Auto gearbox issue

[gjm 3258]

Apologies - not actually a question about a BMW, but one which could easily apply.

Car will not 'proceed'. Select D, 1, 2, 3, and there's no forward motion. There is a sound of auto gearbox components doing something, but no movement. No bad noises, either. Did seem to almost move in 1st.

Select R, and it'll go backwards, no problem.

Previous owner advises that this happened over a period of time, gradually losing the higher gears. Also admits that gearbox had been leaking fluid. A garage advised the very non-technical PO that a replacement gearbox is required.

I plan to drain whatever fluid is in the box, remove the sump and filter, and inspect for debris. If it's clean - no particulate - I'll replace the filter and sump and correctly fill with ATF, and see what happens. There is no indication the garage did this before their diagnosis to the PO.

If there is matter in the sump, I suspect either a rebuild (s/h box quoted at $1200-1600 ? ) or a replacement gearbox will be needed.

Any other thoughts?

[B.M.W Ltd 950]

Top up the gearbox first and see if it drives first... go from there

[gjm 3258]

Been a bit of a delay due to a suspected torn ACL... Surprising just how much that slows down the crawling under cars activities.

Checked trans fluid level. Looked OK...

Drained trans 'fluid'. Ha. Looked like old engine oil. No sign of any debris, but to be honest, not sure I'd have seen any. Certainly nothing on the sump plug.
I'll see if I can drop the sump over the weekend.

[B.M.W Ltd 950]

Very dark or black oil in a auto trans means burnt clutch plates. It normally smells burnt as well. Caused by slipping, warn out clutch plates. Some times when the linings disintegrate the clutch plates weld themselves together causing a trans lock up. Either way it's terminal - trans out, rebuild  and torque converter overhaul with a trans cooler and line flush. 

[gjm 3258]

That'd fit with the rest of the story. Leaking fluid, low fluid, slipping plates... 

Oddly the fluid doesn't smell burnt. 

[Kiwi_BMW 89]

If the fluid doesn't smell burnt then it may have other issues causing no forward drive.

What vehicle is it and what transmission?

[gjm 3258]

3 hours ago, Kiwi_BMW said:

If the fluid doesn't smell burnt then it may have other issues causing no forward drive.

What vehicle is it and what transmission?

1990 Mercedes W201 190E 2.0 with the 4G-Tronic 722.400 (W4A 020) automatic transmission.

There were several different versions of the 722.4xx, fitted to the W201, W202, W124 (and possibly other models), but I've been told the differences were the number of plates, and not ratios. Trying to confirm that.

[coop 261]

Had a similar issue with one of my 722.4 W140s. 

The pushrod at the end of one of the servo pistons and acting on one of the bands used for 1st, 2nd and 3rd dropped ontop of the valve body due to excessive clearance as the band/drum had worn. 'B2' band (google it). 

Mercedes sell different rod sizes to compensate for the wear. I think there were three lengths to suit the B2. It was around $4 ex Singapore. 

An easy fix as long as you don't mind ATF dripping on you. 

 

How does a 190E go with the 3.0? Should have come like that from the factory!

Edited August 5, 2020 by coop

[gjm 3258]

11 hours ago, coop said:

Had a similar issue with one of my 722.4 W140s. 

The pushrod at the end of one of the servo pistons and acting on one of the bands used for 1st, 2nd and 3rd dropped ontop of the valve body due to excessive clearance as the band/drum had worn. 'B2' band (google it). 

Mercedes sell different rod sizes to compensate for the wear. I think there were three lengths to suit the B2. It was around $4 ex Singapore. 

An easy fix as long as you don't mind ATF dripping on you. 

 

How does a 190E go with the 3.0? Should have come like that from the factory!

The extra capacity makes a reasonable difference, but to be honest, the 2.6 is the cream of the daily driving crop of 190Es. (16v cars are more 'focused', the 1.8, 2.0 and 2.3 4-pots are solid, dependable but not especially exciting.)

Making the 2.6 engine bigger is like adding sprinkles to a lovely pudding. (I'm considering a 3.2 build - the engine can go to 3.6 without sleeves.)

This 2.0 I've picked up is a really lovely car. Some rust nibbles around the lower boot opening, but otherwise almost mint. I feel it's worth a bit of effort.

