Mitsubishi Colt 1.6L 2006 model (hatch) CVT problem
 

Hi,

at 476,000 km the CVT on my brothers Colt is playing up.

Pressing down on the accelerator pedal doesn't result in any revving if it is in drive, reverse, second or low.

If it's in Park or Neutral it does rev.

I just changed the transmission oil and it was fairly dirty with a lot of metal on the magnetic sump plug.
It had been changed at 419,000 km previously.

Sometimes it won't rev in Park either... but only for a brief moment.

My brother has been getting it to engage by revving it in Park then dropping it into reverse... and then back into drive. This is somewhat dangerous and very inconvenient.

The ECU light is not on and there are no other error signals on the dash.

This sounds like either a mechanical or electronic problem.

Can someone help narrow this down further? Which part is causing the problem?

:-)
This is an Australian Colt. It's been very reliable, the engine still has maximum as new compression and it still looks pretty good... so we don't want to scrap it unless it's absolutely necessary.

PS. Put an SP II rated auto transmission oil into it before realising the manual specifies SP III... although I doubt that's the problem as it was doing this before. A clean oil change is still better than dirty oil?

The dirty oil in the CVT is due to my sister who owned the car previously and failed to change the CVT oil at the specified interval. Thus the last CVT oil change was probably overdue by a fair bit. The specified interval is 90,000 km and I'm pretty sure she went double that or even more as I can't remember her ever changing it... and I changed it a lot earlier (she's lost the log book... so I can't check).

Apparently a faulty brake light switch can make a CVT play up.

Just checked the brake light... and it is working (meaning the switch has to be working).

CVT started to work again... maybe the oil change did it some good?

Doesn't seem to have any problems when it does run... so presumably the CVT itself is still OK.

Either something mechanical got clogged or something electronic is playing up?

No warnings coming up... but perhaps I ought to attach the OBDII scanner to it and check? ...if I can find it?

:-)

How sensitive is the car to the ATF oil?

The shop sold me SP II rated oil and the manual specifies an SP III rating.

Likewise the manual says 8.1L of oil... but the dipstick shows full at 4L.
Is the manual wrong?
I checked the oil coming out of the sump... and there was only 4L.
...so unless the last mechanic made a mistake and the dipstick is wrong... then the manual is wrong or there's an extra 4L hiding in there somewhere?

Is the CVT very sensitive to which fluid is used? I've heard lots of opinions over the years but it's hard to know what the real facts are?

If the ATF still comes up dirty after the change I can do another flush and put the correct SP III rated oil in it?
I bought 8L so I've got another 4L which won't get used otherwise?
I can go back tomorrow and change it over to the correct SP III grade.

I used Penrite DX-III (the III fooled me) in the CVT this time. It's just a mineral oil.

ATF DX-III (Mineral)

SP III is semi-synthetic or fully synthetic in the other two products I looked at... but the girl recommended this one.

ATF fluid is a bit pricey (~$40/4L) so I didn't want to pay any more unless it was absolutely necessary.

:-)

BTW: If anyone is wondering... it's really easy to change the ATF in the CVT on the Colt.

The plug is right near the front of the engine on the right-hand side of the car (looking from the front).

One big fat 24 mm plug with a huge magnet on it.
Just drain the oil into an oil pan (same as a normal oil change).

Putting the ATF back in is easy.
Refill via the dipstick hole.
It's a little hard to get to the dipstick hole (it's under the air intake of the air filter):
Just get a funnel and attach a hose (a big ~1 cm hose).
Hose needs to be ~30 cm (longer is OK but can become fiddly).
Drop the hose into the dipstick hole (which is huge) and pour in 4L of ATF.

You should be able to do this in 5-15 minutes.
The only slow bit is waiting for oil to drain into the dipstick hole without overflowing.
You have to add a bit... wait... add a bit... wait, etc...
If you fill too fast it will overflow from the dipstick hole.

If you overflow a little don't worry... it's only an issue if most of the oil ends up on the outside of the engine.

:-)

Usually I tend to use better quality oil in any auto transmission... as ATF and gear oil are probably the two most neglected oils in car.

Thus if you put in a high quality one it might last a bit longer and stop the transmission from failing?

It was the 8L that put me off the higher priced oil in this case.

The standard mineral oil wasn't cheap... the semi-synthetic and synthetic was about $10 more expensive (per container).

BTW: The oil that came out of the CVT still felt OK... but was unusually dirty.
The previous oil change the ATF was more like water when it came out.
I didn't do that one... my sisters mechanic did.
He was horrified by the amount of metal that came out.
I was impressed that my sisters lack of maintenance hadn't killed the CVT.
...and continue to be impressed by the endurance of the CVT.
None of our traditional auto's ever managed to get to 476,000 km. Same for the manuals.
They all needed replacement well before this.

:-)

PS. This is the first time we've ever had a problem with a CVT... and we've owned a string of them both on bikes and cars.

CVT oil was still VERY dirty the next day and it still wasn't shifting consistently.

Went back to Autobarn and paid $10 more to upgrade to the fully synthetic Penrite CVT fluid:

CVT FLUID V (Full Syn.)

The magnetic sump plug had picked up tons of metal in the one day after changing the oil... and without taking it for a drive anywhere. Mostly just idled it in the driveway a lot.

After changing the oil this time it came up much cleaner on the dipstick.

Transmission worked briefly then stopped working again.

Can't work out if it's a mechanical problem or an electronic one?

The throttle sensor was playing up a long time ago. Maybe it's playing up again?

:-)

BTW: Does anyone know why the alternator belt adjustment is maxed out?

The mechanic fitted a new belt but we found that it remains fairly loose because the adjuster is at the end of its travel (can't tension it further).

Either the new belt is longer than the original or there's some wear in the system somewhere?
I can't feel any movement in the alternator bearings which is what the mechanic suggested it was.

It tends to screech badly when starting due to the loose belt... although it seems to have settled down a bit as it's worn in.
The mechanic came back and checked the vehicle and the belt... and swears it is the right one.

:-)