How to remove and replace a Porsche 944 fuel tank (Square Dash Model)

THE WHY?

If you've ever asked yourself "Should I buy an early (square dash) or a late (oval dash) 944?" then this article may be the deal breaker. Having put my 944 in for a service my mechanic discovered a leak that appeared to be coming from the fuel tank. No big deal I thought, I'll buy a second hand one from a breakers or ebay. However upon further investigation it turns out Porsche significantly changed the material of which the fuel tank is made from between the early (square dash) and later (oval dash) 944. The square dash 944 (and 924) has a fuel tank made from steel, whereas the oval dash model has one made from plastic. More investigation reveals that the fuel tanks are also of different capacity (oval dash has the larger 80 litre capacity, compared to square dash's smaller 66 litre). Even more investigation finally concludes that the plastic fuel tank will not fit the early (square dash) 944's as the cross-member that supports the transmission is non-removable and therefore blocks the insertion of the larger plastic fuel tank.

So the options I had were:

a.) Buy a new steel fuel tank from Porsche for near £1500.00!
b.) Repair the old tank
c.) Buy a good 24 year old fuel tank from a breakers £40.00

I went for option 'C'.

For the record and from research on forums it seems the steel fuel tanks are susceptible to cracking due to the vacuum that causes the fuel tank to contract and expand. They are also susceptible to corrosion, externally and internally.


THE TASK


You'll need the following tools and a lot of patience and a spare pair of hands:

Socket set
Spanners
Couple of screwdrivers (flat and cross-head)
Container to empty petrol into
Clamp-able pliers
Trolley jack or two
Axle stands
Waxoyl (Spray version) - optional
3M Scotch Weld 80 Spray Adhesive - optional



THE HOW TO


(Amateur mechanic Job Time approx: 2-3 days)

You want to start by emptying the fuel tank as much as possible before you start. I did this by driving the car until the fuel light came on solidly on the dash.

The next thing to do is disconnect the battery, as fuel and sparks don't mix.

Now undo the fuel cap to release any vacuum or pressure in the fuel tank.

Next slide under the rear of the vehicle and locate the main hose between the lowest point of the fuel tank and the fuel pump. If you have a fuel clamp or a pair of clamp-able pliers then clamp the hose nearest the fuel pump and proceed to undo the jubilee clip that fastens the hose the fuel tank.

Below is a photo of the fuel pump with the main hose removed.

With the jubilee clip loosened get your empty container positioned below the tank to catch the remaining fuel. Wriggle the hose off the fuel tank and catch all the excess fuel until completely drained. You can now undo the much smaller hose that is also connected to the lowest part of the fuel tank.

Jack up the rear of the car as high as possible and set it on axle stands.

Now remove the rear section of the exhaust by undoing the 3 connecting bolts on the exhaust tube in the centre of the car and then unhook the rear box from its rubber hangers (shown below).

Next remove the four bolts that secure the exhaust heat shield (shown below) to the underside of the car.

Now remove the transmission (See this post for instructions)

Now it's time to get inside the car. Start by completely removing the carpet from the boot area.

Next pop out the rear quarter window on the fuel cap side and completely remove the interior panel of the same side (See this post for instructions)

Lay down the rear seat and un-clip and pull back the carpet from around the side of boot of same side to expose the fuel filler cover (Shown below)

Undo the surrounding screws, not forgetting the two small nuts at the base of the cover. Then as shown in the photo above position a screwdriver in behind the cover either side and pull towards you. The cover may resist at first because of the black goo it is secured with, but it will come away eventually to expose the filler hoses (shown below).

Undo the jubilee clips on all the hoses and pull off, with the exception of the largest hose which you can slide upwards to reveal the corner inlet of the fuel tank.

Now lift the large silver heat shield square located on the floor of the boot to expose the plastic cover for the fuel sender. Prise this up to in turn expose the sender wires. Make a note of what wire goes where and disconnect them all (shown below).

Get back underneath the car and locate the two large straps at either end of the fuel tank (shown below)

Undo the bolts and unhook the straps, the fuel tank is now only supported by the steel cross member it is wedged over.

Get your hands behind the rear most edge of the fuel tank and pull down. Keep wriggling the tank up and down checking that the fuel filler hoses aren't trapped. This part takes a lot of effort and patience as the tank is an extremely tight fit over the cross member and has probably never been removed before. Trust me the tank will eventually come free. You may need to unbolt the fuel pump from its rubber mounts if it gets in the way.

With the fuel tank removed we can now clearly see the fixed cross-member that stretches the width of the car underneath and the fuel filter bottom right (shown below).

As stated at the beginning of the post I decided to source a replacement tank from a breakers yard, it had a bit of dent in the side and some surface rust that I cleaned off. I then Waxoyled the whole tank to prevent further corrosion. I would also recommend you get them to pressure test the tank as I did. This helps prevent the problem of putting a tank back on that is the same or worse than the one that came off. It may also be worth checking the condition of the rubber hoses as they may have started to perish and go hard after 24 years of use and replacements would probably be a good idea.

