Spark plug tightening force

Hi everybody, today I’ve replaced spark plugs. First I tightened them by hand and then with just regular wrench as I don’t own torque wrench. I’ve torqued them for 3/4 of a turn. From manufacturer specs it should be tightened to 20-30 NM. Took the car for a spin and runs fine, even better than before. I’m a little worried about the spark plugs being overtightened as I know they might over heat and at worst destroy the engine… Would taking them out and tightening them with torque wrench help? I’ve heard that once the washers are squished the plugs cannot be torqued correctly anymore. Thanks in advance for any advice

There are some situations where a torque wrench can’t be used to tighten spark plugs because of access.


Plugs will not overheat because they are to tight so you can cross that worry off your list .

Sounds like they are plenty tight, I would let it go till the next time needed. For me it would be in 100k miles.

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Torque wrenches are not always the best answer. A burr or deposits on the threads could cause the torque to vary from plug to plug. The important thing is that you get the proper gasket compression.

If the spark plugs have a crush washer on them, they typically should be turned 3/4 to 7/8 turn after contact. Generally you can consider contact when the plug is in finger tight. The box the plug came in usually gives the spec for after contact.

Plugs that have a tapered seat and no crush washer, are usually tightened to 1/16 to 1/8 turn after contact.

Although I have several torque wrenches, I no longer use them on spark plugs.

Edit: If you remove a spark plug with the crush washer and reinstall it, treat it like a tapered seat. Once the washer has been crushed, you can’t crush it much more, so about 1/8 to 1/16 turn is enough on the second time around.

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Just leave them alone in my humble opinion. I’ve never used a torque wrench. Just a ratchet and after snug just a quick tug on the wrench. I’ve just done it by feel for the last 60 years. If there is a crush washer then you can feel it crush and just a tug after that. You don’t want to strip the aluminum or alaminium however you choose to say it though.


Thanks everybody for answers. As @bing said I’d leave them be. @keith thank you for the detailed answer. I did the 3/4 turn as I found on NGK website. Felt the washer crush after aprox. half a turn and then I’ve torqued it so its snug -> aprox. 1/4 of a turn. Did that very cautiously. I’m probably stressing a bit but its my first car so I hope you understand :slight_smile:
Thanks again!

There should be no problem because you followed instructions which is a lot better than some procedures.

I’ve never met a mechanic who used a torque wrench for spark-plugs. I’ve never used one and never ever had a problem.

Torque wrenches are great for critical bolts like Head bolts, or anything that is cast and has a gasket. I own a couple and I just don’t do the big stuff, just PM…I haven’t used a torque wrench in over a decade.