Dodged a BIG bullet: high pressure fuel hose.
07-23-2014, 04:47 PM
#17
Former Vendor
You should have no soft fuel lines on your vehicle, if it is of 1985 to 1995 vintage. The exception being the hose discussed above (which should be changed) and the fuel line from the filter to the chassis (which should also be changed.)
If you have an "early" car, with rubber hoses to the injectors (and possibly to the fuel pressure regulators), the correct hose is N020 281 1, which is 7mm inside diameter.
Only use a rubber hose with clamps on the barbed connections of a late model car, if you want the car to burn and want to collect the insurance. The barbs will cut the hose, plus the "shrinkage" of the rubber hose over the barbs will allow this hose to leak with-in months of installation.
A great rule of thumb to remember....that is universal in the automotive industry:
Only use a rubber hose with a clamp over a perfectly smooth metal surface that has a bulged area (away from where the clamps is tightened) to keep the hose and clamp from blowing off the smooth area! Be prepared to check and tighten the clamp on a regular basis to compensate for the shrinkage of the rubber fuel hose.
Any other application is not only stupid but dangerous!
If you have an "early" car, with rubber hoses to the injectors (and possibly to the fuel pressure regulators), the correct hose is N020 281 1, which is 7mm inside diameter.
Only use a rubber hose with clamps on the barbed connections of a late model car, if you want the car to burn and want to collect the insurance. The barbs will cut the hose, plus the "shrinkage" of the rubber hose over the barbs will allow this hose to leak with-in months of installation.
A great rule of thumb to remember....that is universal in the automotive industry:
Only use a rubber hose with a clamp over a perfectly smooth metal surface that has a bulged area (away from where the clamps is tightened) to keep the hose and clamp from blowing off the smooth area! Be prepared to check and tighten the clamp on a regular basis to compensate for the shrinkage of the rubber fuel hose.
Any other application is not only stupid but dangerous!
07-23-2014, 10:30 PM
#18
Rennlist Member
It's not worth deliberating on what to replace and what to leave if you have original hoses, considering the age of our cars and the packed engine bay ... replacing the lot is well worth it for peace of mind, and should be #1 on the priority list for any new owner.
A pic of Gregs works of art.
A pic of Gregs works of art.
07-24-2014, 12:21 AM
#19
Team Owner
Nice picture, **** hot, Good stuff
07-24-2014, 02:20 AM
#20
Pro
Thread Starter
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
https://rennlist.com/forums/928-foru...-reminder.html
https://rennlist.com/forums/928-foru...uel-lines.html
That bridging hose problem no so uncommon then. Need to be 1/2" longer. Or maybe they were and have shrunk with age.
Thanks Rob.
.
07-24-2014, 02:26 AM
#21
Pro
Thread Starter
It's not worth deliberating on what to replace and what to leave if you have original hoses, considering the age of our cars and the packed engine bay ... replacing the lot is well worth it for peace of mind, and should be #1 on the priority list for any new owner.
A pic of Gregs works of art.
A pic of Gregs works of art.
What $$$ Dave?
.
07-24-2014, 02:32 AM
#22
Pro
Thread Starter
(Goes looking for his Shetland).
07-24-2014, 09:53 AM
#23
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Join Date: May 2014
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You should have no soft fuel lines on your vehicle, if it is of 1985 to 1995 vintage. The exception being the hose discussed above (which should be changed) and the fuel line from the filter to the chassis (which should also be changed.)
If you have an "early" car, with rubber hoses to the injectors (and possibly to the fuel pressure regulators), the correct hose is N020 281 1, which is 7mm inside diameter.
Only use a rubber hose with clamps on the barbed connections of a late model car, if you want the car to burn and want to collect the insurance. The barbs will cut the hose, plus the "shrinkage" of the rubber hose over the barbs will allow this hose to leak with-in months of installation.
A great rule of thumb to remember....that is universal in the automotive industry:
Only use a rubber hose with a clamp over a perfectly smooth metal surface that has a bulged area (away from where the clamps is tightened) to keep the hose and clamp from blowing off the smooth area! Be prepared to check and tighten the clamp on a regular basis to compensate for the shrinkage of the rubber fuel hose.
Any other application is not only stupid but dangerous!
If you have an "early" car, with rubber hoses to the injectors (and possibly to the fuel pressure regulators), the correct hose is N020 281 1, which is 7mm inside diameter.
Only use a rubber hose with clamps on the barbed connections of a late model car, if you want the car to burn and want to collect the insurance. The barbs will cut the hose, plus the "shrinkage" of the rubber hose over the barbs will allow this hose to leak with-in months of installation.
A great rule of thumb to remember....that is universal in the automotive industry:
Only use a rubber hose with a clamp over a perfectly smooth metal surface that has a bulged area (away from where the clamps is tightened) to keep the hose and clamp from blowing off the smooth area! Be prepared to check and tighten the clamp on a regular basis to compensate for the shrinkage of the rubber fuel hose.
Any other application is not only stupid but dangerous!
So for the 86 I have, can you give the the part numbers for everything fuel-hose related that I should replace? I appreciate it a bunch!
07-24-2014, 10:17 AM
#24
Rennlist Member
Which years came with the crimped-on problem hoses from the factory...or did they all originally have these?
