I avoid driving my Z in the pouring rain but this happened twice. There was water penetrating into the car on drivers side (a lot). The water flows down along the left side passing the hood release. I tried to find the leakage but I couldn't find anything. The drains in the cowl area (left and right) are not blocked. There is no rust hole in the firewall.
When I wash the Z and water runs into cowl slots water collects under the cowl and does not drain off respectively very slowly. There is effectively no downgrade (?)

I found a thread at classiczcars where guyz discussed the problems and remarked:

1. "Personally I think it's leaking in from your windshield gasket (even if it's new) as the water can go from the top off the roof, hit the windshield gasket at the top, run all the way down, find it's way to the inner lip of the area (I know it can cause I had light rust there when I tore my Z apart) and then into one of the holes in the area. My Z leaked at the corner where water can pool due to the nature of the curves of the windshield. It wasn't a big leak, but in a good rain it would flood the drivers side."

Remark: my windshield gasket is new.

2. "Under the cowl (the piece between the hood an the windshield) there is a fresh air intake. It is right about the area you are describing the water is coming from. It has a "snorkel" type build. It's about a 6" square 6" tall. There is a "hood" that covers it to prevent water from entering. Along the base it is sealed with caulking. This caulking is probably where your water is entering the car. Water will drip down your heater fan area."

Remark: what does this guy describe here? Is there a picture of this part?

Besides: there is also water flowing on the battery. I think there is a seal missing at my car at the top end of the engine bay (look at the arrow on the picture - it's not my car). Is there a seal at this place normally?

Thanks for your help.
Thor

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T. Link
Germany
1971 240z (HLS30-16506)

Yes, there is a seal there that goes all the way across and under the access doors.

What's the name of this particular seal or this part of the engine bay? I'm sure MSA or Dragon Auto will have them in stock.

_________________
T. Link
Germany
1971 240z (HLS30-16506)

It is known as the "HOOD TO COWL SEAL". This seal would not function as a water barrier, more as a rubber seal to the hood to prevent vibration damage.

There are two drain tubes on each end of the area under the cowl. These allow water to drain down from inside the cowl to the ground from inside the fenders. On older Zs they can be either damaged, blocked or missing altogether.

Interior water leakage can also come from water draining from the cowl area into the blower air intake. The air intake is directly in front of the passenger (right) side. The blower plenum is (was) sealed to the air intake at the firewall. Time can degrade the seal causing water to find its way in.

OR you can have a bad windshield seal as previously stated. But if your windshield was removed when you painted the car your new seal would have corrected this.

Got to be one of these!

_________________
John Taddonio
1970 240Z
1977 530Z
1984 300ZXT
zcarnut@hotmail.com
FB: Zccr zcarclubofrochester

I can think of another possibility. At the rear of each front wheel well there should be a water barrier, which keeps roadspray from being thrown up from the front wheels, into the door hinge area.

Thor, please look under both sides of your 240Z with a light, and make sure there is a 'wall' in front of both door hinges (Carl calls them 'mud barriers'). If you can see the hinges from under the car, you're missing one of these.

I remember your Z was recently dismantled for painting. Maybe (maybe) one of these barrier walls was lost. (The first 240Z I looked at for you, here in CT, was missing one of these).

Also, there are several rubber grommets in the firewall, which allow cables (such as the hood release cable) to pass through, but keep water from entering the cabin. In the dark garage, I would turn on the underhood trouble light, close the hood, and get down into the driver's side footwell under the steering wheel, and look for light coming thru. Water is insidious, especially when driven by wind or splashed by tires ~ where you can see light, you can get water.



Frank

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1970 240Z

Yea Thor, I don't think that seal is the problem, but you'll need it anyways. John hit it on the nail, Frank as well. I think I just got some of those mud flaps in my last truck load of Z parts.

I don't see how the inner fender mud seals would prevent water from entering the cabin. Even if water got past them, it would be onto the door hinges which are outboard of the inner door seals. If the door seals are intact, water should not get inside the car.

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John Taddonio
1970 240Z
1977 530Z
1984 300ZXT
zcarnut@hotmail.com
FB: Zccr zcarclubofrochester

The water moves from above, so I don't think it's a leak at the inner fender. The door seals are perfect. I'm quite sure something with the renewed windshield weatherstrip must be wrong...

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T. Link
Germany
1971 240z (HLS30-16506)

Thor, replacing the windshield seal takes talent. Not only does it hold the glass in place, but it also seals on the pinch weld around the opening. If it is not properly "fed over the lip" of the pinch weld (with a hearty string and dowel, see the service manual) it will not seal properly, thus water can get in.

Try removing the dash trim panel and look to see if the rubber seal is OVER the pinch weld all the way around.

I'm guessing this is the culprit if you had your windshield replaced at some point.

_________________
John Taddonio
1970 240Z
1977 530Z
1984 300ZXT
zcarnut@hotmail.com
FB: Zccr zcarclubofrochester

John, the dash trim panel, is that the panel where the VIN is fixed? I will remove it and look for the rubber seal.

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T. Link
Germany
1971 240z (HLS30-16506)

Yes, the metal panel at the base of the windshield where the defroster outlets are. I believe there are about 5 screws that secure it. Once removed, you should be able to check the integrity of the windshield seal all the way around.

Good luck!

_________________
John Taddonio
1970 240Z
1977 530Z
1984 300ZXT
zcarnut@hotmail.com
FB: Zccr zcarclubofrochester

I'll try my best. Hopefully you've found the cause. Thanks a lot John!!!

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T. Link
Germany
1971 240z (HLS30-16506)

and that's why parts cars with bad seals have a very rusty dash trim. Makes sense.

I had the same leak and it turned out to be the windshield at the lower corner of the gasket. I replaced the glass and the new gasket did not fit as tight as the factory one. 3M makes a good sealant that you can push into the space between the gasket and glass. Thier website will have it listed.It dries but does not harden . I even ran a thin bead around the gasket and no more leak. Jim

I think your talking about "Butel" and you can get a tube at any glass place.