LT230 Transfer Case - High Capacity "cooled" sump             

I'm Sure you have noticed that on extended motorway driving, or long days working hard "offroad" the heat that can be "felt" coming from the tunnel area inside the car is quite significant. This comes mostly from the transfer box as its continually working while the vehicle is in use, I still find it a little strange how the box has no "factory" cooling system installed like the Auto box etc.

 I'm aware it does or "should" not get up to auto box temperatures during normal use, but some cooling in my opinion would be a good thing, it would not only extend the "life" of the oil, but should in turn as a direct result extend the life of the internal parts of the transfer box. Disco 2's in the NAS and Jap markets have an additional gearbox temp switch fitted in them which is wired up to the dashboard over temp light as used by the Auto box models, why they all don't have it who knows!!

This switch for whatever reason is never fitted to UK spec vehicles, I'm not saying its "needed" in all cases, but you never have any idea if your "over temping" your transfer box oil or not.......this may be more relevant to vehicles with chipped engines and modified drive trains as all these factors will affect the temp of the transfer box during either on road or offroad use..

With this in mind, and the fact I still fully intend to head to a hotter climate to "play" one day, adding some "protection" to the transfer box would definitely be a worthwhile modification. One product to help with this issue I really liked was the extended capacity "cooling" sump for the LT230 made by Roverdrives in Canada.

This is a simple bolt on solution for the LT230 box fitted to Discovery 2's, it also fits previous models that use the LT230 transfer case. It simply replaces the existing bottom cover on the transfer case and as well as having the "cooling fins" cast into it, it actually increases the capacity of the oil by about another 3/4 of a litre, which again can only be a good thing as more oil will "absorb" more heat and if its being cooled as well its serviceable life will be extended.

You may also notice from the above picture that it has a "blank" where you can if you wish drill and tap the sump to add your own additional temperature switch.

To install the sump I removed the FWD cross member from underneath the transfer box to make it easier to fit the sump, I think you could probably do it without removing it, but its far easier out the way.

NOTE !!! These bolts are often VERY corroded and will shear off if to much force is applied.......I "felt" a couple when first attacking the job and they did not move straight away......so with that in mind I heated ALL of them with a blow torch in turn and used lots of penetrating fluid before attempting to undo them. Fortunately they all came out and I feel it was most likely the heat of the blow torch that did the trick. You may well find some of yours have all ready been replace with nuts and bolts because they have been sheared in the past, whatever your situation if your not "prepped" for a fight, then it may well be a wise choice to install the new sump without removing the cross member. I STRONGLY recommend the use of 6 point sockets for this job.

Once the cross member was off I then  drained the oil as per the transfer box box oil replacement page. Next you simply unbolt the lower transfer box cover, then carefully clean up the mating surface ready for the new sump.

It was also nice to have a little nosy inside the transfer box to have a look at the condition of the gears etc in there. It's certainly not possible to check it all out, but from what I could see there was no obvious wear or damage on any of the gears in view, which I was quite happy about.

The new sump comes with a gasket, some thread lock and 10 nice new shiny stainless cap head bolts and washers. The original cover is / was not installed with a gasket, it is simply RTV'd on.....I could not decide which was best, so I used the new paper gasket and a fine smear of RTV on the bottom of the transfer case. Only time will tell if it leaks or not, but to date (300 miles) its still leak free.

Use the thread lock supplied with the kit and install all 10 bolts hand tight first, then tighten / torque to 18Lbs ft in an opposing manner to pull the sump on evenly.

Refit the cross member (if removed) and tighten / torque the bolts to 26NM or 19Lbs ft. Its a VERY good idea to install the cross member bolts soaked with an anti-seize grease to stop them corroding in the future to aid removal  further down the line with out the need for a blow torch again!!. Once the sump is installed, simply refill as per the transfer box servicing page noting you will now need up to 3 litres of oil due to the extended capacity.

Overall a very nice product and I hope it does as much good as it looks!!.