Water drainage near the front tires

[aochider]

I jacked up the rear end for the first time and a bunch of water came out of the front drainage holes (picture of the area I'm talking about below).

Seems kinda odd to me because it hasn't rained here in over a week. Makes me think something is plugged, but I'm not familiar enough with this car's (1978 280Z) body to know.

[Mikes Z car]

I think that is an important discovery and may bring to light the real reason the front frame rails under the seats rust out. There are two drain holes that I have seen in the frame rails under the seats. One is toward the front of each frame rail under the feet of the driver and passenger. Another hole is towards the back of those same frame rails somewhat in line with the back of the seats. The bottom of those frame rails are fairly flat and unless the water just happens to find the hole it won't all drain out at least that is what I think is happening. The attached picture is of my car before I had welded in new sheet metal. I used a hammer and screwdriver to hammer the hole downward under the driver's feet to make it easier for water to drain out as I had access due to metal that was cut out for rust repair. There may be another way to pull the metal down around those holes to encourage draining or it might be possible to make additional holes in the frame rail with the edges of the holes bent down. A metal structural engineer would know more about how holes in the center of a beam don't affect the strength much.

I'd say what you saw is likely normal though the water may have come in through a hole in the front of that same frame rail where the front wheel can throw water on any hole in the area just above of the tension rod mounting point where those two rubber bushings are. A hole there might need to be plugged to prevent that. Hope that made sense.

Frame rail under the seats visible where hole is:

Edited July 6, 2014 by Mikes Z car

[siteunseen]

There's 2 drains on the sides of the wipers cowl, the vented piece that covers the wiper motor below the windshield. They drain out behind the front tire's inner fender. I'm not sure that's what you're talking about though but you should clean them out too. I think there's 4 screws where the hood meets that piece then you pull it towards the front of the car and viola! it's out. I blew mine out with an air compressor. Here's some pictures, https://www.google.com/search?q=280z+cowl+drains&rlz=1C1BOFA_enUS494US494&espv=2&tbm=isch&tbo=u&source=univ&sa=X&ei=gTW5U8cL17PIBP_jgfgK&ved=0CBwQsAQ&biw=1280&bih=620#imgdii=_

[Mark Maras]

I agree with Mike, Frame drainage holes seem to be better at allowing water in than out, Upon opening up my rails for a look see, aside from rthe rust I was surprised to find the insides were still wet with Northwest liquid sunshine. Car had been garaged or under cover for more than six months. Theoretically, more holes will weaken the rail but flaring the holes may compensate & strengthen the rails back to near original specs. I haven't decided whether to try & totally seal the rails or add flaired holes, Either way I'm leaving doors to access the rails from the inside.

[EuroDat]

It looks like you mean the frame rails. That is going by the photo you posted. Can you circle the area in question using microsoft paint or similar.

If its the rail. The rails are not water tight, but once water gets in they work as a catchment area and hold it. There are lots of holes for mounting things like fuel lines etc and they are not completly seam welded to the floor pan which allows water to creep in during wet driving conditions. All that and the minimum rust prevention used in that era and you have a rust restoration just waiting to break through and show itself.

A member in our local club drilled 5mm holes (2 in each rail) in the low points of his rails to allow water to escape. If rust has already started this wont stop it, but it could slow it down a little.

Chas

[aochider]

Thanks for the advice everyone.

Yes, the frame rails are what I was talking about.

I like the idea of drilling one more hole on each side actually, not sure if I'll do it though. I always felt like a car's metal body should be inherently shaped to move water away from the interior and down to the ground. Surprising how many little pockets or leaks-waiting-to-happen are designed into them though. But, I'm not an automotive engineer or a business person.

[Mikes Z car]

Consider the idea that if you were an automotive engineer you would design them properly!

[bartsscooterservice]

It would be better to have no drain holes at all. Air+water = rust

It looks like you might need a new undercoating aswell

Edited July 12, 2014 by bartsscooterservice

[EuroDat]

The purpose of a drain hole would be to allow the water that found its way in escape. Not saying its the best solution, best would be to prevent it getting in in the first place.

You mentioned that you jacked the rear of the car up and water came out the front of the rail. That means its been trapped in there for some time and could take months to evaporate.

Its a bit like the floor pans. Once water gets in there and can't get out its going to make the situation a lot worse. Draining it won't stop the rust, but when the weather clears it will dry quicker and slow the rust progress down a little.

The undercoating in your photo looks like its starting to crack and lifting in places. Thats when the rust proofing turn into a rust enhancer. When it starts to lift away it can leave bare metal exposed to the elements. The cracks allow water in and hold it there causing rust.

Eastwood sell kits (rattle can with a small hose) to spray chassis and frame internals, but this will only work on a new or repaired rail with no rust. Once rust takes hold its very hard to stop.

Thats my experience with Fiats 127, 128 and pre 70's Holdens. If you think Zeds are bad for rust, Fiats are up there with them in the top 10 list.

Chas