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Going back in time the 2134 was THE hose to use in these applications.
Technology moves on. In relative terms "short term" 230F v 287F is still short of what is needed. I would estimate that heat soak for the hoses at the back of the engine is more like 350F.
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Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission? George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
The early spec for Porsche was similar to 2134. The standard hose was and still is N 020 281 1 - 7mm x 13mm. Still used today on the fuel injection hoses.
For the main fuel hoses Porsche used Cohline 3017/3124 vulcanized rubber with a Polyamide sleeve. They still do. Ethanol will effect those hoses but less so with the Polyamide core.
We (928sRus) now use hose that exceeds SAE30R7 and is way more flexible and compatible with Ethanol.
Ethanol is the culprit, and as you can see in previous posts, has a devastating effect on our fuel hoses.
You need to use hose that is compatible with Ethanol.
I'm pretty sure the inside of my car is close to 122 deg when in the sun, let alone the engine compartment...
Let's not neglect the specified minimum radius. Tough to say from the pics but it may be the failed hose is under the 55mm radius (not diameter). That's a pretty lazy curve.
Just for reference, here's a roughly 55mm bend radius:
So what happened in the time between a good spec from Porsche in 198x, and the 2134?
It went backwards?
Not a Carl comment...a materials one.
After 1984, Porsche quit using rubber fuel hoses, in all pressure applications.
They used rubber on the low pressure return hoses, in the engine compartment, until 1989, when everything got "updated" to high pressure plastic, covered in a rubber sheath.
Way more heat in the 32 valve engine compartments. Tighter bend radius. Fuel started to have "evil" additives. 928 Engine fires became more commonplace, in the '81 to '84 vehicles.
Somewhere along the line, people decided that going back to rubber was a great idea.
The only great thing about rubber hose is the profit margin.
$10 worth of hose and $6 worth of crimps for how much?
Like I've said, all along, a bunch more of these cars need to be wrecked or burned, before they rest get really valuable.
The old saying "If you've got an $75 head, buy an $75 helmet" applies to more than just heads....
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
Works absolutely fine for our cars if installed correctly. Carefully remove the sharp edges of the barbs on the fittings. Use good quality EFI hose clamps (edges are turned upwards so they do not cut into the wall of the hose).
I sold them for a long time with zero issues if installed correctly and the clamps checked for tightness every 12 months. I took a set of my 93 GTS after 10 years and they were perfect.
I prefer the latest SAE 30R7 hose as it is even better than the Gates barricade. Very flexible and ethanol resistant to a higher level. When used with high pressure hydraulic crimps hoses are good for many years of service for a reasonable cost.
I can attest to it. I'm using your house and EFI clamps. Done in 2013 and going on 8 years trouble free on the high pressure passenger side fuel line!
While I have plenty of hose, I don't have plenty of GOOD EFI clamps.
I can attest to it. I'm using your house and EFI clamps. Done in 2013 and going on 8 years trouble free on the high pressure passenger side fuel line!
While I have plenty of hose, I don't have plenty of GOOD EFI clamps.
I got a huge laugh, out of your post!
Eight years without a leak or fire is not something I consider to be a long time...or to be proud of.
Your original hoses were over 20 years old, in 2013...and were, most likely, not leaking.
But let's dig deeper...
How many miles traveled in 8 years?
And honestly, how often do you lift the hood and look at/check the rubber fuel hose/hoses?
I've got a feeling that my regular clientele are a bit different than you (and many others, here on Rennlist.) Most of my clients never lift their hoods. They make an appointment for us to do that....every 7500 miles or so, for an oil service or a major service.
They don't expect to have a fuel leak....ever!
Not in 8 years, not in 20 years, not in 30 years. Never.
And with my pieces, I can guarantee that they never will!
And I also guarantee that no one else, here, can make that statement....
Not to change the subject too much, but is there a better replacement for the hose that exits the fuel tank?
They seem to fail if the car sits too long.
I agree - see post #33 - it is a molded hose and not easy to replicate. If you use generic hose there is the chance it will kink. Especially on the older cars where the pump is attached to the cover.
I agree - see post #33 - it is a molded hose and not easy to replicate. If you use generic hose there is the chance it will kink. Especially on the older cars where the pump is attached to the cover.
I have a couple of these lying around. I think this will address the kink.
I got a huge laugh, out of your post!
Eight years without a leak or fire is not something I consider to be a long time...or to be proud of.
Your original hoses were over 20 years old, in 2013...and were, most likely, not leaking.
But let's dig deeper...
How many miles traveled in 8 years?
And honestly, how often do you lift the hood and look at/check the rubber fuel hose/hoses?
I've got a feeling that my regular clientele are a bit different than you (and many others, here on Rennlist.) Most of my clients never lift their hoods. They make an appointment for us to do that....every 7500 miles or so, for an oil service or a major service.
They don't expect to have a fuel leak....ever!
Not in 8 years, not in 20 years, not in 30 years. Never.
And with my pieces, I can guarantee that they never will!
And I also guarantee that no one else, here, can make that statement....
Rubber fuel hose is ridiculous.
I got a great laugh out of your post too. Especially since I lift my hood every weekend to disconnect the battery tender with a good looking fuel line in front of me before going for a drive.
Ignore is a wonderful tool 8>)
Just remember that contrary to what is said in your post rubber hoses have been used for fuel applications for eons on cars of every type.
Porsche still supplies rubber hoses today for the 928.
If you buy the injector hose kit, for the early L-Jet cars, from Porsche it still uses a rubber hose to the same spec. as the Cohline 2134.
Likewise 999 181 152 50 used on the 85/86 S3 cars.
Front fuel hose, FPR to console, FPR to fuel cooler used on the 87 to 95 cars are all rubber. We still sell these today.
THE BIG Elephant in the room is Ethanol. Especially when it is left to sit in a hose for extended periods. See post #33 and by the way that hose is rubber to.
Better hose materials are readily available that meet of exceed our cars parameters and most importantly are compatible with Ethanol. Those hoses are a better option in the long run.
And YES "HIS" hoses have leaked to.
Well, I am complete newbie here on Porsche matters, but let me throw in my 2c. I just replaced the U fuel hose in my 86.5, as I was already replacing the rear damper (you can read all about it on my introduction thread). I am pretty darn sure I still had the factory original in there, serving for 35 years, throughout ethanol percentage increases. The hose says "COHNEN 370 08 00 V 8 85" on it. As I was there already, I wanted to make sure to replace this with the best possible replacement. An extra $100 is worth it if you are saving a $25k car from engine fire, in my opinion.
Here are pics of the originals. For the life of me, I could not unscrew the hose from the damper, but since I was replacing that anyway, I gave up and removed them together.
I replaced it with a new Kevlar fuel line from Greg. I have nothing but admiration for the quality of this product. I mean: LOOK AT IT! Please excuse the tacky lemon cloth behind it, I was taking the photo on our dinner table. Works flawlessly and bends well.
07-11-2021, 08:46 PM
George Layton March 2014
