: Changing Spark Plugs on Northstar?



caddybrougham87
09-20-04, 01:26 PM
hi all this is my 1st post on these forums. well anyway, my father has an 1994 cadillac deville concours, and the spark plugs need to be replaced. he tried doing the job, but couldnt and broke a wrench in the process. i was wondering if someone could give directions or a step by step process on how to change the spark plugs for this northstar engine. also we are going to change the wires if anyone knows how to go about that, that would also be great. thanks

Paul

foo
09-20-04, 02:34 PM
It's real easy with a socket extension and a socket wrench with flexible head. The plugs are really in there tight though, if you can get an air impact to get them out it would be better but I got mine out ok without it

Roswell256
09-20-04, 04:18 PM
I have a 94 Concours and have replaced my wires and taken out my plugs

The easiest way that I've found to do this is to take the coil pack off the top of the engine.

When you look at the engine standing in front of it. The coil packs are to the back left. you can't miss them as its where all the plug wires terminate. There should be 3 screws if I'm correct. One on each side and one on the back. After unpluggin the two wires on the left and the two wires on the right, unscrew it and set it up on top of your enfine. Now pull the plugs in the back. Replace the plugs and then one by one. Pull the wire off of it. Match it to the same length one on the new set and replace the wire. Once you have the back done you can go ahead and put the coil pack back on if you'd like. Just put it on in the reverse order that you took it off.

Now do the fron. one by one take the wire off, match length, then replace. Its that simple. If you have any problems let us know. We will be glad to help.

eldorado1
09-20-04, 07:20 PM
I would highly recommend you NOT using an impact wrench on the spark plugs, unless you like removing the heads, and retapping the plug holes for larger plugs. If you broke a wrench, you must've been using one of them chinese wrenches... they're not in there all that tight, as long as the last person put antiseize on the threads (assuming it was changed after the factory ones)

ShadowLvr400
09-20-04, 08:26 PM
Removing the coil packs does make getting the rears out a lot easier. If he broke a wrench, the previous person over tightened or didnt anti-seize the plugs when installed. You'll have to figure out a way to get the leverage to break them loose. Additionally, you can spray some WD-40 or other greaser/deruster in there. Next time you start the car, it'll burn the stuff out with a bit of an odd smell, but not overly dangerous. (Just dont pour gallons in.)

BeelzeBob
09-20-04, 10:27 PM
Use an air impact to knock them out. The shock of the impact is a very effective way of removing the spark plugs in an aluminum head. It will not hurt the threads. You obviously do not want to install the new ones with an impact but taking the old ones out is commonly done with an impact with great success in my part of the woods..... If the threads are damaged with an impact then you would have surely damaged them with a normal socket and rachet....if you get them out at all.

Never use antiseize on spark plugs. The OEM plugs that GM provides are nickel plated on the shell to prevent seizure and corrosion but they will stick in the head pretty hard. Anti seize can cause severe overtorqueing of the plugs due to the slippery nature of it and it can easily foul the spark plug electrode and porcelean..especially if you every try to start another plug into the hole with antiseize on the female threads in the head.

eldorado1
09-21-04, 01:04 PM
Never use antiseize on spark plugs. The OEM plugs that GM provides are nickel plated on the shell to prevent seizure and corrosion but they will stick in the head pretty hard. Anti seize can cause severe overtorqueing of the plugs due to the slippery nature of it and it can easily foul the spark plug electrode and porcelean..especially if you every try to start another plug into the hole with antiseize on the female threads in the head.

I'm still going to use antiseize on my plugs... Granted, more than likely I'll never replace them again (assuming they last 100k), but I'll make it easy on the next guy ;)

"Most threads on spark plugs designed for aluminum head applications are precoated to reduce the risk of thread damage. If you’re in the habit of applying a drop of antiseize compound to the plug threads before they go in for added insurance, you might want to reconsider this practice. One vehicle manufacturer warns against this practice because antiseize acts like a lubricant and may allow the plugs to be overtightened—which can damage the threads. Their advice is to reduce the tightening torque on the plugs 40% if you decide to use antiseize on the threads."

growe3
09-21-04, 01:46 PM
I have not had any trouble removing the spark plugs. They can be tight, but it is not that big a deal.

I would never use an impact tool on a spark plug. There is no need to do so.
If the plug is that seized, I would rather rock it loose with a 1/2" drive ratchet, with a little penetrating oil and work it out; rather then "rip" it out with an impact ratchet.

To make it easy, I just use a 1/2" drive ratchet to crack them loose, then spin them out with my 3/8" drive ratchet.

To install them just us the 3/8" ratchet.

If you use a flex joint or better yet a flexible spark plug socket, there is also no need to remove the coil pack.

-George

caddybrougham87
09-21-04, 02:13 PM
thanks guys, keep the info coming if you got some. so far its been a big help. i will probably attempt to change the plugs and wires this weekend with my father.

