Several Failed Attempts Installing Spark Plugs

[Rhinoserious]

Well, after some time researching how easy/nooby a spark plug replacement job is, I figured I would jump in and try to replace my own since I just bought my car, it's almost at 30k miles, and I want the experience.

Well, I heard the most spark plugs are pre-gapped, and the SP-532 are advertised as such, so I didn't bother gapping when I tried it the first time (had heard of gapping previously).

Well, the engine rumbled and shook when any amount of boost applied and idle was rough, so took them out and the porcelain was cracked on all of them and broken on one.

So, I attempted a couple more times with different gaps. Tried .025, .028, and .030 again (OEM gap).

.025 and .028 were both wrong as there was still some misfire under boost, with .030 being VERY rough like first time and causing porcelain breakage once again.

I just want my car back. I scheduled a service on thursday, gonna deal without a car for now I suppose.

I know that spark plugs are supposed to be torqued, but I've talked to several friends that have done spark plug changes and none of them use a torque wrench, just tighten it until you cant anymore with your normal wrench.

Has anyone else ran into this before? Or heard of anyone not being able to get spark plugs right?

 

[maestromaestro]

Cracked porcelain? Did you go like an ape with “the tightening”?
It’s 14 lb-ft, I believe. Very little. Check your coil packs. The SP that you referenced should be correct for the FiST. Here’s a useful How To:

https://www.fiestastforum.com/threads/diy-spark-plug-change-for-fist.6828/

 

[M-Sport fan]

Are you sure that these are the correct plugs?

The porcelain surrounding the center electrode/tip should NOT be cracking at all, on the correct size/reach plug, unless the detonation/pre-ignition is off the charts (like the engine can not even idle, let alone run rough and shake).

Did pieces of the porcelain actually fall onto the tops of the pistons?!?!
You DO NOT want that as it could take out your turbo's blades on the exhaust side.

In reference to mm's post above, is it the top portion of the plug that is cracking (what the coil boot attaches to), or the porcelain around the tip, in the combustion chamber, like I was referring to??

 

[New_Daily]

As Others have suggested your issue seems more serious than than just the install. Torque is only 10 ft-lb I believe. I just did Ruthenium plugs custom pre-gapped from Ron at Whoosh to .028 and it runs perfect.

However having said that, for how ”basic” a spark plug change is, it can be one of the most nerve wracking of the standard maintenance jobs on a car. You’re threading right into head and if something goes wrong.......

A couple months ago I did plugs on my Tacoma. Toyota. Runs forever. And on the passenger side 2 of the plugs I had to use a 14” breaker bar the ENTIRE time I was unthreading the old plugs. I was shitting bricks the entire time thinking I was totally screwed. But got the plugs out in the end. No issue. Just put a good amount of anti seize on the new ones.

 

[slopoke]

I know that spark plugs are supposed to be torqued, but I've talked to several friends that have done spark plug changes and none of them use a torque wrench, just tighten it until you cant anymore with your normal wrench.

I would suggest you get a torque wrench, even if it's an inexpensive one from Harbor Freight. It'll save you from having an "oh shit" moment, like when the force to turn the wrench on the plug or any other fastener for that matter suddenly goes away. As in the threads are now stripped. Cheap insurance compared to having to pull the head and pay to have a thread repair installed.

 

[Fiestig]

I know that spark plugs are supposed to be torqued, but I've talked to several friends that have done spark plug changes and none of them use a torque wrench, just tighten it until you cant anymore with your normal wrench.

Just painful to read.. Its ok though..

1. Nothing should be cracked or broken on the plugs. If broken it will foul causing rough idle/misfire as the insulator is damaged
2. Can't tighted until you can't tighten anymore is not a good process to follow for many modern cars. If you don't have a torque wrench: Tighten til just barely snug and then an extra quarter turn is about perfect.

 

[Rhinoserious]

Are you sure that these are the correct plugs?

The porcelain surrounding the tip should NOT be cracking at all, on the correct size/reach plug, unless the detonation/pre-ignition is off the charts (like the engine can not even idle, let alone run rough and shake).

Did pieces of the porcelain actually fall onto the tops of the pistons?!?!
You DO NOT want that as it could take out your turbo's blades on the exhaust side.

In reference to mm's post above, is it the top portion of the plug that is cracking (what the coil boot attaches to), or the porcelain around the tip, in the combustion chamber, like I was referring to??

So, it was the top of the plug which the coil boot attaches to. That's the part that has always cracked when the gap is too large. Pieces of the porcelain did NOT fall onto the pistons. The one time a plug was broken apart (with pieces already fallen off) I managed to get the pieces out before extracting the plug.

