Posts of varying effort on technology, cybersecurity, transhumanism, rationalism, self-improvement, DIY, and other stereotypical technologist stuff. Crazy about real-world functional programming.

Changing spark plugs on a 2006 Ford Econoline 4.6L V8 engine

The hippie van's odometer recently ticked 100,000. According to ancient mechanic lore, machines last longer if you do preventative maintenance on them. As a long-term oriented kind of guy, I looked through the service schedule to see what needed to be done.

Although my camper van exudes the ineffable and defies being put in a neat little box, the base of it is a common machine: a 2006 Ford Econoline E-150 cargo van with a 4.6L V8 engine. At the factory they install spark plugs in these things, and after 100,000 miles they need to be replaced.

I asked the local mechanic for help. They said it would take them about half a day of labor to do the spark plugs and responded with a quote for $550. Incredible! Doesn't changing spark plugs take an hour tops? The auto shop said that in the typical car that's true, but in my particular van the spark plugs are really hard to get to. Suspicious, I said I'd have to think about it.

Researching on my own, I found this sweet YouTube video where a mechanic describes the procedure and also the parts involved to do this on the exact engine in my exact model van!

Okay, so given how long these videos (the one above and the related video) are maybe changing them really is a huge pain in the butt. The cool mechanic in the video even used the words "getting it done in a weekend". Also, unlike the average car which has a 4 cylinder engine, my van is a V8 which means double the work there alone (V8 engine = 8 cylinders = 8 spark plugs to replace). Worse still, the van in the video is a 5.4L engine, whereas mine is a 4.6L engine, which are reportedly even more difficult to deal with.

Furthermore, and I don't normally recommend this, read the YouTube comments on those videos and you'll see another Ford mechanic chime in. There's a running joke in the Ford mechanic community that spark plugs in these vans are so annoying that you're supposed to leave them for the next shift to handle.

Okay, so that auto shop wasn't pulling my leg after all. By now I was in too deep though! According to those videos, no expensive tools or equipment are required, nor any particularly fancy displays of dexterity or grace. Since the bulk of the cost of changing spark plugs is fidgeting inside of the engine compartment surely that's work that I could just do myself, and save some cash. Right? Right.

Oh, did I mention I've never even so much as changed my own oil before?

Fortunately, I have some things going for me.

  1. This work is normally done by humans, which means it can be done by me, because I'm human too!
  2. I have the internet at my disposal which should connect me to a global community of experts if I run into problems. Besides, it doesn't require even so much as lifting the car. Changing my own spark plugs should be well within my capabilities.
  3. The van is not our primary mode of transportation, so it's okay if it goes down for awhile. I can move as slowly and as carefully as I need to. The pressure to get this done quickly is off.
  4. I can always take it to a mechanic if I screw it up. I probably won't screw it up so badly that they'll want that much more money than they originally quoted me (so long as I go to a different mechanic, so they won't have that "so you've come crawling back attitude").

Having resolved to do this myself, I carefully re-watched the video above (and the related video) and ordered the parts.

  1. Spark plugs ($20); these are the things that ignite the air/fuel mixture in the cylinders
  2. Coils ($100); they're rubber heads that protect the plugs and also bridge the electrical system to the spark plugs
  3. A tiny tube of anti-seize lubricant ($6); you smear a small amount of this on the new plugs before you insert them
  4. Dielectric compound ($20). Smear this inside of the new coil heads before you install it.

Well, almost. I still have to round out my tool collection a bit, so I dropped by my local hardware store (True Value Eugene represent!) and picked up:

  1. Socket specifically made for spark plugs. They have little rubber bushings inside that grab onto the plug when you unscrew them so you can pull them out.
  2. "Universal" joint. Oddly named; they reduce the risk of cracking the spark plug if you twist the socket wrench at an odd angle of attack. Pretty much impossible to work in the cramped quarters of the Econoline van engine compartment without one
  3. A 4" extender (or two) for the socket wrench, so that I had clearance for the wrenching action
  4. Disposable nitrile gloves, always a good idea for when handling things coated in grime

Oh, I also happened to have an air compressor (found for $30 on Craigslist!) left over for a different project. The mechanic in the video above stresses that it's important to blow the compartment out no matter how clean it looks so you don't risk letting debris fall into your cylinders while the engine is exposed. Yowza!

With all of the tools and parts in hand, I sketched out a plan of action while I waited for a several day stretch of clear and sunny weather.

To start, I would remove the air intake (disconnecting the air intake sensor) and do a thorough initial blowing out of the engine compartment. I had recently taken this van to Burning Man, so the inside was practically caked on with alkaline playa dust.

With the front portion blown out, I went into the driver/passenger compartment, removed the center console ("doghouse"), and blew it out from the inside.

