8 speed fluid change-level the truck or level the trans?

[AmosMoses]

Everyone seems to say to check/change trans fluid with the vehicle level but this is vague. To level the transmission you have to jack the back up about a foot or so using a level on the bottom pan mounting surface. I believe I didn't fill mine enough with the vehicle level because of a whine that occurs sometimes. Ive checked the level 3 times going by zf's instructions.

Ive got the back jacked up now about 10 inches and the bottom pan surface is not quite level yet. Ive run out of travel on my floor jack and am running out of ideas and wondering if Iam overthinking it. The fact is the trans is on quite a bit of an angle sitting on its wheels on flat concrete. Looking for advice if anyone knows proper procedure.

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[ShadowsPapa]

 

[AmosMoses]

Thanks shadowpapa. These transmissions must be pretty flexible on fluid level to be installed on various vehicles with various mounting angles.

 

[ShadowsPapa]

Thanks shadowpapa. These transmissions must be pretty flexible on fluid level to be installed on various vehicles with various mounting angles.

Yeah, there's a lot of variation in the angle they sit at.

Biggest thing to me - the temperature of the transmission.
If you have JSCAN or AlfaOBD, you can probably monitor that from your phone, save some back and forth.

 

[Maximus Gladius]

Level the frame. The back tires DO NOT have to be off the ground and spinning through the gears to transfer fluid through the system. Ive done both, wheels up and on the ground. It comes to the same oil level at the end anyway.

One key point of error Ive seen others posting their own pan drop videos and when they first filled the pan up to the fill hole and cap off, they go upstairs to start the engine and wait for temps to rise, then go through the gears, then go back down, pull fill cap and fill to proper level within temp window.

Please don't sit up top and wait. Your pump is sucking air. The pump will draw up the 3 or so quarts of oil you put in there, and after that, it sucks air and air does not lubricate. As soon as engine is started, jump down under and fill that tranny up till oil dribbles out. Cap it and go back upstairs and wait for temp and the running through the gears, then go back down and make your small adjustments in level.

Dont use an oil applicator thats been used for something else. Use a brand new one, large enough to hold 3 quarts to fill tranny as soon as engine turns on.

You mentioned a whine..... please elaborate. What gear(s) do you hear it?

 

[SRFRAT67]

As a first time jeep owner I absolutely love the vast amount of technical knowledge I have gleand here since purchasing my Gladiator last year. I consider myself mechanically inclined but for some reason this transmission service procedure weirds me out...lol. I can't tell you how many different videos I have watched and each one seems to be different. I do have the official MOPAR procedure and keep reading it over but think I might take it to a local Jeep specialist shop that I trust as Ime going to be doing the tranny, front and rear diffs, new diff covers and transfer case. Ime probably overthinking it. Thanks ShadowsPapa for this video, the best I have watched to date. Ime going to talk to the local jeep guys this week to discuss this procedure and if I like what I hear will have them do the work, depending on labor. I already have the fluids and gaskets, but not the pan as I am considering an aftermarket pan. Its also a matter of my time and availability to do this service, works got me running..lol.

 

[ShadowsPapa]

Level the frame. The back tires DO NOT have to be off the ground and spinning through the gears to transfer fluid through the system. Ive done both, wheels up and on the ground. It comes to the same oil level at the end anyway.

One key point of error Ive seen others posting their own pan drop videos and when they first filled the pan up to the fill hole and cap off, they go upstairs to start the engine and wait for temps to rise, then go through the gears, then go back down, pull fill cap and fill to proper level within temp window.

Please don't sit up top and wait. Your pump is sucking air. The pump will draw up the 3 or so quarts of oil you put in there, and after that, it sucks air and air does not lubricate. As soon as engine is started, jump down under and fill that tranny up till oil dribbles out. Cap it and go back upstairs and wait for temp and the running through the gears, then go back down and make your small adjustments in level.

Dont use an oil applicator thats been used for something else. Use a brand new one, large enough to hold 3 quarts to fill tranny as soon as engine turns on.

You mentioned a whine..... please elaborate. What gear(s) do you hear it?

You don't want the pump sucking air - whine=bad. The rest isn't spinning inside so won't be a problem - nothing to lubricate other than the pump.

Yeah, no need to jack it up other than for easier access - depending on your truck and your, um, well, size.
This can be done flat on the ground - tires spinning doesn't matter. The clutch packs, etc. fill in any case.

 

[AmosMoses]

Level the frame. The back tires DO NOT have to be off the ground and spinning through the gears to transfer fluid through the system. Ive done both, wheels up and on the ground. It comes to the same oil level at the end anyway.

One key point of error Ive seen others posting their own pan drop videos and when they first filled the pan up to the fill hole and cap off, they go upstairs to start the engine and wait for temps to rise, then go through the gears, then go back down, pull fill cap and fill to proper level within temp window.

