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2001 Eldorado Spark Plug Change

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Hey, I managed to change the spark plugs in my 2001 Eldorado ESC.

If you're interested, read on!

First, remove the 2 13mm bolts that hold down the beauty cover, and get that out of the way. You don't need that in place for what we're about to do.

Let's start with the front bank, and familiarize ourselves with what's going to happen. You're going to have to do this nearly blind on the backside, so lets start here.


That's the front bank in front of you. Part of it is the "cartridge" with the 4 coil packs in it. This is a coil-on-plug arrangement, so there are no ignition wires. 1 less thing to buy.

The wrench you see there is a 1/4 inch drive with a 10mm socket on it.

There are 8 bolts to remove. You can see the 4 across in the middle there. There are 4 more down low, not visible in this picture. They are not directly below, but off sideways to the left a little bit.

Also, you may as well remove the black plastic covering piece in the middle, that will just be in the way. You may have to pull the radiator hose towards you, slightly, to get it out of the way of the 4 lower bolts.


Here we see I removed the black plastic cover piece there in the middle, and the coil pack cartridge is pulled up and out towards me, all 8 bolts removed.

Note: you might have to pull out your oil dipstick, to get the cartridge out. I had to. Kept snagging on the yellow loop at the top, and I was afraid of damaging one or both items. Unplug the plug on the right if you want to, or just lay the cartridge carefully on top of the engine.


Coil pack is out. You see 4 black circles, those are rubber boots. There are springs inside, which connect the metal tabls on the coils to the top of the spark plug. The one on the left is pulled out some. Use a needle nose pliers, get a decent grip, pull straight out towards you.


Rubber boot is out. Hey, there's a spark plug! We're getting somewhere...

Note on the boots: if one shows signs of carbon arcing or other damage, all 8 are supposed to be replaced. Mine looked great. I reused all 8.


There's a new sparkplug. I'm going with NGK. Some people feel only the AC replacement should be used. These NGK's are Iridium, and available quite reasonably on Amazon.


Cehck your gap with a feeler guage. Check your owners manual for the proper gap. Mine was listed as .050 in my owners manual. I am told they vary. Obviously (or maybe not), to feel for a .050 gap, there is no feeler for .050. So, put together a .030 and a .020, press them together, and use that. Do this GENTLY. Don't force it!

These particular plugs were gapped too big out of the box. I had to make the gap smaller.


To get the plugs out, I use this. You're gonna need an extension. The hole is deep. My fingers have zero chance of reaching down there.


Put the socket in there, get it on the plug, and crank it out counter-clockwise.

When placing the new plug, remove the wrench handle. Just use the extension. I have a rubber-cushioned spark plug wrench there, so press your new plug in, insert it into the hole, and then spin the handle with finger pressure only. Make darn sure you're not cross-threading this!!! Finger pressure should be sufficient. You should get a good feel of the plug threading in.

When it bottoms, put a torque wrench handle on it and torque it to 15 pounds.

Put a small dabe of dielectric grease at each end of the rubber boot, and press that back down into place.

Hey, you did one!

Now, do the other 3 on this side. Exactly the same.


My car had these E3 things in it. So someone changed them once already, at some point. Very strange looking electrode on there. Never heard of E3.

Once you have changed all 4 plugs, you can carefully put your coil cartridge back in place. Make sure everything is lined up, including the spring in the middle, that goes in the depression in the middle of the engine. Press down gently, it should go down smooth, nothing binding or anything.

Replace the 8 10mm bolts you removed earlier... And don't forget to put your dipstick back in.

Done! With that side.

I'd like to tell you you're half done, but sadly, we're just getting started.

I hit a post limit once, so I'm gonna continue in a reply....

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Now then, on to the rear bank. Should be the same as the front, right??

Right. It is, actaully. Except...


There's your problem!!!

That's an air valve, mounted over the top of the coil cartridge you have to get out.

This is a real problem to get out. If you're tired, come back to this when you're fresh. It's a fun one.

First off, the valve is mounted to a black metal plate. The metal plate is bolted to the engine with 3 bolts. Start by taking those out. 2 are up top, one is sort of down below the valve. Heh heh, lucky for me, the last person who did this left off the third bolt down below, so I didn't have to bother with that.


Another view


Another view. Once those 3 bolts are out, you can move this thing a little.

Now, there is a steel line that comes into the valve from the right, or from the driver's side. It has a rubber fitting that connects to the valve. It looks like it should pull off, but it won't. On the back side of that line, you will see that there is a metal "tab" on the back of that line, and it is bolted down to the plate with a 10mm nut. Remove that nut, and then you can pull off the line from the valve.

Now, you will be able to move the valve, a little bit.

It is bolted to a steel line on the bottom, that leads down to the manifold.

There are two nuts on the back, on a flange, that have to come off.

You can try this leaning out over the engine bay, or you can put an old heavy moving blanket out over the engine, crawl out there, kneel on firm points of the engine (being very carefull at all times), and then at least work this thing with it right in front of you. I personally think kneeling on the engine was easier.

