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Trans fluid leak

12449 Views 27 Replies 7 Participants Last post by  MARK_C
Hi all,
I have a 2007 RRSC, and recently spotted fluid leak. It appears that the drain plug on the tranny cooler is leaking, possibly has a worn out gasket?
The leaking fluid is oily, very thin, very clean almost colourless.
Picture attached, leaked fluid has been wiped. Is this the transmission fluid cooler? How can I fix this?


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That’s the transmission sump pan, not the cooler. How sure are you that it’s the drain plug that’s leaking and not the mechatronic connector sleeve seals? The fluid may be simply dripping from the lowest point?

If it is the drain plug, you can buy them separately (part no. TYB500020)

Obviously, you should make sure that you can undo the filler/level plug before removing the drain plug.

The correct fluid for your ZF 6HP26 transmission is ZF Lifeguard Fluid 6, which is pretty much as you described - “oily, very thin, very clean almost colourless”

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Thank very much, Phil, I will go check. Excellent schematics.
It may be worth your while, especially if you have done a service, to remove the pan and mechatronic unit to replace the aforementioned sleeve seal, bridge seal, and tube seals.

Replace the filter with only a Genuine Filtran filter, they can be sourced online for around $90.

For fluid, I’ve been using Ford Mercon SP which was designed for the 6HP26 and is within 2% difference of Lifeguard 6. The largest notable difference is the fact that it is red.

Ask for Mercon SP for a 2008 Lincoln Navigator. Do not get the newer fluid, I believe they call it Mercon LV. It’s around $9 a quart average, compared to LG6 at around $20 a quart.

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Okay spent some time under the car wiping and looking for the source.

The area around and above the pan is dry and clean, so the oil is not escaping from any point above the black (plastic?) pan. If there is a suspect, it may be the bolts holding the pan, but outside of their perimeter the area is clean and dry.

Then I spotted something like George Harrison’s guitar (picture markup). After wiping the area clean, one particular spot gently weeps. Not certain if the fin is cracked or it is weeping from around the bolt next to it. But weeping drop collects where the arrow is pointing.

Is it time to replace the whole pan?


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The filter is the whole pan, so if you don't know when the last time the filter was changed you've got nothing to lose. Don't know what genius decided to put a plastic oil pan on the best factory off road vehicle made, but I guess the bean counters have to earn their salary by pinching pennies anywhere they can. My 06 is experiencing the same thing, I've got an oily oil pan on the right side with drips hanging off the bottom of a couple of fins on the right side, no apparent source of a leak, although the area directly under the connector tube is slightly oily, more like the drips blew up there while driving instead of being the source. I've checked all the pan bolts for torque and all are good, so it should not be the pan itself unless it has a hairline crack in it. If its not freezing outside tomorrow thats my project, new pan, connector tube and bridge gasket under the mechatronics unit. We'll see what I find.
There is, of course, the option to replace the plastic (Durethan AKV) sump pan/filter with a steel pan with a separate filter. This is a common ‘upgrade’ for LR3/LR4/RRS owners who would otherwise have to disconnect an engine mount and jack up the driveline assembly to provide enough clearance to remove the plastic sump pan due to the cross-member getting in the way. The L322, fortunately, doesn’t have the cross-member.

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Phil. Thanks for your description. I was wondering about the 2 pce sump and filter vs a regular oem type for ours.
re-torque all the bolts then clean... if the leak stopped you're good. Tho it may not in which case replace the whole pan as you service the trans.
So now a few questions came up here about last time I serviced tranny, if I serviced the tranny, and I should go ahead and service the tranny.

I have changed the differential fluid, but not the transmission as the factory says this is lifetime sealed unit. As well as the known debate whether transmission breakdown shortly after service.

Is the conclusion here to change the transmission fluid and filter?
ZF recommends that the fluid is changed every 160,000 km or 10 years

reducing to 80,000–120,000 km, or 8 years, if the fluid has operated at high temperatures e.g. due to frequent high-speed driving, towing trailers or ‘spirited’ driving

A drain and refill replaces around half of the fluid. If you’re going to use the correct fluid (Lifeguard Fluid 6) then I would say definitely go ahead. If you’re going to try to save a few $$ by using a cheap universal fluid, then I’d say you’re better leaving it alone. A different friction modifier pack could push the adaptions beyond their limit if you have a faulty solenoid, causing a clutch to burn out.

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Okay. The plan is to use all stock, so Rover filter, Rover cover, and ZF Lifeguard 6 fluid. This will take a few days until parts arrive.

I will have to figure out how to push the new oil into place.

So now I am doing tranny service at 11 years / 104,000 Km. Almost within specified interval hopefully don’t introduce gremlins.
Perrier, if you order your parts from https://www.thectsc.com the box will include instructions for the drain and fill.
In my experience, I only drained 5 litters.

You fill it as much as you can, then you put the plug back on temporarily. Start the car run through the gears and wait for the fluid to be between 35-40 Celsius.
Once in that temp region remove the fill plug and fill the rest of the drained amount. You should get a small stream as you do so when full. Stop and put the fill plug back on.

NOTE the car should be running while you do the second fill and make sure you are on a leveled surface.

I hope this helps orient you.
Good lead. Thank you.

I have found my fluid transfer pump to do the filling part.

The fluid I will fill is definitely ZF Lifeguard 6.

Would appreciate input on using ZF branded filter and pan? Or should I stay with the LR branded ones?
Don't mess around with other brands I would say. Stick with the parts that gave you 100k kilometers. Just my two cents.
ZF is who makes the parts for Land Rover. they are the ones who made the transmission!

Read my post again, or ignore me and get the same answer (or waste money listening to others who have not have the same knowledge)

You buy from Land Rover, $200 you buy a ZF (Filtran) part, $90.

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Okay thanks. That's what I was wondering if Filtran the same as ZF (advertisers only say ZF filter) and same as Land Rover
Dealer says transmission fluid is LRN13754. Is this the same as ZF lifeguard 6 ? Dealership did not know


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Buy Lifeguard 6, or Mercon SP as it is the same fluid.

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Over here in the UK the Land Rover part number for the 6HP26 fluid is TYK500050, but the original fluid (i.e. before ZF started branding their own) was Shell ATF M1375.4. Seems a heck of a coincidence that the Land Rover part number LRN13754 ends in exactly the same numbers. Is that fluid cheaper than buying the ZF-branded fluid?

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