: How To: Spark Plug & Wire replacement 98 Seville



iametarq
03-17-07, 09:19 PM
Here are the pictures and steps I followed to replace my spark plugs and spark plug wires on my 98 Seville

I ordered my parts from www.rockauto.com

ACDELCO Part # 41950 More Info {PLATINUM PLUG #88892834} SPARK PLUG $5.08 each
ACDELCO Part # 748N {#12192081} WIRE KIT,SPLG INCLS ALL 8 SPLG WIRES $100.89 set

GAP needs to be set on the plugs!

I have 117,000 miles on the car now, when I bought it, it had 73,000 and I am assuming these are the original plugs and wires.

1. Remove the beauty cover, I think they were 1/2" sockets. The 4 in each corner. ;)
http://gallery.iametarq.com/cars/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6003.JPG

2. I thought I was going to have to label each plug, but the #'s are stamped on the block. Thanks GM! No thanks to Chrysler ;) 2, 4, 6, 8 are on the front. 1, 3, 5, 7 are in the rear.

3. Each plug on the coils are also labeled.
http://gallery.iametarq.com/cars/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6006.JPG

4. In my case the wires for plugs 2 & 4 were bundled together and 6 & 8 were the same way. Then those 4 all went into a piece of wire bundle. My original (I'm assuming) spark plug wires also had the # stamped on them. My new ones from Rock Auto did not, what a bummer.
http://gallery.iametarq.com/cars/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6007.JPG
http://gallery.iametarq.com/cars/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6008.JPG

5. In my case I chose to remove the metal plate that the 4 coil packs are attached to. Unplug the 4 electrical harnesses that are plugged into the coil packs. Two plugs on each side.
http://gallery.iametarq.com/cars/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6015.JPG


6. The plate has four 10mm bolts that hold it in place. One on each of the short sides and then two on the back side of the plate facing the firewall. The two side ones are easy to get to. The two on the back side are a bit harder. The hardest one is below the Cruise Control module area under the wires attached to the coil pack for plugs 3 & 8. First Picture below is removing that bolt:

http://gallery.iametarq.com/cars/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6014.JPG

http://gallery.iametarq.com/cars/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6009.JPG

The second rear bolt has a what looks like a positive electrical connector on it as well:
http://gallery.iametarq.com/cars/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6010.JPG

7. Now that the coil packs can be moved out of the way you will see the other four rear plugs.

http://gallery.iametarq.com/cars/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6017.JPG

8. Now Remove all of your spark plugs carefully keeping the spark plug wire near. I chose to set the boot back in the hole the spark plug came out of so I would not lose the routing of the original spark plug wire.

9. Once all your plugs are removed, install your new plugs with the plug gap set to .050" My plugs were not gapped, but the instructions indicated that anyway. The FSM says to torque the spark plugs to 11ft-lbs.

10. Now that your new plugs are in carefully remove one spark plug wire at a time, remembering how it was routed. Route your new cable the same way the old one was. Secure it on the spark plug and then onto the corresponding Coil plug. As you do each spark plug wire, reapply the wire wrapping and secure it to protect the spark plug wires from heat. Make sure the plug wires are in the little 'divots' for the wires so they don't move around.

11. Double check all your boots and plugs on the coils before re-bolting the coil plate to the block.

12. Start the car, check for any problems, if no problems detected, re-attach the beauty cover!

Here are my old plugs:

http://gallery.iametarq.com/cars/cadillac%201998%20seville%20sls/engine/spark%20plugs/IMG_6013.JPG

http://gallery.iametarq.com/cars/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6018.JPG

EcSTSatic
03-19-07, 11:50 AM
Great post iametarq. This will help the newbies immensely!

A few tips that will make things easier:

Whether you keep your wires or replace them, twist them off - don't pull or you may rip the boots off.
Replace your wires one at a time so that you don't mis-wire them
Keep track of which cylinder each plug came out of so you can "read" it when you are done.
Start your new plugs by hand and get a few turns on them before you put a ratchet to them. It will help to keep you from crossthreading the plugs in the head.
As mentioned before, check your new plug gap, don't rely on the factory set gap for various reasons.
Feel/listen for a click when you install your wires to be sure they are fully connected.
Optional: blow out the head recess for the plug. It my help to keep debris from falling in the cylinder when you remove the plug.

iametarq
11-18-10, 11:47 PM
Here are the pictures and steps I followed to replace my spark plugs and spark plug wires on my 98 Seville

I ordered my parts from www.rockauto.com

ACDELCO Part # 41950 More Info {PLATINUM PLUG #88892834} SPARK PLUG $5.08 each
ACDELCO Part # 748N {#12192081} WIRE KIT,SPLG INCLS ALL 8 SPLG WIRES $100.89 set

GAP needs to be set on the plugs!

