
and was able to substitute the broken washer with the old one and.....Fixed El
Cheepo!
When doing anything with
the steering wheel/ rack, and the column u.j. has to be removed, pay attention to
the number of column turns in relation to the steering rack pinion shaft, or you
may fall down the same hole as I did...That rotary coupler thingy that is fitted
behind the steering wheel (connects horn and airbag electric's) is internally
not unlike a half wound clock spring, where the "spring" is in fact a
paper thin ribbon wire, If the column is permitted to rotate freely once it has
been released from the u.j. , for example in a clock-wise direction, the
ribbon may become over-wound and if the u.j. is then re-fitted with the road
wheels straight ahead, the first time that you turn full lock right the ribbon
cable snaps, and no horn or airbag ...
Next: - whilst
travelling down the motorway, I noticed that horrible pungent smell of burning oil in the
cabin, when I got home I looked under the bonnet and there was oil everywhere
particularly around the turbo, I thought " shit that looks expensive".
The next day I power washed
the whole engine off and ran it for half an hour, oil appeared to be coming from
the rocker box region, so I replaced the rocker box gasket and all appeared to
be well for a couple of thousand miles and then more of the same. I again
replaced the rocker box gasket and all appeared to be well for the next couple
of months and THEN after a quick thrash ...same again, so I cleaned it off again
and closely observed the engine whilst it ran.
I thought I saw a small air
bubble emit from no. 4 inlet to head gasket so I revved it some more and saw more
oily air bubbles come from the same joint. I concluded that the inlet gasket
must be leaking but more importantly, what was oil doing in the inlet tract ???
It could come only from two sources 1 the turbo was dumping oil into the
intercooler and staying there until I booted it thereby blowing it into the
engine or 2 the engine was breathing heavily and, as the breather discharge tube
was routed into the air filter housing, it may have accumulated in one of the
hose bends until I again booted it and it was forced into the inlet tract ...I
decided that the best course of action was to isolate the breather system and clean out the whole induction tract
and if the oil re-appeared it must be the
turbo seals. I routed the breather tube off down the chassis. This done and a
couple of days later I inspected the insides of the pluming and it was full of
oil, leading me to the conclusion that the source was indeed the turbo seals.
I spent the next few eves
trolling the net for info on turbos without much joy, but meanwhile the car
started emitting copious amounts of blue smoke from the exhaust (particularly
when setting off from the lights, in fact people where turning on their lights
thinking it had come dark). In fear of being nicked by P.C. Keen, I decided to
take the car off the road until I could solve the problem.
I scrolled through the
motoring press for turbo specialists and rang loads. I was quoted prices of
between £300 (if it wasn't too bad) and £800 (if it needed a new central
bearing unit). Horrified at this prospect I continued trolling the net for
alternatives. Eventually I came across an article entitled OIL IN TURBO by
a firm call UK turbos (as I remember) who detailed turbos often being blamed for
oiling the system, when it more often than not was caused by other factors but
manifested itself by the turbo passing oil . The possible causes they suggested
were:-
1 Where a blocked oil
return- to- sump pipe thereby causing the oil level in the turbo to rise to
the bearing level and overflow into the compressor (apparently the seals main
function isn't to stop oil from leaking out, but more to stop compressed
inlet/exhaust gasses from getting in , oil retention is a very secondary
function).
2 Excessive crankcase
blow-by (more than 1p.s.I ), which would fight against the gravity required
to enable oil to return to the sump from the turbo, resulting in oil spillover
in the turbo as in (1)
(3) A partially blocked air
filter or restriction in the inlet tract, which would lead to the turbo
compressor creating a great depression on its inlet side. This depression
(vacuum) would in turn suck oil out of the turbo and send it on it's way to the
intercooler.
So as not to be off the
road, I fabricated a manifold to replace the turbo with, and continued running
the car turbo less (normally aspirated) At first I thought the exhaust down pipe
had blown, because there was a right racket coming from that region, in fact one
or two people (pedestrians) asked if my exhaust had gone?
I thoroughly cleaned the
breather and inlet system again, but this time, I, decided to inspect the
intake side of the air filter also. (Which involved removal of the battery to
gain access) as I pulled the battery clear I noticed one of those
"documents enclosed" plastic bag thingys that had once been stuck
to the battery, and was still hanging on by a thread, had been sucked into the
inlet trumpet, (perhaps causing a restriction?). Also the oil breather hose that
I had piped toward the rear of the car had formed a "u", in it, which
had filled with oil, effectively preventing the engine from breathing, in
retrospect, I realize that had also lost POSITIVE CRANKCASE VENTING as any blow
by is normally SUCKED into the inlet tract. I removed and re-sealed the
inlet manifold to the heads and re-fitted the turbo as per original, I also
noted that where the breather hose enters the air filter housing, a steel tube
takes the vented gasses into the centre of the air tract, where the steel tube
is cut off at 45deg, thereby forming a venturi (increasing the "suck"
on the tube). After having measured the turbo inlet diameter, I decided that I
could reduce the diameter of the inlet tract at the point where the breather
entered and not cause any restriction to the system (this I hoped would speed up
the gas flow at that point, thereby causing an even greater depression on the
breather tube). I found a small plastic funnel, which once trimmed, clicked into
place like a factory -fitted item.
Much to the relief of my
wallet everything has been perfect ever since. No smoke, No oil visible, in
fact oil leaks that I reckoned where coming from various parts of the engine
mysteriously disappeared (don't arf blow about dunnit). All that work for a poxy
plastic bag huh?
Also it failed the M.O.T.
and I had to fit new discs and pads all way round, and new front wheel
bearings (tight buggers aren't they).
The sump developed a crack
and dumped a lot of oil onto my driveway, which I removed and brazed up. Most
of the instrument illuminating bulbs had blown which required me to solder new
ones in place. Both the back and middle exhaust boxes leaked and I fabricated new
skins for them.
If you haven't yet fallen
asleep, I hope this article proves useful to someone.
BRUCE MOXON
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