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Am i doing this right? (rust repair)


s30zgt

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Hello

 

Long time lurker on this site recently turned Z owner here. Picked up a good condition 1971 240z last weekend and have been thinking about all the things I want to do to her. I knew that one of the biggest mistakes a person can make is by just rushing into things so I told myself that I needed to take it slow and do things right the first time. At the moment she is running and, besides a carb running a little rich, could easily be a daily driver but I want to first fix one of her flaws, the surface rust. I plan on having the car repainted later but I want to stop the rust from getting worse in the mean time.

 

Having spent the whole last week reading here(the search function has been my best friend), classiczcar, and many hotrod websites about rust repair and prevention, there seems to be so many different ways of doing it but I think I have a good idea on how to take care of the rust but could definitely use a second opinion. Links to products just incase anyone sees something that may have an adverse affect with something else.

 

Procedure:

1: Angle grinder with an Abrasive disk from 3M (http://www.shop3m.com/61500187564.html) to remove majority of the rust

2: Use navel jelly to remove remaining rust (http://www.loctiteproducts.com/p/s_trmt_naval/overview/Loctite-Naval-Jelly-Rust-Dissolver.htm) and rinse off with water dry with cloth.

3:Spray on Duplicolor primer (http://www.napaonline.com/Search/Detail.aspx?R=DC_DAP1689_0006445893), let cure

 

Barring that the procedure above is correct, I have a few questions.

 

Question 1:Should I use etching primer? I am a bit confused to its purpose. Ive read it has phosphoric acid in it so it protects against rust or that its a waste of money and that regular primer should be fine if the metal is prepped right. Is etching primer necessary?

 

Question2: Should I put a coat of paint to protect the primer? (The Z is color code 115 blue metallic so I would be using http://www.napaonline.com/Search/Detail.aspx?R=DC_BGM0539_0006528495 ) IIRC primer is porous so it could let in moisture which could start the rust all over again.

 

I will post pics of her soon and this weekends progress. Any suggestions will be helpful and I would rather be told I’m doing something wrong than pay for it later. Thank you for time and patience.

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if i were you as long as it's surface rust you can loose the navel jelly. just sand down to metal and hit etching primer on it. you can't leave it primer for long a week to a month is fine but primer can't take the u.v. exposure and will start to dry out and crack. what i did on my truck was got a H F grinder and a few 90 grit flap wheels (the guy house painted my truck to hide rust :(( ) and then just hit it with some rubberized undercoat it's ok to sand and paint so you can top coat right over it. its been through rain a few times and no rust. another thing you might wanna look into is eastwood rust converter and rust encapsulater. you wont need such a agressive flap wheel if you try that maybe start with 180 grit and go up. and remember when doing body work the human eye can see 180 grit scratches so work up to finer sand paper to get rid of them

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Proper rust repair is dependent on the type of rust damage your correcting. I'm assuming this is surface rust from exterior paint failure and not perforations from the sheetmetal rotting due to moisture entrapment in the rockers and such.

 

The assumption is exterior paint failure . In this case removal of the rust to clean bare metal is critical. Care should be taken to not damage ,warp or create more harm to the metal than the rust .damage . Stripping the entire panel to bare metal is recommended . If you have several spots of visual rust you will more than likely also have several small spots of rust under the paint that are not visable. This cowl panel shows what I am speaking of. This was a California car that has been maintained well over the years.

 

DSC00079.JPG

 

The rust removal method should be matched to the location and size of the rust damage. For tight inaccessable areas a sandblasting guns with "blackbeauty' may be preferrable to naval jelly. Some light surface rust on flat exterior surfaces can be easily reoved with a light sanding of 80grit paper. I would recommand the black 3M clean and Strip wheels for rust removal

( 3M 07460, 07461 , 07466 ) All bare metal should be treated with a metal conditioner prior to the application of a zinc based primer ( for rust prevention and adhesion) before the application of a primer surfacer. All primer surfacers are pourous and should be top coated with an exterior paint for best long term results.

 

I would stray away from the dulicolor paints and go to a local PBE supplier and get the professional quality aerosol primers for best results.

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Thank you guys for all the info. Here are a few pics of the rust to help illustrate the problem.

 

IMG_20110218_101633.jpg

IMG_20110218_101653.jpg

IMG_20110218_101725.jpg

IMG_20110218_101741.jpg

IMG_20110218_101850.jpg

IMG_20110218_102908.jpg

 

@palosfv3

here are a few pics of the cowl panel. looks to be in good condition i think.