I have 117,000 miles on the car now, when I bought it, it had 73,000 and I am assuming these are the original plugs and wires.

1. Remove the beauty cover, I think they were 1/2" sockets. The 4 in each corner. ;)
http://autos.marktarquini.com/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6003.JPG

2. I thought I was going to have to label each plug, but the #'s are stamped on the block. Thanks GM! No thanks to Chrysler ;) 2, 4, 6, 8 are on the front. 1, 3, 5, 7 are in the rear.

3. Each plug on the coils are also labeled.
http://autos.marktarquini.com/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6006.JPG

4. In my case the wires for plugs 2 & 4 were bundled together and 6 & 8 were the same way. Then those 4 all went into a piece of wire bundle. My original (I'm assuming) spark plug wires also had the # stamped on them. My new ones from Rock Auto did not, what a bummer.
http://autos.marktarquini.com/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6007.JPG
http://autos.marktarquini.com/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6008.JPG

5. In my case I chose to remove the metal plate that the 4 coil packs are attached to. Unplug the 4 electrical harnesses that are plugged into the coil packs. Two plugs on each side.
http://autos.marktarquini.com/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6015.JPG


6. The plate has four 10mm bolts that hold it in place. One on each of the short sides and then two on the back side of the plate facing the firewall. The two side ones are easy to get to. The two on the back side are a bit harder. The hardest one is below the Cruise Control module area under the wires attached to the coil pack for plugs 3 & 8. First Picture below is removing that bolt:

http://autos.marktarquini.com/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6014.JPG

http://autos.marktarquini.com/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6009.JPG

The second rear bolt has a what looks like a positive electrical connector on it as well:
http://autos.marktarquini.com/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6010.JPG

7. Now that the coil packs can be moved out of the way you will see the other four rear plugs.

http://autos.marktarquini.com/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6017.JPG

8. Now Remove all of your spark plugs carefully keeping the spark plug wire near. I chose to set the boot back in the hole the spark plug came out of so I would not lose the routing of the original spark plug wire.

9. Once all your plugs are removed, install your new plugs with the plug gap set to .050" My plugs were not gapped, but the instructions indicated that anyway. The FSM says to torque the spark plugs to 11ft-lbs.

10. Now that your new plugs are in carefully remove one spark plug wire at a time, remembering how it was routed. Route your new cable the same way the old one was. Secure it on the spark plug and then onto the corresponding Coil plug. As you do each spark plug wire, reapply the wire wrapping and secure it to protect the spark plug wires from heat. Make sure the plug wires are in the little 'divots' for the wires so they don't move around.

11. Double check all your boots and plugs on the coils before re-bolting the coil plate to the block.

12. Start the car, check for any problems, if no problems detected, re-attach the beauty cover!

Here are my old plugs:

http://autos.marktarquini.com/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6013.JPG

http://autos.marktarquini.com/cadillac%201998%20seville%20sls/engine/spark%20plugs/.cache/640x480-IMG_6018.JPG

The Gold
12-01-10, 10:17 PM
Great tutorial ! THANKS.
About how many hours did it take to do all this? Man, glad you got new plugs !!

detroitrust
01-14-13, 12:59 AM
Is there any way to update this thread with pictures? This seems like a great write up and exactly what I am looking for to tackle a plug change in my 97 eldo.

Submariner409
01-17-13, 04:32 PM
Google "cadillac forums 1997 northstar spark plug change" or something similar, always preceded by "cadillac forums .... .... ....".

Pre-2000 takes AC Delco #41-950 Platinum plugs. Nothing else.

RandyT.
02-24-13, 11:18 PM
Some Auroras have the wrong gap listed on the engine stickers .060 instead of .050, GM changed the recommended gap. I don't know if Cadillacs are like this, but I thought I would bring it up. Here is a link to a thread with more advice on '95-'99 Northstar tune ups.

95 Spark Plug Replacement (http://http://aurorah.proboards.com/index.cgi?board=1stgen&action=display&thread=2802&page=1)