REMOVING THE GAS TANK ON A 'O3' C4S

[creekman]

2003 996 C4S

 

I've had a gas fume stink for a year, but because I had another project on the lift that couldn't be moved so I soldier on since the car ran fine.  Well, I finally got the car on the lift, pulled down the belly pans and found that it was a gas leak, not fumes... It never leak enough to show on the floor.  However, I can't find the source of the leak.  it looks like pulling the tank is not easy, or next to impossible...  I read what Bently had to say, but I was hoping for real time help on the subject from someone on the forum...

 

I tried several search requests and a big '0"...  I'm sure there are posts on the subject, I'm just not asking the request right...

 

Thanks,

 

Mitch

[judgejon]

Good luck, Mitch.  My only experience is getting down to the tank from the top. 

[JFP in PA]

51 minutes ago, creekman said:

2003 996 C4S

 

I've had a gas fume stink for a year, but because I had another project on the lift that couldn't be moved so I soldier on since the car ran fine.  Well, I finally got the car on the lift, pulled down the belly pans and found that it was a gas leak, not fumes... It never leak enough to show on the floor.  However, I can't find the source of the leak.  it looks like pulling the tank is not easy, or next to impossible...  I read what Bently had to say, but I was hoping for real time help on the subject from someone on the forum...

 

I tried several search requests and a big '0"...  I'm sure there are posts on the subject, I'm just not asking the request right...

 

Thanks,

 

Mitch

 

This is an absolute bear of a job, as the tank has to come out of the bottom of the car.  Literally everything beneath it needs to come out first, then the tank drops down.

 

You might find this helpful: GT2/Turbo gas tank removal

 

Good luck!

[creekman]

Hi Jon, Glad you're still on the job... 

 

The trouble is the leak/weep is in the fill pipe connections or the other 2 hoses that come off the lid on top off the tank.  What's between the top and bottom of the  tank exterior is a mystery.  We pulled down the tank supports straps and nothing happen.  There appears to be another strap

that's forward and on top of the saddle bags.   To get to the bolting of the strap on left side you would have to remove some water pipes, that would be the last thing I would want to do, UGH...

 

P.S. I'm not even sure this what holding it in place, but something, that's for sure...                                

[JFP in PA]

The tank actually sits on a couple of protruding lugs that require you to lift the tank upwards, and then move it slightly forward before it will lower out of the car (page 552 in the link I sent you).  The tank tends to take a "set" to these lugs, so you need to give it a shove upwards first.

 

As noted above, everything underneath the tank has to come out, including the water pipes.  This is not a fun project..................🤬

[creekman]

OMG, you ain't whistling Dixie...  The trouble is it's probably loose hose clamp or a bad hose.  I doubt it's a crack in the tank.  I also noticed that when the tank is full it admits the most/worst gas fumes.   Are the gas tanks in the 4S subject to cracking?  I have my power steering pump mounted in the cavity after removing  the front diff.  I'd like to see if I could replace the 2 hoses under the black derby (C4S) first if I can find the other end.  I gently pulled on them and it seemed the fumes were worst after doing that.

 

I bet Porsche would get a couple grand for R&Ring the gas tank...  I think the San Antonio Porsche dealer gets $170.00 hr. now.

 

Many thanks for your help, at least I know now what I'm dealing with, and I don't like what I see.  The trouble is I might fix the gas tank problem, but now I've got a leaky radiator pipe or P.S. pump leaks.  In the end I'll do what I have to do.  

 

Mitch

 

P.S. I forgot one thing, when I installed the LS3 motor the additional horsepower would have shredded the tires so I opted to change the rear ring and pinion to a taller gear, but no such luck on the front diff which was removed.  So that was one less thing we had to take down...   If any one needs the front differential and driveshaft I'd nearly give it away.

Edited June 17, 2022 by creekman
Additional information to possibly clear up earlier posting.

[JFP in PA]

Porsche gas tanks are very durable and positioned in such a manner that they do not see much in the way of physical damage while in service.  By far, most tank related issues are where the filler neck assembly meets the tank, the tank venting system, or at the top where the pump access is.

[creekman]

Sorry for dragging this out and for so long...  I think we finally found the smoking gun, a vent line that has a valve in it...  The PET that I use shows a single 30" line with a valve

for $225.00. That in itself is over the top.  After getting the incorrect part twice from my Porsche Parts guy I went to Sunset Motors in Beaverton, OR.  The parts manager was very sharp, it turns out there's 2 vent lines on my C4 and my PET doesn't show the one I want, doesn't make any difference since Porsche no longer makes that available.

 

I see 2 options:

 

1.  Find a used one, but dealing with wrecking yards can be costly... I use to deal with Parts Haven in the Bay area, anyone know if they're still in business?  Or are there other reputable people I might try?

 

2.  Would take the new wrong part and cut out the valve and insert it with rubber hoses and hose clamps into the old line.  I would think it's a low pressure hose so why wouldn't that work?  The only downside you've got a $10 valve that cost $225.  But if it gets my car on the road so be it...

 

3.  Anyone have another idea...

 

 

I want the part on the right that is no longer available...

 

[JFP in PA]

As your project requires such a huge amount of work, I would vote against the boneyard part as you could end up with a bad part after all that labor, and only finding that out when the car is fully back together.  Using the new valve and appropriate hose with quality clamps would seem a safer pathway if you cannot find someone sitting on the new part somewhere.