Please don't sit up top and wait. Your pump is sucking air. The pump will draw up the 3 or so quarts of oil you put in there, and after that, it sucks air and air does not lubricate. As soon as engine is started, jump down under and fill that tranny up till oil dribbles out. Cap it and go back upstairs and wait for temp and the running through the gears, then go back down and make your small adjustments in level.

Dont use an oil applicator thats been used for something else. Use a brand new one, large enough to hold 3 quarts to fill tranny as soon as engine turns on.

You mentioned a whine..... please elaborate. What gear(s) do you hear it?

I decided to try filling it with the back tires raised up 10 inches. At this height the pan is more level but not quite. Would probably take another 2 inches for the pan to be level. My theory being that at higher temps the pump is sucking air for some reason from 1st to second shift. I never notice it in other gears or when the trans is below 180F.

So with the back wheels elevated 10 inches I crawled underneath and started to unscrew fill screw. Fluid leaked out so I quickly closed it.
I started the engine and let it idle with a cold baseline temp of 70. I crawled back under while idling and pulled the screw. No fluid came out so I filled it with about 1 quart until it trickled out. Went back up and continued to idle until I hit 90F. Then I held rpm for 30 seconds and then let idle and shifted gears R D M1 M2 holding each gear for 10 seconds and then returned to park. Temp was at 100 at this point so went back down and checked fluid. I removed screw and oil streamed out pretty quick so I let continue until there was very little coming out and then closed it back off.

At that point I set the back end on the ground and drove it around for about 30 minutes. Temps held 185-190. It shifted normally and there wasn't much whine although I did hear it faintly going from 1st to 2nd gear. Its always done this since buying used with 30k miles. My jt before this one did not make the noise.

So the transmission now has roughly 3/4 more fluid in it. Ive drained and filled it twice starting at 50k miles. It now has 56k. Iam using mopar 8/9 speed oil and PPE pan. I still have another 9 quarts and a new filter I will change a 3rd time this spring probably since its getting cold out.

 

[Maximus Gladius]

I decided to try filling it with the back tires raised up 10 inches. At this height the pan is more level but not quite. Would probably take another 2 inches for the pan to be level. My theory being that at higher temps the pump is sucking air for some reason from 1st to second shift. I never notice it in other gears or when the trans is below 180F.

So with the back wheels elevated 10 inches I crawled underneath and started to unscrew fill screw. Fluid leaked out so I quickly closed it.
I started the engine and let it idle with a cold baseline temp of 70. I crawled back under while idling and pulled the screw. No fluid came out so I filled it with about 1 quart until it trickled out. Went back up and continued to idle until I hit 90F. Then I held rpm for 30 seconds and then let idle and shifted gears R D M1 M2 holding each gear for 10 seconds and then returned to park. Temp was at 100 at this point so went back down and checked fluid. I removed screw and oil streamed out pretty quick so I let continue until there was very little coming out and then closed it back off.

At that point I set the back end on the ground and drove it around for about 30 minutes. Temps held 185-190. It shifted normally and there wasn't much whine although I did hear it faintly going from 1st to 2nd gear. Its always done this since buying used with 30k miles. My jt before this one did not make the noise.

So the transmission now has roughly 3/4 more fluid in it. Ive drained and filled it twice starting at 50k miles. It now has 56k. Iam using mopar 8/9 speed oil and PPE pan. I still have another 9 quarts and a new filter I will change a 3rd time this spring probably since its getting cold out.

I would encourage one more check of the fluid level, with frame level, back tires on the ground (not ass end way up) and be done going through the shifting of gears with brake applied right at the beginning of the temp window (87F) and cap it by 90F.

It’s been suggested that it’s better having more oil (checked at 87F than less oil when at the hotter end of 122F where more oil has to drain out. )

This is also why you got a larger volume tranny pan, to have more oil than stock pan but if you’re capping off the fill plug @100F, you may as well just have a stock pan that was capped off at 87F.

I had two transmissions replaced under warranty for having a whine in 1st and 2nd gear. First one only had 500kms and they heard it and was warranty replaced. The next tranny had the same whine and I was told to just drive it a while, I had warranty AND I also had oil analysis reports to back up abnormal wear metals and when the lab highlighted the iron was too high, it went in then and replaced.

Both whines in 1 and 2 were determined to be pump failure.

 

[ShadowsPapa]

My theory being that at higher temps the pump is sucking air for some reason from 1st to second shift. I never notice it in other gears or when the trans is below 180F.

Gonna toss this out there to consider -

Below 180 degrees, the fluid level will be lower, and more likely to be low.
ATF expands a fair amount with heat, so if anything, over 180, the fluid level should rise and quiet a whine.
(I have the same issues with my leaky TF272, when cold, and after leaking enough fluid, the pump will whine a bit until it's totally warmed up then it's quiet. But when I fill it like I should, it never whines, cold or warm)

And - I can't think of any reason it should whine when it's warm but not cold other than maybe there's a pump issue and the thin fluid just doesn't quiet it?