 

[Kiwi_BMW 89]

On 8/5/2020 at 5:35 PM, gjm said:

1990 Mercedes W201 190E 2.0 with the 4G-Tronic 722.400 (W4A 020) automatic transmission.

There were several different versions of the 722.4xx, fitted to the W201, W202, W124 (and possibly other models), but I've been told the differences were the number of plates, and not ratios. Trying to confirm that.

As you say there are many 722.4 transmissions, they are a hydraulically controlled transmission so the many variants although basically the same are quite different and the control ie valvebody, governor, vacuum modulator etc are calibrated to cope with different shift patterns and timing depending on model of vehicle, weight of vehicle, diesel or petrol and kw rating.

Coop is correct a no forward drive can be caused by the B2 (rear band) servo pin falling out this is usually caused by wear and the plastic retainer clip breaking allowing the pin to fall out.

To give you an idea of hydraulic vs electronic control, GM had 73 different build versions of the 4L60 transmission and when they changed to electronic control of the same transmission I think the number of different builds was reduced to 6 or 7.

[gjm 3258]

Drive failed gradually (or so I'm told). Top - 4th - gear stopped engaging, then 3rd, 2nd, and 1st. Reverse still engages smoothly. That suggests (to me) low fluid, yet fluid, yet level indicated on the dipstick isn't far off where it should be.

The 722.400 was only installed in the 190E 2.0.

I'd stay away from the 'boxes from any of the diesels. Totally different engine characteristics.

I've been offered a 'box from a W202 C220. This car had the M111 engine which is a later, more powerful engine; I was wondering if swapping the torque converter would help make up any differences?
The M111 superceded the M102. It's a 16v engine (the M102 is 8v) with more top-end power, but the 8v engine delivers its power earlier in the rev range.

M111 2 Litre 136 HP @ 5,500 rpm; 190Nm @ 4000 rpm
M102 2 Litre 122 HP @ 5,100 rpm; 172Nm @ 3500rpm

Edited August 6, 2020 by gjm

[Kiwi_BMW 89]

15 hours ago, gjm said:

Drive failed gradually (or so I'm told). Top - 4th - gear stopped engaging, then 3rd, 2nd, and 1st. Reverse still engages smoothly. That suggests (to me) low fluid, yet fluid, yet level indicated on the dipstick isn't far off where it should be.

The 722.400 was only installed in the 190E 2.0.

I'd stay away from the 'boxes from any of the diesels. Totally different engine characteristics.

I've been offered a 'box from a W202 C220. This car had the M111 engine which is a later, more powerful engine; I was wondering if swapping the torque converter would help make up any differences?
The M111 superceded the M102. It's a 16v engine (the M102 is 8v) with more top-end power, but the 8v engine delivers its power earlier in the rev range.

M111 2 Litre 136 HP @ 5,500 rpm; 190Nm @ 4000 rpm
M102 2 Litre 122 HP @ 5,100 rpm; 172Nm @ 3500rpm

If the transmission has enough fluid to engage reverse then it has enough fluid to engage forward gears

None of the clutch packs engaged for 4th are used in 1st or 2nd.

Clutch pack K1 is used in 3rd and 4th.

Band B2 is used in 1,st , 2nd & 3rd

Since you have reverse the one way clutch which is used in 1st and rev is OK, so no drive in 1st indicates a problem with B2 since B2 and the one way clutch are used for 1st.

You aren't going to get any gears apart from 1st and reverse, unless the valvebody is calibrated to apply 2nd for take off on normal acceleration (some were calibrated this way and only applied 1st on take off when using more throttle)

Since you say the oil doesn't smell burnt it doesn't indicate the plates and bands are burnt and worn away, if the trans had been slipping and worn the lining off the plates and bands causing a loss of drive through excessive clearance of the bands and clutches the oil would have a burnt smell.

If you install another transmission ensure the modulator is the same colour as the one in the transmission you are removing and put a pressure guage on the transmission and adjust the pressure to the spec of your car.

From memory the 722.400 had a green modulator and a pressure setting of 46psi  this is measured at 50kph with the vacuum line off. (it would pay to check that to see if my memory is correct, it's been a while since I set one up)

Modulator is shift feel (so pressure control)

The TV cable is shift timing.

[gjm 3258]

Plan for this weekend is to get back under the car, drain the torque converter (for those that don't know - that can be done separately on a Mercedes gearbox ), remove the plate on the side of the gearbox and remove the B2. Inspect.

Any work of this nature has been taking a back seat due to a suspect torn ACL. That really doesn't help with the getting up and down off the ground aspects of home car maintenance.