Torque converter lock up

[Johnnojack]

What is the best way to figure out if the torque converter is locking up when it should? W202 C250 Turbodiesel.77.6 transmission going to do a filter change and don’t want to put it back together if this isn’t working. It shifts very smoothly,

[tsharkey]

Hi - I own said same vehicle - are you getting an EPC error ? I don't think I have ever had that issue. For the filter change, have you bought the specialist fluid and dipstick so you can make sure its not over / under filled. They are meant to be sealed for life but I changed a filter a few years back. The 722.6 is great transmission.

[John Green]

What is the best way to figure out if the torque converter is locking up when it should?

If the torque convertor is locked up, you will not see a sudden increase in engine speed when you accelerate. If not locked up you will. Have a read up on how these work and you will see what I mean. Each transmission design is a little differant, but the concept is the same.

The 4 speed auto used in the EA/EB/BF falcons had a really obvious lock up convertor, if you paid attention it was like driving a modern 8 speed auto. Each gear would start with the torque convertor slipping a little, then lock up. As it locked up the RPM's would drop, then build up with engine speed until the next change. This was then repeated each time it changed up a gear. If you accelerated hard before it locked up the RPM would rise sharply, if you accelerated hard after it locked up it wouldn't.

[Bartman4800]

Like John said.

I had a 2006 Ford Focus auto with a lockup on 4th gear only. It felt like it was going into 5th, around 80k an hour.

Bart