So far the rust I've found on the slicktop is where mungyz said. A pillar behind the guard. I had minor surface rust there. And the concerning rust I have is at the top where the windscreen moulding sits. I'm going to have to resolve this when the new windscreen goes in, cause I can see it growing into the roof. And ATM with the paint job I'm doing, I don't need to be coming back to this in a years time. Apart from these two, I haven't seen any more rust... No wait. Yes I have. Between the Hiro wing and the hatch, wasn't prepped correctly last respray (not my own work) but there were bubbles forming under the hatch paint. This got a bare metal sand back and a rust treatment. Good as gold now.
worst I saw was the body panel directly below the back most point of the rear quarter window. Right against the front of the rear wheel well. Window wasnt sealed properly and water dripped down the inside of the chassis and fell down onto the join between the wheel arch and the side panel. On one car, I had to cut out a pce 12 inches long and 2 inches wide to get it all
I had a spot at the top of the windscreen - under the targa rubber on the RHS.... noticed it before it did much more than lift the paint a bit, and stripped and repainted it - seemed to be trapped under the rubber, and not making it back to the water drain......
I did read through all the posts....Did anyone say the battery area? thats my only area that needs attending to.
Here's what I found on my car after stripping the interior Sound deadening on the firewall had retained water after the heater core burst, causing sizeable surface rust This long section was found near the hatch release This was found at the back of the rear passenger footwell, quite decent There was also an odd section in the roof once I removed the head lining, above the rear passenger's head. The strip underneath the targa hook was also starting to bubble with rust all the way along. All pretty easy fixes, nothing significant. Glad I caught them now. Makes me wonder how many other Z32's are rusting away under the carpet.
Another one is the B pillar targa drain pipe which runs from the top to the bottom rear sil, if that blocks up, and with salty air / water.. You're going to have a stuffed sill. That occured on my previous 2+2.
Thi sbeing said there are non Acetic curing silicons - these have no problems being in contact with metal - a lot of plumbing silicon is of this sort as you can not seal a metal flashing and expect it to last without this - these are labeled as a neutral curing silicon. I was a Plumber/Gasfitter before I started panelbeating
One criminal spot for rust is around the stock spoiler. Everyone goes straight for the little sides, but dont stop looking there. Open the hatch and pull the plastics off. When the moisture gets under the stock spoiler it will also come in throught the bolt holes. The moisture will also rust up all under the plastics if left alone. Definitely worth checking if it hasnt been already.