First, I have successfully replaced even the rear plugs in my Caravan from underneath so I'm not a total putz....
With that said- my other car is Protege...1 plug came out no problem...the other 3 will turn anywhere from 1/4 to a full turn before binding up, i.e., getting too hard to turn. The one plug that came out was clean with normal wear and no deposits. No anti-seize was used on any of the plugs but this hasn't been a problem in the past. All plugs have approx 80,000 miles on them and are bosch plats. Car currently gets combined MPG of 34, idles and runs great...
Any thought on getting them out? I noticed that on #4 (goes a full turn) that it seemed a lot easier to turn when the engine was still hot. Should I be doing this hot or cold? Or should I just run this into a shop and give them my wallet.
I noticed that the one that made the full turn was a lot easier to turn while the engine was still really warm..not hot..should I try it with the engine hot? The aluminum head should expand out from the plugs more than the plugs expanding out into the head, I think. (I live in Houston so it's not like 40 degrees outside anyway).
Might not hurt to have it warm, I'm just concerned that having it too hot might make the aluminum spall more easily if the plugs have a ring of carbon on them that must be broke free.
I've tried the soak overnight last night...to no avail...plug #4 turned one full turn yesterday...same today...the other two are maybe 1/4~1/2..soak, turn, soak turn...the only difference was that as the cooled completely they just got harder...which is why I wondered about hot turning them...odd thing with #2- he came out all the way and had no deposits on him after 40,000 miles (the others have been there since who knows when, I'm estimating
80,000 but could be 100,000- #2 came out no problem in 2002 while the others were in exactly the state they are now)
So...do I try it hot anyway? Or just wait for the plugs to give me trouble (and when they do what will it be- bad gas mileage? Or will the car simply not start or start running rough? )...at least half of the mileage has been pure highway - dallas to houston at 70~80 so these plugs could go a while longer, methinks.
Again, my sincere appreciation for the feedback on this, I'd really like to run this car until the wheels come off.
My choice would be to do what you have to do to get them out *now* - it's only delaying the inevitable, and it will only get worse to put it off.
You are using a true penetrating oil, and not something like WD-40, I take it? (PB Blaster is an excellent brand in your auto parts store.)
Regarding the advice of not trying it hot - that's good advice, but you have a difficult problem, and sometimes they require bending the rules a bit to tradeoff risks and damage. The two conflicting things about doing it hot are: (1) The clearances will indeed open up due to difference in temp-co's - that works in favor of doing it hot. (2) The aluminum is more subject to wiping at higher temperatures, so of course that's an argument against doing it hot.
If trying to remove them cold with a little (but not too much) more force doesn't do it, then do it hot, but apply less force - the hope being that the additional clearances will allow them to come out with minimum damage to the head threads.
Something to consider: After saturating them with true penetrating oil, do the moderate removal torque with it hot. Leave them turned out as far as they will go, then let it cool off (the idea being that the contraction will help compress the carbon that is in the threads). Then do the hot thing again - turn them in again, saturate with penetrating oil again, get it hot, then turn them out again with moderate torque. After the first time or two of that, you will be able to see if you're making headway or not. If so, try it one or two times more.
If still making progress, but still not free to turn all the way out, I would stop at that point - it may be that you are just damaging the threads (rather than gradually removing the interfering carbon), but by stopping at that point, you should still have plenty of good thread left for the future. You may end up having to have the heads removed - better to do it to get the plugs out with threads intact than to have it done because you have to helicoil new threads into the heads.
Short of pulling the heads now, I say you either have to gently try the hot method, or go to more torque with it cold. Either way it's a risk - not an easy decision. But I definitely say don't put it off - the risks are at their lowest now (compared to running with those plugs until they won't run any more. Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")
I've been soaking them (or rather, #4, the easy one) with Breakfree CLP...this weekend was the trial run so to speak. Next weekend with three days off I'll be back down here to give it another go.
Thank you for the recommendation on the penetrant- I'll go look that up this week.
I am really curious to get at least one of these guys out and have a look- why would all but one have a carbon build up to that degree?
One last question related to trying it hot- will the engine be able to start and run with the plugs backed out to any degree to allow it to get hot again? With number #2 I can say it's around 11 full turns on the wrench to get one plug in or out....#4, the easier one, came a full turn out hot, and maybe 1/2 ~3/4 cold, with Breakfree soak.
It probably would. I'd be more inclined to turn the plugs back in before starting it up to heat up (if they are not too bound up from cooling off with them turned out).
You're welcome. No guarantees no matter what you do short of pulling the heads, but I would do what I could to avoid that expense for such a seemingly "simple" problem.
Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")
Interesting...continuing to Google search with additional keywords PB & Kroil along with Spark Plug...appears that I have carbon fouling up into the threads possible...or maybe some crud got carried in there..or perhaps that little bit of oil on the threads coked them up.
So now it's off to penetrant land and a possible side order of heating!
Thanks to everyone for the information and feedback!
Another poster mentioned the reach of the offending plug's threads may be extending into the chambers-likewise allowing carbon to build up. Whenever you get the sobs out-check and make sure they are the correct plugs for yer application. Additionally, you might try a decarbonizer treatment to soften up the carbon on the threads from the inside of the engine. Hang in there. Respectfully submitted,
Best penetrant I have used-mostly on exhaust manifold flange studs/nuts. Amazing stuff can be tough to find in some areas. As to the decarbonizer treatment-the one I am thinking of is offered at shops and it made by Snap-On. Hang in there. Respectfully submitted,
What about water down the intake with the engine running. That used to be a de-carbonizing method that a lot of people swore by (the theroy is that the water gets absorbed into the carbon and turns to steam when it heats up and breaks the carbon loose).
Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")
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