Sump Guard

We spent his weekend beating sheets of metal. 

As we will be driving off road, in areas that even a car salesperson would cringe at, we need to protect bluebird (our trusty 1.0L Micra). Now, after allowing her to breathe (see our Snorkel), we need to get a sump guard fitted.

Now, you don’t really NEED a sump guard. If you drive like a granny, stay on roads and avoid any form of adventure, you can probably make it without a sump guard – but where’s the fun in that?!

What’s a Sump, and Why Does it Need Guarding?

The engine sump, or oil pan, is the reservoir at the base of the engine that holds the engine oil. If you stick your head under your car, you can see it sticking out from under the base of the engine. The oil it holds is essential for lubricating, cooling and cleaning your engine. Its position in the engine bay puts it right next to the potholes and rocks you are speeding over and a good knock can break it open like a coconut – at which point you’ll see a large black puddle of your precious oil on the floor! You may then hear some awful knocking or just silently lose power, most likely both at once. But whatever it sounds like, your engine will quickly drain of oil and seize up never to start again.

The second problem is gravel and pebbles when driving long stretches. These will quite literally grit-blast your sump, until it’s as thin as paper, and eventually pierce it. Cue the engine seizing and never starting again.

 So, how do we (try) to prevent this?

The concept is quite simple really. Find a sheet of steel or aluminum. The thicker, the stronger it is… but also the heavier. Weld some brackets on the car, and then bolt your sheet to the brackets. Simples.

Points to keep in mind:

• Steel weights more than aluminum, but is also stronger. Aluminum sheeting weights roughly 45% less than steel, but need to be 3x thicker to maintain the same strength.
• Aluminum is pretty hard to weld, and near impossible to weld in the middle of nowhere.
• Steel on the other hand, can be welded with a car battery and some arc welding rods (https://www.youtube.com/watch?v=8tHJ0NSjZnM)
• In an ideal world, Duralumin (aluminum/copper alloy) would be used….

We opted for a 1.5mm steel guard, with a 40mm x 20mmm steel tube “cage” to add stength. This should be strong enough to protect from even the biggest of rocks, while being lighter than a 6mm aluminum guard. So without further ado, some pictures…

Step 1: Cut some steel to the right shape/size. Repeat 4-5 times, each time making the sheet smaller until you have the right shape.

Step 2: Test fit the cage.  Don’t weld it on just yet…

Step 3: Bash that sheet until it’s bent. The front lip serves to keep gravel off the sump, and in case you hit a rock front-on, stop the rock ripping the sump guard down. I then welded the cage on, and added a piece of angle-iron behind the “lip” to provide more strength.

Now, weld on some brackets on the car. You may need to strengthen the front cross-member as it’s paper thin on the micra.

Finally, put the sump guard on the bracket and bolt on. This isn’t ideal as the nuts are protruding – so I’ll modify it next weekend to protect the nuts a bit more.