Here are a few photos of the replacement non-leaking tank that I sourced from a breakers (note the expansion tank hanging off the bottom of the photograph and the fuel sender top left in the first photo).

Not shown in the photos is the large foam pad that sits around the fuel filler neck part of the tank. I carefully removed this before spraying the tank with Waxoyl. It was then finally put back on and stuck down with 3M Scotch Weld 80 spray adhesive before the tank was reinstalled.

Tank installation is the reverse of removal.

For more information on the steel fuel tank cracks and repair procedure if you can't source a replacement tank then follow this forum post. It also shows the differences in dimensions of the early and later 944 tanks side by side.

How to fit a short shift kit to a Porsche 944

THE WHY?

It has to be said that the 944 doesn't have the lightest gear shift you'll ever come across. So it makes sense to keep this part working as efficiently as possible. There are several ways this can be achieved. The first and by far the simplest is to make sure the transmission oil has been refreshed (A  job that only takes an hour, but can make your drive feel 100 times better). The second and third options involve replacing the shifter mechanism at either the gear stick end or the transmission end. Over time you'll find that wear and tear take their toll and the shift will not be as precise or as smooth as it should.

Since I had the transmission off the car and had noticed quite a bit of play in the plastic ball joint on the linkage I decided to replace it with and after market short shift kit.


THE TASK

This job is far easier if the transmission is off the car, however it is still do-able with it still attached. You'll need:

Socket set and/or ring spanners
Short shift kit (Bought mine off ebay, but you can also buy a really nice one from here)
Hammer

and maybe....

Hex rod and two rose joints (see foot of post)
Hacksaw (see foot of post)
Thread tapping set (see foot of post)



THE HOW TO

(Amateur mechanic Job Time approx: 1.5 hours (off the car) or 2+ hours (on the car)

Firstly identify the original shifter linkage and support arm attached to the gear box. If your transmission is still attached to the car the linkage sits on top of the transmission. You'll also need to slide back the rubber boot and undo the bolt that connects the linkage to the shift rod that runs through the car before you can continue.

Now remove the black rubber boot completely by sliding it off the linkage rod (you'll need to re-attach this to the new linkage later).

Next undo the nut and bolt at the top of the linkage where it joins the support arm. At this point the bolt on mine sheered as it was so old and rusted. If the same happens to you then you can either buy a replacement from Porsche or make you're own alternative support arm using some hex-rod and a couple of rose joints (See end of post for details on this).

Assuming you've not had problems undoing this nut and bolt you can then proceed to remove the small bolt that fastens the linkage to the shifting stub on the side of the transmission (Note: the flat side of the shifting stub that the bolt presses against). Having removed the bolt a small tap to the side of the linkage with a hammer should remove it from the stub and the transmission completely leaving only the support arm attached to the transmission at one end.

Here is a photo of the new linkage (left) beside the old one (right).

Installation of the new short shift linkage is the reversal of removal, taking care to line up the flat side of the shift stub as you slide on the linkage and do up the bolt. Then reconnect the support arm to the linkage and finally slide the rubber boot back on.

Here's what the finished article should look like.

Now for those of you that are interested in the support arm (The orange rod in the picture above). Having researched the short shift kit on the web before I attempted this modification there are several manufacturers all offering roughly the same piece of kit at varying prices. Some of the short shift kits come with a support arm similar to the one I made and some (like the one I went for) just make you use the original arm (and had the bolt not sheered then I would have reused the arm).

To make the arm you will need to source a length of hex-tube / hex-rod. In the UK this is easier said than done as most hardware stores don't stock it. Fortunately because I have been going Karting since the age of sixteen I happen to know that hex rods are used as the steering track arms on these vehicles. So a quick search on ebay for 'Kart track rods' brings up a number of results right away and at some very reasonable prices. The good news about buying them off ebay is that they usually come with the rose joints already attached at either end. If they don't then you'll need 1 x 8mm Left Hand Thread rose joint & 1 x 8mm Right Hand Thread rose joint (They are also known as 'track rod ends').

If you've bought your Kart track rod then you'll instantly notice that it has an 8mm thread cut into it at each end, one will be a left handed thread and the other will be right handed (Right handed threads are standard on virtually every screw you've ever come across). We need to make the rod shorter which means cutting off one of the ends. Leave the left hand threaded rose joint attached to the track rod and measure it up against the original support arm. Mark the length and use a hacksaw to cut off the standard right hand threaded end (we don't need this bit). You will now be left with left handed threaded length  and will need to re-tap an 8mm right hand thread into the sawn end. Once this is done attach the right handed rose joint and you'll have an adjustable support arm. By simply using a spanner to turn the rod you'll notice it'll pull the rose joints inwards and by turning the other way it will push them outwards.

Simply attach it in place of the original support arm using a couple of 8mm Allen bolts and some washers as shown in the photo above (Using Allen bolts instead of normal hexagonal bolts allows the rose joints to move more freely).