It has been several months bit I have an update on the fluctuating RPM issue.
Finally having spare funds to pay for it, I took my V50 to the garage to have the oil changed last week. When I called them later that day the garage told me they were having problems getting a service kit for it and they though it might be a main dealer only part but they weren't answering.
Knowing that the current Covid-19 restrictions were impacting many businesses I emailed my local main dealer (Lipscomb, Maidstone) myself and a few hours later received a reply (were my garage actually trying?). There is no service kit, all you can do in the gearbox (an AW55-50) is change the oil. The staff member at the dealer also sent me a full breakdown of the gearbox that was on my car with diagrams and parts lists. All super helpful. With the information he had provided I found further information on a third party website that described the differences between the AW55-50 on different brands of cars and some Volvo only features.
V50 then went to garage and a couple of days later was done (there was no hurry). Total cost was £150 which I thought was very good especially and the oil was 'special expensive stuff'.
That drive home the problem was still there. No surprise I thought, the oil needs time to work its magic. Second drive out and it seemed perfect. No real fluctuation, well maybe a little but nothing you would worry about. Was it fixed? This was a longer drive so maybe this is what it needed. Third drive out, a fairly short drive, and there is was back again, a good 200 rpm fluctuation. Damn it.
I have not given up though, firstly it has only had two short drives, and one moderate one. Secondly and more interesting for me is one of the things I read about the gearbox, some Volvo only features, specifically relating to 'Slipping Lock-up'.
The first link I found mentioned 'Volvo Shift Modes', specifically 'Locking Slip-up' where it described the symptoms exactly.
This makes me think, is it actually not a fault but it is incorrectly enabling and disabling too frequently?
https://www.sonnax.com/tech_resource...urers-part-one
Slipping Lock-up – Slipping lock-up mode allows for a smoother lock-up engagement while reducing vibration and noise. The computer maintains a 50 to 200 RPM torque converter clutch slip in this mode. The following conditions must be met for this mode to activate:
Gear shifter must be in the D, 4, or 3 position.
Transmission must be in 3rd, 4th, or 5th gear.
The transmission input speed must be 1100 RPM or higher and the throttle opening must be 35% or less.
Engine coolant must reach a certain temperature.
Transmission oil temperature must be at least 40°C (104°F), but not to exceed 120°C (248°F).
Over the next few weeks I will continue to test the V50 and also carry out further research. I have not given up on it yet and I am hoping a full solution can be found that doesn't involve £1,800 for a new gearbox. I really like the V50 and would if it is economical to do so, keep it.
#2 link:
https://www.sonnax.com/tech_resource...dy-information