Countless comments and posts, in countless forums, reiterate relentlessly that the M42 exhaust manifold (on some accounts, to have been sketched by Da Vinci in his Italian artisanal workshop alongside drawings of the Vitruvian Man and the ornithopter flying machine), is more than perfect in its functions of rate and flow. But this isn’t a perfect car, and we’re not perfect people, but the following analogy will be; Da Vinci’s flying machine likely never flew, and neither will we! Wait…
Step 1: Target Acquisition
Because we’re as committed as is reasonable to reducing waste, we acquired an exhaust manifold in a parts lot after convincing ourselves that the crack in the old one that we welded shut, will likely crack open again anyway, and thus warranting replacement. We’ll do our local metal scrap guy a solid and leave the old one at the curb instead of throwing it in the recycling bin. We paid $100 for a used fuel tank, spare M42 ECU and the titular exhaust manifold from a guy on Craigslist after following him from his college dorm apartment to a barn in the sticks, disregarding every thing we learned in every true crime podcast we’ve ever listened to about not going to a second location. The deal was too good to pass up obviously.
If you want to make future removal of post-manifold exhaust bits easier, weld on a flange. We found this one for $25-shipped on FB Marketplace and you’ll see how we affix it properly later on after a few more riveting blocks of images and text.
Step 2: Swinging – Getting that lower control arm out of your face.
Make the entire process easier on yourself by in-order unbolting the lower control arm bushing brackets (also known by fuckboys as lollipops), anti-roll bar endlinks, and anti-roll bar bracket on the exhaust manifold side of the car. This will let you swing it away from the car so that there won’t be as much banging around as when you were smashing around blindly in the dark for that condom your dad gave you a year ago after you finally moved out.
We removed the entire 22mm ST anti-roll bar to touch it up in a few spots where rust has started to develop. Because it’s made of a spring steel, rusty spots will exacerbate a decline into un-spring-steel-like qualities. This was also a lesson in proper preventive care because one of the few things we did right in the early years of building this car was using a proper silicone grease inside the anti-roll bar bushings. While anti-seize is an alternative we used in other areas of the car, it would’ve been detrimental here. Most off-the-shelf anti-seize products eventually dry out by design, leaving a powdery barrier between metals, but, would have been abrasive to the painted surface of the bar, eventually leading to rust. We’re also going to recondition the fasteners, washers, spacers, and brackets before we re-install it all later.
Step 3: Manifold Removal – The only danger to it, was us.
Removal, surprisingly, was the easiest part. While it can be done with a simple combination of a 3/8″ ratchet, 11mm deepwell socket, and a short-ish extension, you’ll save yourself a sore chest by using some sort of right-angle device. We used one that chucks right into the 1/4″ drive of our knuckle-savior impact gun. That and a 6″ magnetic bit holder placed betwixt the gun and the right-angle attachment (not pictured), gave us all the access we needed to reach every nut without having to switch back to simple primitive, proletariat hand tools. Seizing the means of production doesn’t imply that we can’t use power tools. An air-powered ratchet is a cheap alternative if you have a tank and air hose available.
In our case, this manifold had been removed and retrofitted with a new flange once before, so your disassembly process after the 4-to-2 collector might be different, but moving the suspension components out of the way will still be necessary to a hassle-free extraction of the manifold itself. Once we had all of the fasteners removed, we unbolted it from the aforementioned flange, and snaked it out like a toilet rooter from a clogged septic tank.
Recommendation: You’ll find that the fasteners will come out as either the nut alone or the nut and stud together. If both come out, watch this surprisingly short (50 seconds) and effective video on how to remove the stuck nut so that you can re-install the studs and use them as guides during the new manifold’s installation.
Step 4: New Manifold Preparation
Apologies in advance, but this process will be a little pacific to our situation. As in, the wrong side of the ocean. This was our second time dealing with an incorrect manifold, both having been built for a right-hand driven car, and we weren’t ready to fuss about the time and money required to tool-up a new one. The original manifold’s third cylinder tubing, ( a manifold which we will euphemistically refer to as “eBay sourced”) didn’t clear the motor-mount by any reasonable stretch of the imagination and for lack of material and welding skill, had to be replaced.
We got lucky and found one that was known to be persuaded with minimal percussive maintenance, so we glad-handed the old one off to some sucker for 20 dollar-menu burgers, and got to work dinging the new one up (with a combination of propane heat and a claw hammer) and welding on the appropriate accouterments. Because this one was still more than a little wrong we had to open up the bolt holes on the base plate to help align it, and weld a new M18x1.5 02 sensor bung to a mirrored position near the end of the manifold since it was making kissey faces with the floorpan of the passenger-side of the cabin. After that, we cut down the flange to the necked-down smaller diameter and welded it to the end of the manifold. We accidentally used an E71TGS instead of our stainless flux core wire so we’ll have to keep an eye out for premature corrosion since there’s no chromium in the weld to help protect against it.
Next week, check back in for the thrilling conclusion, where we deliberately post pictures in conjunction with textual descriptions of all the ways this process went wrong and how we eventually struggled together as a crew to pay our copay for group therapy in the aftermath.