I'm 100% they are correct! SP-532 every time. Advanced auto parts sold me some bosch ones that "fit my vehicle" even though they actually only fit dodges, jeeps, and chryslers. That was frustrating.. the misfires were VERY apparent when I tried installing those.

I just remembered that I'm getting my car registered on monday so I may just have to go to the auto shop tomorrow and get a torque wrench and new plugs, and just try again, but with correct tightening and a .028 gap.

 

[Ford ST]

What type of socket are you using?
Is it possible the socket is damaging the spark plug?

When I do spark plugs I use a high-quality spark plug socket. I also thread them in by hand with the socket until they stop to make sure I don't cross thread. Sometimes I use a torque wrench most of the time I just tighten them up a little bit more with a ratchet.



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[Rhinoserious]

What type of socket are you using?
Is it possible the socket is damaging the spark plug?

When I do spark plugs I use a high-quality spark plug socket. I also thread them in by hand with the socket until they stop to make sure I don't cross thread. Sometimes I use a torque wrench most of the time I just tighten them up a little bit more with a ratchet.



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I use a magnetic one I bought from a local auto store(The big 3, autozone, o reilly, advanced). It's pretty high quality I think, but I've never shopped anywhere else except those places and harbor freight, so my version of "high quality" may be different from you guys. I don't think its the socket, only time all the plugs get damaged is when they're all set to a gap that's too big.

Part of the problem may have been me just tightening too much, but we'll see later today. Maybe I'll finally get it right, who knows?

 

[wetwea33]

Oof this is a very cringe worthy post. hand thread the plugs down with the extension till you cant turn so you make sure the plug isn't cross threading in. then use the socket and give it maybe a quarter turn. You can use a torque wrench but for something so simple I really dont find it necessary and its not a rotating part. If you have trouble doing this I would just leave working on the car to a professional.

 

[DEss]

So, I attempted a couple more times with different gaps. Tried .025, .028, and .030 again (OEM gap).

.025 and .028 were both wrong as there was still some misfire under boost, with .030 being VERY rough like first time and causing porcelain breakage once again.

You broke 2 sets of motorcraft plugs already? Do you have pics?

How was the motor running before you changed the plugs? If it was running fine, measure the gaps of the old plugs and put them back in.

I'm surprised the YouTube vids would suggest to tighten til you can't tighten anymore. I recommend you try to thread them in by hand and only use the rachet for the final 1/4 to 1/2 turn. And, even then, choke up to the head of the ratchet to reduce the chance of applying too much torques.

DEss

 

[Capri to ST]

This thread reminds me of the first time I put spark plugs in my old Capri which is the reason for my forum name here. They were incredibly easy to get to so I thought I would do it myself. I will fully admit my mechanical skills are crappy, so I asked my professional mechanic friend how to do it. He echoed what you guys have said on here, don't tighten them too much. I then proceeded to tighten them too little. Next time I drove the car, there was this incredibly loud very upsetting hammering type sound, bat bat bat bat bat. I popped the hood, and one of the spark plugs had blown out of the cylinder and was hanging by the plug wire.
I called my mechanic friend all worried that I had caused major engine damage, and he laughed and said that's one of the few times he's heard of someone tightening them so little that one blew out, but that it sounds a lot worse than it is, and the car was probably fine. It was, it ran great for many years after that. Next time it needed spark plugs I took it to a shop.

 

[Ford ST]

Most shops will do this on a walk-in basis it's about a 15-minute job.

I can't draw a straight line with a ruler there are preschoolers that have better penmanship than me it's embarrassing big time. My point is sometimes we're just not good at things and maybe working on cars is not for you. Allow guys like me to do it for you.


If you have your old spark plugs and they are not damaged put those back in.



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[RubenZZZ]

You’ll get a misfire at idle if your coil pack isn’t connected properly.

The boot is long enough that it’ll miss the spark plug tip and sit on the side. It’s possible the interior clasp did not grip the tip of the plug as well.


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[M-Sport fan]

I use a magnetic one I bought from a local auto store(The big 3, autozone, o reilly, advanced). It's pretty high quality I think, but I've never shopped anywhere else except those places and harbor freight, so my version of "high quality" may be different from you guys. I don't think its the socket, only time all the plugs get damaged is when they're all set to a gap that's too big.

Part of the problem may have been me just tightening too much, but we'll see later today. Maybe I'll finally get it right, who knows?

