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1994 NAS Defender 90 Soft Top, 4.6 V8 Install and Upgrades

This 1994 Defender 90 has come to us from Alabama for some badly needed repairs, a number of upgrades. The truck has over 100K miles and needs a fair bit of work to get back into shape. The first thing to address in this 90 is the installation of a new 4.6 V8 engine.

Here you can see we have removed the stock 3.9 and the nest step will be to tear it down and see what we can re-use form the old motor on the new 4.6.

From the looks of the oil filter we pulled off the old 3.9, it doesn't look like much, if anything will be able to be used off the old engine.

The lower end of the engine isn't any better. The oil system in this 90 is completely full of sludge, mud, water and crud.

Here is a shot of the bottom of the oil pan. Yikes! This motor is junk. This is what comes from lack of service on a Rover V8. The PCV system hasn't been serviced and over the engines life it has been overheated and gone without oil changes for far too long.

Here is a shot of one of the reasons why this engine would have not been on top of its game. The stretch in the timing chain (green arrow) will make this engine hard to start and make it perform poorly in all conditions.

Now that the engine has been removed we can start to clean up the engine bay and get things back in order to get ready for the new 4.6 install.

Here is some good news for this Defender, a brand new, balanced 4.6 engine. This engine will call the engine bay of this white D90 home and make all the engine troubles go away, and with correct routine servicing it will last a good long time, unlike the previous 3.9.

Along with the new 4.6 this D90 gets a new R380 5 speed gearbox to replace the worn out original LT77 unit. Here you can see we have set up the new R380 on the existing LT230 transfer case and crossed over all the parts to make for a correct and long lasting install. Why have ECR install your new gearbox instead of a local shop? Go here for a few reasons.

This image shows the new 4.6 all dressed up with some of the cross over parts from the 3.9 and a host of new parts including our performance injectors and all new service items like plugs and wires. This will assure that the 4.6 will deliver max. power and reliability after our installation.

Next step to complete the engine install is to upgrade the chip the EFI computer to let the EFI system know it has a 4.6 under the hood instead of just a stock 3.9. Here you can see the chip installed in the original ECU. This set up will now be installed into the 90 and we'll fire the engine up for the first time..

Here you can see we have completed the 4.6 install and we have successfully done the engine start up. The 4.6, now mated to the new R380 5 speed, is working well and with some new seals and gaskets in the transfer case this 90 is no longer leaking everywhere.

To make sure an oil leak, or worse yet an engine oil fire, does not occur in this 90 we have swapped out the troublesome factory oil cooler lines for stainless steel lines with performance fittings. These serve 2 purposes. One, they are not prone to leaking or coming apart like the factory lines and two, the new lines stay well clear of the RH exhaust manifold so that the engine oil is not super heated by the exhaust as it heads to the oil "cooler" in the radiator. For more on oil lines go here.

Inside the 90 we have started to get things in order as well. The dash plastic parts have been badly beat up and most are cracked and broken so that things are not working like they should. The heater control cables are seized, some are broken, and the steering column surround grinds on the steering wheel. All of these items are easily fixed to make the dash secure, make the heater controls work with just one finger and make the truck squeak free. It just takes some new parts and a little care during installation. The green arrow points to the new dash surround we have installed and with that installed all the other systems can be made to work correctly. You will also notice we have removed the AC system fro this 90 and put it back to stock with the correct footwell vents and the correct fuse box cover.

The front and the rear driveshafts in this 90 had issues, so instead of doing costly repairs to those stock parts, we went ahead and replaced the damaged shafts with new HD CV driveshafts mated to GBR driveline adapters (rear shown above). We did this because the owner of this 90 has plans for a better suspension and a 3 link front end in the future and these new parts will work now, and they will "grow" with the project as more items get installed, so in the long run these are strong durable shafts that will save money.

Next step was to complete the install of the upgraded top. The top was put on the 90 but the modifications for the gutter kit installation had not been done. At the customers request we powder coated the gutter kit (green arrow) to give the 90's top system a nice finished look.

To make this 90 a little more off road ready we will be adding a set of ECR ROX sliders. Here you can see we have removed the factory sill trims and will now fabricate the sliders for the 90. We will also be giving the alloy rims a new coat of color to help the 90 stand out in a crowd. Then we will do some test miles and get the Defender ready to head South.

Here you can see the ROX sliders have been fabricated, primed and paint and installed. These units have Hi-Lift jack points front and rear for easy tire changing on the trail and are tough as nails.

At the rear the ROX sliders mount to the frame via some added beef that we install on the frame. The stock frame is not strong enough to take real off road abuse in this area, so we make the frame able to handle our sliders (see arrows). Once the steel strengthening piece is welded in place the sliders can be bolted to it. We also use 3 bolts and reach all the way to the frame rail so that the slider can not "lift" or "twist" when you hit an obstacle. This assures that our sliders will never hurt the body of your truck like some cheaper units do.

Up front the sliders are mounted to the frame via 5 bolts. This prevents any "twisting" like the units that bolt to the bulkhead bolts. We do we do this? Because we have seen a lot of other mail order sliders bend and/or damage the body of peoples Defenders, and we think the purpose of a slider is to protect the body, not damage it. If we loose a few bucks because we can't offer these units mail order, so be it. We will only put our name on products that work.

Here you can see the finished project ready to head back to Alabama. We have made some nice upgrades to this 1994 NAS D90, including a new 4.6 V8, and done a host of needed repairs. We have also tossed in some off road goodies that will make this Defender even better on the trail (and look good doing it). It is now ready to hit the road or the trail.

If you have needs for your Defender, from routine service to wild modifications, contact ECR. We'll be happy to help make your Defender world class... just like this one.


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