Member Since: 03 May 2021
Location: Genève
Posts: 36
Separate gearbox oil cooler installation
Hello girls and boys !
So basically I own my disco3 V8 since december, and ever since I bought it, I felt that something was going wrong with the gearbox, laggy, bumpy between 5th to 6th on the highway and not performing like it should.
The independant repair shop I bought it from told me that there was nothing to repair on it, that everything was like it should, gearbox oil change and filter had been done 10K km a few month back, don't worry sir just drive it.
OK cool. I start driving it the whole month of january and february and I notice a klonk noise coming from the front left suspension when I drive on bump or offroad. Found the problem, it was the front anti roll bar that needed new mounts. The guys in the shop did the whole front left suspension arm and didn't even take the time to check the anti roll bar...
Here start the story about the gearbox, I then lift the car to remove the whole protection skirt under it and check that anti roll bar and when disconnecting my front alluminum skirt I notice that it is greasy and that doesn't smell motor oil... OUF ! at least no problem with a leaky head or something. I trace down the leak to the lower part of the radiator where the gearbox's oil pipe connects. This is the moment I realise I drove that car for nearly 3 months, with a oil pipe leaking and god knows that this ZF fluid is vital for our gearboxes.
I start to check on the forum and find out that our super well engineered radiator may have some tendency to leak coolant into our transmission fluid via their shared compartment. That was it for me, I decided to mount a separate oil cooler attached to the front radiator to cool down my gearbox oil and avoid any contamination in the futur. Here is how I did it and how you can also do it.
The radiator I used is designed for old VW Beetle :
You can use any radiator you want that fits the front space between the front grill and your radiator, I had order a chineese one on ebay, my god if you'd seen the sh*t I received, I just couldn't mount it on my car.
I like that one also because he had both inlet and outlet fittings on the side of it and not the top or bottom.
The whole radiator came with 12mm inside diameter pipe, some clips and some pieces for adapting it on a VW beetle that I didn't need for my mod. My choice for this radiator came from the fact it didn't use AN fitting, I wanted something simple that I could fix anywhere in the world with clips and pipes.
To connect the two new extension pipes I bought some stainless steel connector to a local specialist in my Geneva town. They look like this in shape, but the photo here shows some brass connector I also considered for my mod. You will need 13mm in diameter to be able to fit the connector to the original LR pipe coming from your gearbox and avoid any leaks, original tubes are 12mm in diameter.
So then moving to the front, I have a custom steel bumper that clears a lot of space in the left wheel arche therefore I don't know how hard it will be for you normal bumper drivers to get to that pipe. What I did was raise the suspension to offroad height and then turn the wheel fully left side and shut the car engine off. Then there is a concave black plastic protection attached on the chassis with 4 plastic pins, remove the pins and remove that plastic cache, I didn't have to remove the wheel arche liner, just the plastic cache near the chassis. Once removed you'll see this :
Red arrow shows your lower gearboy oil pipe, blue arrow shows that if not protected well or attached properly, that pipe rubs on your water coolant pipe, hello leak in a rocky road in the desert .
Once you did this, remove your front grill (easy), remove the top front fan cover and move the lower part of the fan cover away to the left (when seating in front of your car/passenger side (Left Hand Drive)).
So my disco V8 is a 2005, one of the very first to be produced, I don't know for diesel engines or the later V8 versions but my coolant pipe for the steering fluid is located right in the way of where I want to install my new radiator. Instead of dismounting it and use tool to bend it risking to damage it I used my hands. I recon its not super aligned, but its not leaking at least and it still holds in the left plastic bracket that holds it tight to the radiator.
Then you have the free space to disconnect the two pipes. the lower one I did it via the wheel arche and the upper one via the bonnet. Here you can see the lower one still attached and the upper one removed.
The pipes will both leak some transmission fluid but in my case it was nothing spectacular, considering most of my fluid was already on the roads when driving while leaking ... keep upper pipe close to the coolant reservoir and insert your connector, secure it with circular clips, add your new pipe and secure it. Run the pipe from the bonnet to the lower pipe, same deal, clean, insert your connector (in some case you'll have to force fit it don't be affraid but don't break your original LR pipe it might be old) and connect your new pipe. Run both of your new pipe between the radiator and the coolant tank by removing the soft plastic cache on the front right of the radiator.
On this picture you see the upper one pipe still attached on the radiator, the arrows show the lower pipe that I pulled up for the sake of the photo.
Pay attention that the screws of your clips don't rub on other pipes or anything they could damage with vibration while driving.
Don't forget to clean with a pipe and pressurized air your old radiator compartment and then seal it either with a 13mm plug or like I did, connecting a tube between the two old radiator fittings. The later unfortunately brings more tubing to the front engine bay but I had no plugs that day when I did the mod.
Here you see the two new pipes passing between the coolant reservoir and the radiator.
Last step is to build a bracket using pieces of steel I had in the garage and bolt the radiator to the chassis. I used foam scotch that I sticked to the back of it so that it doesn't rub on the original radiator and also on the lower part to protect the steering fluid pipe from rubbing with the new radiator. AND VOILA !
Last thing you have to do is cut holes in the front right soft plastic cover to let your pipes pass through it, I used a cutter knife.
I hope this topic will help any of you guys that were wondering rather or not they should do it. I am not a mechanic, I am an experienced DYI mechanic and this mod is EASY to do. I took my time and it was done in 2 hours. I lost most of my time figuring out a bracket to hold the radiator
Radiator kit is 100€, bought 2 meter of 12mm (inside diameter) oil pipe for 10€ the meter. Also bought an oil syringe and 2 liters of ZF 6 Fluid for 60€. Stainless steel connectors were 5 bucks for both of them. That mod cost me under 200€ and few hours of work, but my gearbox will never get watered and the cooling will be better. I don't have my tool right now I ordered it but I will provide numbers for gearbox oil temperature under load etc...
Please keep in mind that if you loose some fluid before installing the mod or during, you WILL HAVE TO TOP YOUR GEARBOX UP ! I used the ZF transmission fluid 6 and the ZF service procedure to top up my gearbox and it appears I lost 1 liter on the road... only 30ml got out of the pipes and radiator when I did the mod. Refilling your gearbox must be done motor running and under specific oil temperature, refer yourself to the ZF 6HP26X service manual for the procedure, the entire thing deserve a ''how to'' in my opinion.
Last words, don't trust a word of what a car dealer tells you to sell you a car, if you feel anything is wrong with your car, listen to your guts and get your hands dirty, my only regret is not to have listened to mine and do this mod earlier. This is my first contribution to this awesome forum, if you have any remarks, suggestions or questions, please shoot. Always eager to learn from my mistake.
Until next time, drive safe fellow disco lovers.
13th May 2021 2:57 pm
Dixie Dean
Member Since: 06 May 2006
Location: Halewood
Posts: 298
Thanks for that thread. Can I ask what I should search for to find similar radiator?2008 D3 HSE Stornoway Grey with Ebony Leather, towing a Coachman VIP 575
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