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Fuel Expansion Tank and Rollover Valve Replacement
 
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Pelican Technical Article:

Fuel Expansion Tank and Rollover Valve Replacement

Steve Vernon

Time:

2 hours2 hrs

Tab:

$65

Talent:

**

Tools:

Philips, Flathead screwdriver, 5mm Allen, 10mm, 7mm socket, 13mm wrench, pick

Applicable Models:

Porsche 993 Carrera (1995-98)
Porsche 993 Carrera 4 (1995-98)
Porsche 993 Carrera 4S (1996-98)
Porsche 993 Carrera S (1998)
Porsche 993 Targa (1996-98)
Porsche 993 Turbo (1996-97)

Parts Required:

Expansion tank and/or rollover valve

Hot Tip:

Get a friend to help lift it out the firewall

Performance Gain:

Functioning Evap system

Complementary Modification:

Check your fuel hoses and lines

The fuel expansion tank and roll over valve are part of the complete fuel and EVAP system on your Porsche 993. The tank can crack over the years and develop leaks. If you are smelling gas coming from under the hood, the fuel tank expansion tank, rollover valve and all the lines should be checked immediately and replaced as needed.

The rollover valve comes into play if you ever roll your car and prevents fuel from venting out the top of the tank by simply closing the valve when the car is inverted. The valves very seldom need to be replaced and if you have rolled your car this valve is probably one of your lesser concerns.

Over the years your car may have been serviced by multiple people including previous owners and this can lead to parts replaced with different size fasteners and hardware. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches.

The expansion tank sits on top of the fuel tank (red arrow).
Figure 1

The expansion tank sits on top of the fuel tank (red arrow). If your tank is cracked, split or leaking you need to replace it right away.

You do not need to remove the firewall to remove the tank but this is one of those places where it is handy.
Figure 2

You do not need to remove the firewall to remove the tank but this is one of those places where it is handy. The hard line on the rollover valve can get brittle and removing the firewall will give you more room to work with the valve and decrease the chance that you might break the line. If you break the line you will need to pull the fuel tank to replace it. If you want to pull the firewall (red arrow) please see our article on firewall removal for additional assistance.

The roll over valve sits in a cut out in the expansion tank and is held in place by a rubber grommet around it (red arrow).
Figure 3

The roll over valve sits in a cut out in the expansion tank and is held in place by a rubber grommet around it (red arrow).

If you have removed the firewall gently push the rollover valve out from the expansion tank (red arrow), this will give you more room and cause less stress on the line a fittings when removing the tank.
Figure 4

If you have removed the firewall gently push the rollover valve out from the expansion tank (red arrow), this will give you more room and cause less stress on the line a fittings when removing the tank.

Use a 7mm socket and remove all of the hose clamps on the two hoses from the fuel tank to the expansion tank.
Figure 5

Use a 7mm socket and remove all of the hose clamps on the two hoses from the fuel tank to the expansion tank.

If you have the original hoses on the original tank these are going to be stuck on the tanks hard.
Figure 6

If you have the original hoses on the original tank these are going to be stuck on the tanks hard. Use a small flathead screwdriver and some lubricant and spray between the hoses and tubes then run a pick around them to break the seal. The outlet from the tank is plastic and glued to the tank, you do not want to break these or you are buying a new gas tank.

Remove the three 10mm bolts holding the expansion tank to the fuel tank (red arrows).
Figure 7

Remove the three 10mm bolts holding the expansion tank to the fuel tank (red arrows).

Be sure to remove the spacers before you remove the tank as they have a habit of falling down between or under the fuel tank.
Figure 8

Be sure to remove the spacers before you remove the tank as they have a habit of falling down between or under the fuel tank.

Wiggle and lift the expansion tank until it slips off the hoses connecting it to the fuel tank.
Figure 9

Wiggle and lift the expansion tank until it slips off the hoses connecting it to the fuel tank. Turn the tank over and use a 7mm socket to remove the rollover valve hose from the bottom of the expansion tank (red arrow).

If you are replacing the rollover valve you will need to pull the fuel tank to follow and remove the flex line (red arrow).
Figure 10

If you are replacing the rollover valve you will need to pull the fuel tank to follow and remove the flex line (red arrow). Please see our article on fuel tank removal for additional instructions.

With the tank tilted forward you can remove the hard line for the rollover valve from the back of it (red arrow).
Figure 11

With the tank tilted forward you can remove the hard line for the rollover valve from the back of it (red arrow).

With the tank out of the way you can disconnect the line just before where it exists under the vehicle.
Figure 12

With the tank out of the way you can disconnect the line just before where it exists under the vehicle. Installation is the reverse of removal.

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Page last updated: Fri 3/24/2017 03:12:51 AM