8 Speed Transmission Filter Change Question

WS6FirebirdTA00 · March 31, 2019

I noticed the top of the 8 speed filter has a metal piece riveted to the top.

Any idea what this is for? I am going to put on a B&M pan on tomorrow, already did one drain and fill with the new M1 fluid. This will be the 2nd drain and fill so I wanted to change the filter and add capacity to do a final flush next oil. Before I pull it down I wanted to get some feedback.

tyler.frost92 · April 2, 2019

On 3/31/2019 at 2:52 PM, ws6firebirdta00 said:

I noticed the top of the 8 speed filter has a metal piece riveted to the top.

Any idea what this is for? I am going to put on a B&M pan on tomorrow, already did one drain and fill with the new M1 fluid. This will be the 2nd drain and fill so I wanted to change the filter and add capacity to do a final flush next oil. Before I pull it down I wanted to get some feedback.

Unrelated, but how are you draining and filling fluid? Through the port on the side with a fluid extractor?

WS6FirebirdTA00 · April 2, 2019

I dropped the pan.

Pulled out the level plug and let the excess drain, then I lowered the end closes the motor. I left two bolts in the back as it drained.

I refill using the GM adapter tool for the level plug. I was expensive for what it is, but man it was handy. I am swapping to the M1 LV ATF HP fluid proactively and was doing multiple flushes.

The B&M pan is nice, but you will need to move the exhaust or have someone pull down on it. I highly recommend dropping it though. There is a wire cover over a connector at the rear of the transmission that pops off because the pan hits it. Really a pain because the factor pan comes off without much issue.

I have to drop the pan again to replace a magnet unfortunately. You have to secure them with screws in the new pan and I cracked one going too tight.

tyler.frost92 · April 4, 2019

On 4/2/2019 at 5:10 PM, ws6firebirdta00 said:

I dropped the pan.

Pulled out the level plug and let the excess drain, then I lowered the end closes the motor. I left two bolts in the back as it drained.

I refill using the GM adapter tool for the level plug. I was expensive for what it is, but man it was handy. I am swapping to the M1 LV ATF HP fluid proactively and was doing multiple flushes.

The B&M pan is nice, but you will need to move the exhaust or have someone pull down on it. I highly recommend dropping it though. There is a wire cover over a connector at the rear of the transmission that pops off because the pan hits it. Really a pain because the factor pan comes off without much issue.

I have to drop the pan again to replace a magnet unfortunately. You have to secure them with screws in the new pan and I cracked one going too tight.

So you can drop the pan without pulling the exhaust? and do you have a part number for the gm adapter plug?

WS6FirebirdTA00 · April 4, 2019

Yes. The stock pan came out fine. It is tight, so be careful. It isn't so tight though that it is risky.

Here is what I ordered. It isn't cheap, but it made life easy. I made a step adapter with barbed fittings to hook it up to a hand pump. Then I pulled off the larger hose on this fitting as it was running to do the level checks.

DT-51190 Transmission Oil Fill Adapter - http://www.freedomracing.com/dt-51190-transmission-oil-fill-adapter.html

WS6FirebirdTA00 · April 4, 2019

If you want the new oil, make sure to get this kind:

https://www.summitracing.com/parts/MOB-124715-1

Mobil 1 Synthetic LV ATF HP 124715 with the blue label. The black label is an older formula from what I see. This new one has the J-xxxxx labeling on the back. I am not sure if all new LV ATF HP will be this formula or if they will carry the black and blue labels. They sell a case of 6 for $68.99 on Summit. I did one flush with the stock pan (6 qts), one flush with the new pan (9.5 qts) and after a 3rd one I hope to be around ~90/10 ratio of new to old. I will do a 4th and final at 15,000 miles.

I do feel like so far with the new fluid it is behaving better cold, but honestly I didn't have a huge issues before I did this. I just wanted to get the newly recommended fluid in there ASAP. I only have about 6000 miles on the truck.

ksiesel · April 8, 2019

Do you have any pics of the GM tool to fill the trans? How about the part number for it?

WS6FirebirdTA00 · April 8, 2019

DT51190, link is above

I just order hand pumps on Amazon and cut some hose/made a barb adapter to fit it all up.

ksiesel · April 8, 2019

Thanks for the link to the tool. I’m not all that familiar with the transmissions with the stand pipes in them so I’m probably going to ask some dumb questions.

So there is no drain plug, right? You just take the pan off to drain.

There is a plug that has a stand pipe behind it and you pump the ATF in there to fill. How do you know when to stop filling as you’ll always have some ATF running back down the stand pipe - it’ll just be a lot more volume if you have the fluid level above the stand pipe?

Level has to be set with the engine running, right? If so, do you start the engine PRIOR to filling with ATF, or are you just topping off after an initial fill?

Fishbait · April 8, 2019

Great find on the Bosch tool!

