2011 D5 Post sales inspection

[Kev0607]

Originally Posted by gmonag

The gearbox flush procedure, which is often referred to as "The Gibbons Method"(because it was posted here a few years ago by a poster called gibbons), is actually the same procedure as described in VIDA. The sump is drained (2.2lt), then the oil return from the oil cooler is disconnected so that the old oil is diverted to a bucket and fresh oil is added to the return line to replace that just drained. The engine is started, the oil starts to circulate, old oil goes in the bucket, fresh oil goes down the return line to replace it.

This circulation goes on continuously whenever the engine is running. Intercepting the old oil and replacing it with fresh oil will not stir up crud any more than it does all the time. In fact, diverting the old oil will remove any crud with it (which is the whole point).

Draining the gearbox sump will deliver 2.2lt of old oil. The gearbox holds over 7lt. If you drain and refill, the new oil will mix with the old and the second drain and refill will change another 2lt of the mixed (diluted) oil. You will have to repeat the procedure a dozen times to change the oil completely. The flush takes about 10 minutes and you only need to do it once.

You are correct. It is my car and I will do as I want, but please stop spreading this old-wives tale about flushing stirring up crud in the gearbox.

I'm aware of the Gibbons method, but its also interesting how any Volvo garage I've brought my car to doesn't actually use it, despite it being listed in Vida as a procedure.

Your car must be low on transmission fluid if you can only drain 2.2 litres out of the sump... More like 3L comes out, or maybe even slightly more than that. It isn't an 'old wives' tale, plenty of other Volvo forums & generic ones across the globe also mention the drain & fill being the most simple & preferred method to changing the fluid. Next thing you'll probably say is "Don't believe everything you read"... I've also been advised by professional garages not to flush a transmission too, so there's a trend there.

Anyway, like I said before, do as you please. Happy flushing!

[NMB]

From what I can gather, I think there are two opinions on this thread:

Opinion 1) Do the flush the technically correct way and replacing 99% of the fluid. If the gearbox has no pre-existing faults (hidden by the older oil) then you will have a great smooth auto box. If the box subsequently fails then the oil change has just brought forward failing components and you need to deal with the repair/replacement.

Opinion 2) Drain and replace the oil without flushing and you will have cleaner fluid which should prolong the life of the gearbox and you will feel better than the gearbox has been serviced.


As a home taught amateur DIY mechanic I just want to do things the right way. However, I am also scared of things I don't understand (Auto Gearbox fits this category as do many other things!!) and I don't really want to service something only to have to replace the gearbox when it may have been ok if left alone.

I think the reality is not how you want to it, more so are you prepared to deal with the replacement of a £1,500 gearbox if it goes wrong.

[dambat]

OK, here's the long answer as to why it's generally a bad idea to only replace 50% of your ATF if your gearbox is otherwise in good nick. I've done valve block rebuilds and full rebuilds on a number of gearboxes (mainly ZF 4HP22).

Transmission oil is designed to be shear stable, and in modern fluids, often slightly shear thickening. As it breaks down, it becomes shear thinning. This exponentially increases wear due to:
(a) The oil is not properly adhering to friction surfaces.
(b) The oil viscosity profile is wrong, which results in fluid accumulators not working, low pressure, etc. This results in clutches coming in late or early, which may mean (for example) that you have clutches simultaneously engaging or engaging with high velocity shafts. As a driver, you won't notice this (apart from harsher shifts), but it is doing a lot of damage.
(c) as you get friction particles in the fluid, this wear is accelerated.

ATF fluid modifiers (additives) help with the viscosity issue, but only partially, and are nowhere near as good as the proper spec fluid.

Gearbox malfunction is down to three issues:
(a) Valve block (or control component issues). In modern gearboxes like the TF80SC this is mainly the solenoid valves, which is pretty easy to repair. This is mainly due to accumulation of particulates in bores, but also possibly hydraulic valve bores and feeder lines, and in older gearboxes, gumming up of governors etc, but in the TF80SC mostly solenoid valves.
(b) Friction surface wear. The core gearbox is well worn out, with the valve block mainly hanging in through luck. This is 200,000km+ with no services.
(c) Hard part failure. A gear has broken or serious bearing (there aren't that many) failed. The ZF 4HP22 had this issue with one of their planetaries, and I believe the V8 TF80SC has one also with the main rear gearbox bearing.

In my experience, if your gearbox is terminal, it's terminal, because you have failed to maintain it. You may get another year out of it before the valves completely stick or the friction plates fail. Putting fresh oil in (either 50% or 100%) will make the shift better but will not save you. OK, in some circumstances a complete oil change will flush enough particles to block an otherwise good valve, but in others they may clear a blocked valve. Your valve block is stuffed either way and you’re living on borrowed time.

Personally, I do changes about every 60,000 km, and 5 y. Fluid is fine at 100,000 km, and is starting to deteriorate badly at 150,000km.

TLR the best option is 100% replacement of fluid in a car that is normally driven about every 60,000 km or 5 years.

[BlueRubber]

Thanks for that great explanation dambat!

I think part of the problem is that a lot of people buy these cars 2nd hand with no gearbox service history.
For example, my 2002 v70 was purchased with 125,000 miles and it never had the gearbox oil changed.
The gearbox was ok when I bought it but slowly started to flare in certain conditions.
I assume the gearbox is quite worn at this point and I do a dump and sump every now and then to try and eeek some more life out of it.