6L80 (V8 Trans) experiences after power flush?

[Dart77]

Don’t do a full flush on the auto transmission. If it’s got high mileage on it then it can be relying on the grit in the fluid to provide sufficient friction for the engagement clutches.

If you flush all of the fluid then you will remove all of the grid which can result in the transmission slipping, forcing an immediate rebuild. Standard pan drop and filter/fluid change is entirely sufficient and a full flush is always unnecessary.

Thanks JD - that's an angle I hadn't heard of before, but makes sense. The only thing though is, wouldn't any rough bits /grit in the fluid have a bad effect on the valve body operations? I thought the filter was supposed to ensure that the fluid was completely material free? So even if it's bad fluid, eg overheated or lost some of its properties, it's still fluid with no material in it. (unless the fluid around the clutches goes a different route to the fluid through the valve body? Don't have much knowledge on the workings of them).

 

[Dart77]

It might be the clutch purge feature u can do to them that is the issue, as it purges the clutches of any debris. It can be caught up in them which is why it has the warning not to do it on transmissions with a lot of km

Could be. I'm only a bit familiar with older 3 speed (non electronic autos) so these features are all new to me.

I wouldn't have thought that a bit of material would do much to the clutch workings, I was more thinking of the tiny orifices throughout the valve body getting stuff in them from the pressure flush. That is, if these have a valve body? ! In the older 3 speed ones the valve body was like a hydraulic computer. Maybe these days they have a different way, like hydraulic solenoids and stuff.

 

[Dart77]

no doubt ultra tune have an expensive machine to simultaneously capture old fluid & add new fluid, but as you say, is it detrimental to a high mileage transmission? The old VS did start slipping after a fluid exchange, but who knows if it was buggered to begin with. Before i got rid of it, changes from 1st to 2nd became very hard & 3rd back to 2nd would slip. 230,000km

Interesting... Makes you wonder how doing something that should make them improve, actually exacerbates the issues. It happens so often in auto repairs. The yanks in the vintage car scene also have a saying, "If it ain't broke, fix it 'til it is!" So funny, but so true.

 

[J_D 2.0]

Thanks JD - that's an angle I hadn't heard of before, but makes sense. The only thing though is, wouldn't any rough bits /grit in the fluid have a bad effect on the valve body operations? I thought the filter was supposed to ensure that the fluid was completely material free? So even if it's bad fluid, eg overheated or lost some of its properties, it's still fluid with no material in it. (unless the fluid around the clutches goes a different route to the fluid through the valve body? Don't have much knowledge on the workings of them).

No filter will collect 100% of the particles, only particles down to a certain size. Doing a full fluid flush probably wouldn’t pose any problems for a low mileage transmission but once it’s got a lot of miles on it and the clutches are worn the small grit particles could be the only thing stopping the gear clutches from slipping.

 

[Dart77]

No filter will collect 100% of the particles, only particles down to a certain size. Doing a full fluid flush probably wouldn’t pose any problems for a low mileage transmission but once it’s got a lot of miles on it and the clutches are worn the small grit particles could be the only thing stopping the gear clutches from slipping.

That's very interesting. I'll run these things past a guy I know who is a workshop manager of a place that does automatic servicing and used to work at Holden, and also used to have an SS 6.0 Auto. Will post back when I have more info.

My layman's (backyarder mechanic) way of thinking though, is if the clutches are worn to that extent and it's only poor fluid that's keeping it running well (which mine is - no complaints about it's shifting) then it's going to start playing up sooner rather than later anyway.

Also wondering, if ATF with minute particles in it helps an auto with worn clutches to shift better, then maybe all these additives invented for ATF to use in high mile and slipping have things like that in them?

Here's a quote from a mechanic's review of Lucas trans additive. Sounds exactly what you're talking about: his VY which was running fine, gave the auto a service and then it started slipping.

"As a mechanic by trade I normally wouldn't recommend or use additives of any kind. I have serviced hundreds of transmissions (rebuilt dozens) over my career. Serviced the trans on my old VY Commodore (was working fine) but then noticed a shudder/slip when cold at first use and holding in first gear. It was fine afterwards but I was not happy, I thought it might be the Ryco filter kit as I always used another brand before. Anyway I added half a bottle of Lucas trans fix (new transmission in a bottle) and I am amazed, no slipping, smooth shifts,it's like a different car. I couldn't speak more highly of this product and would not hesitate to recommend it to anyone whether it's for issues or general upkeep of your trans. Good stuff 5 stars."

