Transmission Fluid Replacement and Transmission Oil Pan

[LazarusTheGrenny]

Starting a transmission fluid change discussion here as several of us have been discussing which pan kit part numbers are appropriate (and potentially an OEM upgrade from the plastic, if available)

@scottg @Krabby and I have had a recent back and forth on discovering the specifics of self-servicing the Grenadier's version of the ZF 8HP. Will port that discussion over in subsequent posts.

 

[Kevin Mokracek]

I just watched a Grenadier service video and the mechanic said all fluids can be changed by the owner but he does not recommend changing the transmission fluid or filter pan, he said have the dealer do that at the 84k mile service. He said it can really jack up the transmission for some reason that he didn't get into.

 

[LazarusTheGrenny]

From @scottg :

Start of Quote:
Before you take your Grenadier's pan off, confirm the new aluminum pan has the 2nd transmission fluid uptake port. Most ZF pans have one large uptake port as part of the filter, Grenadier's use a ZF pan with a second, smaller uptake port similar or identical to the BMW G20/G21s (this pan's setup is for BMW "mild hybrids") if I recall correctly, also part of the filter. The attached picture shows a Grenadier's ZF pan with the second port at the top left. I'll post more when I have time and have better understanding about what the 2nd port does -- it's either there because we have the engine stop/start feature and this 2nd port is to help keep the ZF ready to go in those cases and/or some other reason(s). I haven't found a metal / aluminum ZF pan that has a filter with this 2nd port, and I'm not sure if I can grab the filter with the 2nd port and retrofit to an aluminum pan without the backing mount behind that 2nd port on the pan's floor. If anyone has done this, please post.
/end quote

 

[LazarusTheGrenny]

@Krabby suggested:
"Could the second uptake be to prevent fluid starvation when the trucks are at extreme angles? Off camber or steep in/declines?"

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My input from that thread:

@scottg great catch here, thank you for posting and sharing this photo.

Interesting development. The pans that I got do not feature that aft pickup. That’s quite curious. The pans/filter’s that I received from FCP Euro are OE ZF and Genuine BMW but do not feature this second fluid pickup. Doesn’t seem like any aftermarket option has one either and I would steer clear of those anyhow. Nor do the 8-speed Jeep Wrangler steel pans.

I was just about to do this service within the hour and now I will refrain for further research & need to source a different OE pan with this fluid pickup configuration, otherwise there certainly could be a pressure variance that the transmission won’t like.

Let me grab those part numbers that may no longer be applicable and some photos of the pans, gaskets and filters.

Edit: Part Numbers for the two aluminum ZF/BMW (same supplier) pictured below:

• M3/M4 pan for ZF 8HP: 24119504520 (Link to FCPEuro product page)
• X3M/X5M pan for ZF 8HP: 24119503407 (Link)

*Important NOTE: ^these may not be compatible with the Grenadier's specific 8HP configuration, and/or with the Grenadier's frame cossmember & aft transmission mount, and may interfere with tool access for rear pan bolts.

I think both you and @Krabby are likely some version of correct: perhaps for start stop (although other models have had this for at least a decade) but certainly for high pitch and roll angles (off camber), it’s a bit odd I would expect there to be enough fluid in the sump given depth of the pan and fluid volume. Hard to know without reviewing any engineering data.

Re: mild hybrid setups: I wonder if the newest gen X3M 8HP would have this filter setup with an aluminum pan/deep fin design.

We likely need to start a separate thread for the topic of transmission fluid changes and pans.

@scottg do you happen to know the part number for your Grenny pan you pulled off?

 

[LazarusTheGrenny]

I just watched a Grenadier service video and the mechanic said all fluids can be changed by the owner but he does not recommend changing the transmission fluid or filter pan, he said have the dealer do that at the 84k mile service. He said it can really jack up the transmission for some reason that he didn't get into.

Hey @Kevin Mokracek, I just watched that video as well!

Great brief from Warner Ineos (powerhouse dealer in North America) and recommended watching, especially on the differential "dipstick" tid bit. Much of this info is being collated by @Rok_Dr from his own and other sources which is excellent and can be found on the forums.

The essential theme to what Todd was speaking to is well known with automatic transmissions. In that, as the transmission's clutch packs and associated mating surfaces wear, the fluid retains much of that foreign object debris (FOD) in suspension and that acts as a friction modifier to allow the transmission to not slip when shifting or transferring torque. Typically this is more of a concern for high mileage vehicles which have never had the automatic serviced and then when the fluid is changed, the transmission performs poorly. The better approach is to service appropriately and avoid the roulette of never changing the fluid, until it's too late. Can also be an issue with some flushing services that evacuate too much of the fluid from the internals. There's certainly additional nuance that I'm not covering, but in essence we should be servicing the transmission with intention.

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This thread is to discuss the applicable transmission pans and the procedures for drain & fill, as it most certainly can be done and ZF (supplier of our lovely 8-speed 8HP series transmission) recommend much shorter service intervals. The servicing isn't mind boggling, just requires attention to detail (pan, filter, fluid, tools) and conditions (mainly transmission temperature window for proper filling), and thankfully we have a temperature read out in our onboard "Offroad - Temperatures" menu right on the dash! So no diagnostic tooling required for the broad temp range required to fill the transmission properly.

Drain and fill video here (among many other BMW DIY service videos for the B58 engine): FCPEuro ZF 8HP Transmission Fluid Change

NOTE: I recommend that folks certainly go to the dealer or qualified shop to have any maintenance that's out of capabilities or comfortability performed there. That said I've had 'qualified' places not perform work correctly, including dealers (Ineos dealers included) and had to rectify their work after careful post inspection. As well, warranties may be affected by DIY maintenance particularly not having proper records or using improper parts/fluids/etc. so at one's own risk there.

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Many are also interested in swapping to an aluminum pan from the OE plastic for impact, servicing, and thermal reasons. And there are many vehicles which use variants of this transmission which have aluminum, deep finned pans that are factory/OEM/genuine parts from ZF, BMW and possibly some other OE catalogues. The critical part here is that @scottg has identified that we have a different oil pickup configuration.

So the general hope of this thread is to identify the right parts and any procedural learnings to be able to service this transmission by DIYer's who want to do it and/or perform an OE like upgrade at the same time.