Smoothing the engine bay. 

Now this process is a satisfying yet tyresome thing to do. But the end results speak for themselves. To motivate yourself throughout the process, you have to tell yourself of the moment when you pop the hood and on display is an immaculate bay with ultra clean engine. It's a labour of love for sure. 

At this point, if you've read the previous (pt.1) blog, you have read through some of the details, but I will recap in case you missed. 

The E36 engine bay isn't the best looking bay out there. It's just not great to look at, so you really have to put in the work to make something special of it. Firstly, the main thing that jumps out at you is the gaping hole in the fire wall. No one ever does anything with this, so we had to do something special with it: ie plate it straight over. This also included plating the ECU/Wiring box holes also. Again something that no one does. 

One tool that came in super handy when removing the random brackets and spot welds, was the spot weld drill bit. It's a 2pc kit and makes the job super easy. Well worth buying one instead of trying to grind your way through. 

I had plated up a number of the holes in previous years, so I had a head start somewhat. But nevertheless, there were still plenty of holes to plate. Once this was done, it was then onto the seam welding of as many spot-welded panels as possible. This is so that when you get to the filler stage, your work doesn't begin cracking on the first drive. The seam welding stiffens up the chassis considerably.

The heater matrix cover I made (in the photo) was the trickiest thing to do in the bay, as it was just all trial and error. After just a single but lengthy attempt, this is the final thing. 


All the welding was done with a MIG. 
Now that the welding was done, the next stage was to start the filler-ing after a bit of primer over the welds to lock them in. I used just a standard off-the-shelf filler and ensured each of the welds was a smooth as can be before this. This is important so that you don't have to go thick with the filler. You ideally wanna be tops 2-3mm thick on filler. Any more is a bit silly. Now that filler was being applied, it was a case of getting a load on there quickly and efficiently. You'll be looking at around 4-5 filler sessions, so you don't need to take your time with the first. Main thing it to get the welds and seams covered. 
A quality piece of advise I got from good ol' Pimp-My-Ride was to go in with a heavy grit paper to start with. This is because the first few coats you simply just need to shape it. Yes, you will have sanding marks and deep ones at that, but the last few skims can sort this out. You don't wanna waste time and you will literally double the time spent if you only sand with with 240 grit. You just need to shape the bay first and then finesse it secondly. 

As you go, you don't need to primer it each time as most of the time it's obvious if you need to filler and smooth more. This saves tons of spray cans and you can usually do an entire bay process with 2x primer spray cans from halfords. You will also only need either 1x big can of filler or 2x smaller ones. Remember you can waste a lot of money of stuff like this so it's best to be a bit more logical in the process instead of wasting an extra £100 for no reason on primer and filler.

Now, for the next step there is sadly no 'special pill' I can give you. It simply just takes time. My tip is to do things in stages and divide the engine bay by 4x sections. So 4 quarters. This means that you don't get overwhelmed with is to typical when working on your own project by yourself. Over the course of the week, I managed to do the entire bay to a 95% standard. This was about 6hrs per day spent on each quarter. It's a ton easier when you just commit to getting a section done in your mind instead the 'entire bay'. Just a little tip there!

Now once you've completed the mission of smoothing each bit to a pretty decent level with your 60 grit paper, go over the whole bay with a 180 grit just to smooth over an small ridges left from the 60 grit. Once that is done, you want to crack open, or buy, some filler primer. Not a small spray can, but this time get yourself a proper spray gun. This is so you can do multiple coats, build up a thick layer and also save a lot of money by not getting 40 cans of filler primer instead. 



Filler primer is amazing. It saves tons of time and lives an insane finish. Remember all of those 60 grit sanding marks? They're basically gone. You'll need to do about 2-3 coats and then sand down with some 240grit before the next. At this stage you wanna do any little bit of filler work that you may have missed (this will happen), but it's a lot easier to see when the bay is in a uniform colour. 



Now the bay is at a stage where the finesse comes in. It's 95% there which is good for most people. But being the shop car, it needs to show our quality of work that we expect on everything to come out of our shop. So stay tuned for Pt.3 of the Mabilis E36 build where we'll get up close to the bay and some other bits too! 

Thanks for reading. 
September 25, 2023 — Isaac Brain