You can remove those nuts with either a really stubby 10mm ratchet (1/4 inch), or you can try a gearwrench.


That's a stubby ratchet there...


That's a gearwrench attempt. The gearwrench wouldn't move on the left side (passenger) nut, so I went to the stubby ratchet. Which barely moved. I was getting like 1 click per attempt, so this is a long tedious process, taking those two bolts off. Move the valve around a little if you can. It won't move much, but a slight move can improve your angle, and restore some of your will to live...

When you get those off. it will move. There's a little black plastic line on top of the valve, that pulls straight off, don't forget to do that before you get all excited and emerge from the engine bay with your prize....


Ha! It's off!!! I'm giddy with excitement... Never thought I'd see it come out.


Here's the valve, free at last...


This view of the bottom may help to see what was going on during that blind attempt to remove the two little nuts... It's got 2 threaded studs sticking out the bottom...


Again, before you get too excited and start pulling out the coil pack, unplug this wire here, which is laying across the thing, and will be in the way if you don't.


This again is the 1/4 inch drive, 10mm socket... A longer extension is a little easier. That extension is overkill. I don't have anything in between, sorry. And again, just like the first bank, remove the 8 bolts.

The back side is not silver, it's all black. Other than that, it's identical. Unplug the pack and get it out of the way.


Pack is out, the nearest boot is out. As you can see, it's identical to the other side.

These plugs may be in tighter than the other. I dunno if it's because there's more heat on the backside, or if the previous installer got carried away. I dunno. But the two middle ones back here were REAL tight.

So again, do all 4 of those, just like you did the front. This is doable leaning over the passenger side for the first three, and the driver's side for the last one. Drape the moving blanket, or an old towel, over the fender while you're doing this. Let's not scratch the mint Eldorado while we're doing this, eh??

And when you're done, re-assemble the whole mess.


There it is, reassembled and back in place. (g** d***** piece of ****....) Sorry, muttering. My 97 ETC didn't have that. Plugs were much easier before some genius decided to put an air valve right there...

Hey, light up the smoking product of your choice, grab your beverage of choice, have a seat, and bask in the warm smugness that is only enjoyed by someone who did it themselves and saved a bucket of cash...

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Very nice write up and photos. Thanks its good for the group

A couple of things however, you used dielectric grease, with the spark plug boots they say not to use it, because the boots are inpregnated with it, not sure about the coil packs, but if you get a miss, keep that in mind, the earlier manuals caution against the use of it.

Also, AC DELCO plugs say specifically NOT to smoke after handling their plugs!!! :lol: as you will get flu like symptoms!, not sure if the plugs you used have the same issue..

Good thread, Mike

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Well done Patrick and your words/pictures are certain to help guide others in the future.

My nagging feeling is-- maybe part of the reason you had to tackle the job was related to the E3 plugs you found installed. And I'm not convinced you made the "best" choice by installing new plugs other than ACDelco 41-987s. You will know for sure if you have to do this job again in less than 100,000 miles.


Drive your car.

Use your cell phone.


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  • 2 months later...
  • 6 months later...

Just out of curiosity. How long did this process take? I plan on tackling this in a few weeks in my baby, and wondering how much time I should have available. I'm a "average" grease monkey. I mean, it took me 3 hours to replace a belt/tensioner on my wife's Explorer.

2 or 3 hours for this?

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  • 4 weeks later...

Sorry Splitz, I've been away... I had a heart attack awhile ago, but I seem to be fine now. Went straight to the emergency room, and within minutes, straight to the cardiac cath lab... Now I'm like my own used luxury car... Throw a few parts at it, do a little work, good as new....

You're probably done by now, but I would say the front 4 were easy. An hour?? It was no biggie.

The rear bank, it's all gonna depend on how long it takes to get the air valve out of there.

When I got it out, I was beat. I went back the next morning and did the plugs, and put it back together.

2-3 hours for the back, unless you have a better way to do it than I did.

Hard to say if I had seen the write up first... I spent so much time trying to figure out how to get those nuts off....

I am happy to report my car is running fine.

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  • 1 year later...

because most all modern engines use aluminum heads (including the northstar) an anti seize lubricating compound should be use on the

sparks plug threads..

without it the plugs will probably not be able to be removed the next time you want to change them.

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because most all modern engines use aluminum heads (including the northstar) an anti seize lubricating compound should be use on the

sparks plug threads..

without it the plugs will probably not be able to be removed the next time you want to change them.

This is not always true, the AC DELCO plugs have an anti-seize nickel plating on the threads and using anti-seize on them can foul the electrode and cause a misfire. This is the reason they say to replace the plug once it is pulled and to NOT re-install it because the anti-seize is disturbed. THis is the reason I only use AC DELCO as I do not know if the aftermarket plugs have this plating

It is also unnecessary to use dielectric grease on the OEM ignition wires as it is impregnated into the boots and using additional dielectric grease can cause a misfire.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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