UpFixenDerPorsche

Searching for a worsening oil leak, finally narrowed down oil filler neck area.

Removed bridging fuel hose. Shock. Horror. (Now I must say at this point that I've had a new hose ready to go in for some while, but health issues have kept that on the back burner).

Removed hose and ... auugggghhh .... where it had been obviously chafing against the filler neck.








The old hose was soft and pliable when hot, but rigid when cool. So the hose was chafing against the filler neck when hot, and when cool and rigid was lifting the filler neck off the sealing surface hence the leak.

So - anyone who has not recently inspected or replaced this hose THEN GET OFF YER BEHINDS AND DO IT!


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UpFixenDerPorsche

Gee - since engine bay fuel fires are greatest cause of Shark deaths - I would have thought my post might have attracted more interest.

Apart from the Shark-Lethal implications of the situation I described (does this imply a dreamy obliviousness of being burnt to a crisp), I should point out that I was under no obligation to go to the effort (time, effort, good quality pics) to share my good fortune / experience with the 928 community.

So given the complete lack of any sort of acknowledgement of personal effort on my behalf, I have to wonder why I should be bothered to share any useful tidbits in the future.

Over to you folk.

UpFixen.

PHIL928

All the ones I've seen end up looking like that, but as far as I'm aware it's usually the rear "U" hose that bursts first.

UpFixenDerPorsche

Well gee thanks Phil.

Good to know that fuel spraying under high pressure from a split fuel rail bridge hose won't be so worrisome as one to the rear. Not.

Again - why do I bother?



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UpFixenDerPorsche

Then there's the link to oil leaks from the base of the oil filler neck.

Just sayin'.

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Mrmerlin

Thanks for posting a heads up,
after looking closely at the hose you posted,
it does have small cracks in it as well as the rubbing section.

Its good you replaced it.

NOTE the other 4 lines should also be replaced if they have not already been swapped out.

The usual ignition source will be from an old ignition wire thats got leaks,
so also check the ignition wires while running the engine in the dark.

Shawn Stanford

Something else I need to figure out how to check...

Dave928S

I'll second what Stan said to avoid a carbeque.

My GTS lines (all of them) looked OK, but on closer examination and flexing, you could see the start of deterioration.

Instead of waiting for a failure I've just replaced the lot, including the rear hoses, and all ignition leads and caps.

I've got GB lines, which are a vast improvement over stock, and worth every cent

Alan

How about:



There should be room - it should not be lifting the oil filler neck - something else is up with that...

This is a bit surreal... you need to get a ledger, a clock and a much smaller horse

Alan

Rob Edwards

Good to point out your experience with the front S4+ fuel hose rubbing on the filler neck, particularly for newer S4+ owners who were not yet active when others posted about the same experience.


https://rennlist.com/forums/928-foru...-reminder.html

https://rennlist.com/forums/928-foru...uel-lines.html

Alan

You might also consider this: https://rennlist.com/forums/showthre...eferrerid=6055

None of this is new to those of us who have been here a while, there have been many more than those threads on it. It is good to bring it up from time to time for the new folks though.

Pretty sure that straight up neglect is by far the biggest silent killer of 928s - and while that certainly does include some of these fire cases, it includes many many other things as well - fires are just more newsworthy...

Alan

GregBBRD

If you proceed to the next step and cut that "hose" apart, you will find that the "outer" rubber portion you are looking at is actually just a protective sleeve. The "metal" sleeves that look like crimps at the ends are not crimps, at all, but simply a metal sleeve to keep the rubber protective sleeve from curling up (which is why you can spin them with your fingertips.). The cracks that you see in this outer protective rubber sleeve are completely inconsequential.

Inside that protective rubber sleeve, you will find a high pressure plastic hose that is installed over the barbed ends. That high pressure plastic hose is what contains the fuel.

What you have taken a picture of is a very common "groove" that occurs from this hose rubbing on the filler neck. Fortunately, this hose very rarely fails from this rubbing, since it takes a very long time to wear through both the outer rubber protective sleeve and the inner high pressure plastic. (I've actually never seen one of these hoses rubbed through and leaking.)

Regardless, it is a very good thing to watch out for....and perhaps more importantly, the inner plastic liners are generally very brittle at this point in time.

The stock hose is still available, for less that $60.00 (US) from Porsche. I also make a custom replacement hose (more expensive...better materials than the stock hose) that is slightly longer and does not rub on the filler neck.

As mentioned above, the hose that attaches the fuel damper to the fuel regulator, in the rear of the engine, is a far more common failure point, due to the higher heat from where this hose is routed. Virtually every single one of these hoses need to be replaced.

The return hose from the fuel regulator to the fuel cooler has two individual designs. 1987 to 1989 vehicles used a rubber hose with crimps. This design was superceeded to the later style hose with the protective rubber sleeve and inner plastic high pressure regulator sometime in 1989. Anyone with the rubber hose with crimps should not be starting or driving their cars....the fire potential is just too high. (If anyone needs pictures of the two versions of this hose, to be able to tell which hose is on your vehicle, I can post pictures of the two versions.)

I make replacements for all of these hoses, with lifetime guarantees. Roger at 928 R US and 928 International both distribute all of my fuel hoses.

TRA

What exactly is the correct ID for the soft fuel lines?

Cadillac art

The return hose from the fuel regulator to the fuel cooler has two individual designs. 1987 to 1989 vehicles used a rubber hose with crimps. This design was superceeded to the later style hose with the protective rubber sleeve and inner plastic high pressure regulator sometime in 1989. Anyone with the rubber hose with crimps should not be starting or driving their cars....the fire potential is just too high. (If anyone needs pictures of the two versions of this hose, to be able to tell which hose is on your vehicle, I can post pictures of the two versions.)


Greg,
Please post the comparison pictures.

GregBBRD

Here you go:

This picture shows both the early version return hose (on the left) and the superceeded version (on the right.) Look carefully at the "crimps" (the early hose is actually a crimp and the late hose is just a protective sleeve over the outer protective cover.)



Here's a close-up of the two hoses and the "crimps". You can easily see where the hose on the left has tooling marks where the crimp was compressed over rubber hose. This rubber hose shrinks and will invariably be loose on the pipe, allowing fuel to leak, especially when cold.

If you have this early version hose, your car is "unsafe at any speed". Update the hose to the later style hose (Porsche still has this hose), or buy one of my replacement hoses......immediately. I keep at least a dozen of the replacement hoses, from Porsche, in stock, at all times. We re-order when our inventory drops below 6 units. Cost is about $65.00 for the Porsche version. My custom lifetime guarantee hoses is $180.00 (made from polyester PTFE with crimped Forged German ends.)


Hope this helps.