WD40 under the coul? will it harm the wires?

I grew up spraying wd40 under the cowl of our '77 merc 115hp. Made it look real good but that was 30 years ago, is there anything else out there that is better? I have heard that wd40 could hurt the wire insulation and rubber parts although I have never really seen this in person. What are the negatives to silicon spray. I am sure this has been discussed in the past in here but can we touch on it again. Thanks

please excuse the typo in the tittle line

Why are you spraying anything?

well i was told when i was young, possibly incorrectly, that wd40 would help with corrosion and help displace water. Growing up on the Space Coast, i thought that is what it was developed for(metal corrosion protection). My main concern is that I have heard that wd40 could possibly harm rubber and plastic parts and maybe the wire insulation. Living in FL with all the salt i guess every little thing helps, just want to make sure i use the correct stuff. Are you saying i should not put anything inside the cowl?

I've heard that WD-40 will make rubber hoses break down. You should use Hilco Lube, Sea Foam, or BoeShield lube to fog down the engine with.

Since my engine sits on a boat in saltwater, this is another step I always do in my preventive maintenance. I take the cowling off, and spray everything down with fresh water, to rinse any salt creep off, then, I leave the cowling off in the sun for a few hours, to let it all dry out, then I go back and fog with a protective lube. This has worked well for me over the years.

Unless you are getting salt water under the Cowling I would recommend that you just do a periodic inspection - we have no had any problems with out salt water outboards with this over the years and do not spray anything.


If you are getting water under the cowl - figure out why and fix that problem.


If you want to spray stuff on your engine use a product designed for this but you should not have to do it very often

I would use silicone spray before wd40

Captain Ahab said:

Unless you are getting salt water under the Cowling I would recommend that you just do a periodic inspection - we have no had any problems with out salt water outboards with this over the years and do not spray anything.

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Trust me, when you leave a boat in the water for 300+ days out of the year, salt creep can and will find its way into anything and everything, even if your cowling is sealed up good. I've seen a lot of motors where the owner didn't bother to fog anything, and it's a rust-bucket. None of my motors have ever looked like that, they look brand new under the cowling, regardless of age.

If you are getting water under the cowl - figure out why and fix that problem.


If you want to spray stuff on your engine use a product designed for this but you should not have to do it very often

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I haul my boat out about 4 times a year, to do an inspection on everything, and to lube everything down.

We leave our boat in the water about 9 out of 12 months and have never had a problem with salt water under the cowling - we DO NOT spray the engines down as there is really no need. We also run offshore (100 miles plus out) at least 15-20 time each season plus all the inshore trips in all sorts of weather. never had a problem with salt water getting up on the outboard motors


I understand what you are saying and if it works for you great

I see it as preventive maintenance, and it's something I've always done. You're right, there's probably no NEED to do it, but, oily metal can't rust, that's how I look at it. I do the same thing with my jet skis and the engine in my jetboat.

One thing I would caution against, though, is spraying the underside of the flywheel and the magneto assembly. Since oil traps dirt, and dirt can interfere with conductivity, you don't want to put any oil on these parts.

I have heard that WD40 is not good for rubber, and the stuff evaporates. Where I work we sell a product called corrosion x. THey make two versions, both are spay cans but one has a heavier viscosity. I use the HD stuff on my engine and It really does help keep the salt off and prevents corrosion.

https://www.corrosionx.com/gifs/hd_can.gif

You can use this stuff on everything.....works real good on my reels too.

WD-40's main ingredient id fish oil, ive never heard anything bad about it. i use it on everything from a squeaky hinge to my AR-15......

shawnfish said:

WD-40's main ingredient id fish oil, ive never heard anything bad about it. i use it on everything from a squeaky hinge to my AR-15......

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That is absolutely a myth - I spoke with the makers of WD-40 and they state that is a 100% petroleum product - no fish oil of any kind - they also post it on their web site:

https://www.wd40.com/about-us/myths-legends-fun-facts/

"What a Fish story!
Myth: WD-40 contains fish oil.
Fact:
Consumers have told us over the years that they have caught some of the biggest fish ever after protecting their fish hooks and lures with WD-40. We believe this legend came from folks assuming that the product must contain fish oil since it appears to attract fish. Sorry Charlie®, it just ain’t so.

WD-40 Company has taken steps to respect and conserve the environment, and encourages its users to do the same. While WD-40 can be used to help protect fishing equipment from rust and corrosion, WD-40 Company does not recommend using WD-40 to attract fish."

shawnfish said:

WD-40's main ingredient id fish oil, ive never heard anything bad about it. i use it on everything from a squeaky hinge to my AR-15......

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I'd caution against using WD-40 for firearms, especially one like an AR-15 with its tight tolerances....as WD-40 tends to varnish when it heats up. A better gun oil would be something like CLP.

Lots of guys with the plastic boats with I/O and inboards spray down the engine with CRC, Boesheild, or T9 (I think that's the name). Boat motors are used in wet environments, and it can't hurt to use it. I live on saltwater, and the salt air eats everything. I spray CRC on most everything we keep outdoors. When I first moved here, my bbq turned to a rust pile in about a year. :shock: