I have a 07 Heritage that I bought in early 09. The only thing I didn’t like about it was the fact that the ends of cooling fins were extremely oxidized and kind of crusty. As time has passed they have gotten nothing but worse (they became nearly black) no matter what I tried to do to shine them back up, and I tried alot of things. I might add mine are the “highlighted” fins. They are machined,but are not the “bright” machined fins that the 08’s and later models have.I’ve searched everywhere for an answer/method on how to clean and brighten them back up and really found nothing of value. There are a lot of posts on the HDforums and elsewhere with people talking/complaining about the same thing, but there has never been a good answer on how to clean them. Well, I found the way. Sometimes the simplest things are the best things.



What you’ll need:

-White vinegar

-Water

-Scotch Brite sponge (you can buy at the local grocery store)

-Soft Cloth



Instructions:

Warning: Be carful using the Scotch-Brite sponge around chrone. It will indeed scratch.

Mix 2 to 3 tablespoons of white vinegar in a quart of water. Dampen one end of the scotch brite sponge with the liquid. You want a little liquid in the sponge, but not sopped with it. Using the wet end of scotch brite side scrub along the length of the fins. If need be, switch to the dry end of the scotch brite and do the same thing for a while and then switch back to the wet end. Stop and leave the remaining liquid on the fin. The vinegar is a mild acid and will actually etch the aluminum/oxide. Use a dry cloth to remove the liquid and polish the fins. Wet a clean cloth with clean water and clean the fins, then dry. And lastly polish again. When you are satisfied use the HD engine brightener on it. The cleaned part of the fins are bare aluminum and will tarnish over time. The brightener has silicone it and will protect you work.



It’s a little tedious in the tight areas, but on the bottom 2/3rds of the cylinders you can use the full width of the sponge, getting 4 or more fins at a time so it goes fairly fast. This method will not round the edges of the fins. The whole engine took me about two hours. Be patient and a couple of cold beers along the way doesn’t hurt... I do plan on doing this again because there is a little bit of dark spotting left here and there. I did get 95% of it on the first pass though. I’m just picky when it comes to the bike.



Hope this help someone out.



Here are a couple of pictures of the results. Wish I’d have gotten a before picture. L

 

I have to be honest, I don't think I have ever seen any that has been oxidized before. I am sending my heads and cylinders out this winter to have the show cut put on the fin tips. That would take care of your problem but in doing so I hope mine don't oxidize like that after I get them done. I would think there would be something out there that one could brush on or apply to the fin tips to keep them from doing that.

 

You may be right about something being out there, but I've searched long and hard for an answer and never found anything useful. If you search the hd forums you'll see the conversations/complaints on this. One thing I'm going to do today is get me some Mothers aluminun wheel polish and try a small spot to see if I can make the fins "bright". If I can, then this effort would be a home run..

From the looks of your bike you have an 08 or later. Those don't seem to develop the problem. I am speculating that on the 07's and older HD machined the fins and left them raw. That would explain the corrosion problem, particularly if the owner doesn't use engine brightener or equivalent from the beginning. My two cents.

 

Agree with Ya Tbone. I've never seen any or heard of any fins thats oxidized.

maybe too much time near the saltwater..

My 07 jugs still look as good as new to me.



.

 

Thanks Pitbull. My fins are ok at best and this is a good idea to keep up on them.

 

try "Sonax"

 

Oct1949, you happen to be correct. The original owner bought it in Corpus and it stayed there for about a year and that is probably why they were so bad.

fxdx2k, The method that I layed out is for some pretty SERIOUS restoration. I'm not sure you'd want to try it on yours if the fins are "ok". But, if they get grey/black and/or crusty then this it the way. If your's have a light grey color, or getting there, try Mothers aluminun wheel polish first. Make sure you engine is stone cold when you use it. Put a little on a thin soft rag and get after it. Follow the directions on the can. The stuff you get on the black can be removed with 409 or Lysol all purpose cleaner. The Lysol is the the best cleaner I have ever come across. It works great on most anything.

I did try the Mothers on a half dozen fins this morning (I was lazy today) and it did brighten them up even more. See the attachment.

I did a search and pulled a few threads off of this forum. I am not in the boat alone..


https://www.hdforums.com/forum/detailing/256498-cleaning-aluminum-fins.html



https://www.hdforums.com/forum/general-harley-davidson-chat/597265-what-is-the-best-way-to-clean-corroded-front-cylinder-fins.html



https://www.hdforums.com/forum/touring-models/861706-cleaning-engine-fins-and-base-of-cylinders.html



https://www.hdforums.com/forum/softail-models/817433-cleaning-fins-on-black-engines.html

 

tony i you check around, from what i heard you wont have to do anything to keep the diamond cut fins clean and sparkly....

 

They can and will oxidize given the right conditions. I'm a mile from the Gulf of Mexico and find myself in a constant battle against crap like this.

 

Yep, I know what you're talking about. I lived on the Gulf coast for 10 years myself. It's a never ending battle.