Right amount of torque installing spark plugs

mercury
grandmarquis

#1

Hey all :wave:, so I have a misfire on cylinder #1 that’s tripped my check engine light ( got the codes read at my local auto zone). And I think I want to give it a try and replacing them myself… I’ve watched and read many articles on how to and it doesn’t look too daunting getting to the plug… the only thing that I came across that led me here asking for adivice is the amount of torque that’s required in installing the new plugs. I know Ford recommends 13 foot pounds, I think I’ll have to go back and check on that. but most of the videos that I saw and one in particular by a Ford tech says that it’s best to torque them down to 23-25 foot pounds because at the factory specifications of 13 foot pounds they’ve been known to “blow out” of the head? Anyway, I definitely don’t want that to happen so I figured I’d ask for your guys opinions and advice on this matter


#2

I’ve never used a torque wrench for sparkplugs.

If you want to use a torque wrench, the torque spec might actually be in your owners manual.


#3

Ford may have issued a TSB for your engine, with updated torque recommendations. It’s worth some research.


#4

I’ve never used a torque wrench when installing spark plugs.

This is because on some applications, you can’t get a straight access to the spark plugs. And if you’re using a swivel joint to gain access to the spark plugs, a torque wrench is useless.

I use the old tried and true method when tightening spark plugs.

If the spark plug has a tapered seat, I tighten the spark plug until it seats, and then tighten it 1/16 of a turn.

If the spark plug has a gasket seat, I tighten the spark plug until it seats, and then tighten the spark plug 1/2-3/4 of a turn.

Tester


#5

I’ve never used a torque wrench for plugs either. Just give 'em a good tighten with the ratchet. Don’t hulk out on them or anything - get them tightened to where they don’t turn anymore and then give them a moderate crank. If you happen to be overly muscular, adjust that down to a very light crank. :wink:


#6

I just hold a 2/8 drive ratchet by the head in my fist and tighten by rotating my wrist.


#7

I can guarantee you that if you torque them to 25 Ft. Lbs that they’re going to strip out before they tighten. And the plugs do not blow out because they’re torqued to 13 Ft. Lbs.

Tighten them as Tester mentions. For me, I’ve never torqued a plug in my life and that’s a lot of plugs. Just snug them up…they won’t come out.


#8

Is that the same as a 1/4 drive ?


#9

I’ve never used a torque wrench either. Just snug them up by feel. For the first time in 50 years though I paid someone else to change mine and get their hands all scraped up. I dunno if he used a torque wrench or not.


#10

Appreciate all the responses so far! :slight_smile: I figure i might as well just change them all out while I’m at it. But the consensus is to not use a torque wrench and just use a ratchet/handntightening then when installing them and giving them one last snug after they are seated in.

Should I use anti seize on the threads? Or is that more of a preference that some people use while others don’t ?

Also one last thing, should I just use mortorcraft boots&plugs? Or are there other brands out there that make better plugs ? I read that NGK makes good spark plugs but maybe just OEM would be better?


#11

If the cylinder heads are cast iron, which I believe is true on your Grand Marquis, a small amount of anti-seize on the plug threads will help in future removal.

Just change the plugs first. And if the engine runs smoothly with no Check Engine light, you found the miss.

Tester


#12

Always stick with OEM, aftermarket plugs often cause problems down the road.


#13

Might want to consider the wires too at the same time.


#14

You didn’t state the year of your car, so no way for me to check, but if the factory service manual says the recommended torque is 13 ft-lb, then best to use that. If you’re concerned they plugs will work themselves loose, just check them every month that they are staying in tight as you first installed them. The discrepancy might be that on older engines the threads in the head become a little carbonized so at the recommended torque they aren’t twisted in quite enough b/c the carbon is preventing the plug from turning freely. Suggest to take a look at the threads with a bright flashlight/mirror. Pretty sure that overtightening will end up resulting in much more work and cost for you than under-tightening with even a weekly check of the plugs until you are certain they are staying put.

I always use a torque wrench on my Corolla’s plugs, which are very easy to access, a straight shot. But on my Ford’s v8 I only use the torque wrench for the plugs at the front of the engine. For the harder to reach ones, requiring an angled u-joint adapter approach, I do it by feel, based on what it felt doing the easier ones, and how many degrees I had to twist them from first contact.

I always use a tiny dab of some form of anti-seize, both on my Corolla, and my Ford.


#16

I believe after '97 Ford went to the coil on plug set up on these cars… so according to my knowledge it’s just the boots and plugs that need changing on my model… but I’ll double check on that


#17

I’m sorry, it’s a '98. And you’re right it is 13lbs of torque. The plugs on this care are pretty simple to get to so that’ll make my job a little easier. I was just unsure because of what I heard on some of the YouTube videos


#18

That was my guess.


#19

YouTube can be helpful or detrimental.


#20

Well that wasn’t too hard!. Got the new boot and plug in put into place, started up the car and she’s running pretty smooth with no light on the dash. I Made sure i hand tightened them first when I was installing them and then used the ratchet to finish the job and they went in without a hassle.

Anyways, I Can’t thank all you cartalkers enough for some of your advice and opinions on the matter! :slight_smile:


#21

This is the old plug