Would it be better to warm up engine before replacing spark plugs? (if very cold outside)?

if engine is too coldwill it make it more difficult to get spark plugs unscrewed? can explain?

Best Answer:

JJ: NO, some engines specifically state to do it cold.

Other answer:

No! That is an old trap. The warm metal has expanded, so if you put plugs in the cold plugs seat too far in and the head tightens around it. Not so bad this time but you had better hope you never have to remove the plugs again because they are probably not going to come out. My father told me about people who used to replace the tapered spark plugs in Model Ts with the engine warm – those would never come out.
warming up your engine before changing out your spark plugs is not reccomended. The main reason because most cylinder heads are made of aluminum, which is a very soft metal. if you try to replace the spark plugs while the engine is warm, not only will you risk burns, but you risk crossthreading the plugs and making them impossible to get out.
Grandpa Jack:
Spark plugs aren't usually parts that have to be changed immediately for the car to run. Personally, I wouldn't freeze my tail (or at least fingers…) off changing plugs at 6°F. Unless you've got plugs that just don't work at all, I'd wait to change them until it's either warmer outside or you find a nice warm indoor place to change them. Going another few days or a week etc., before changing them to wait for some warmer weather isn't going to hurt anything.
I always heat the engine up good and as soon as it's cool enough to work on, the plugs come out easy without drama.

It's easy to get the front bank plugs out on a FWD car, then restart the engine and heat it up again for the rear plug set.

Breaking the plugs loose is easy when the engine heads are still hot, especially if you have aluminum head threads.

Pilsner Man:
It doesn't make any difference, except as a source of heat for you. I wouldn't screw with them now, that can wait.

I bought a Toyota truck years ago and it had 85000 miles on it. The plugs looked original, so I changed them after driving it for a few weeks to check MPG. The old ones were so worn that the gap was .075". The new plugs made no difference in the MPG or power.

It makes no difference at all. I'd much rather work on a cold engine.
A few degrees below zero is nothing to metal.
ABSOLUTELY NOT. In fact, attempting to perform ANY service that doesn't REQUIRE the engine to be running on a hot engine is asking for trouble. I wouldn't do any work OUTSIDE in this weather if it could be avoided, but anything above room temperature isn't helpful.
That is what I'd do.
Jake No Chat:
That is not needed. It would make no difference except to make it more likely that you may be exposed to hot metal and get burned.

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