cygnusx1 Posted November 14, 2009 Share Posted November 14, 2009 OK my new 240Z has decent Urethane paint on it that was sprayed in 1987. It is in decent shape. The car had been stripped to the bare metal and then it looks like they did a Zinc coating on the bare metal, then they sprayed it and undercoated the bottom. The problem is that it seems that the Urethane paint is de-bonding and flaking from the zinc layer on the metal in certain spots. It is mainly in the engine bay due to either lack of prep or heat. I don't plan on painting the entire car for the next two or three years but I want to prep/paint the engine bay now while it is totally empty. When I do paint the car, I don't know what color it will be so I think I want to make the engine bay black to go with any exterior color in the future. Can anyone recommend a good way to strip off the Urethane paint in the engine bay without ruining the zinc prep that is on the base metal? The car is currently immobile in the garage and I really can't roll it outside to use a hose. Any rinsing will be done with spray bottles of water and a drip pan to catch the runoff on the garage floor. Quote Link to comment Share on other sites More sharing options...
palosfv3 Posted November 14, 2009 Share Posted November 14, 2009 If the top coat is brakeing away from the primer/sealer, it will continue to do so unless the entire topcoat is removed. There is no easy way to strip the engine compartment. You may get lucky at the PBE store, they made a aerosol topcoat stripper for the early 90's GM delamination issue on the Corsicas and Berattas. It should still be available and was designed to only removed the color ( sometimes it also took the primer ). Its hard to tell the extent of the problem from the pics. If I had to venture a guess on the cause , the top coat may have been applied beyond the sealers application window. Quote Link to comment Share on other sites More sharing options...
z2go Posted November 14, 2009 Share Posted November 14, 2009 I too am in the process of stripping my engine bay, I found that heavy duty Aircraft Coating Remover did a great job, not sure about the effect on any zinc coating. Is the zinc coating necessary to have? I'm not a paint pro, just learning as I go... is it possible that it was just an etching, rather than zinc? Unless he had the car dipped, in which case I could see you not wanting to ruin that. I found that when I used the stripper, the metal underneath appeared to have a dull grey finish (this was under factory paint). I'm guessing yours wasn't at all like that. In any case, stripping the bay seems to be a complete P.I.T.A. operation, tons of time and patience and the right wire brush attachments seem to do the trick on my application. I wonder though, for yours, if you won't have to etch the metal once you remove the paint? Does a zinc coating accept primer normally? I'm interested to see if others know the answer to this. Quote Link to comment Share on other sites More sharing options...
g9m3c Posted November 14, 2009 Share Posted November 14, 2009 I'm pretty sure that zinc coating was part of the factory's anti-corrosion application.... Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted November 14, 2009 Author Share Posted November 14, 2009 I am calling it zinc because it has the appearance of galvanized metal. I am not 100% sure it is zinc. I will try chemical stripping in a few spots like the strut towers to see how it goes. It isn't the first time this car has been completely stripped because there is no trace of the original silver paint under the red paint, unless what I am calling zinc, is actually scuffed original silver. I doubt it though. I tried scratching it and it felt like metal. Quote Link to comment Share on other sites More sharing options...
palosfv3 Posted November 14, 2009 Share Posted November 14, 2009 Most Zinc based primers or epoxies are a bright green or yellow green in color. The Datsun factory applied no internal anti-corrosion measures , similar to todays new autos, during manufacture. The process wasn't refined or used until the late 1980's. Zinc coated sheet metal is a relatively new material. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted November 14, 2009 Author Share Posted November 14, 2009 So I could be looking at just the bare steel of the body under the paint chips. Quote Link to comment Share on other sites More sharing options...
yetterben Posted November 15, 2009 Share Posted November 15, 2009 I doubt its the bare steel. Under my brake master i have the same issue factory paint is coming off in sheets. My engine is out as well. I planed to just scrape what i can ( i just painted the outside). I plan to just marine clean metal ready and por15 the entire bay. Time consuming for sure but what else can you do unless you SB the whole thing. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted November 15, 2009 Author Share Posted November 15, 2009 Yup I checked it well tonight, it is definitely bare steel underneath the flaked off paint. Apparently the PO was not kidding when he said they stripped the car to bare metal before the repaint. The paint chips are the same color on both sides and the metal is exposed. I am on the fence. I may just chip off the loose paint and "spray can" the chipped areas to match until I paint the whole car in a couple of years. Or I strip and paint the engine bay now with spray cans in semi-black, then paint the outside of the car professionally in a couple of years. I am not going for show or full resto right now. I just want a fair weather driver/track day Z that I can keep totally rust free until a "real" paint job in a couple of years. The key goals right now are drive-ability and preservation of this straight, NO RUST, chassis. Quote Link to comment Share on other sites More sharing options...
jtburf Posted November 15, 2009 Share Posted November 15, 2009 If the spots in the picture are all your looking at simply sand the area, clean well with a deglosser,mask then prime followed by as close to the same color as possible. Now if you had both the time and money, soda blasting it back to bare metal and starting over with an two part paint with be the ticket... Good Luck, John Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted November 15, 2009 Share Posted November 15, 2009 Check into dry ice blasting, it leaves no mess behind and should be clean enough to have done in your garage. I say prep it right and once, get the engine bay ready for paint. It will make the bodywork lots easier to work through in the future if you know the tedious engine bay is ready to roll. Breaks it up into parts. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted November 30, 2009 Author Share Posted November 30, 2009 I went the cheap and quick route. Didn't want to take too much time and effort because in a few years the car will get re-painted correctly. I felt that this paint has another 3-5 easy years of life left in it to allow me to save up. Wiped out the rattle can tonight but I think it does the job. It's not a pro finish but I wasn't expecting one. I just wanted a clean look with no exposed metal surfaces to rust. Looks fine in the dark. I'm not sure how it's going to look in the daylight but I don't really care too much. The main defect you would notice is the variation of gloss level. Maybe after the paint is dry, I will go over it with some polishing compound to even it out. Maybe not. BEFORE: AFTER MATCHED RATTLE CAN: Quote Link to comment Share on other sites More sharing options...
piston Posted November 30, 2009 Share Posted November 30, 2009 wow. gotta admit that rattle can match came out pretty good! Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted November 30, 2009 Author Share Posted November 30, 2009 hehe thanks. I ordered the can of paint from http://www.automotivetouchup.com/ I am very happy with the quality of the paint and the nozzle. Quote Link to comment Share on other sites More sharing options...
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