The gap should have NOTHING whatsoever to do with the upper body of the plug getting broken/cracks.
It is totally how they are being installed into the head (over torqued, or 'angle-torqued') which results in that happening.

 

[TyphoonFiST]

First off....NEVER EVER USE a ratchet to install the plugs. The only time to use a Ratchet is in removal. They need to be started out by hand with an extension and proper socket. Then spun down to where they cannot be spun by hand with the Extension anymore. Then you should use a Torque wrench and put them to spec. Did you put dielectric grease into the coil boot? If so.....wrong again. Dielectric grease should be used on the sides of the spark plug porcelain where the coil boot meets the plug to avoid sticking/ melting over time. If there is too much dielectric grease used it will kill the transfer of current from the coil pack through the spring that runs down to the spark plug terminal/ tip....Hence the Di in Dielectric. Ill put money its a coil thats not seated/on correctly...hopefully. Good luck!

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[Rhinoserious]

Little update here!

Thanks for all the help/advice guys.

I DO think the gap directly caused porcelain damage, there is literally nothing else that could have. Was ultra careful upon insertion and removal, like one piece of advice in here I did hand tighten using the extension I had, and only actually tightened it snug with a ratchet at the end. AND there was never any porcelain damage with smaller gaps. I definitely disagree that it couldn't possibly be the gap.

Anyways, today I had a friend drive me to autozone, picked up some new plugs, same as all the rest I've used, SP-532. Bought a gauged/metered torque wrench(with the ft. lbs. display, not clicks) as well so I could tighten accurately. Got home, measured the gap on all 4, they are all right around .028, which is fine by me. Didn't mess with the gap, installed them, torque'd to spec, and my car works perfectly fine now with the expected amount of power and no misfiring when boost is applied.

I'm not gonna take the advice about leaving future car work to the pro's... I'm gonna keep learning on my own car, doing my own work, and making mistakes along the way. Of which there will likely be many.
I did replace my rear brakes as my first job (which included replacing a caliper due to a seized piston) so I'm confident I'll be fine goin forward.

I also did not use any dielectric grease.. Just a small amount of blue threadlocker on the threads of each plug.

 

[DEss]

I also did not use any dielectric grease.. Just a small amount of blue threadlocker on the threads of each plug.

If a youtube vid suggested to put loctite on the sparkplug threads, I suggest you stop watching that person.

DEss

 

[TyphoonFiST]

Little update here!

Thanks for all the help/advice guys.

I DO think the gap directly caused porcelain damage, there is literally nothing else that could have. Was ultra careful upon insertion and removal, like one piece of advice in here I did hand tighten using the extension I had, and only actually tightened it snug with a ratchet at the end. AND there was never any porcelain damage with smaller gaps. I definitely disagree that it couldn't possibly be the gap.

Anyways, today I had a friend drive me to autozone, picked up some new plugs, same as all the rest I've used, SP-532. Bought a gauged/metered torque wrench(with the ft. lbs. display, not clicks) as well so I could tighten accurately. Got home, measured the gap on all 4, they are all right around .028, which is fine by me. Didn't mess with the gap, installed them, torque'd to spec, and my car works perfectly fine now with the expected amount of power and no misfiring when boost is applied.

I'm not gonna take the advice about leaving future car work to the pro's... I'm gonna keep learning on my own car, doing my own work, and making mistakes along the way. Of which there will likely be many.
I did replace my rear brakes as my first job (which included replacing a caliper due to a seized piston) so I'm confident I'll be fine goin forward.

I also did not use any dielectric grease.. Just a small amount of blue threadlocker on the threads of each plug.

Who is the youtuber that told you this?!?! This should be rank pulled and demoted from any type of advice given in life ever.....if this is for real they should really think about doing us all a favor and even mother nature.

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[SrsBsns]

I'm all for people learning to work on their own cars. Seems like too few people know how to even change a flat tire these days, let alone change spark plugs. But some mistakes can be fixed and some can lead to SERIOUS damage.

You should not have put loctite on the plugs. There is no reason to do this and will make changing the plugs in the future more difficult than it needs to be. You can use anti-seize (I don't) which will prevent the threads from sticking... which is what treadlocker is meant to do.

There is good and bad information on youtube. The problem is that if you follow the instructions from someone and, even if they get the results they want, if you make a mistake or it doesn't work for you, you're responsible and out for the time and $$ it takes to fix it.

I recommend finding a competent friend to work on the car with you or spend some time with a shop manual. Get the right parts, the right tools, do your research and stay safe.

Edit: if you just put threadlocker on, I HIGHLY recommend you go and pull the plugs now and wipe it off if you still can.