 

[J_D 2.0]

My layman's (backyarder mechanic) way of thinking though, is if the clutches are worn to that extent and it's only poor fluid that's keeping it running well (which mine is - no complaints about it's shifting) then it's going to start playing up sooner rather than later anyway.

Correct. The difference is that if the grit in the fluid is the only thing keeping it going then it will be a slow decline giving you time to budget for the inevitable repair after it starts slipping.

Flushing the system forces that hand immediately as it will go from no problem at all to slipping so bad you can’t drive it at all.

If you’ve got the money in your pocket to pay for an immediate rebuild then there’s no problem with flushing it (other than the few weeks you will have to wait to book it into the mechanic). If you don’t have the money on hand to rebuild the transmission then don’t tempt fate by flushing it.

 

[Ginger Beer]

2 man job preferably

The best way to flush is do your filter service, refill with fresh fluid, then just disconnect the return line after the cooler and run a line to an oil tray

One person starts the car and puts it in drive, the other makes sure the fluid actually goes into the drain pan, and also tells the one in the car to put it in park and shut the car down when the pan has about 2 litres in it, refill the trans, then rinse and repeat until you have flushed all of the old fluid out

You'll need at least enough fluid to do a dry fill, plus a litre or 2 in reserve for top ups

Time to do the whole job is around 1 beer for the one actually working outside, and 2 or 3 for the lazy bum sitting in the car starting it up and putting it in drive 5 or 6 times

 

[vr304]

That's very interesting. I'll run these things past a guy I know who is a workshop manager of a place that does automatic servicing and used to work at Holden, and also used to have an SS 6.0 Auto. Will post back when I have more info.

My layman's (backyarder mechanic) way of thinking though, is if the clutches are worn to that extent and it's only poor fluid that's keeping it running well (which mine is - no complaints about it's shifting) then it's going to start playing up sooner rather than later anyway.

Also wondering, if ATF with minute particles in it helps an auto with worn clutches to shift better, then maybe all these additives invented for ATF to use in high mile and slipping have things like that in them?

Here's a quote from a mechanic's review of Lucas trans additive. Sounds exactly what you're talking about: his VY which was running fine, gave the auto a service and then it started slipping.

"As a mechanic by trade I normally wouldn't recommend or use additives of any kind. I have serviced hundreds of transmissions (rebuilt dozens) over my career. Serviced the trans on my old VY Commodore (was working fine) but then noticed a shudder/slip when cold at first use and holding in first gear. It was fine afterwards but I was not happy, I thought it might be the Ryco filter kit as I always used another brand before. Anyway I added half a bottle of Lucas trans fix (new transmission in a bottle) and I am amazed, no slipping, smooth shifts,it's like a different car. I couldn't speak more highly of this product and would not hesitate to recommend it to anyone whether it's for issues or general upkeep of your trans. Good stuff 5 stars."

I used that Lucas stuff in my Mazdas transmission that had never been serviced and yes definitely made a noticeable difference to it, Lucas make some really good products and no I’m not sponsored by them lol if anyone from Lucas sees this feel free to send me some products

 

[Dart77]

I used that Lucas stuff in my Mazdas transmission that had never been serviced and yes definitely made a noticeable difference to it, Lucas make some really good products and no I’m not sponsored by them lol if anyone from Lucas sees this feel free to send me some products

That's good to hear - both that review I quoted plus your experience, gives me faith. I have been using Lucas Power Steering leak Fix for years and with good results also. Apparently it acts to swell up the rubber/soft seals inside, so reducing the leak past them.

 

[Dart77]

Correct. The difference is that if the grit in the fluid is the only thing keeping it going then it will be a slow decline giving you time to budget for the inevitable repair after it starts slipping.

Flushing the system forces that hand immediately as it will go from no problem at all to slipping so bad you can’t drive it at all.

If you’ve got the money in your pocket to pay for an immediate rebuild then there’s no problem with flushing it (other than the few weeks you will have to wait to book it into the mechanic). If you don’t have the money on hand to rebuild the transmission then don’t tempt fate by flushing it.

Sounds like words of wisdom - ta for that. For a rebuild on one of these, I doubt there'd be much change out of $5k ! Just the R & R and road tests would be at least $800 - they're charging $150 an hour these days.