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1986 951 - new to us
have been slowly refurbing things - fuel lines, etc
running well
wet passenger carpet after heavy rains here in the bay area
removed battery and not what we wanted to see!
plenty of rust in the battery tray and some holes
at least it's not a mystery where the water is coming from
IMG_3900.jpg (2.58 MiB) Viewed 938 times
seems like this is a common issue
what are the options for repair?
cut out/weld in a new tray?
unfortunately, welding is not something I've ever done
so if this is the right way to do it - any recs for shops in the bay area?
or anyone local want to teach me how
Sleepy wrote: Sat Nov 22, 2025 5:19 pm
1986 951 - new to us
have been slowly refurbing things - fuel lines, etc
running well
wet passenger carpet after heavy rains here in the bay area
removed battery and not what we wanted to see!
plenty of rust in the battery tray and some holes
at least it's not a mystery where the water is coming from
IMG_3900.jpg
seems like this is a common issue
what are the options for repair?
cut out/weld in a new tray?
unfortunately, welding is not something I've ever done
so if this is the right way to do it - any recs for shops in the bay area?
or anyone local want to teach me how
I found a used tray on eBay in early 2021 and had a local body shop guy in San Jose who does side jobs cut out the old one and weld in the good, used one and it came out fine. I can give you his contact info if you PM me.
German Autobody in Santa Clara does exceptional work and is Porsche certified. Be prepared for sticker shock though, as this isn't a typical job and will take some time from someone with old-school body shop skills. I did my own, mostly just worried that it's too tedious a job for body shops to spend the time needed to do right. I'm not a body work guy (at all) but the repair gets covered in seamer and then hides under the battery, so it's more about making a functional water-tight repair than esthetics...
I had a junk yard cut out a battery box, but ended up not using it. After drilling out the spot welds and pulling off the battery bracket, the actual rust area was small enough to patch. I figured the less original body I had to remove, the better. I just used a piece of 18g steel from Home Depot, cut with a dremel and shaped on a vice. The most tedious part of the job was the brackets under the battery box. I had to get creative to get those back in their original locations. Once the patch panel was in, I fixed up the battery bracket and used used the drilled-out spot welds to put it back exactly where it was. Then I put Wurth seam sealer over it all (like the factory did originally) and finally painted it with code-matched SprayMax catalyzed paint. It's not going to win any awards, but I was happy with how it all came out.
I had this on my car a few years back, it was a lot like yours. It was worse than Tom's because on mine the worst part was up near the firewall - it looks like yours is bad there too. I DIY'd as much as I could (removing the dash, wiring, ABS lines which most cars don't have etc.) and had a classic restoration guy do the metalwork and painting. I have him a good battery tray cut from another car.
It looked great but it leaked again a year or two later and I had someone else patch it up. It has been solid ever since.
Mine looked really bad, maybe worse than yours so the good news is it can be saved. I paid those 2 guys around $1100 each and the amount of work I did disassembling stuff for the first repair would probably have cost that much again. Assuming you don't have to get it done twice, I would assume it'll cost in the region of a couple of grand.
It looks like Photobucket is partially hiding the image but I think you can see the area where the firewall meets the floor of the battery box area and the wheel arch here: https://rennlist.com/forums/924-931-944 ... -area.html
Since you have an early Turbo it should be a bit simpler. That corner of the car is where Porsche put all the options in later years!
Mine has the ABS module, hard brake lines, the ABS computer, cruise control, airbag (passenger airbag sensor and airbag computer)....lots of stuff that needs to be moved away for welding.
As an FYI for future info... a proper vent tube on the wet lead acid battery would have mostly eliminated the corrosion and rust. I can't remember if the 944 has provisions for that or not as I run AGM batteries don't really have this requirement.
Sleepy wrote: Mon Nov 24, 2025 12:47 pm
For people that have had to do this repair more than once - what was the reason? What is necessary for a successful long term repair?
Identify rust areas
Cut out to good metal
Patch, weld
Seam sealer
Paint
Any other tips to make sure it’s done correctly?
I had mine repaired again, but it was just that the first guy didn't seal things up. I don't know the exact details because I had someone else fix it, so I never really got to see it. I think the solution you outline will last forever if done correctly.
