Photo Essay - Bf Falcon Spark Plug Replacement

[PhilMeUp]

It’s well known that late model Falcons will backfire if the spark plugs and/or coils are worn. My BFIII Falcon has been backfiring occasionally lately. I should replace both the spark plugs and coils together but I’m trying to control my vehicle costs. I’ll replace the spark plugs first and see if that fixes it. If not, then I’ll have to cough up a bunch of money for new coils.

With coils, there is plenty of discussion on various forums about which ones to get. There are the genuine Ford ones (part number: BAF12A366A), but they are extremely expensive. If my backfiring continues then I’m probably going to try a set of the VDO coils (part no: A2C59513771), which can be found easily enough for around $135-150 per set (ie less than half of Ford’s current price).

There is a previous thread that also covers this, along with a bunch of useful contributions: http://www.fordforums.com.au/showthread.php?t=11229532

Photos:

My engine bay - it’s a bit dusty, but not too bad for a car with 326,000km on it. I clean the engine bay with CT18 degreaser and a brush every few months.

This is an Egas (ie dedicated LPG) Falcon, so petrol cars won’t have the hose that runs across the top of the coil cover (in the middle of the engine bay).

If you’re going to do this job, it would be a suitable time to wash the engine bay before starting. Still take care to not get water past the coil cover and into the spark plug holes, but if you do then it’s not a huge problem because you’re going to be removing the spark plugs anyway.

When washing the engine bay, you’ll hear warnings about not getting water past the rocker cover - that’s the black plastic cover sitting on top of the rocker cover (ie the green thing). If you get water past the rocker cover then it will go down into the spark plug holes, shorting them out. That means running on less than six cylinders.

To remove the coil cover, the first thing to do is to disconnect the two hoses.



I use Bosch FR 7KPP 33 U+ spark plugs, which I’ve previously bought individually for between $7 and $12 each. I didn’t know until recently that they also come in this six pack, which works out cheaper. The Bosch part number is P38-6 - quote this when calling shops to check for stock.

This pack retails for $44.90 from Supercheap Auto, or $40.49 with a Supercheap Auto Trade Account Card (ie 10% discount). That works out to $7.48 each at full price, or $6.75 each with the trade discount.

As I’ll cover later, getting to the rear spark plug is a problem. I bought some 1/4” extension bars, a 1/4” to 3/8” adaptor and a Bikeservice BS9133 spark plug socket. The BS9133 has a 3/8” drive, hence the adaptor. I don’t have any 3/8” stuff as I’ve always standardised on 1/2” sockets and ratchets - it’s only recently that I’ve been adding some 1/4” stuff to my collection.

On the right side of the photo is the 1/2” stuff that I normally use - ratchet, long extension bar and socket.



I’ve always had trouble getting the rear spark plug in and out with my usual 1/2” stuff. Tonight I tried an experiment with a different socket and ratchet setup.

I’ve bought a couple of these spark plug sockets previously to use on my KTM enduro bike. When I bought the KTM back in June, I found that normal sockets were too wide to fit into the narrow KTM spark plug hole. This is what I ended up getting for the bike, so I bought another one to use on the taxi.

If you have a late model four stroke enduro or motocross bike then I recommend that you get one of these sockets - if it fits into the KTM head then it will fit into anything. I keep one in my motorbike toolbox and one in the bumbag that I wear when riding.

They are in the motorbike section at Supercheap Auto - it’s usually at the end of one of the aisles, so you’ll probably walk past it without noticing. Ask the staff where it is.

Oh, and 16mm = 5/8”.



I figured that with such a thin wall, the socket would be easier to get in and out of the rear spark plug hole. However, when I later measured the outside diameter of this and my old 1/2” socket there was minimal difference. The Bikeservice one is 20mm thick and my old one is 21mm thick. However, this is still the only socket that I’ve found that fits into the KTM head (besides the original KTM socket, which sells for over $60).



Remove the hose that goes to the LPG converter. Conventional pliers or multi-grip pliers would also do the job, but I use the needle nose pliers because they open up enough to fit over the clip.

I squeeze the pliers closed and then push the clip to the right. The hose will then slide off the connector.



The same applies to the rear hose.



That last hose runs through a clip at the back of the coil cover. That’s why I disconnect the hose - so that I can get it out of that clip. I then remove the PCV valve. PCV = Positive Crankcase Vent.

If you want to replace either the PCV valve or the plastic elbow, here are the Ford part numbers:
PCV Valve Part Number: AUC 6A666 A
Plastic Elbow Part Number: D9AE 6B892 AA



The disconnected rear hose has been removed from the clip, and the PCV valve has also been removed from the coil cover.



The air intake pipe is held in place by two bolts. Undo those two bolts, pull it forward so that the rear of it clears the top of the firewall area and lift it away.

