JohnnyRocker

Two DIY projects I plan to attempt over the holidays on my 2004 996 C4S Cab (57,000 miles).

(1) Plugs and Coils
(2) Oil Pressure Sending Unit

I've owned the car for one year (7,000 miles) and as far as I know these are the original parts. During my inspection this year a couple of the coil packs showed small cracks. I think replacing all of the plugs and coils after 9 years is a good idea.

I have also recently been receiving "Oil Failure" messages and the oil pressure gauge will drop to 0 but within a minute the message goes away and then maxes out on 5. the first time it happened I almost had heart failure, but in researching I see this is common. Most of the time it operates normally and I check my oil several times a month (it's always kept in range).

From all of my research I see that both of these projects are going to be challenging based on the ability to access the parts. I will be using jack stands in my garage.

will I be able to replace the oil sending unit more easily when I have the coil plate off? I'm not quite sure how I'm going to replace that part since it seams too far back in the engine compartment. any tips on attempting that job?

Should I remove the exhaust to remove the coil packs? I've read that the brackets and Cat are in the way, so is it really worth the extra effort or not?

I really appreciate the info in this forum. It is giving me the confidence to go after these DIY projects and learn a lot about my car (and save $$$$!).

Thanks!

peterfrans

I have done both jobs on mine, for the same reasons.

I had to remove the exhaust to get to the coil packs and plugs. Removal of the exhaust is relatively easy (a clamp and three bolts per side). The packs towards the front of the car are easy to get to, but the rear ones are more difficult.

The oil pressure sender is easiest to get to from below, through the right wheel well. An socket extension and a crowfoot socket are really helpful as there is not that much room.

pfbz

Removing the exhaust helps quite a bit in visibility, though not all that much in access. It also comes off fairly easily... I would suggest pulling them for your first plug change just so you can get a better view of what you can't easily reach. After you do it once, it's probably faster to not remove the exhaust and just do it by feel. As I said, clearance is pretty much the same, just makes seeing things a bit easier.

Removing the exhaust bracket itself would make the plug swap cake, but is removing the bracket is no easy task and believe involves slightly lowering the engine to get to the top bolts. Not worth it.

The cat is not in the way at all.

The two rearmost plugs and coil pack bolts are the most challenging to get to, particularly the passenger side. Make sure you have flex head ratchets, long and short extensions, a good assortment of universal joints & wobble extensions, a good spark plug socket, and the needed torx and external (reverse) torx bits and sockets (torx only on later 996's) to cut down on the swearing a bit.

Two tools I bought *after* my plug/coil change that I purposely picked up to make my next plug swap easier where these:

Mini ratcheting bit driver for an easier time with the torx bolts on the rear-most coil packs. Earlier year 996s use allen head bolts instead of torx bolts, I think much easier to deal with. A standard 3/8" torx bit socket is too bulky for the limited space, no chance at all with a torx screwdriver. 'L' shaped torx wrenches (similar to the cheap L shaped allen wrenches that come with every craftsman tool set) might also work well.



External torx ratcheting wrench. The *perfect* tool for removing the external torx bolts on the later year 996 coil heat shields. $17 on Amazon.



Wobble extensions if you don't already have them...

peterfrans

btw it's not the cat that is in the way, its the muffler itself. I would also replace the clamps which provide a gas tight seal. I did not at first and had to replace them afterall.

JohnnyRocker

I had thought about replacing the clamps if I were to remove the exhaust. I think this convinces me to remove the mufflers and add clamp replacement to my project.

For tools I have a swivel head ratchet, short and long extensions and one joint wobble. I think all I need to add is a torx ratchet wrench. I also have a 19mm crowfoot socket for the Oil pressure send unit.

nymart

Unless your cab is different than my 2004 C4S, you don't have torx screws on your coils. Mine were 5mm allen head bolts. I just did (or at least did 5 out of 6) today. Be prepared for many broken bolts when you try to remove the mufflers unless your bolts have much less rust than mine did. I just posted this as I can't for the life of me figure out how to get to the passenger side coil furthest back. https://rennlist.com/forums/996-foru...placement.html

dmw996

I just did my plugs Thanksgiving weekend. Coil packs were ok and no leaking spark plug tubes -yea! I removed the rear wheels and exhaust and it wasn't hard at all. I went to Lowe's today and bought stainless hardware to replace my 4 carriage bolts/nuts. Pelican had the best price I found on muffler clamps - $9.00 each side.

I would be done but I am searching locally for a muffler shop to do me a Fister-D bypass hack. First place said no. 2nd place was closed today. Surely somewhere around the Birmingham AL area I can find some help with this.

Anybody in Alabama has this done?

pfbz

Not sure when they made the cutover, but they gradually starting introducing '997' parts on later production 2004 996's... Mine has OEM torx fasteners on both the coil pack bolts and heat shields.

peterfrans

On my 2005 C4S it is indeed all torx

JohnnyRocker

I just finished the job. Thanks everyone for the tips, tools, and tricks.

I ended up leaving the mufflers on. Mine has the factory sport exhaust system and I wasn't sure about the removal process with the motorized gizmo being attached..... I don't think the mufflers got in they way too much. I was able to see everything from lying on my back and working underneath. If you need to replace the oil preasure sending unit - do it from below with a 19mm crows foot on an extension. It was slow process (7 hours) and a little knuckle bleeding, but well worth it.

Both projects done - Feels good!

Hope everyone has a safe and happy New Year!

BED997

Dmw996 did you ask Eurasian about the Gundo? They may also know a shop in town.