My relationship with my 1997 Land Rover Discovery has been generally positive since I added it to my fleet back in April 2021. The big lug’s never left me stranded, and it’s been a joy to drive around town, on the highway, and off-road. It accelerates and stops just fine and has only exhibited a few annoyances, like a cooling issue I solved with a brand-new radiator. It’s not all sunshine, though. The Discovery also has an uncanny ability to keep me guessing where its various fluid leaks are.
Right when I think I’ve got it nicely sealed up, it throws a curveball right at my face. Thankfully, the head gaskets and valve cover gaskets were done not long before I bought it, so those have been fine, but I did have to deal with a bad oil pan gasket.
I only recently discovered that the oil pan gasket was leaking as much as it was. After a thorough underside cleansing at my local DIY car wash to remove more oil and sludgy mud, I could see that oil was seeping out the back of the pan and finding its way onto the driveshaft. That was doing me a real kindness by slinging it all over the underside, protecting it from the elements. Well, I appreciate the effort, but there are no elements here in Southern California to protect against. To continue my everlasting journey of trying to properly seal up this ancient chunk of Detroit aluminum, I got to work.
Luckily, I bought a new Garage Boss oil drain pan when I picked up two gallons of 15W-50 Rotella and a new filter. The drain plug is something like 22 mm, so if you don’t take considerable care removing it, a lot of oil pours out extremely fast. Thankfully, not a drop ended up on my gigantic blue tarp. This tarp’s come in handy, by the way. It’s great if you’re wrenching in an apartment parking space, like yours truly, and don’t want to upset your landlord with leaks or other oopsies.
Next up was changing the filter, which was a snap. While I had that off, I replaced the oil cooler lines’ o-rings and ensured I tightened them back on properly with a crowfoot wrench, as they started leaking a teeny bit of oil after I replaced them a few months back.
Then, I got to work loosening the 13 mm oil pan bolts and nuts. To aid in this task and ensure I didn’t strip any bolts, I used a jack handle as a mini breaker bar to carefully loosen each one — no broken bolts! The tricky bit, however, was slowly loosening all sixteen in such a sequence so that it gradually relieved pressure across the whole pan. This took a long time because I was extra careful. Once I got all the bolts off, I jacked up the front end of the Disco just a tad to be able to clear the front axle. The pan came off easily, however I was horrified at what I found with it removed.
There was an alarming amount of silicone everywhere. It was caked up in big globs alongside the inner-edge of the block and floating in the pan (though the latter could’ve been from removal). Whoever did the gasket before me was a bit too liberal in their application to say the least.
To make matters worse, the massive chunks I pulled out of the pickup line were extremely worrying. I’m genuinely surprised I’ve never had any oil pressure issues. I thought about the possibility of the sensor not working properly, but I was later reassured by the light coming on briefly upon my first startup. I thoroughly removed all the old oil from the system when I drained it, including from the cooler lines.
I then took the pan and gave it as thorough of a cleaning as I could. Using brake cleaner and Seafoam, I scrubbed a layer of sludge from the bottom of the pan until it was nice and metallic again, cleaned up the mating surfaces, and situated a brand-new cork gasket in place with some zip ties.
I learned the zip tie trick from the Mazda 2 community, as some owners experience premature oil pan gasket leaks. I tied up all four corners via the pan’s bolt holes so the new gasket would sit on there straight during removal. Once it was in place with a few bolts lightly screwed in, I clipped the ties and put the bolts in their place. This worked generally well, however it was tough to get the gasket perfectly straight between the pan and the transmission. Eventually, I got everything lined up and all was ready for torquing.
Following a careful and annoyingly lengthy torque sequence, I got all the nuts and bolts torqued down to 19 newton-meters, or 160 inch-pounds. This should’ve been easy in practice, but the tight quarters of laying on my back underneath the vehicle made it awkward and severely limited my mobility.
After carefully refilling the old sewing machine with fresh oil, checking the level, and making sure I didn’t forget anything, I turned it over and let it sit for a spell. The oil pressure light was on for a millisecond at startup, but otherwise everything looked and sounded good. Once it was up to temperature, I revved it a bit and didn’t see any seepage. I’m not going to say I’m out of the woods yet, as I don’t want to jinx anything. Plus, I need to take it on a proper, several-miles-long test drive and then re-examine its underside. But so far, so good.
I learned a valuable lesson during this fix. Despite having done some minor underbody once-overs at the carwash since I bought my Discovery, the thing still needed a proper cleaning before I could tell exactly what was feeding oil to the front driveshaft’s surface. I think I’m going to pay a local shop here in Southern California to properly degrease, scrub, and hose down the underbody so I can more skillfully keep an eye out for leaks.
Of course, the Discovery is far from being completely sealed. I swear, at least 40 percent of the reasoning behind the Discovery badge is because you’re always discovering leaks. I still have a very miniscule leak in a transmission cooler line, as well as a master cylinder that likes to occasionally shed a little fluid. Both of these leaks are teeny and don’t even drip onto the ground. But hell, I guess that means it’s the perfect time to replace them, as I don’t want them getting any worse. Anything I can do to help ensure that all the dolphins, rays, and various fishes a few miles down the road here in Long Beach aren’t swimming in ATF.
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