Hi Emilio, from Australia.
Post by emilio e acquaI own a 1992 rover mini mayfair automatic catalyst 998cc carb.
Change the oil and put a new filter in it! 8-)
The vast majority of problems with the Mini Auto are caused by low oil
level or dirty oil or filter. Do not get lazy about oil changes. The
motor won't be harmed - the oil pump capacity is HUGE and if the
oilpressure drops, the gearbox stops working, so people turn the motor
off, but the gearbox WILL give trouble on low or dirty oil.
Post by emilio e acqua1) on "hard" accleration, the second gear is engaged a few seconds or
not enaged at all (and skips from 1st to 3rd).
Shift pattern is uneven. Tends to suggest oil pressure problems.
Post by emilio e acqua2) At high rpms transmission slips from 3rd to D, does not slip at low rpm,
in other gear changes or during kikdowning from D to 3rd.
Do you mean it slips as it engages 4th from 3rd? That suggest low oil
pressure.
Post by emilio e acqua3) when engine and trasmission are really hot (highway driving),
forward ranges are not engaged at idle speed and i have to accelerate
a few to engage (in this case it makes noise)
A sort of long horrible chirp noise as the forward clutch grabs...
Almost always caused by low oil pressure, otherwise forward clutch may
be worn.
Post by emilio e acquaCan you help me? I obviously want to keep my mini alive, it's so cool!
It sounds like the gearbox oil pressure may be down. The primary causes
for this would be low oil or clogged oil filter.
Do you have a workshop manual? The diagnostic procedure for the auto is
in there.
For your problems, you need to check, in order of increasing difficulty
and decreasing probability:
7) Check engine/transmission oil level.
Note, sometimes the torque converter oil seal leaks and the torque
converter slips badly for the first minute or so of driving. Overfilling
the motor oil about 1/2" (13mm) on the dipstick will stop the symptoms
without having to pull the car apart to fix the cause. You may as well
run the oil level between "full" and 1/2" above full, rather than risk
problems running it near the low oil mark.
8) Carry out an oil pressure check.
There is a small bolt (7/16"AF head?) in the front of the oil filter
housing which plugs up the hole where you can connect an oil pressure
gauge. With the engine warm, the oil pressure should be between 75psi
and 85psi (5.3 - 6.0kg/cm^3, 530kPa - 600kPa) in all gear positions
except reverse, when it should be 115 to 125psi (8.0 to 8.8kg/cm^3,
800kPa - 880kPa). You'll need a gauge for this. Most auto transmission
specialists should have suitable gauges and adapters, or you can buy a
suitable gauge and flexible hose from an industrial supplier. Very few
in-car gauges that you buy at car parts shops will go high enough.
9) Check the oil filter head O-ring seals or fitting of the joint
washer.
eg: make sure the oil filter is not interfering with the oil flow or
pressure in any way. In fact, replace the filter while you're there.
13) Remove and clean the valve block.
This is not as difficult as you might expect! There is enough room
with the motor in the car to get the front cover off the transmission
and remove the valve block. If you need to do this, let me know and I'll
scan and send the appropriate section of the manual to you.
20) Check main oil pump and flow valve, the supply and feed pipe seals,
and main oil strainer seals.
Now we're getting into serious stuff. I had an auto once which
periodically lost all drive and oil pressure. It turned out the pressure
relief valve which is in the pump on the auto was sticking wide open. A
different oil pump fixed that.
Post by emilio e acquaI live in rome, italy, and rover no longer provides service for old
minis. Other mechanics are really afraid of automatic gearboxes, as in
italy most people prefere manuals.
Get a workshop manual. Find a mechanic who is interested in more than
just doing oil changes on Fiat Unos all day. The auto is actually fairly
easy to work on and the manual is pretty clear. I've done extensive work
on Mini autos including a rebuild, but I've never had a manual geabox
apart. There are one or two awkward bits and some tricks, but they're
really not very difficult.
Post by emilio e acquaExcuse me for my funny english, and thanks in advance for replies!
Your english isn't half as funny as my italian. 8-)