Is it serious? - Auto box problems

Phil Robson

Phil Robson

Well-Known Member
I have just bought a straight & original series 1 V8 that's done around 120 miles in the last 8 years. On test it went OK (tho' I didn't 'razz' it).

Trying to drive it properly is now presenting problems. It accelerates OK through the gears (I think - I've only had manuals before) but runs out of steam at about 45mph & starts slowing down. It seems to change up OK again once I have slowed to nearly stopping (but again runs out of puff at 45 ish). I had a problem stalling on a very steep hill when setting off aswell.

Fluid level & condition looks to be right.

The manual seems to suggest a 'seized unidirectional clutch'!

Que?

Phil. ???
 
Hi
Just an idea;could he fuel pump be at fult,runs well up to 45 while the the float bowls are full,then slows when they're empty?
The slowing allows the float bowls to fill back up and the engine runs well until the bowls empty again???
Just an idea as I say
Cheers
Spike
 
Thanks spike,

The engine will sustain high revs in P or N, so do you agree that would suggest fuel is OK (although engine is not under load)?

Another point; having checked previous threads on auto boxes, the condition of the fluid is apparently critical. Mine looks OK but I did need to top it up with 1 ltr (still doesn't work properly), & didn't notice a funny colour when I rechecked it.

Could it be that the fluid is duff? I would imagine is at least 10 years old, possibly much more, & with only a very few miles in that time. Would renewing it make a difference? Does the 8 litres it requires include the torque converter?

I know nothing about autoboxes as you have probably gathered!

Phil. :(
 
I would check other engine power items 1st before thinking gear box

Get a service kit for the fuel pump, plugs, points etc. and the see how it goes then.

John
 
My first thought would be a blocked fuel filter, but I'd check all the normal engine tuning parts at the same time.
I've never known auto fluid to go "off" it just gets contaminated by faulty parts in the box, either swarf from hard parts, water (coolant) getting in it, or friction material from clutches and bands, which when they go overheat the fluid and make it look and smell burnt.
8 litres will be including the converter (which you can't drain.)
 
I agree, it's quite common for an engine to rev cleanly, but then not be able to run properly under load.
 
Thanks guys,

Had a run out today & car pulled reasonably well up to around 55mph, then started faltering. It's better than it has been!

When it warmed up thoroughly however, it returned to doing about 40 before trouble hit. Is this gearbox oil getting warm & thinner?

The petrol, by the way is reasonably fresh.

Cheers,

Phil. :(
 
Problems when hot tend to point to coil & condensor, especially if the car coughs and splutters - can tick over fine and rev freely without any problem in neutral

If you put the car in 2nd at 40mph can you then rev upto 60mph ? - I still don't think it sound like gear box though
 
Guys - many thanks & it's good to be back with the forum! I was going to reply before it went down.

Harveyp6 was spot on! I changed the fuel filter & got an instant transformation. A few months on & I've got a nicely re-run in P6. It's great!

Thanks again,

Phil. :D
 
I was going to say (But you've solved it so maybe this'll help in future.LOL) that a gearbox problem would usually be indicated by high revs.

Either high because the vehicle stayed in say 2nd or even 1st gear. Then it's just be high revs and no shift into 3rd.

Or high because (and in my experience usually this is what happens.) the engine revs and revs while no forward progress due to slippage. It also does this when low on fluid. But you can definitely tell as the engine will just 'rev and rev' and no progress. (VERY slow acceleration!)

Also, similiar when say a modulator valve goes and you either get VERY high revs and a sudden WHAM into the higher gear. (Or a variation on this, it won't shift up unless you manually shift it or shift into Neutral then back into Drive. been there donew that! LOL)

So in esseance:

Engine won't "pull". IE: lack of "grunt". = Engine.

Engine pulls/winds out but no (or very little) forward motion = Tranny.

:D
 
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