CadiJeff
09-21-04, 08:41 PM
First of all, WELCOME!

hmmm broken wrench?................your sure this is a northstar and not a 4.9?(they still made those in 94 right?) The n* plugs are easy to change. Just get a plug socket,and an extender, the plugs are right there on top of the heads in the valve covers. It shouldn't take more than 20 min to do. if you are having problems geting to the rear ones try removing the strut tower brace. The wires are even easier just remove the protective plastic wire cover on the drivers side and replace them one at a time. While your at it you might consider replacing the coil packs being a 94 (asuming they are the origional) they are probably starting to wear out.
good luck

94CaddyConcours
09-21-04, 09:47 PM
I just changed my spark plug couple month ago. What kind of brand do the majority of Cadillac owner use OEM or Aftermarket.
-Bill

eldorado1
09-22-04, 02:54 PM
I just changed my spark plug couple month ago. What kind of brand do the majority of Cadillac owner use OEM or Aftermarket.
-Bill
<shrug> I think I put in autolite double platinums. I don't like Bosch's stupid 4/3/2 prong designs, so I had to have the shop order them :rolleyes2

caddybrougham87
09-22-04, 09:09 PM
great news all, my dad changed the spark plugs and wires today, and he said the car is really purring now. thanks for all your help.

peteski
09-23-04, 12:42 AM
<shrug> I think I put in autolite double platinums. :rolleyes2

I seem to recall recent spark plug thread where Bbob specifically recommended against using Autolite plugsin N* . Search the archive if you are interested.

But judging from your posts on this thread, you seem to disagree with Bbob in general...

Do what you like...

Peteski

94CaddyConcours
09-23-04, 05:36 PM
What wrong with using autolite?

Ranger
09-23-04, 10:03 PM
I seem to recall recent spark plug thread where Bbob specifically recommended against using Autolite plugsin N* . Search the archive if you are interested.

But judging from your posts on this thread, you seem to disagree with Bbob in general...

Do what you like...

Peteski
I too recall that thread. It had somthing to do with the wrong heat range and toasted the eingine.

eldorado1
09-25-04, 07:42 PM
I seem to recall recent spark plug thread where Bbob specifically recommended against using Autolite plugsin N* . Search the archive if you are interested.

But judging from your posts on this thread, you seem to disagree with Bbob in general...

Do what you like...

Peteski
Son of a mother... You people don't tell me these things ahead of time? :banghead:

http://cadillacforums.com/forums/showthread.php?t=19402&highlight=autolite+plugs

From what I can see, it's in reference to regular copper electrode plugs. I would assume the insulator design (and obviously electrode and ground tang) would be slightly different for the double platinums. I don't know this for sure, but I have been running them so far with no problems.

I don't disagree with everything Bbobynski says... He is quite knowledgeable. I do disagree with the antiseize and impact wrench thing though. Antiseize is very important on parts you want to be able to remove later. I have a story about impact wrenches and spark plugs... Once upon a time, there was a grand prix with a 3.1L v6. It had aluminum heads. One day, a guy came along, and attempted to remove the first spark plug with an impact wrench. (Of course, he waited until the engine cooled down like you're supposed to do :thumbsup: ) Upon his first try, he removed the spark plug successfully! Yay! Imagine the horror when he saw the threads in the aluminum head came with it ;) Moral of the story: go by the directions of others until you come upon a better way. :yup:

Pjs
09-26-04, 09:17 AM
Son of a Biatch..........

I just replaced my plugs a couple months ago w/ Autolite platinums...swear by the autolites, but then again, I've never had a N* before. Well...better safe than sorry...I'm going to go get a set of AC's right now.........

eldorado1
09-26-04, 10:40 AM
Son of a Biatch..........

I just replaced my plugs a couple months ago w/ Autolite platinums...swear by the autolites, but then again, I've never had a N* before. Well...better safe than sorry...I'm going to go get a set of AC's right now.........

Glad to see I wasn't the only one who didn't get the letter in the mail :D But if the plugs melt my engine, I'm gonna borrow bbob as a material witness, and get autolite to buy me a new engine :want:

peteski
09-27-04, 03:14 AM
Son of a mother... You people don't tell me these things ahead of time? :banghead:

<snip>
I don't disagree with everything Bbobynski says... He is quite knowledgeable.<snip> Moral of the story: go by the directions of others until you come upon a better way. :yup:

I'm glad I was able to shed some lite on those Autolite plugs (pun intended).
:coolgleam

Well, Bobynski (Mr. Northstar in my book) is the "other" person I listen to when I work on my engine. :cool:

Peteski
("ski" in our names is purely conicidental)

94CaddyConcours
09-28-04, 09:00 PM
Should it be the Bosch Platnium 2 or 4?

growe3
09-28-04, 11:20 PM
Should it be the Bosch Platnium 2 or 4?

I would say neither one.

I have used the Bosch Platinum 4 tip. I put them in shortly before a California smog check. I did pass but the readings were high. I also felt like there was a small power loss, hard to define. I kept them in a couple of weeks; I then put in a set of Champion double platinum tip. I could feel the engine was smoother and the power was back. Out of curiosity I went back and asked the guy if he would take a reading just to see if there was any emission difference. He was curious also, so no charge. The car was now reading normal, very clean emissions.

Go figure, I don't know why, but the Bosch definitely didn't do the job right.

I know the Champion double platinum tip plugs #7013 work fine. The AC 41-950 is also the correct plug for your engine.

I would advise using one of these plugs.

-George