Kevin ( @Maximus Gladius ) - thoughts?

 

[AmosMoses]

Gonna toss this out there to consider -

Below 180 degrees, the fluid level will be lower, and more likely to be low.
ATF expands a fair amount with heat, so if anything, over 180, the fluid level should rise and quiet a whine.
(I have the same issues with my leaky TF272, when cold, and after leaking enough fluid, the pump will whine a bit until it's totally warmed up then it's quiet. But when I fill it like I should, it never whines, cold or warm)

And - I can't think of any reason it should whine when it's warm but not cold other than maybe there's a pump issue and the thin fluid just doesn't quiet it?

Kevin ( @Maximus Gladius ) - thoughts?

That jives with what Maximus said about filling at cooler temps will allow for more volume of oil.

Another theory I had was that perhaps the inlet that the filter neck fits into was machined slightly oversized and once it expands with heat, suction is weakened and less oil is picked up through the filter. I bought a replacement filter for my ppe pan and on the next oil change I will check fit with the filter out of the pan before putting it back together. Plastic will expand with heat just like aluminum but maybe not enough to keep a good seal with the o-ring it uses. Just a thought.

 

[Maximus Gladius]

And - I can't think of any reason it should whine when it's warm but not cold other than maybe there's a pump issue and the thin fluid just doesn't quiet it?

Kevin ( @Maximus Gladius ) - thoughts?

So much here one could unpack on the experimental table.

One needs to be able to try several ways to attack a whine including the moving of the cold side of the temp window from 87F (30c) to let’s say 84-85F and keep a close eye on the normal operating temperatures. Are we staying in the same range of what’s normal 188F (ish), does it climb, does it drop ? That’s going after the whine with more oil volume but we don’t want to submerge the part of the transmission we see when the pan is dropped and your looking at the solenoid section. This is where I tend to believe the engineers who set the “cold end” of the temp window to 87F or 30c, designed that oil level to still be safe with as much volume of oil as possible to be allowed,….or is there still some wiggle room for more??

Another option would be to be able to do a tear down and examine the parts and pump with experienced eyes like you. Internal parts can be purchased now to do your own rebuild as @StanH has in his possession.

I liked this thread as soon as it was posted because I struggled with the vagueness of what “level” meant and i too was on that OCD learning curve to understand and experiment …and i too had to know, does level mean transmission or frame??

I was on the hunt to solve the whine I had in 1 and 2 and was closely watching my analysis reports. The whine showed levels of iron on a steeper incline than the other metals. Something wasn’t right. I was comparing other numbers from Blackstone posted on YouTube from a pan drop done at 60k miles on a BMW SUV with a ZF tranny. All looked well according to the tech doing the pan drop so I compared those numbers with what I was seeing.

Another option would be to maybe try a thicker viscosity ATF as you mentioned maybe the thinner viscosity just isn’t lubricating. Is the whine oil starvation, plugged screen or is it simply tolerances are too tight or is a thicker viscosity needed or some other brand of ATF needed that has a different additive package??

Maybe it’s yes to all this but it’s a struggle to do what’s right for the transmission if there’s warranty or not to consider.

 

[Sandman 4x4]

Who knows what level is to be found in the bowels of the ZF trans? The ShadowsPapa!

 

[Batterycap]

I get using the jack to level - but get some ramps. The one's made of plastic are affordable and durable. I've been using the same paid for years. My driveway has a slight incline. I will put the ramps behind the vehicle and back up until I am leveled out. I use them on the front wheels to do oil changes and whatever else requires their use. Slick garage floors and ramps don't get along. Use them on dirt, concrete, or asphalt.

 

[g2020]

Everyone seems to say to check/change trans fluid with the vehicle level but this is vague.

@Maximus Gladius helped me write the ATF testing procedure, for the automatic transmission, outlined in my post on ATF Equivalents. See the section called Testing.

7. Make sure that the vehicle frame is level; the front end of the frame should not be higher than the back end​

When a transmission service is performed at a shop, the vehicle is on a lift and is frame-level.

Also working with @Maximus Gladius on a set of written ATF installation instructions (coming soon). By "helped me" and "working with", I mean that he tells me how it's done, and I document his guidance to match my style of writing.

I have added the video on checking fluid level, first shown in post #2, to my post on ATF Equivalents. The host of the video is in a wheelchair. I mention this because I have seen references to him on other sites and he is somewhat famous for his excellent presentation skills.

Here are the title details of the video:

ZF 8HP 8-Speed Transmission
Fluid Level
Checking Procedure
Department of Automotive Technology
Weber State University​

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