[creekman]

Agreed JFP, but it comes with a price...  I hadn't thought of that condition, but you're right just as soon as you button everything up that valve could take a dump.  That brings me to my next question. A few days ago my car buddy and I were trading germs by blowing through the ends of the piping.  The new one would pass air blowing in either direction, the old one would only allow you to blow one way so we immediately decided that was the cause of all my problems.  The new one was sent back for credit as we were expecting the correct one for my car.  I receive it today, but it was the same as the one I had just sent back, again I blew through it both ways without any resistance, then I blew through the old one and now it passed air as opposed not allowing that.  I wonder if the valve was just stuck close?  There's no power to that valve, does anyone know what it does???

 

And why you can blow through it from either way, again what does this valve.  Whoever answers correctly wins the crochet' Bath Tub.  I guess for the same reasons that were stated earlier it still holds true.  Still you took half the car apart to get to the gas tank and if you don't want to it again, replace the valves. Do we think the circled valve is a check valve so if the canister is full, the valve closes and diverts the fumes to another location.  It would be nice if you're spending a thousand buck a roooos to know why...

 

 

 

[JFP in PA]

These valves are prone to sticking; with gas fumes passing thru them, over time they can develop a build up of a varnish like coating which is glue like in consistency. 

[creekman]

JP in PA,

 

I cut out the new valve and have attached with a 1/2" fuel hose and hose clamps.  I'll post a picture once it's back together...  What motivates these solenoids to open and close?

 

[JFP in PA]

Solenoids are electrically operated, but that valve does not look like a solenoid, so I would have to say that either pressure or vacuum causes it to change.

[creekman]

I've blown in it and suck without any change, maybe I'm just out of suck...  The valve as PET calls it is directional.  It appears  by the directional arrow that it is some kind of a return line to the tank.  When you mention pressure, I believe I was getting pressure build up my tank as it took 2 hands to turn the gas cap.  We'll know soon if it's a done deal...

 

Thanks again for your help and support...

[JFP in PA]

I would guess that the valve is directional, most valves you find in the middle of lines tend to be so, we just don’t understand what triggers it into action.

[creekman]

Well, it's been a long journey, but we took down the gas tank, not an easy job.  As JFP said everything under the gas tank has to come down, We tied up the control arms to same removing them.  We used a pickle fork to break loose the ball joint on the tie rods.  We damaged the boots and bought TRW rod ends for giant savings.  But it still would have been better to buy the special ball joint removal tool because if you can't remove the ball joints using old school methods and your rod ends are in good shape don't use the pickle fork...

 

There's is a round gasket at the fill pipe, that is/was where the gas was eeking out,  but it was because of back pressure in in the tank and the pressure found the weakest link in a very complicated system.  The fumes are collected and stored in the charcoal canister.  the next time the engine is started those fumes are moved through the system to be placed in the running cylinders only to be burned up.  The engine makes the fumes, then turns around and burns them up. 

 

I didn't find anyone that shared a similar problem to mine.. I probably spent $1,000 plus on all the solenoid valves, gaskets, etc.  My warped mine decided that better do it right and not do it again.  However if there were a next time I would check the valve that's shown below.  For several reasons, it's the only one that can be removed without dismantling the car. Secondly it's the only valve that has no electrical connections, it only works with either vacuum or pressure which I assume/guessing does not operate with the same forcefulness has an electric assisted one.  My valve was stuck, then several days later when I blew and suck on it it opened.

 

The part that carried the valve for my C4S is longer available so I bought the similar part, cut it out and installed it in my old hose. I was so done with this I went ahead and spent the $225 to get this little plastic valve, but what I might have done would be to clean the valve soaking it in diesel and reinstalling since it was accessible.  I still had the leak in the gas tank fill it was very small and without back pressure it might not have leaked...

 

But so far without having driven it, but have run the engine it has been a success...  I'll report back if there's any changes. I still love the car after owning for nearly 10 years.  While it's on the lift I'm giving the underside a good wash job, the aftermarket GT2 bumper over needed some TLC, The aftermarket back-up camera needs adjusting, and the list goes on...

 

Thanks for all who responded and especially JFP from PA...

 

 

 

 

[JFP in PA]

As these cars age, and parts become superseded or no longer available, it becomes increasingly difficult to keep them on the road.  But with some persistence, creativity, and a lot of hard work, you have done a great job to keep yours going.  And to quote that great TV sage, Roseanne Roseannadanna, "It's always something............"  Now, it is a holiday, so go have at least one "cold one" 😉

[creekman]

Quoting, "it's always something"... I have the nasty job of removing the front half of the car and putting humpty dumpty back together again, but with some collateral issues.  I I asked my helper, did you align the steering wheel, Josh said I put it back together the same way it came apart, but he didn't... The steering wheel is off of being centered 20% or more.

 

Can you remove the steering wheel without creating more problems and reset it?  I used vernier calipers to install the new rod ends...  I guess an alignment shop can adjust the tie rods to put the steering wheel back to zero which is aligned with the wheels?  We could drop the steering rack, but that's a lot of work....

 

Any thoughts would be appreciated...

[Loren]

Yes the alignment shop can do the mechanical stuff but you will need to reset the steering angle sensor using PIWIS, PST2, or Durametric.

[creekman]

Loren,

 

Can you remove the steering wheel which I'd say is now off 20% and re-install with the wheels straight ahead and the steering wheel is in the same orientation?  I saw a 'how to' video on installing an aftermarket wheel and it didn't appear that there were any posts or direction light triggers on the bottom of the steering wheel hub to worry about.  If so it would save me a trip to the alignment shop.  Am I correct...

 

Thank you, I'm glad you're still on the job...

 

Mitch

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[JFP in PA]

Yes, you can remove and re-center the steering wheel, without doing anything else, but after getting an alignment you are going to need to reset the steering angle because of the suspension work.