Using impact driver to r/r Spark Plugs

[The Critic]

One of my friends has started using an impact driver (not impact wrench) to remove and reinstall spark plugs on cars that come in.

He says his procedure is to break the plugs loose (slightly), then use an impact driver to remove the plugs. For reinstall, he says he screws the plugs in by hand for the first few threads, then runs 'em down with the impact driver...and finishes off with a torque wrench.

With this procedure, he's claiming that he is able to do the job in under 40 min while the book time is around 100 minutes.

Now, with a cold engine, assuming that the impact driver is not exerting a large amount of torque - I can see this being safe. Mazda put out a TSB a while back (#01-036/06) stating to never use impact tools to remove/reinstall plugs, but after watching the recent Ford 5.4 video, I wonder if it's actually a viable time-saver if done properly?

Thoughts? Personally I'm not brave enough to try it, but...

 

[Brybo86]

I would think removing a spark plug with an impact would be fine. but...

I would NEVER use any kind of impact to reinstall plugs, Always thread by hand then use a torque wrench to finish. What happens when he strips out the threads? Whoop$$$

Plugs are normally like 10-20 ft-lbs of torque. How much torque is this impact driver he is using?

Also I don't see how using an impact can shave off 60% of the job time. Mb like save 3 minutes.

 

[The Critic]

Originally Posted By: Brybo86
I would think removing a spark plug with an impact wouldn't be too bad...but..

I would NEVER use any kind of impact to reinstall plugs, Always thread by hand then use a torque wrench to finish. What happens when he strips out the threads? Whoop$$$

Plugs are normally like 10-20 ft-lbs or torque. How much torque is this impact driver he is using?

Also I don't see how using an impact can shave off 60% of the job time. Mb like save 3 minutes.


The impact driver alone doesn't save 60% of the time. Having done the job before, I think it saves about 20 min from manually loosening and running down the plugs.

I think his Makita impact driver is similar to mine - about 120 ft lbs max; obviously it has a variable speed trigger.

 

[FowVay]

This is precisely why I NEVER take a vehicle to a car garage.

 

[KrisZ]

Just wait until he gets really hard to remove spark plugs and ruins the threads.
I could only feel safe using this method in iron heads, but in aluminum, forget about it.

 

[toneydoc]

That dude has some good cajones. I would NEVER do that to a spark plug. I always hand tighten them. And I always put a small amount of antiseize and have never had a problem getting them out or a bad thread situation. I am sure it will only take one plug with a problem to convince him that saving a few minutes is not worth the stress that one plug will cause him for a while.

 

[Kruse]

There are some videos out there were some Ford techs are using the impact to remove them on the 5.4 heads with the problematic spark plugs. I can see them doing that. But there is no way I'd use it to install them, even if it's just to save a little time. I know you said impact driver and not impact wrench, but by using your hands the whole way, you get a feel if there are any problems with either the threads of the heads or the plugs. IMO, he's taking a bad short cut.

 

[chestand]

I removed plugs recently from an Acura 3.2 head. Had I used and impact gun, I would have been stripped out at least two of the holes.
Plugs that have gone a long time in aluminum heads are sometimes difficult to remove and save the head's threads. I used a technique of back off slightly/soak w penetrating oil/wait/repeat and all came out well.

 

[scurvy]

If I understand this correctly... he breaks the plugs loose by hand and then uses an impact driver just to remove them. Then he starts the new plugs by hand and uses an impact driver to run them on, finishing with a torque wrench.

So all he's using it for is to spin the manually loosened plug out and the manually threaded plug back on? I have a hard time believing this allows him to do the job 60% (or even 20%) faster. And if he's using a cordless impact that can generate 120 ft-lbs, he's one trigger slip away from buying the Time-Sert 3221 kit.

An air ratchet will do the same thing without the risk of grossly over-torquing the spark plugs. Some folks get away with doing dangerous things all the time safely, perhaps your friend is one of those people.

 

[SwampSurvivor]

Originally Posted By: scurvy

So all he's using it for is to spin the manually loosened plug out and the manually threaded plug back on? I have a hard time believing this allows him to do the job 60% (or even 20%) faster. And if he's using a cordless impact that can generate 120 ft-lbs, he's one trigger slip away from buying the Time-Sert 3221 kit.


HE isn't. The CAR OWNER is. It's ridiculous when mechanics who should know better do careless things like that to save time.

I bet he generates a lot of extra income from stripped heads.

 

[The_Jeff]

I fail to see the time savings as well. I break loose with a 10" bar then from there on out use a stubby ratchet and foot long extension. Usually goes so smoothly I hold the extension in one hand and spin the ratchet with one finger on my other hand.

OTOH something like a transmission pan with 20 bolts or an ecotec air filter contraption with 7 torx screws I break out the cordless drill with "clicky torque" gizmo and proper adaptors to spin down and save time. (Though I still break loose manually.)