I had the shudder and the torque converter was replaced two years ago. Well the shudder is back and I was told by my Chevrolet dealer that I need to do the flush with the new Mobil 1 Synthetic LV ATF HP 124715 at a cost $500.00.

On my previous 4l60e transmissions I used the procedure outlined at this link: https://www.gmfullsize.com/threads/how-to-4l60e-transmission-flush-filter-change.179148/ .

I don't see any reason why we can't use the same steps for the 8l90e with the exception of adding fluid . I believe the transmission lines at the radiator are the same as the old 4l60's and 6l80's. If not it shouldn't take much to source the connectors.

All in with fluid,filter and tool I should be under $300.00.

WS6FirebirdTA00 · April 8, 2019

This was really simple. Fluid was $68.99 for 6 quarts and that is all you need for the stock pan per flush. The tool is about $55. You can get a new filter and gasket (I got a gasket for backup and the filter for the 2nd flush). I am doing a total of 3 flushes, plus a 4th with my next oil change. That should have me at <10% of old fluid, roughly.

All the bolts on the pan are 10mm. There are 15 of them.

First, take out the level plug, though I would recommend checking the initial level first (mine was low, but not sure how much). This will drain out all the fluid in the pan to the gasket level (see picture of the inside of the pan, also a shot inside the B&M pan since I have not found any online). Once the fluid slows coming out of the check port, start to drop the pan.

I took all the bolts out closest to the motor and left 4 at the back remaining. I slowly started to back out the two center bolts and two side bolts closest the rear. I took out the two in the center and continued to drop until most, if not all of the fluid was now out of the pan. I angled it towards the motor so the exhaust would not hold it up trying to drain from the back.

The pan will clear the exhaust, but be careful. I attached (will have to put in a 2nd post due to size) picture of the bottom of the trans. There are some connectors in the back you don't want to snag trying to get it out. Mine cleared without issue.

If you want to change the filter, it simply pulls down. There is an oring style seal and it makes it much easier than the old ones that had the seal pressed in the trans. Push the new one up and there is a spring that keeps it in tension/contact with the pan - presumable to keep it from moving around.

The gasket is reusable and only goes on one way. There are also alignment points that go into the pan and the transmission when putting it back on. Make sure these line up so it seats properly.

Once the gasket it on and aligned to the trans get some bolts finger tight (may be easier to put the pan up separate from the filter for clearance, then put the gasket on the pan - checking for the alignment pins to be in place). On my new filter and new pan I noticed I needed constant pressure, which I assume was the compression of the spring on the back of the filter. My stock filter did not need this the first time I dropped the pan. I assume (and hope) the newer spring needed the pressure and the factory one took a "set".

Torque the bolts to 80 in-lbs (INCH POUNDS!!!!) in a criss cross pattern. I am not sure the factory pattern but worked towards the outside from the center. I got them snug by hand that way and then went 2 more passes with the torque wrench.

With the factory pan, pump in 6 quarts through the level checking plug. I screw the tool on, keep the pump connected and keep going. With 6 quarts when it is to temp it may require some to be drained. That is much easier. The B&M pan took about 9.5 quarts. If you change the filter it may take another 1/4 quart or so, not sure. If you keep pumping it in and don't take off the pump it won't flow out on you. If you remove the tool quickly, you can put the plug in. Have some rags and oil pan ready. Worst case, wait until you start and add the last 1-2 quarts with it idling.

There is a check procedure online, but it basically states get the trans to temp driving around and keep the oil temp between 95F and 113F. Put it in park and wait at least one minute. Pull the plug and let excess drain out or add until it can drain. The tool fits flush, so I just pull the hose off if I am needing to add some to top off.

Sorry this wasn't quite step by step, after typing this much I should have separated it better

Edited April 8, 2019 by ws6firebirdta00
add pictures that are resized

WS6FirebirdTA00 · April 8, 2019

Resized pics and added in last post

Edited April 8, 2019 by ws6firebirdta00

Fishbait · April 8, 2019

Nice write up WS6. The pictures with the pan removed were a lot of help as I need to replace the wiring harness with the Trans temperature sensor.

It is my understanding that the sensor it is built into the wiring harness. Has anyone here replaced the harness themselves? I am going to order the harness and replace it when I do the flush.

WS6FirebirdTA00 · April 8, 2019

Thanks. I have a few other pictures if needed. I am also going to drop the pan one more time for a sanity check on the filter and wires. I wasn't happy how I had to fit the B&M pan on. I am going to drop the exhaust as a had a loose manifold bolt and have been concerned about the seal. I ordered some new seals for about $30.

Just curious, what happened with your sensor, did it fail?

Fishbait · April 8, 2019

Yes ,their vendor changed their manufacturing process and some of the harnesses were faulty. I get low temperature readings on my transmission even when I'm towing.

I believe there was a TSB that replaced them under warranty.

I would appreciate it when you pull your pan off if you could look at the wiring harness and see if it's pretty easy to replace. If it's not too much trouble. It looks like it just snaps in.