There are no bolts that attach it to the throttle body - it just pulls off, along with the small rubber tubing that connects to the rocker cover.



Now that I have full access to the rocker cover it’s time to remove the rocker cover bolts. There are eight of these - they are loosened with a 5mm allen key. The rear one is a nightmare to get to, and I don’t bother to put it back in.



Here are the tools that I use to remove the rocker cover bolts. I’ve always used a Sidchrome 5mm t-bar - the ball end gives me a bit of room to move with the angle of it. I don’t have any allen key sockets, so lately I’ve been using a Torx T30 socket with a cordless electric drill.

To remove the rear bolt, use a normal 5mm allen key. It’s frustrating and fiddly - you do it little bit by little bit. Which is why I don’t bother putting that one back in - it gets added to the box of spare bolts.

Don’t forget the fibre washer that comes out with each coil cover bolt.

When working on cars and motorbikes, you’ll use 4mm, 5mm and 6mm allen keys sometimes. The Sidchrome t-bars sell for around $15-20 each. I ended up buying the complete set several years ago for $57 - http://www.sidchrome.com.au/products/8-piece-t-handle-hex-key-set-metric



Once the hoses are out of the way and the coil cover bolts have been removed, I have full access to the coil cover. During all this, I keep the oil filler cap in place to ensure that nothing can get into the oil. When removing the oil cap, make sure that the rubber seal in the top of the cap stays in place - it will sometimes come loose and stay on top of the engine.



The coil cover removed. There is a rubber seal that goes between the coil cover and the rocker cover (ie the green thing). Sometimes that seal will come off with the coil cover, and sometimes it will stay on the rocker cover.

On the coil cover there are six rubber plugs. When the coil cover is in place, these rubber plugs press down onto the coils to ensure they are kept in place.

When removing the coil cover, sometimes some of the rubber plugs stay on top of the coils. If this happens, remove them from the coils and fit them back into the coil cover.

As soon as the coil cover is removed, I put the oil cap back on.



Once the coil cover is out of the way the coils can be disconnected. I use a flat blade screwdriver to push the clip outward and then press down on the clip with the pliers that I used earlier to disconnect the hoses.



The coils, all disconnected. The coils can now be removed.



Now it’s time to start on the spark plugs. In the past I’ve used the ratchet setup at the top of the photo - a Sidchrome ratchet, a long extension bar and a conventional 5/8” spark plug socket. This stuff is all conventional 1/2” drive.

But, that hasn’t given me access to the rear plug. In the past I’ve stuffed around with all sorts of stupid attempts - getting the plug loose is easy enough (with a shorter extension bar), but getting the socket and plug out is the difficult part. I’ve ended up fishing with a screwdriver with Blutak on the end to get the spark plug socket and plug out.

Tonight I tried a different combination - a 1/4” setup that will give me better access to the rear spark plug. It ended up working perfectly for getting the old spark plug out, but wasn’t so good for getting the new plug back in (I couldn’t get the socket to come loose from the new plug).

Because the 1/4” extension bars are so narrow, I only needed the one universal joint to get the rear plug out.



Loosening the rear spark plug. As you can see, the universal joint allows the extension bars to move to an angle that allows the ratchet to rotate.

It doesn’t show in the photo, but that rear spark plug hole is actually underneath the top of the firewall and piping. Hence the difficult access.



Once I got the spark plug loose I disconnected the ratchet and rotated the extension bars easily enough by hand.



Putting the new rear plug back in was where problems began - getting the plug in and tightened up was easy enough, but then the socket wouldn’t come loose from the spark plug (ie the extension bar would come loose instead). The rubber inside the socket gripped on too tight. I tried putting the spark plug only half way into the socket, but it still took too much force to get the socket away from the spark plug.

With everything having gone so well so far, this project now came to a grinding halt. I ended up with the socket stuck to the spark plug once I tightened it. The extension bars just disconnected from the adaptor. Despite my 185cm height, I couldn’t reach over far enough to see down the spark plug hole.

There were various attempts at dropping extension bars down, but I couldn’t get them to push into the adaptor on the end of the spark plug socket. This ended up getting frustrating, which is a very polite way of saying that I got really, really, really, really, really pissed off.

I eventually managed to get an extension bar to plug in properly. I removed the plug and then had to figure out how to get it back in and tightened, but in such a way that I could also remove the spark plug socket afterward.



After trying a few things, I ended up removing the rubber from the spark plug socket by pushing a flat blade screwdriver through from the top.

[PhilMeUp]

This is the combination that I ended up using to put the rear spark plug back in. I carefully dropped the spark plug in on its own, and then slid the socket and extension bars down over it.

I tried, but couldn’t get the rubber to go back into the socket. It’s obviously a tight fit - being intended for motorbikes, this socket will need a relatively tight grip on the spark plug. It’s not intended for car use.

