Auto Trans Service

[abg]

I'm planning to service my auto trans next week with a complete flush of oil and filter change. The DIY way I've seen done on other cars is to remove the trans oil hose leading to the radiator and run it into a drain pan. The engine is run for 10 seconds at a time to drain a fraction of the oil and is topped up with same amount that drained. This is repeated until the oil runs clear. What I'm unsure on is weather to drop the pan and change the filter before or after flushing. Has anyone done this before? Maybe someone with the service manual could post the official procedure, it would be greatly appreciated

Haven't had any luck finding any info on this in the search or the FAQ, but maybe I'm just blind.

[Calaber]

I assume you have the old four speed auto? The service procedure for them is to release the oil pan gradually and let the oil spill over the back end into a tray, until you can completely remove the pan. Pull down the filter which is just a push fit into the seal. The service kit will include a new seal but they are generally ok to leave in and a bitch to remove. The pan should be cleaned out thorougly, including the small separate magnet which is covered in grey crap (metallic filings from the trans internals). Replace filter and pan gasket, then refill with about 5.5 litres of Dexron. This only drains about 50 - 60% of the oil because it doesn't drain the torque converter. I haven't seen your method used for a normal service.

The method you outline would eventually drain all the old fluid, but unless the old fluid is really dark or burnt, it's difficult to tell when you are draining old or new fluid, so you can't be sure when you have removed all the old stuff. It would be time consuming and go through a fair bit of fluid, but it would work. I wouldn't replace the filter until all the old oil had been drained.

[harro_VR]

I usually use a machine to do it, change the filter, then take bout 4L out, pump 4L back in and so on till the oil appears cleaner prob use bout 20L to do a good flush! So i would say it would work dpoing it this way.

[Benboy]

What would you hope to gain from changing the fluid but NOT the filter. Seems to me that in doing so you will be exposing your nice clean fluid to a dirty filter !! No gain. However, here's step by step.....

Normal maintenance and lubrication requirement do not necessitate periodic transmission fluid changes. If a major failure, such as a clutch, band, bearing etc has occurred, the transmission will have to be removed for repair and the converter replaced.

Automatic transmission fluid is red coloured when new, after use it turns a light brown.

Transmission Drain & refill

1. Place a pan under the transmission, then remove the transmission drain plug and drain fluid from thransmission assembly.

2. Remove the oil pan retaining bolts and carefully remove the pan from the transmission, as it will still contain a small amount of fluid.

3. If replacing filter:
(a) Remove the transmission filter from the assembly by gently prising out with a screwdriver.
(b) Remove the filter neck seal from the transmission case using a slide hammer and seal removal tool (J23129)
(c) Coat the two new seals with Vaseline then install into filter neck.
(d) Install the new filter and spacer sleeve into the transmission case.

4. Position a new gasket on the oil pan, and install the pan onto the transmission (after cleaning etc) tighten bolts to specification.
(Note: before installing fluid pan clean the magnet and position it in the correct location inside the oil pan.)
FLUID PAN BOLTS............................................. ......................11Nm

5. If not already fitted, install a new drain plug and seal tightening to specifications.
DRAIN PLUG.............................................. ................................20Nm

6. Fill the transmission through the filler plug hole using specified transmission fluid, until the fluid starts to flow back from the hole. Temporarily replace the filler plug.
SPECIFIED FLUID...................Pre07 models...............DEXRON III
Post07 models..............DEXRON IV



7. With the engine running, and brakes applied shift the transmission through all gears holding in each position momentarily then return to Park position.

8. When transmission fluid is at 40 - 50 (degrees) C remove the filler plug and allow any excess fluid to drain out.
(Note: The fluid temperature can be checked using the Tech2 diagnostic tool.)

9. Install the filler plug, tighten to specifications. Before installing inspect plug and O-ring and replace if required.
FILLER PLUG.............................................. .................................20Nm

[IMG][/IMG]

[FnomnaVZ]

Yeah, basically I've done what you mentioned twice now - but haven't done the pan drop and filter change yet.
So I ran fluid out of the top radiator fitting until it just starts to splutter, got 4L of Dexron VI and put it in, check levels.

Followed this How To: 4l60e Transmission Flush/Filter Change - GMFullsize - Chevy & GMC Truck Forum and I think it goes on to mention the filter change and pan clean.
Didn't get the proper brass fitting but just mangled together my own fitting to push in there. Anyone know where to get the proper size fitting for that radiator outlet?

[greenacc]

Radiator shop would sell you the fittings.
After doing several variations of this service on my old VS, the method i'd recommend which i reckon would give you the most effective job per hour of work would be drop the pan and change the filter, clean and replace pan and gasket, refill, then take the hose off the radiator and drain another 4 litres. At most you could repeat the last step one more time. Any more than that i believe is a waste of time. If you want a really good clean out just repeat the whole process in a month or two after the new fluid has had a chance to flush all the loose crap out of the trans. A quick flush is not going to catch it all.

[abg]

Thanks for the replies everyone. I'm a bit unsure on what fitting is needed to rig up a drain hose. I found 1/2" UNC threaded fittings, is this the right thread?

I checked out the current fluid level today and found it was way overfilled. I drained out 1.3L via the dipstick but it's still sitting a few mm above the max hot line. Anyone know if this is likely to have caused any damage?

[FnomnaVZ]

You did check with the engine running after a drive, yes? If it was way overfilled, see overfilled auto transmission l460e - Google Search

I think I measured the nut thread was about 18mm?
edit: so does that make it a 3/8" NPT fitting?

[abg]

After a lot of searching and not finding any fittings that came even close to the right size I decided to drop down the lower pipe going to the radiator into a drain pan. A deep socket was zip tied to the line to help weigh it down. If I was to do it again I'd slip a bit of clear PVC hose over the hard pipe and drain it into a large bucket as there was a bit of splashing in the shallow drain pan.