Joseph R. Demers
Z Car Tips and Tricks IZCC #4072
 
JRDemers' Homepage
 
 
IZCC #4072
    
    Tank Ventline Repair
    One of the major problems facing someone trying to rebuild a 30 year old car is the lack of parts. Occasionally, if the car is a "classic," aftermarketers will step in and reproduce parts. Or, someone will discover a replacement part that will work as well as the original. In the case of the fuel tank ventlines on my 1970 240Z, however, neither of these seems to have occured. In trying to solve the "exhaust-fumes-coming-back-into-the-car-because-of-destroyed-vent-line-grommets" I happened upon a cheap and yet beautiful solution. I also replaced all the ventlines themselves even though one of them has a 180 degree bend in it. Afterall, necessity is the mother of invention. In this page you will find everything you need (including part numbers and listings) to repair those 30 year old ventlines making the car safer and much better fumewise.
     By far, the most difficult portion of this repair was trying to reproduce the two large diameter lines which pass through the cabin floor at the very back of the car behind the rear interior panel. They are no longer available from Nissan nor are the grommets which seal them as they pass through the floor of the cabin. After completing this project I discovered that the lines are now available from Motorsport Automotive at http://www.zcarparts.com (1-800-633-6331). However, Motorsport Automotive does not have the grommets and I have not been able to locate a source; so the heat shrink tubing still appears to be the best alternative. Also keep in mind that you need to seal up the tail lights and make sure that the overflow tank is not leaking if you really want to get rid of the fumes. As always, carefully check over your fuel tank when you drop it to check for leaks - maybe even get it professionally clean and tested.


The Parts List
    A major problem I found was trying to procure 5/8" fuel line! If you go to an autoparts store and buy 5/8" fuel line chances are, THIS IS NOT FUEL LINE but heater hose - don't use it! It isn't safe to use with fuel. I have however, discovered McMaster Carr online, and this has made my life much simpler. You may order Buna-N hose by the foot! The stuff I order online I sometimes arrives the next day. Here is the parts list with the McMaster Carr parts numbers:

 1 of Part Number 7270K3:                                  $3.44
  Polyolefin Thick Wall
  Adhesive-Lined Tubing 9"
  Length, Black, 1.1" Expanded ID
   This is what you will use instead of the grommets - heavy duty adhesive shrink tubing!
 

 6 ft of Part Number 5645K12:                            $6.30  .
  Fuel and Oil line Transfer
  Buna-N Hose SAE30R3, 1/4" ID,
  7/16" OD, 3" Min Bend Radius
    I did not order this item because it is available at any auto store and  you don't need this much of it

6 ft of Part Number 5645K24:                            $6.90
  Fuel and Oil line Transfer
  Buna-N Hose SAE30R3, 3/8" ID,
  19/32" OD, 4" Min Bend Radius
    I did not order this item because it is available at any auto store and  you don't need this much of it

 4 ft of Part Number 5645K16:                            $7.00
  Fuel and Oil Line Transfer
  Buna-N Hose SAE30R2, 1/2" ID,
  3/4" OD, 3" Min Bend Radius

 6 ft of Part Number 5645K15:                            $8.88
  Fuel and Oil Line Transfer
  Buna-N Hose SAE30R2, 5/8" ID,
  7/8" OD, 6" Min Bend Radius

 1 ft of Part Number 54595K21:                           $4.65
  SAE 100R4 Oil Suction &
  Return Buna-N Hose 3/4" ID,
  1.14" OD

As I mentioned, one of the fuel vent lines (the 5/8" beast) requires a 180 degree turn. As I discovered all the other bends are shallow enough to not cinch the tube. This 180 degree turn however requires you put a steel liner in the fuel line to prevent cinching (you might also try a steel spring, but don't use copper - the sulfur in the gasoline reacts with the copper). This turned out to be the most difficult part of the project! I ordered some 15 mm OD steel tubing from  McMaster Carr. You get a lot of it, but it is hard to bend to 180 degrees and even harder to get it into the 5/8" fuel line! In hindsight I probably would have done more searching to find something of that OD but with a thinner wall.

 1 of Part Number 50295K33:                             $14.83
  Metric Steel Tubing
  12mm ID, 15mm OD,
  2 Meter Length

Oh, You will also need a heat gun - no torches please!!!!!!
 

Making The New Ventlines
    Here is a picture of the original larger ventlines which come off of the back of the fuel tank and pass into the car (click for blow-up):

There are two approximately 4 ft sections of 1/4" and 3/8" lines which are not pictured because they are commonly stocked sizes at the auto parts store and there are no tight bends in them. Both go through grommets, but that will be discussed later. Replacing the 6 ft, 1/2" ID line pictured above is relatively easy since it has no sharp bends. However, replacing the 5/8" line is difficult because it has a 180 degree and a 90 degree bend in it. As it turns out, the hose from the list above can make the 90 degree bend without kinking, so that leaves the 180 degree bend. I decided to make a steel sleeve with a 180 degree bend in it that would fit into the hose. I ordered the 15mm tube described in the parts list because I could not find anything else that would fit into the 5/8" tube. This steel tube was extremely difficult to bend (sorry no pictures of me fighting with tubing bender!!!) and I wish I had done some more searching for a thinner walled tubing then what I had (I think I have seen stuff in hobby stores which is steel but very thin wall). Three points to consider: DON'T USE COPPER - it will react with the sulfur in the gasoline. How much sulfur is in gasoline these days? Don't know, but I have been told not to do it so I don't. If you have to bend the tube without the aid of a tubing bender, fill it with sand and cap the ends - this SHOULD prevent kinking. Finally, this is Buna hose, you may use grease or other petroleum products when you try to get the bent steel pipe into the 5/8" hose. I trimmed as much of the steel down as I could so that it really only prevented kinking at the tightest part of the curve. Here is a picture of the old hose (top) and the new one:

Not a perfect copy, but hey, it is under the car! As a matter of fact, here is a picture of it under the car and connected to the passengers side, rear of the tank ....

The reason that this connection is viewable is because I cut out the rear panel so you could see it better (yeah right, it was torn up in an accident - I haven't put the replacement on yet).

    Now, after the lines have been fed through the "nipples" in the floor (here the passengers side one is shown without the vent line):

I chose to put some asphalt "caulk" (available almost any auto shop) around the line but feel this step is actually unnecessary (in the above picture you can see the caulk and the piece of shrink tubing). Next, I slid a piece of the shrink tubing down the line to cover both the line and the nipple (about 3" of shrink tubing). Here is the important point: THIS IS THE FUEL TANK VENT!!!! NO OPEN FLAME OR POINTS OF IGNITION THIS INCLUDES A HEAT GUN!!!! However, now that you have been suitably "flamed," I used a heat gun, OUTSIDE ON A WINDY DAY!!!! Here is a picture of the shrunk tubing:




As you can see it turns out very nice and VERY tight....

As soon as I get some more pictures developed I will be adding a bit more info to the page, but for now, this should keep you busy for a fewe days.