View Full Version : Something to loosen Spark Plugs??? Spray?

05-23-2007, 01:59 PM
I installed new plugs two years ago.
I did not put on anti seize.
I'm afraid they may not want to come out too easily.

Is there something I can spray on them that will loosen them up?
What is the best procedure? Let sit overnight?

05-23-2007, 03:44 PM
Spray some penitrating oil on them let them sit overnight and give it a try. Sometimes them come out easier when the engine is warm, but watch out for the hot maifolds. You may have more luck with a six sided box wrench than a spark plug wrench and it less likely to brake the plug that way.


Andy B
05-23-2007, 05:42 PM
Blaster is a good penetrating product. Warm up the motor, spray in on the plug bases then let it set overnight. That should do it.

05-23-2007, 06:06 PM

Have you actually tried to get them out yet? What Rejoice said about the penetrating fluid (PB Blaster, Kroil, etc.) is pretty much the ticket.

On our boats, I think getting a box wrench in there may be an exercise in futility but you could try (sheer lack of maneuvering room).

05-23-2007, 08:35 PM
Use Break Away made by Cyclo.

05-24-2007, 08:42 AM
Kurt, on my 351 with Barr manifolds you can get a box wrench in on the plugs, and sometimes it's the only way I can break mine loose. The spark plug wrench tends to tilt and slip but the six sided box wrench gets the job done. But your right it is tight down there, I trimmed the fiberglass lip on my engine box and the inch or so makes all the differance. I also make sure to remove the plugs ever year even if I'm not replacing them. Sometime I replace the just because they are rusty on the outside. I also remove and reinstall the manifold bolts every year. These are just things that I've learned the hard way and don't want to ever to do the hard way again.


05-24-2007, 12:47 PM
I purchased a short handled box wrench to do mine in my old boat. It was the only thing I could get on the plugs approaching from the front or back of the console. Was always a pia

05-24-2007, 01:18 PM
Rejoice / Jim... I'll have to try the box wrench method - never have. A couple of the back plugs always give me fits when I try to get to them with a conventional plug socket.

One of the things I do is spring for the double plat plugs which have Nickel plated bodies - that goes a long way toward keeping them rust-free. I wait until Auto Zone or someone has a sale on Autolite plugs and get them for ~$3 @. With the Platinum plugs, I find I can get more time from them than conventional plugs and they don't come out looking a mess - personal choice. I still use anti-seize on them.

05-24-2007, 01:27 PM
Kurt, those back plugs are a bear, that's where the box wrench really helps. The starboard side especially, where the plugs face forward, in fact everything on the starboard side is a pia...

Tom Morris
05-27-2007, 11:38 AM
Blaster will do it

Captom Key largo

05-27-2007, 11:49 AM
I have always liked the Bosch Platinums. They seem to last forever on the bikes, so I would think that the same would apply with marine application. I do like the idea of pulling them anyway.


05-27-2007, 02:01 PM
A friend of mine, who happens to be the best auto mechanic I've run into says:

Platinum plugs don't give as healthy of spark and carbon foul more easily. Engines designed for platinum plugs have a cleaning cycle built into the software, which purposely leans out the mixture ocassionally. The creation and factory installment of platinum plugs begat 2 things; the ability to advertise 100K tune-ups and a "workaround" for those installations that are a total PITA to change plugs (partway pull engine, etc.).

He's a firm believer in using the factory spec plugs including brand...not just cross-checked.

Just passing along his thoughts/analysis.

05-27-2007, 02:35 PM
Not to be at all contentious but, I changed out the original Motorcraft plugs in my boat's 351 @ ~25 hours because their bodies were so awfully rusted. I put Autolite double plats (APP-24) in and pulled them @ ~125 hours - they were in perfect shape - insulators nice and grayish-tan and the gaps were only a couple thou wider than where I'd set them - no sign of fouling. I re-gapped, put them back in and they are still in the engine at 165 hours. Just reporting what I personally experienced.

Autolites are the absolute, spitting image of Motorcraft plugs and the parts guy at my local Ford dealer allowed (under his breath, mind you) as how Motorcrafts are made by Autolite - don't know if it's true or not but he did say it. I am a firm believer of using the brand that an engine manufacturer recommends: Ford = Motorcraft or Autolite, GM = DELCO, Chrysler = MOPAR

Now, I do have an MSD ignition system in my boat, which may help with any problem Steve's friend alluded to, of that I am not sure.

However, I do know, for a fact, that those funky looking Bosch plugs, with the tiny, #20 wire-sized center electrode, buried inside the insulator, did not work worth a damn in my '94 Bronco's 302. My fuel economy dropped by ~20% and the engine ran like crap at highway speeds. I thought I'd gotten a defective set and the ppl at PEP boys (to my surprise) replaced all eight with new but they didn't work either. I had an MSD system in that vehicle as well. I put Autolite double plats back in and all the problems went away.

05-27-2007, 03:02 PM
ya, I've always associated Autolite with Motorcraft. I've also installed a lot of "cross referenced" plugs. Some with better results than others.

I think his/my point is; just because the cross-refernce sheet says it's the same, it may not be.

I found out about the cleaning cycle by accident. I replaced plugs and thermostat in my wife's '95 Mustang. I put in a 180* stat (spec'd at 195*)and platinum plugs. In time I developed a "ping" due to carbon build-up. Well...the 180 stat never let the engine get past 178*. It never kicked into "cleaning mode" as the treshhold was 180+*. After spending $500 at Ford, just to have the problem return after a couple weeks, I took it to Lon and the above is what was discovered. The plat plugs are still in there, but the stat was swapped to 195*. I do have to decarbon with Seafoam about once per year or it gets to pinging again. A contributing factor was a MAF sensor contaminated by the oil from a K&N filter (so the story goes). I'm back to paper elements with a rebuilt MAF sensor.

As engines get more sophisticated and emissions rules get tighter...the systems get more tempermental to any changes.

05-27-2007, 04:22 PM
Try PB Blaster & A hand impact won't shear them off.

05-27-2007, 04:23 PM
Oh I forgot no room.