Need advice on changing 90 SC spark plugs. It looks like a nightmare job...

flowerse123

Registered User
I have owned my SC since 1998 and have never changed the plugs. It's time, nightmare or not. Any adviced would be greatly appreciated, thanks, Eddie
 
I have owned my SC since 1998 and have never changed the plugs. It's time, nightmare or not. Any adviced would be greatly appreciated, thanks, Eddie

Eddie, there are numerous posts on this subject that detail how people change the plugs. It is intimidating the first time, but not too bad. For me, I do the driver's side from under the car and the passenger side from the top after removing the air tube from the TB to the MAF. The secret for me is a 1/4" sized ratchet that has a 3/8" size head, a 1" long extension, maybe a 3/8" swivel, and a spark plug socket. Good Luck
 
My advice is take everything out of the way. I know people say they change them easier from under the car, but I've never had any luck with that. My advice is for the passenger side, take the belt off and unbolt the AC compressor and hang it out of the way. Between that and taking off the intake tube, you will have plenty of room. The driver side is the tough one. I would rather spend a little more time to take everything out of the way and then have an easy time changing the plugs instead of fighting everything the whole way. First take the upper intercooler tube off, then take the intercooler out, then remove the power steering pulley and unbolt the bracket that goes from the power steering pump to the water pump. Next get under the car and remove the bolt that holds the lower intercooler tube to the accessory bracket. Once that is done, remove the 3 bolts that hold the driver's side accessory bracket to the head, and hang the whole bracket off to the side. Next unbolt the lower intercooler tube from the return plenum and slide it as far forward as you can. Doing this, you will actually have enough room to get your hand in there, and you can change the plugs on that side fairly easily. After the plugs are changed, just reinstall everything in the reverse order, make sure your intercooler tubes are sealed up, and you are good to go. After doing it several times, it takes me about an hour to get everything off the front of the motor, and another hour to reinstall everything, and then the plugs are easy once it is all off, so figure about 3 hours total to do plugs and wires, and it is a relaxing 3 hours since you can actually see what you are doing, as opposed to being pissed off and cursing and hurting your hands trying to contort into tiny spaces to get a plug boot off or on, or to start threading in the spark plug, only to maybe save a total of half an hour by the time the job is done.
 
My advice is take everything out of the way. I know people say they change them easier from under the car, but I've never had any luck with that. My advice is for the passenger side, take the belt off and unbolt the AC compressor and hang it out of the way. Between that and taking off the intake tube, you will have plenty of room. The driver side is the tough one. I would rather spend a little more time to take everything out of the way and then have an easy time changing the plugs instead of fighting everything the whole way. First take the upper intercooler tube off, then take the intercooler out, then remove the power steering pulley and unbolt the bracket that goes from the power steering pump to the water pump. Next get under the car and remove the bolt that holds the lower intercooler tube to the accessory bracket. Once that is done, remove the 3 bolts that hold the driver's side accessory bracket to the head, and hang the whole bracket off to the side. Next unbolt the lower intercooler tube from the return plenum and slide it as far forward as you can. Doing this, you will actually have enough room to get your hand in there, and you can change the plugs on that side fairly easily. After the plugs are changed, just reinstall everything in the reverse order, make sure your intercooler tubes are sealed up, and you are good to go. After doing it several times, it takes me about an hour to get everything off the front of the motor, and another hour to reinstall everything, and then the plugs are easy once it is all off, so figure about 3 hours total to do plugs and wires, and it is a relaxing 3 hours since you can actually see what you are doing, as opposed to being pissed off and cursing and hurting your hands trying to contort into tiny spaces to get a plug boot off or on, or to start threading in the spark plug, only to maybe save a total of half an hour by the time the job is done.
Correct me if I'm wrong, but if the car still has the stock bracket that connects the accessory bracket to the water pump, you will also need to remove the power steering pulley to remove that bracket, which people often have issues doing (I actually put that bracket back on 3 or 4 times during various engine installs before I wised up and left it off). Depending on the level of skill of the OP, a little bit of fighting changing the plugs from under the car will likely be easier than trying to chase a vacuum leak when the intercooler tubes don't get re-sealed properly.

I've also never removed the A/C compressor to change the passenger plugs, but I can see where that would give you better access to the plugs and is relatively easy to do.
 
Yes, that bracket requires removing the power steering pulley, and I did list that as one of the things to remove. I don't know why people have trouble with it. The tool is readily available at most parts stores, and it takes all of about 5 minutes to get the pulley off, and maybe another 10 to reinstall it. My car also has that bracket left off just cause it is one less thing to have to worry about, but that shouldn't make much of a difference in terms of which way do the plugs. Personally, when it comes to working on cars, I don't understand fighting something the whole way just to save a few minutes. If fighting it could save you a few hours, then maybe, but for doing plugs, it definitely isn't worth it to me. As for fighting vacuum leaks, using the teflon gaskets and a little bit of ultra-black RTV, I have never had a problem with it, and I would reccomend the same to the OP.
 
