Yet another gearbox issue for the E53 4.4i... please help!

[gadden]

Hello all,

spent hours of reading through various threads, but i found only 1 similar case for a 4.4i E53 with external trans cooler and a colder thermostat .

Mine is an EU version 4.4i E53 2001 (pre-facelift)

Long story short, i've had issues with the model. I've went through a torque rebuild 50k kms ago + fluid change because of hard downshifts. Afterwards done external cooling as it was again starting to act up after 30mins+ drives. Ext cooler was done around 20k kms ago give or take a couple of thousand.

So far so good. I believe the torque was at its limits now and will had to be rebuild again (first rebuild i don't thrust very much, shady mechanic).

This was a couple of days ago when i went to the shop and told them to change the thermostat for a colder one. Reason for this was the 2nd hose failure in 6 months, leaving me stranded. Car is too old for 106 degrees Celsius. The colder thermostat is from a 7 series diesel and a perfect fit (+a resistor to avoid the errors as it is mechanical).

All good, car runs at 95C now... but i am now getting a sort of stutter or jerking in what seems like switching up form 3-4 gear. This is only visible with very gentle throttle handling - i.e. stuck in traffic, or keeping a constant speed at 1.5k - 2k RPM. Happens on hire RPMs as well if my foot is stationary on the gas. If i give it a bit more gas - doesn't occur, shifts with no issues. Its as if it tries to shift to 4th but doesn't make it

ATF temp is at 75C now. As much as i read everywhere that people having trouble with high temp, is this a low temp for a heated-up car? I'm baffled with it now, no idea what to do except maybe try and put the original 106C thermostat and see how it goes, somehow though i believe this will not cure my current problem. Prior to the colder thermostat change, it always ran smoother when colder or not fully warmed up.

Should i bother with looking into reverting to the original thermostat, or removing the ext cooler to see if any of these mods is the reason for the problem? Or its just a coincidence that it happens now after the colder thermostat change...

Timing chain replacement was 10K ago, if it matters.

Of course my fear is going to the trans shop for a rebuild as i recon they will want to rebuild the whole thing for half the money the car is now worth.

Any input is appreciated.

Sorry if i messed up somewhere with the English, not my native language

Best Regards