The procedure I'd follow for replacing each spark plug is

  1. Disconnect the spark plug coil from power. There's a little tab on the (tang?) connector that lets you disengage them.
  2. Blow thoroughly around each coil with the air compressor
  3. Unscrew the bolt holding on the coil. Start it off with a socket wrench to break it loose, then switch to a screwdriver with a socket bit on the end so you don't have to try to maneuver the whole socket wrench inside of the compartment.
  4. Remove the coil, exposing the spark plug
  5. Use the air compressor again to blow out the area around the exposed spark plug
  6. Use the special socket wrench to unscrew and pull out the spark plug out of the cylinder (thanks, rubber bushing!)
  7. Blow out around the area a final time, being careful not to direct anything into the engine
  8. Prepare a new spark plug: unwrap it, apply a small dollop of anti-seize, and carefully ease it into the cylinder; they're delicate, so avoid having them clang around
  9. Hand-tighten the spark plug (by twisting the socket on the end of an extender) as much as possible, 90% of the way or more, before slipping the wrench onto the extender and putting your elbow into it
  10. Prepare a new coil: unwrap it, apply a dollop of dielectric compound to the head, and push it down into the cylinder. It should enclose the head of the spark plug. If you pull the plug back out, it may even make a popping noise.
  11. Bolt the coil down, hand tightening the bolt with the screwdriver. I specifically didn't use the socket wrench for this because I didn't want to risk breaking the bolt head off
  12. Reconnect the coil to power
  13. Start the engine on the van and see if we can hear any misfires. If it idles smoothly, it's probably fine.

There. One spark plug changed. Repeat seven more times.

In total it took about 7 1/2 hours of physical struggle spread out over 2 days. Not counted was the research and also scratching my head in the middle, wondering about strategy. Each plug was in a unique spot and required a different approach to get out. Some of the plugs were quite challenging to reach, and the space so cramped you can only get like one click on your ratcheting action so it can take what feels like forever to unscrew them. Lots of stuff was in the way, like a thing called a "fuel rail", but I didn't feel comfortable removing them because I didn't want to end up even deeper out of my element.

My procedure above worked, although it had a benign but alarming flaw. About halfway through the spark plug replacement I noticed the check engine light was on. Concerned that I screwed up a plug and without really thinking I revved the engine to see if I could maybe force a misfire. At that point a wrench icon lit up in my dashboard, which meant the van's computer had switched to limp-home mode: the engine revved down, no matter how hard I pushed on the pedal. Shit. Something's definitely wrong. Am I going to have a really expensive repair bill after all?

Calming down a bit, I took stock that it wasn't misfiring at idle. Something else must be wrong. Probably I knocked something else out while fidgeting under the hood. Perhaps if I could probe the on-board diagnostic computer it could give me more detail behind that check engine light.

On-board diagnostic computer? Yup! A little piece of legislation called the Clean Air Act, enacted in the 90s, requires all cars sold in the United States to come with an on-board diagnostic computer to control emissions. Better yet, these computers have a standard interface ("OBD2") and you can buy tools to read them. Nowadays the tools are quite cheap, only $12 for a Bluetooth enabled one that would beam detailed sensor information directly to my smartphone. Sweet! I ordered one and went back to finishing the plugs.

A few days later the OBD2 reader arrived. I connected it to the diagnostic port on the hippie van (below the steering wheel) and paired it with a compatible free app (Torque Lite for Android, in this case). Two faults appeared on the screen. Looking into them further, neither of them had anything to do with spark plugs! Yes!

The faults had to do with the air intake sensor being disconnected, which you will remember I had to move out of the way to get to the plugs in the first place. Automobile engines dynamically combine air and fuel inside of each cylinder at varying ratios depending on environmental factors and performance requirements to ensure a certain degree of efficiency. With the air intake sensor being disconnected, the engine computer had no reliable way to make those decisions so it kicked into limp home mode. Essentially ordering me to take it to a mechanic.

Of course, since I had finished the plug replacement, re-installed the air intake and reconnected the air intake sensor, the condition that led to the faults was eliminated. The check engine light was simply a ghost representing a past problem. I cleared the faults (from the Torque app) and the check engine light went away and didn't come back. Van seems to run fine now.

Total cost: under $200 in parts and tool upgrades, which means I saved about $350 by doing the labor myself.

Wait a minute though! Didn't I spend about a day at the office worth of labor on this? In the end, did I really save any money?

That's the wrong way to look at it. Doing it myself was part of the adventure! A fundamental part of a tune-up on my van! On my terms! If I could properly do this repair, and even reason through a scary spot instead of bailing out and taking it to experts at the first hint of trouble, what other seemingly out-of-reach car repair work am I capable of?

Cast in this light, outsourcing this work so that I could spend a day with my feet up watching Netflix (or whatever) would mean missing out on this important personal growth opportunity. I'm super stoked that I did it and can't wait for the next even more daunting car maintenance or repair task.

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