Heh heh, even though I can do much of engine work and repairs and stuff like that......needless to say, there are some things that I'd gladly pay someone else to do, just so I don't have to deal with the hassle of it. Changing spark plugs on these cars is one of those things. :D
 
I do it Kurt's way. Driver's side is so much easier from underneath, at least for me. A good quality flex head ratchet is a big help. So is a stubby ratchet. A boot puller is another huge help. That can be very hard ... the heat can really glue those boots onto the porcelain.
 
Some of us don't have the luxury of a lift. I do both sides from the top. It just takes a few days to heal but it's doable. You do need to move the stuff Kurt mentioned on the passenger side. I also disconnect the A.C. line at the dryer.
 
Some of us don't have the luxury of a lift. I do both sides from the top. It just takes a few days to heal but it's doable. You do need to move the stuff Kurt mentioned on the passenger side. I also disconnect the A.C. line at the dryer.

I don't have a lift, or even a garage. :confused:
 
Some of us don't have the luxury of a lift. I do both sides from the top. It just takes a few days to heal but it's doable. You do need to move the stuff Kurt mentioned on the passenger side. I also disconnect the A.C. line at the dryer.
I do have a lift today, but I have owned my car since 1994....long before I got my lift around 2006 or 2007. And depending on what is broken on my lift, I might still change them using ramps from underneath.
 
I do have a lift today, but I have owned my car since 1994....long before I got my lift around 2006 or 2007. And depending on what is broken on my lift, I might still change them using ramps from underneath.

Don't forget your piece of cardboard to lay on. Keeps the back of your head from getting scraped up. Also makes a surprisingly good insulator in wintertime ... if you can keep it dry. :D
 
My advice is take everything out of the way. I know people say they change them easier from under the car, but I've never had any luck with that. My advice is for the passenger side, take the belt off and unbolt the AC compressor and hang it out of the way. Between that and taking off the intake tube, you will have plenty of room. The driver side is the tough one. I would rather spend a little more time to take everything out of the way and then have an easy time changing the plugs instead of fighting everything the whole way. First take the upper intercooler tube off, then take the intercooler out, then remove the power steering pulley and unbolt the bracket that goes from the power steering pump to the water pump. Next get under the car and remove the bolt that holds the lower intercooler tube to the accessory bracket. Once that is done, remove the 3 bolts that hold the driver's side accessory bracket to the head, and hang the whole bracket off to the side. Next unbolt the lower intercooler tube from the return plenum and slide it as far forward as you can. Doing this, you will actually have enough room to get your hand in there, and you can change the plugs on that side fairly easily. After the plugs are changed, just reinstall everything in the reverse order, make sure your intercooler tubes are sealed up, and you are good to go. After doing it several times, it takes me about an hour to get everything off the front of the motor, and another hour to reinstall everything, and then the plugs are easy once it is all off, so figure about 3 hours total to do plugs and wires, and it is a relaxing 3 hours since you can actually see what you are doing, as opposed to being pissed off and cursing and hurting your hands trying to contort into tiny spaces to get a plug boot off or on, or to start threading in the spark plug, only to maybe save a total of half an hour by the time the job is done.

3 hours--is this what you'd estimate a shop would take to do? Or would it be less, since they can easily access the lower side of the car? Do some of the spark plugs have to be accessed from the top, or can all of them be accessed from the bottom? I'd imagine, in theory, if a shop has a hoist, that they can put a light from down below and see it better, which would save time.

You mentioned "cursing" and being pissed off. I imagine i'd be doing a lot of this if I were to try to do it myself on the SC.

:mad: dropped a wrench :mad: can't see in there properly :mad: spark plug boot broke off on the plug :mad: why didn't I make someone else do this and pay them to get angry and be demoralized, while I sit at home and relax? :mad::mad::mad:
 
I just did the plugs and wires on my 95. the hardest part is getting the car up on the jackstands. After that I did 5 from under the car and the front pass side from above, Just unbolt the ac comp and move it to the side.:)
 
3 hours--is this what you'd estimate a shop would take to do? Or would it be less, since they can easily access the lower side of the car? Do some of the spark plugs have to be accessed from the top, or can all of them be accessed from the bottom? I'd imagine, in theory, if a shop has a hoist, that they can put a light from down below and see it better, which would save time.

You mentioned "cursing" and being pissed off. I imagine i'd be doing a lot of this if I were to try to do it myself on the SC.