IMG_20110218_102331.jpg

IMG_20110218_102347.jpg

IMG_20110218_102402.jpg

 

Does it still look like sandpaper would be sufficient over the abrasive disk?

 

also heres another quick question. My friend thinks that the paint on the roof may be salvageable. What do you think?

IMG_20110218_101916.jpg

IMG_20110218_101924.jpg

IMG_20110218_101946.jpg

 

and here are a few miscellaneous pics

IMG_20110218_102603.jpg

lucky number 7

IMG_20110218_102511.jpg

color code was 903 not 115

IMG_20110218_102929.jpg

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Most of the rust in your pics is surface rust caused mostly from the failure of the paint . Strip the entire car to bare metal !!!!

Trying to paint over the failed finish will cause problems in the painting process . If you dont strip it your better off buying Lotto tickets , you would get a better return on your investment.

 

Your cowl panel is in worse shape than the one in the pic I posted. It should give you a good idea of what is lurking beneath the paint on your car.

 

The best inexpensive way of stripping that finish is to use an 8 " diameter 3m 05580 pad on a variable speed buffer with either 80 or 40 grit paper. You will have to experimant a little for the correct combination of speed and paper for the best result.

 

If your going to get this involved in this project you will also find it more cost efficient to avoid the aerosols and go straight to the spray guns and bulk automotive paint materials,

 

 

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While i would love to strip the car down and get a completely new paint job, this was really just to stop or slow the spread of the rust until i can afford to have the whole car repainted. A band-aid if you will. Would sanding, metal treat, etching primer, reg primer and paint to protect the primer work as a temp fix?

 

@palosfv3

When you say the cowl is in worst shape are you referring to the paint finish or rust? From what i can tell the pic you posted looks to have been originally green sprayed with silver with rust stains along the edges and the grill openings or is that bare metal? From when i looked at the cowl this morning i saw no real signs of rust. Paint failure yes but no real rust.Thats not to say there couldnt be rust hinding under the paint.I will try to do a more through exam of it tonight.

Edited by s30zgt
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Question2: Should I put a coat of paint to protect the primer? (The Z is color code 115 blue metallic so I would be using http://www.napaonlin...0539_0006528495 ) IIRC primer is porous so it could let in moisture which could start the rust all over again.

 

 

 

You are correct. Primer is porous and lets moisture in. Epoxy primers are non-porous but the cheap stuff in

the spray cans.. its questionable if that is a true epoxy. So i'de say use a rattle can epoxy with a rattle

can blue paint over the top of the rust areas. Then wax the whole entire car with a good car wax. That will

help protect the rest of the car.

 

 

or... take it to earl scheib for a cheapo paint job

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Trying to band aid the finish on your car is futile. Your in LA and the rust on your car is not going to get any worse in the near future unless you park it on the beach near the ocean. Think about how old the car is and how long it took for the rust in question to form. Save your money until you have enough to paint it the right way. You state its running a little rough . This should be your first problem to tackle. Why paint a car that may not be able to run ? Drive it a little and get to know what this car does well and what it needs . Then map out a plan for what to fix first.

 

The pic of the cowl panel I posted was stripped to bare metal with a chemical stripper. I did this to show how the rust forms beneath the paint . Additional pics of this car and the paint process can be found at .

 

https://picasaweb.google.com/wgmauto/1974Datusn260z#

 

This should give you an idea of what is involved .

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Thanks again guys, specially palosfv3. The z community continues to amaze me with all the great enthusiasts and their wealth of knowledge. The only reason I wanted to tackle the rust is because while I do live in LA I happen to live about 10 mins walking distance from the beach and the thought of the sea air slowly eating away at my z is enough to keep me awake at night. I do plan to work on the carb and other minor things but the surface rust seemed to me to be the biggest glaring issue. I guess I might be buying a carb rebuid kit this weekend and not all the paint supplies haha.

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Most of the rust in your pics is surface rust caused mostly from the failure of the paint . Strip the entire car to bare metal !!!!

Trying to paint over the failed finish will cause problems in the painting process . If you dont strip it your better off buying Lotto tickets , you would get a better return on your investment.

 

Your cowl panel is in worse shape than the one in the pic I posted. It should give you a good idea of what is lurking beneath the paint on your car.

 

The best inexpensive way of stripping that finish is to use an 8 " diameter 3m 05580 pad on a variable speed buffer with either 80 or 40 grit paper. You will have to experimant a little for the correct combination of speed and paper for the best result.

 

If your going to get this involved in this project you will also find it more cost efficient to avoid the aerosols and go straight to the spray guns and bulk automotive paint materials,

 

+1 on that one....people painting over old crappy paint has made me alot of money!

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