 

[scurvy]

Originally Posted By: Miller88
HE isn't. The CAR OWNER is.


My post was in response to the OP and we both referred to the person removing Triton spark plugs with an impact in the third person singular.

Not sure why so many pronouns are being flung around.

Originally Posted By: elejefino
OTOH something like a transmission pan with 20 bolts or an ecotec air filter contraption with 7 torx screws I break out the cordless drill with "clicky torque" gizmo and proper adaptors to spin down and save time.

Something like that you can certainly benefit from a motorized driver. I've found plenty of uses where my cordless drill and a socket or hex adapter works wonders (like with Ikea furniture). Even removing spark plugs from a Triton I could see some value in using an impact (although still risky) but never for installing them.

 

[JHZR2]

Granted it is a different item, but I used an impact to remove the diesel injectors on my MB when I was getting them balanced. The recommendation was to do so because the sustained force of using a regular bar can cause more problems than the slight impact to break them free, FWIW. Worked fine.

 

[SwampSurvivor]

Originally Posted By: scurvy
Originally Posted By: Miller88
HE isn't. The CAR OWNER is.


My post was in response to the OP and we both referred to the person removing Triton spark plugs with an impact in the third person singular.

Not sure why so many pronouns are being flung around.

Originally Posted By: elejefino
OTOH something like a transmission pan with 20 bolts or an ecotec air filter contraption with 7 torx screws I break out the cordless drill with "clicky torque" gizmo and proper adaptors to spin down and save time.

Something like that you can certainly benefit from a motorized driver. I've found plenty of uses where my cordless drill and a socket or hex adapter works wonders (like with Ikea furniture). Even removing spark plugs from a Triton I could see some value in using an impact (although still risky) but never for installing them.


I mean that the mechanic stripping spark plugs using an impact gun isn't going to be eating any of the cost of the heli-coils. He's just going to tell the customer that their spark plugs stripped and the car owner will be paying for the extra parts and labor.

 

[Trav]

If its the Makita 18v impact gun i'm thinking about what's the problem?
He is breaking them by hand and using this thing just as a driver not an impact, for long threaded plugs in hard to reach locations or with little movement it will save time.

It sounds like he is just running them down at a slow RPM and not impacting at all putting them in. As long as he is starting the threads by hand first also no problem.
I run transmission bolts up all the time with this tool at low rpm, it stalls at less than 1 ftlb then i snug them with a small 1/4" ratchet, i get a full turn or more with that after the driver stalled.

I think folks are freaking because of the term "impact", he is using it as nothing more than a very low torque driver to run long threaded plugs if i read your post right.
He could use a very small cordless drill/driver for the same thing.

 

[bepperb]

It passes the "it should be ok" test.

It doesn't pass the "would you want it done on your car" test.

I wouldn't rip someone for doing it, but they wouldn't be on my A list either. And I'm sure there are instances where it might be best practice, but it certainly shouldn't be the default for all spark plugs.

 

[Vikas]

Originally Posted By: JHZR2
Granted it is a different item, but I used an impact to remove the diesel injectors on my MB when I was getting them balanced. The recommendation was to do so because the sustained force of using a regular bar can cause more problems than the slight impact to break them free, FWIW. Worked fine.


This actually makes more sense but for some reason it is looked down upon here. Do you recall where you got the recommendation from? Was it from a factory manual?

 

[Trav]

Originally Posted By: bepperb
It passes the "it should be ok" test.

It doesn't pass the "would you want it done on your car" test.

I wouldn't rip someone for doing it, but they wouldn't be on my A list either. And I'm sure there are instances where it might be best practice, but it certainly shouldn't be the default for all spark plugs.


I guess you could say the guy that uses a ratchet shouldn't be on the A list either.
I guess a good mechanic carefully removes every bolt with a box wrench and the best ones use a open end wrench 1/4 of a turn at a time. LOL

 

[Doog]

Impact gun to remove plugs = Ok
Impact gun to install plugs = Not Ok.

 

[bepperb]

Originally Posted By: Trav
Originally Posted By: bepperb
It passes the "it should be ok" test.

It doesn't pass the "would you want it done on your car" test.

I wouldn't rip someone for doing it, but they wouldn't be on my A list either. And I'm sure there are instances where it might be best practice, but it certainly shouldn't be the default for all spark plugs.


I guess you could say the guy that uses a ratchet shouldn't be on the A list either.
I guess a good mechanic carefully removes every bolt with a box wrench and the best ones use a open end wrench 1/4 of a turn at a time. LOL


I don't agree with either of those things. I'm not quite sure what you are getting at? Are you saying not using an impact driver to install spark plugs is being overly cautious? That an impact driver is an ideal device for installing spark plugs?