@db4690
I’ve never used penetrant and never broken a plug. Proves nothing.
Like I said before, I know we’ll not change each other’s minds
We can agree to disagree
Well, in any case, I’m respectfully disagreeing with you
Interesting discussion. It seems like it is possible – in theory at least – that the plug/thread interface could have enough space in there for penetrating oil to soak in over time, without allowing much combustion gas to blow out. There’s the time matter. The oil has a long time to get in, 16 hours in db’s case, but the explosive nature of the combustion yields little time for the hot gas to escape. In fact a small amount may get out, but not enough to affect performance. There’s so much wind blowing around in the engine compartment it would be hard to tell if say 0.5 cc came out through the threads, out of 4000 cc’s displacement. Then there’s the force on the plug during compression and firing, which may push the two parts of the threads tight together, making it even more difficult for the gas to escape.
While measuring a small amount of gas escaping is probably a tough experiment to do in the midst of everything that goes on when the engine is running, it seems like a static (engine not running) experiment could be devised to prove or disprove whether the threads in fact get coated with penetrating oil prior to plug removal. hmm … how to do it though?
Perhaps we should start a discussion on the merits of using penetrant before removing spark plugs
I know what position I would take
And I believe I know what position insightful would take
If somebody wants to start a new and separate discussion about that, it might prove to be interesting
At this point, I’m reminded of that conversation of a few weeks ago. The one where the guy asked about brake pad advice, and he got it. And then he fell hook, line and sinker for posiquiet. And he even seemed to be promoting them, without actually having any personal experience to go on. It was all based on what somebody else told him
The reason I’m reminded of that conversation is because . . . just like in that conversation . . . clearly nobody was going to change the other guy’s mind
I think the penetrating oil works by capillary action. It gradually seeps into the small gap between the threads. Thread machining is not perfect, and there is some gap for the lubricant to seep into. If half the cavity is filled, the force required to extract the plug is half what it once was. And as the plug moves, the entire thread is lubricated. The explosion inside the cylinder at ignition is just about instantaneous, and the gas is not pressed out. I suppose if there was unlimited time, it would leak out, but the exhaust part of the stroke happens quickly too.
I don’t use a penetrant when doing MOST spark plug jobs, but the 3-valve Ford with the two-piece plugs are a much different animal. A horrible design that requires out-of-the-norm techniques to prevent expensive problems. I do believe the penetrant can wick under the crush washer on the spark plug. That washer isn’t that substantial, and some cars don’t even use one, but use a tapered seat instead. And seal just fine.
Aluminum block engine?
The BLOCK has nothing to do with it. Spark-Plugs are in the heads. Is the head aluminum?
I assume, but do not know, thathead would also be Al.
In a hybid vehicle I assume the block is Al .
The head may not be…but probably is. My Vega had an Aluminum block…but cast iron head. In eather case…The material of the BLOCK is irrelevant.
Robert . . . ?!
Anyone able to Google will find that the 2AZ-FXE engine used in the 2007 to 2010 Camry Hybrid has an aluminum head.
Is there any downside to using an impact to remove them? No one else has mentioned this and figure there must be a reason.
I’d be afraid, unless the impacts can be very light.
@cwatkin
The downside is that an impact could theoretically pull the threads out of the aluminum head, along with the plugs
Yeah, I know the odds are in your favor, that it won’t happen
But I wouldn’t want to be that unlucky slob
I can think of plenty of situations where using an impact to remove a fastener also pulled the threads out of the aluminum component
We were installing helicoils in aluminum subframes when I was at the Benz dealership
Gotcha! I seem to successfully remove stuck fasteners with impacts more often than not. Bolts I am sure I would twist off or strip out seem to come out easier with an impact than with simple turning of a wrench. Maybe this is just my luck.
Against all “conventional wisdom” this guy uses a 3/8" impact wrench on a hot Ford V8 Triton (warning…F-bomb alert):
^ Not torque wrenched into place?
Many experienced wrench turners don’t feel the need to use a torque wrench for spark plugs.
There’s an old thread about that.
Not torque wrenched into place?
I’ve known many professional mechanics over the past 40+ years of ownership and working on cars…and I’ve NEVER met one that uses a torque wrench for spark-plugs. They only use them for critical bolts.
^ I have never used a torque wrench on spark plugs.
But now assume there is a published figure for it.