To use this socket again for removing spark plugs, I’ll either try jamming some Blutak into the top of it (ie to stick to the spark plug) or get a magnetic tool to pull the spark plug out.

In hindsight, I should have tried spraying some silicon wax inside the socket rubber to see if that would reduce its grip on the spark plug. Or tried using my 1/2” drive spark plug socket with adaptors to fit the 1/4” extension bars.

There is another solution for this - Snap-on do make some 1/2” universal joints that are narrow enough to fit into the spark plug holes (part number is BLPUJ12). I bought some Kincrome universal joints a while ago, but they are too wide and don’t fit.

Alternatively, just leave the rubber out of the Bikeservice socket and poke one of the coils down into the spark plug hole so that it grabs hold of the plug, and then remove it.

I’m going to have to get decisive about this one of these days - take the damn car to a tool shop, remove the coil cover in the carpark and see what universal joints the shop has that actually fit down the spark plug holes. I’d like to stick with my 1/2” drive stuff.



A photo showing how deep the spark plug holes are.



Before putting the coils back in, I applied some dielectric grease to them. I bought this from Supercheap Auto when I bought the spark plug socket and 1/4” extension bars. These sachets were $4.95 each. I actually bought three, but only one is needed to put enough in the coils on one car.



The rubbers come away from the coils pretty easily. I’ve done this to put some dielectric grease into the copper ends.



I squirted a fair bit into both the copper end and rubber of each coil - that one sachet allows for quite a bit to be applied to each coil. By putting some into the coil rubber, it ensures that the coils will come away from the spark plugs easily enough next time - without that grease, the rubbers stick to the spark plugs and become difficult to remove.



The coils back in place, but not re-connected yet.



The coils have been re-connected.

Before putting the coil cover back on, ensure that the six rubber plugs are in place, and that the coil cover seal is in place correctly. I’ve been meaning to replace this as a precautionary measure, to ensure that a fresh (and softer) rubber seal will help to prevent water getting past it when I wash the engine bay.



Once the coil cover bolts have been put back on it’s time to put the air intake pipe back into place. With the coil cover bolts, I do them up reasonably tight, but not so tight that I strip the threads.

With the air intake pipe, pull it forward toward the front of the car so that it clears the top of the firewall, and then let it move backward into place.



Check that the rubber seal between the air intake pipe and throttle body is good. This one isn’t, so I’ll need to replace that rubber seal as soon as possible. I’m pretty stumped how this happened - I’m aware of how easy it is for this to happen, so have always been extra careful when putting this back in place.

Spraying some silicon spray on the inside of the rubber seal helps the whole lot slide back into place. The same applies to the small rubber tube that connects to the rocker cover.



When putting the two bolts back on, that clip goes on top.



Then feed the rear hose back through the clip before reconnecting the hose. The PCV valve also goes back in.



This photo shows two of the old spark plugs, and I’ve added part of a previous photo to show the electrode of a new one. You can see how the electrodes have worn on the old plugs, particularly the one in the middle.



That’s it. The two hoses have been reconnected on the left side of the engine bay. Start the engine, and hopefully it will idle smoothly. A rough idle will indicate a bad connection between one of the coils and its respective spark plug, which means that you’ll have to pull it all apart again and double check it.

Overall, this is an easy job. Except for:
1) Removing the rear coil cover bolt. I’ve only ever had to do that once - every other Falcon I’ve worked on has already had that one bolt discarded.
2) Removing and replacing the rear spark plug. I’ll come up with a good (ie fast) solution one of these days, and update this thread.

[spinr33]

Great write up I use a 3/8 ratchet and 2 small extensions for the rear plug and a kincrome plug socket these are magnetic no rubber literally do the whole job in 30 minutes.

[FiftyOne]

+ for sticky

(only BBQ's run on gas)

[phantom xr6t]

I use a short wobble extension and a normal extension for the last plug it works great

[PhilMeUp]

Update (24 hours later): Tonight I did the same job on my girlfriend’s taxi. Replacing the rear spark plug only took a minute or two. I used one socket for removing the spark plug (with a rubber insert) and a different socket for putting the new one in (without a rubber insert, so that the socket would lift out easily).

I put together a ratchet setup that could then be used with each socket:
- 1/4” ratchet
- 2” (5cm) extension bar
- 1/4” universal joint
- 5” (7.5cm) extension bar
- 1/4” to 3/8” adaptor

With my normal spark plug socket, I used a 3/8” to 1/2” adaptor. This meant that both sockets now used a 3/8” drive.

Tip: with universal joints, try and only use one. And keep that one as high up as possible - if it’s low in the spark plug hole and the extension bar comes out then it’s tricky to get it to plug back in (because the top of the universal joint falls to the side).