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cowl drain modifcation, thanx Enrique


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Afternoon everyone , I just finished building cowl drains for the Z . There was a thread from Enrique that I found and I followed his instructions and made what you see here . The pvc 90 degree was modified by cutting the one end shorter so it would fit into the rubber drain outlet easier and not bind while allowing the 90 to fit as close to the inner fender as possible . I found some woven tubing at 2$ per foot and and some gear clamps to go around the whole assembly and then secured the rubber drain with some electrical tape . To fit the pvc elbow into the tubing I warmed the hose with a heat gun and the elbow slid right in .When it cooled down the tubing kind of shrunk around the elbow to make a very tight fit . I cut the bottom portion at a angle and then fit the now assembled drain tube into the rubber drain hole . I then taped and clamped into place and the fastened the bottom of the drain with a screw through the plastic splash guard and the job was done . I made the splash guards from a old mudflap and made the seal that you see from some 1 inch round foam that I scored from work .I sliced the foam part way and glued it into place with rvt gasket sealer.The bonus was that the tubing came off a roll so there was a natural curve to it allowing it to fit very close to the inner fender .I was able to build both sides for less than ten $.

Thanks for the great ideas that come from this forum everyday

Hope you all like what I have done








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Looks good. EScanlon showed me this mod several years ago and I did it right then. I agree thanks E. This is a mod that should be contemplated by anyone that has a early Z in my estimation. I used a plumbing one inch 45* PVC elbow instead of the 90* . Not necessary to cut the fitting, it slides right in to hte Cowl drain tube. I used silicone sealer on both the fitting and hose. Same at the bottom to hold the hose in place while installing the fender. I just mention this for future readers.

The parts I used are common items at Home Depot and easy to find. ;)

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Thanks guys for the comments , Just to let you know the pvc is 2.5 inch in o\d and the tubing is a 2.5 inch i\d . Gary I didn't think about a 45 angle , I,m sure it works as well or better . As for cutting the end shorter it was to get as tight a fit to the inner well as possible .

talk to you all later


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  • 1 month later...

I was just doing this job myself the other day and NOW I find this thread. It's funny how similiar the ideas were on this. I didn't see on these threads how the actual inside drain hose was done, so I am going to post my remedy to this issue.

The drain at the cowl is an unusual diameter and I wa having difficulty finding a hose until I was going thru all of my Z junk and stumbled on an old radiator hose. I said to myself," that's it, a radiator hose would have the 90 degree turn and still be smooth and plenty stout." I went down to Autozone and looked thru their shelves and found a hose that was the right diameter and length-8$. Then I went to lowes and bought a 1 -1/4" 90 to a 1" spout and bought the 1-1/4" hose similiar to this thread. The radiator hose was a perfect fit on the cowl drain ID as well as the kick panel OD-very tight. I have about 21$ in this, but the biggest thing I wanted to share was the radiator hose.

By the way, cutting the hose at an angle was a great trick, it was funny since I did the same thing before I saw this thread.






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  • 1 year later...


There are several possibilities to your water behind the dash. The windshield not being properly sealed to the body is one, but that one, IMO, is the rarer of them.

Check to see if the drain tube from the cowl that then exits through the kick panel is still whole and not cracked or has holes. The Cowl Drain Tube comes down from the cowl into the engine compartment and then takes a 90° turn to go out the kick panel, which is where the extension I came up with connects.

The next thing to check is the sheet metal flange at the very front of the cowl where it is welded to the firewall sheet metal. It is possible that the body has flexed and the caulking applied there has now flaked or cracked off allowing the water to seep through.

Check the Fresh Air Vent Flange on the Passenger side of the cowl, and see if the sheet metal around the flange is still intact and not rusted through. While you're at it, check the plumber's putty seal between the cowl floor metal and the Fresh Air Vent Assembly/Blower Unit.

Lastly, the whole purpose of the extension for the cowl drain is that the original hose ends just after it enters the fender plenum. It then dumps whatever debris may have accumulated in the cowl and is then flushed out with the water. Over time you will have all sorts of water retaining debris accumulating between the front fender and the forward portion of the rocker panel.

This is very common and it eventually results in a rusted front fender "leg". People will claim that it is due to the tire kicking debris up there, but careful examination will reveal the splash guard and the rubber flap that keeps the tire's rooster tail from depositing debris there. What the extension does is it conveys ALL of the cowl's drainage OUT of the body and it's crevices. By doing so, you will have a clean and debris-free fender plenum.



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