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Huge loss of economy- could be autobox related but any advice welcome

G

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Have a 93 80 12v UK spec LC 4 speed auto
When I first got it was returning about 24mpg, which I thought was
acceptable as it was running on 285/75 ATs (It's now running on 285/75
MTs). More would have been nice, but I didn't expect huge economy from a
3 ton 4.2l vehicle.
I've just done a 800mile round trip to the lake district from somerset
and have averaged 20mpg all the way- this is at a constant 63mph
indicated (a true 60). Whilst driving up there I noticed a few things- I
don't seem to be getting torque converter lockup- I certainly don't feel
it locking up and the engine revs too high before speed is picked up.
The vehicle is running 2150rpm to maintain a steady 60mph which seems
high to me- to get to 70mph I need almost 3000rpm! Don't forget this is
with oversize tyres too (albeit hard to turn MTs)
There seems to be a lot of drag in the transmission- I don't seem to be
down on power, it just feels like the vehicle is hesitating and being
pulled backwards- it's almost as if I'm pulling a trailer all the time-
vehicle won't accelerate up past 60 as it used to- I have to really
floor it to get it to accelerate. This feels gearbox related- as if the
clutches are engaging when they shouldn't.
A little while ago the Mrs was taking the car to get the Batteries
replaced (a dodgy alternator had destroyed them) when, on a trailing
throttle, the transmission locked up and stalled the vehicle- the o/d
light then started flashing. Unfortunately because the batteries were
then disconnected I never got to find out what the error code was!
What do I do? There is no way I am taking the vehicle to the local
stealer- how often are they going to see and test an old auto anyway?
Are there any tests I can do to ascertain T/C lockup 100%? Is there any
way of resetting the box back to factory defaults in case it's still
carrying a fault? Does anyone know of any LC G/box specialists and how
much I can expect to pay for a proper rebuild (as opposed to a repair)
as well as proper diagnostics?
Vehicle is in need of a C service, but has had fluids and filters
changed in the interim. Wouldn't expect a service to improve economy by
25%! Does anyone have any advice or could I be barking up the wrong tree
completely?
 
Morning James,
Firstly you will find that the consumption on 12valve 80s varies considerably - I have seen two almost identical ones, one returning around 28mpg and the other struggling to hit 20mpg. Obviously suspension lifts, roof racks, tyre sizes, etc will all have an influence.
Coming back to your vehicle, I would need to take mine out for a spin to check the revs/speeds, but it doesn't sound too far off.
Have you tried pressing the overdrive button on the gear stick - is this working OK?
A dragging issue is more likely to be down to the brakes/drive train as opposed to the gearbox - normally if the gearbox is on it's way out you tend to get slippage not dragging.
Rebuilds of the boxes are expensive, usually around the =A32k+ mark so something that you want to avoid if poss. Having said that there is a firm in Exeter that you could use if you have to have work done, but I would explore other avenues first.
Firstly I would check the brakes on each corner to make sure that they aren't binding - just jack up each corner and spin the wheels to check this.
Next I would drain off as much of the gearbox oil as possible - usually you will only get around 4-5l out - the colour and smell of the oil is always a good indicator of the condition of the box - if it has tinges of black in it or smells slightly burnt you may have or be on the way to having problems.
Measure out the oil that you take out and replace it with new Dextron II oil (via the dip stick tube - unfortunately the only way). If the oil is off colour or smells of burning, then I would be inclined to run it for a couple off hundred miles and then do the drain and top up again - this dilutes the contaminated oil.
Unless there is a major problem with the box, I have found the above to be a nice cheap and relatively easy way of clearing gremlins on the box.
You can get more oil out if you raise the front of the vehicle as high as possible on axle stands and also leave it for as long as possible - a lot off oil gets retained in the oil cooler and the torque convertor - time and altitude helps get more out.
If you or your wife experience the gearbox locks up again unexpectedly, I'll dig out the error codes details from the manual for you.

Regards,

Julian Voelcker
07971 540362
[Email address removed]
 
Julian
Sorry to hear about your trouble James.
| Coming back to your vehicle, I would need to take mine out for a spin
to
| check the revs/speeds, but it doesn't sound too far off.
I hesitate to argue with the Guru, but it sounds high to me.
My manual is at a shade over 2500rpm at 70mph in fifth, and I always
thought that the auto box had a lower geared final drive giving around
2300rpm in overdrive at 70.
Or is my memory playing up (again)?
Christopher Bell
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No idea if petrol is comparable to diesel but my petrol 80 (auto) runs at an
indicated 2100rpm at 70mph in O/D if that's any help.
Pete
-----Original Message-----
From: [Email address removed] [mailto:[Email address removed]] On
Behalf Of Christopher Bell
Sent: 26 January 2008 10:21
To: [Email address removed]
Subject: RE: [ELCO] Huge loss of economy- could be autobox related but any
advice welcome
Julian
Sorry to hear about your trouble James.
| Coming back to your vehicle, I would need to take mine out for a spin
to
| check the revs/speeds, but it doesn't sound too far off.
I hesitate to argue with the Guru, but it sounds high to me.
My manual is at a shade over 2500rpm at 70mph in fifth, and I always thought
that the auto box had a lower geared final drive giving around 2300rpm in
overdrive at 70.
Or is my memory playing up (again)?
Christopher Bell
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Jon,
I cannot get to the manuals that you have on Mudtoys, the page
loads from the link here but I can't get through the Mudtoys pages. Is
this intentional or am I doing something wrong.
Regards, Clive.
Regards,
Clive Marks
Home: +44 1293 514600
Mobile: +44 7821 491897
Crawley, West Sussex, UK.
 
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Must be your lockup torque convertisseur not working any more. You
would have to be a drunk elephant to no feel that big guy locking up.
Hear on the list ther is some guys who have manual lockup
convertisseurs, in ANY gears! Would they step themselves forward to
say how that they do?
So James can test it manualy !
 
Jon,
I have EWD232F.
Regards,
Clive Marks
Home: +44 1293 514600
Mobile: +44 7821 491897
Crawley, West Sussex, UK.
 
Hi Jon,
I found your post very interesting since I'm just experiencing a problem
related to ECU.
It started with blinking preheating light when the engine was cold. The
diagnostic shows code 41. We realized that the relay switch for
preheating coil was not functioning but unfortunately the part arrived
just one day after I left for Algeria.
So I did 9000 km without preheating coil - and everything was ok - only
in the morning when the engine was cold the light occasionally went on.
When I came back I replaced it but the light is still coming on with the
same error code. At the toyota garage they told me that it might be
throttle position sensor so I ordered one - it should be replaced next
week. I hope it will solve the problem - otherwise I will have to deal
with ECU.
But the fact is that the light is still coming only when the engine is
cold and especially when you remove your feet from the throttle - after
driving for a certain time on the highway everything goes back to
normal. So I'm not sure if it is not a wiring problem since on Algerian
pistes there was really a lot of vibrations etc...
Regards,
Tom
--------------------------------------------------------------------
1996 HDJ80 (1HD-FT 24V, manual gearbox), OME Lift (6 cm), Safari
snorkel, Front runner long ranger tank (170L)
1996 KZJ95 (1KZ-TE), OME Lift (6 cm), Safari snorkel, auxiliary tank (70L)
 
Hi Jon,
I have a manual gearbox .... so it was obviously misunderstanding I was
convinced that you are taking about "computer" which controls throttle
position sensor, preheating etc... if I remember correctly it also has a
three letter name ...
Regards,
Tom
 
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