Cowl rust blasting

[MH77280Z]

Guys, this is the only rust area i have, the cowl. I am thinking of blasting it as the wire brush is not good enough. This is heavy rust but still no pitting like damage.

Top is ok, Issue is how much i can blast on the lower area. Also i think the passenger side has air passage into the blower motor i believe? my blower motor and air heating works fine. I would assume all the media will just get into the blower motor and through that inn the ducts?

How should i prevent that? or just seal that side and do it with hand, blast the center and driver side only?

[240ZBUILTBYME]

yes there's the intake for the blower motor and also the cowl drains you would need to block and not sure if media would get into the side air plenums too. Pretty difficult with the dash still installed, might be able to block from the top. To properly blast, coat and seam seal that whole area you'd need to remove the whole top cowl panel, which is a pretty involved process. anything less would be a band aid treatment, but if theres not too serious rust you could do what you can with wire wheels and then use something that converts the rust and coats at the same time. I think eastwood has a few products  

[jonathanrussell]

I did this job to my silver 240z a few years ago. 

Blasting wasn't an option for me so I used a combination of wire wheels, paint stripper, putty knives, and phosphoric acid. I soaked paper shop rags in phosphoric acid and placed them on the metal. This is how I removed most all of the rust.

I also cut out the rain cover over the fan blower intake so that I could gain access to areas below it. I reinstalled the rain cover using a silicone sealant rather than welding it. 

After everything was all clean, I epoxy primed, seam sealed, primed again, and painted. 

I should also mention that I had the dash out of the car and the interior was totally removed. This made it easier to deal with the fan blower air intake.

It was a miserable job. I don't ever want to have to do it again.

[240ZBUILTBYME]

Your dash looks pretty cracked, why not remove and have it reskinned? big job though if you arent doing a full restoration.

[MH77280Z]

1 minute ago, 240ZBUILTBYME said:

Your dash looks pretty cracked, why not remove and have it reskinned? big job though if you arent doing a full restoration.

I might take the dash out as there is a slight coolant leak from the vacuum cook valve etc. I have a replacement for that.

Based on @jonathanrussell input too. I am thinking just to properly seal block the passenger side cowl where the blower intake is. Blast the other side as much as possible. Treat the passenger side like @jonathanrussell mentioned by hand. Later take the dash out to change the vacuum cook etc. This way any residual blast media if any can be taken out. Meanwhile disconnect the fan.

 

[MH77280Z]

On 10/5/2022 at 10:32 AM, jonathanrussell said:

I did this job to my silver 240z a few years ago. 

Blasting wasn't an option for me so I used a combination of wire wheels, paint stripper, putty knives, and phosphoric acid. I soaked paper shop rags in phosphoric acid and placed them on the metal. This is how I removed most all of the rust.

I also cut out the rain cover over the fan blower intake so that I could gain access to areas below it. I reinstalled the rain cover using a silicone sealant rather than welding it. 

After everything was all clean, I epoxy primed, seam sealed, primed again, and painted. 

I should also mention that I had the dash out of the car and the interior was totally removed. This made it easier to deal with the fan blower air intake.

It was a miserable job. I don't ever want to have to do it again.

Changed my mind about blasting. What phosphoric acid rust removing product u used? I think i can work it off and then just seal it like you. Appreciate some guidance. Weather is gotten better and dry!!!

Plan on picking up this tomorrow: https://www.acehardware.com/departments/home-and-decor/cleaning-and-disinfectants/rust-removers/13868

Edited January 25, 2023 by MH77280Z

[DatsunZGuy]

This job might be a good candidate for POR 15

 

Edited January 25, 2023 by DatsunZGuy

[MH77280Z]

Looked a lot of reviews and this product Rust Kutter came up on top above OSPHO. Both are Phorphoric Acid based.

https://www.amazon.com/dp/B001U1GW82?psc=1&ref=ppx_yo2ov_dt_b_product_details

This thing works!!! my rust was pretty serious. Scrapped with a big wire brush and this is after first pass sitting for about 30 hours. Good thing is it creates a flaky black surface which I believe is the reaction residue which can be scrapped off with a wire brush. I think results are pretty good so far. I am planning to give it 3 rounds. Using the same treatment in the battery area which luckily dont have any pitting.

Wanted to share the results and the product I used. Probably will also use that wet rag combination as well in harder areas. Slow and steady!!!

Edited April 19, 2023 by MH77280Z

[jonathanrussell]

@MH77280Z Sorry I missed replying to you but looking good. Did you finish the project?

[MH77280Z]

Yes, came out pretty nice. The Rust Kutter was great plus i did plenty of sanding but the paint looks solid. I dont drive in rain or wet anyway so should be good.

[MH77280Z]

Back to factory original ... light blue metallic.

Next new steering and suspension and i will be back on the road. Engine runs great. Need to put back body panels next few weeks.

[MH77280Z]

Update ... finally hood, fenders and front body panels on.

I have yet to install the main door seal which goes around the main doors.

One quick question on these hood to fender bumpers ... I have the front round ones near the firewall/cowl area and they are great and dont let the hood vibrate. I can bring the hood down and slowly push it in to lock. But when I put these 4 fender bumpers I cannot do that anymore, I had to bang the hood down fairly hard to latch. I am not liking that, so far I had removed these 4 and feeling ok. Thoughts?