Painting a Spark Plug

[RCinNC]

Hello all,

As I've learned recently, both through this forum and personal experience, the spark plugs on our bikes can get rusty and corroded from water intrusion into the spark plug wells. I have my plugs out now, and am waiting for new ones and some other supplies to implement some of the solutions I read about in another thread. One thing I can't find locally is ACF-50. I can order it, but it'll take at least a week to get here because it can't ship via air. The rest of the stuff I ordered will be here today. I was considering alternatives to the ACF-50 as a rust preventative, and I wondered about painting the portions of the spark plugs that are prone to corrosion. I have some high temperature engine enamel paint (up to 550 degrees F), and thought that spraying the portions of the plug indicated in the photo would help prevent the plugs from rusting.

Any thoughts from any of the members on this? Is this a workable alternative to the ACF-50? Or is there a more readily available high temperature corrosion preventative that would work in place of ACF-50?

 

[Wallkeeper]

the corrosion protection of paint is directly related to how thick the dry film is. I suggest you will need at least 5 mils and preferably 10 (.005-.010") Silicone or silicone/polyester paint is your best bet at temps in the 350-550 F range.

In the past, the metal bodies were zinc chromate protected. In view of the toxicity and carcinogenic properties of ZnCrO4, I suspect they are currently protected in a different manner. It has been some years since I was last in a plug plant
The area inside against the insulator will continue to bleed thready rust

My question, Is this a problem worth dealing with? The metal body is very thick, not likely to corrode thru before the spark plug needs replacing. The compression washer around the plug should keep water from penetrating the threads for at least the first installation...no promises on the seal if you remove and reinstall it.

Whatever you decide to do, I will be curious how it works out for you

Wally

 

[RCinNC]

You're probably right, Wallkeeper. It may be pointless; I'm going to inevitably end up scraping paint off the plug when I install it, which just creates a vantage point for rust to take hold anyway. I guess I was just surprised on how much rust accrued on two of the plugs in less than a year and about 13,000 miles, and it concerned me a little at how bad they could conceivably get if I'd let them go without checking them for an entire plug replacement interval.

I do appreciate the insight, thanks!

 

[Checkswrecks]

There are corrosion inhibitors other than ACF-50. Boeing's BoeShield T-9 is excellent if you can find it and most Harley dealers seem to carry CorrosionX, which is not as good in my experience but does work. After the spark plug is installed, you might consider a very quick spritz in the hole before putting on the coil tower.

Two thoughts:

1. These are not lubricants and they are not petroleum-based products like WD-40 or other penetrants. Do some Googling into how these "creep" along surfaces and can hardly be felt because the film is only a couple of molecules thick.

2. Don't over-apply them, which is easy to do. A very quick spritz will go a long long way. In aviation, we actually apply in big areas through creating a fog or mist.

3. Places to try calling could be motorcycle dealers and parts stores, car parts stores like NAPA, auto paint dealers, any small airport, and maybe even body shops. I needed a can when on an investigation and the local airport mechanic who had some said that they don't sell it, it was just their own shop supply. Then he sold me their partially used can at the price they'd pay for a new one. win-win

 

[RCinNC]

Thanks, Checkswrecks. I'll be passing by the local HD shop tomorrow when I run some errands, so I'll stop in and see if they carry CorrosionX.

I have a tub of Bel-Ray waterproof grease in the garage, that I used when I repacked my steering head bearings. In the event that I can't find any of these other solutions locally, would it make any sense to apply a thin coat of that grease on the exposed metal portion of the spark plug?

 

[Checkswrecks]

Thanks, Checkswrecks. I'll be passing by the local HD shop tomorrow when I run some errands, so I'll stop in and see if they carry CorrosionX.

I have a tub of Bel-Ray waterproof grease in the garage, that I used when I repacked my steering head bearings. In the event that I can't find any of these other solutions locally, would it make any sense to apply a thin coat of that grease on the exposed metal portion of the spark plug?

Rather than give you a guess, I don't know.
But with the other precautions you are already planning, I'm not sure it's worth trying.

 

[RCinNC]

Actually I got a good suggestion from a member on the V-Strom forum I still inhabit, who suggested a thin coat of copper based anti-seize on the exposed metal part of the plug. I already have some of that, rated to 1800 degrees F.

 

[2daMax]

Grease, if they are high temperature might help to slow down the corrosion. DuPont Krytox grease, made of PTFE or Teflon, comes to mind. High temp up to 399 C and does not wash away with water. Said to be the preferred grease for Drive Shaft splines over Moly based lubes. But they are very expensive.

Avoid using Silicone base items, as if the Silicone somehow gets into the combustion chamber and it meets the O2 sensor, the sensor can be damaged by it.