:mad: dropped a wrench :mad: can't see in there properly :mad: spark plug boot broke off on the plug :mad: why didn't I make someone else do this and pay them to get angry and be demoralized, while I sit at home and relax? :mad::mad::mad:

I think book time for plugs on an SC is more like 5 hours, and the reccomended procedure is to take everything off from up top the way I said, so figure if you paid a shop to do it, you are probably looking at $500 plus parts. Personally, I have never successfully changed plugs from underneath, even in a shop on a lift. Maybe I am missing something, or maybe my hands are too big to get in there, but every time I have tried, I have gotten stuck either with getting the boots on or off, or trying to thread a plug back in, or something, and in the end I had to go from the top to do it anyway, so now I just don't waste my time going underneath, and just go right to taking it apart from up top. This is why, if you are doing it yourself, I reccomend just go right to taking everything apart and going from up top. If you do it that way, it may take some more time, but it is pretty easy and straight-forward, so there will be no cursing, busted knuckles, or scratched up forearms. If you do it on a Saturday, start in the morning and you will be able to take your time and definitely get it done the same day.
 
I think book time for plugs on an SC is more like 5 hours, and the reccomended procedure is to take everything off from up top the way I said, so figure if you paid a shop to do it, you are probably looking at $500 plus parts. Personally, I have never successfully changed plugs from underneath, even in a shop on a lift. Maybe I am missing something, or maybe my hands are too big to get in there, but every time I have tried, I have gotten stuck either with getting the boots on or off, or trying to thread a plug back in, or something, and in the end I had to go from the top to do it anyway, so now I just don't waste my time going underneath, and just go right to taking it apart from up top. This is why, if you are doing it yourself, I reccomend just go right to taking everything apart and going from up top. If you do it that way, it may take some more time, but it is pretty easy and straight-forward, so there will be no cursing, busted knuckles, or scratched up forearms. If you do it on a Saturday, start in the morning and you will be able to take your time and definitely get it done the same day.

5 hours? 500 bucks? Wow. That's enough of a bill to make me want to do this, myself. Thanks for the info on this......i'm not sure if my plugs need to be changed, but want to change 'em out just for my own piece of mind, and throw new MSD wires and a Screamin' Demon on there, too. While the assembly is off, I think that i'll just do a whole bunch of other things (seal up the IC.....I may have a slight vacuum leak; raised SC top; double IC; port the plenum when I put a 75mm throttle body on, etc).

Has anyone had success going from the bottom, only? If they haven't, i'll likely just go from above and remove everything.

These engine bays are TIGHT.
 
I did mine going in from below on the driver's side and above on the pass. side. Didn't remove anything to aid access other than the rubber intake tube pass. side. Next time I'll at least also swing the A/C compressor out of the way. I have the benefit of a large inventory of hand tools, etc. which aid access. As with so many things under the hood of an SC, smallish hands can be an asset.

Most of my effort was removing the old plug wire boots. Installed new wires and had to redo one on the driver's side to cure a slight miss. Found what might be the wrong plugs installed by a previous owner.
 
5 hours? 500 bucks? Wow. That's enough of a bill to make me want to do this, myself. Thanks for the info on this......i'm not sure if my plugs need to be changed, but want to change 'em out just for my own piece of mind, and throw new MSD wires and a Screamin' Demon on there, too. While the assembly is off, I think that i'll just do a whole bunch of other things (seal up the IC.....I may have a slight vacuum leak; raised SC top; double IC; port the plenum when I put a 75mm throttle body on, etc).

Has anyone had success going from the bottom, only? If they haven't, i'll likely just go from above and remove everything.

These engine bays are TIGHT.

That coil pack has been known to cause issues from time to time. The stock piece seems to work better overall. I would keep the stock one if it works ... save your $150.

The MSD wires may be good, I don't know. The stock wires are fine for sure. The only question is, what shape are the old ones in? So those are probably a good thing to replace now.
 
That coil pack has been known to cause issues from time to time. The stock piece seems to work better overall. I would keep the stock one if it works ... save your $150.

The MSD wires may be good, I don't know. The stock wires are fine for sure. The only question is, what shape are the old ones in? So those are probably a good thing to replace now.

The car has a mix of stock wires and Belden high performance ones. Probably more just a uniformity thing on that end that i'd go with some MSD 8.5mm's. I'd assume that a boot or two may be corroded or stuck to the spark plug terminals, but that's just a guess right now.

I've ran a Screamin Demon on my '99 Stang 3.8 with no problems. It's the same coil on both engines. I'm not sure about the reliability with the DIS on these engines, but I think that people start to have problems with these coils when they open up the spark gaps too wide. The coils don't provide any top end HP, but they give good HP and torque throughout the power curve and fire better throughout the RPM range.
 
Change out the plugs each year. Just copper 103s. Started it up this year for the first time and it appears its time to change them. Takes about an hour. Under on the D side and remove the air intake tube on the P side.
 
Got a quote from my mechanics.....it's $150 for the labour on this, and I made sure that they knew that it was the 3.8 supercharged. That's reasonable.
 
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