07-24-2014, 11:01 AM
#25
Rennlist Member
(Actually I see this was answered above as: '87- '89. The car I'm getting is an '86.5 so I'm just trying to get an idea if there are specific mandatory fuel line changes I should make. FWIW the fuel lines on there now reportedly look to be in decent condition, and given that the motor was rebuilt about ten years ago, they may not be the original lines at all.
07-24-2014, 03:34 PM
#26
Former Vendor
The '85 and '86 vehicles are different, with some similar, but different issues.
Two hoses are of primary concern:
There's a rubber hose that runs from the fuel pressure regulator to an adaptor on the back of the block. Porsche's logic was that neither the fuel pressure regulator nor the adaptor could ever move independently of each other, so a rubber hose would suffice. (Plus none of the Bosch "pre-87" fuel pressure regulators had threads....just a tube that accepted a rubber hose.)
Replace that hose using new clamps! Replace that hose with new clamps every 5 years! Use the correct German hose N020 281 1.....not some American sized hose. I make a little kit with the correct hose and two clamps for $7.95.
The second most important hose is the same one that is the source of most fires on the '97 and later cars....the hose that runs between the fuel pressure damper and the regulator, in the rear of the engine. It sits down in the valley between the two heads and just cooks the plastic into a very brittle plastic material. Replace this hose! This hose is NLA. AFAIK, I make the only replacement hose. (Unless someone uses rubber hose with clamps or welds some other fitting onto the existing fittings.) My hose has forged German 90 degree ends that are crimped onto Polyester covered PTFE lined hose. Lifetime guarantee. The hose sells for $165.00. Yes, I know that sounds expensive, but it is 2014, not 1985, and the custom forged German hose ends are $60.00 each!
Another hose that needs to be watched very closely is the plastic return hose that runs from the adaptor on the back of the block to the fuel cooler. This is another one of the "plastic line with protective rubber over the top" fuel lines. This line is not down in the valley between the heads, so it doesn't get quite as hot, however, it does get brittle with age (face it, they are all almost 30 years old.) This hose was designed to "flex" slightly, with engine movement. Again, this "flex" was fine when the hoses were new, but is a real problem, now that the hoses are brittle.
If you do a clutch, replace a torque tube....move the engine around....replace this hose. If you put in new mounts (allowing the engine to move more), replace this hose. If you put in Volvo motor mounts...significantly changing the position of the engine....replace this hose! This hose is also NLA. I had custom adaptors made for the '85/'86/early '87 fuel coolers (they have deep female 16mm threads, while the mid year '87 to '95 fuel coolers have male threads) to allow me to make up a proper hose. Again, PTFE lined Polyester covered, crimped fittings. This hose costs $140.00.
There's a hose from the front damper to the fuel rail. This is the same hose that is pictured at the very first post in this thread. It is still available from Porsche and is less than $60.00. Great value! My version (made in 2014, using modern materials, and in lower volumes) costs $126.00!
The final hose, up front, is the pressure line that runs from the chassis to the front damper. Again, generally hard and brittle....but has generally been very stable for many years (due to old motor mounts.) New Mounts? Replace it. Volvo motor mounts? Replace it the week before you do the mounts! Moving the engine around for a clutch or torque tube job? Replace this hose. This hose is also NLA. I make another fantastic hose that is PTFE lined, polyester covered, crimped ends, with a lifetime guarantee. $165.00.
My hoses are available from 928 International, 928 R US, directly from me, and soon online from 928 Classics.
Hope this helps you guys!
Two hoses are of primary concern:
There's a rubber hose that runs from the fuel pressure regulator to an adaptor on the back of the block. Porsche's logic was that neither the fuel pressure regulator nor the adaptor could ever move independently of each other, so a rubber hose would suffice. (Plus none of the Bosch "pre-87" fuel pressure regulators had threads....just a tube that accepted a rubber hose.)
Replace that hose using new clamps! Replace that hose with new clamps every 5 years! Use the correct German hose N020 281 1.....not some American sized hose. I make a little kit with the correct hose and two clamps for $7.95.
The second most important hose is the same one that is the source of most fires on the '97 and later cars....the hose that runs between the fuel pressure damper and the regulator, in the rear of the engine. It sits down in the valley between the two heads and just cooks the plastic into a very brittle plastic material. Replace this hose! This hose is NLA. AFAIK, I make the only replacement hose. (Unless someone uses rubber hose with clamps or welds some other fitting onto the existing fittings.) My hose has forged German 90 degree ends that are crimped onto Polyester covered PTFE lined hose. Lifetime guarantee. The hose sells for $165.00. Yes, I know that sounds expensive, but it is 2014, not 1985, and the custom forged German hose ends are $60.00 each!
Another hose that needs to be watched very closely is the plastic return hose that runs from the adaptor on the back of the block to the fuel cooler. This is another one of the "plastic line with protective rubber over the top" fuel lines. This line is not down in the valley between the heads, so it doesn't get quite as hot, however, it does get brittle with age (face it, they are all almost 30 years old.) This hose was designed to "flex" slightly, with engine movement. Again, this "flex" was fine when the hoses were new, but is a real problem, now that the hoses are brittle.
If you do a clutch, replace a torque tube....move the engine around....replace this hose. If you put in new mounts (allowing the engine to move more), replace this hose. If you put in Volvo motor mounts...significantly changing the position of the engine....replace this hose! This hose is also NLA. I had custom adaptors made for the '85/'86/early '87 fuel coolers (they have deep female 16mm threads, while the mid year '87 to '95 fuel coolers have male threads) to allow me to make up a proper hose. Again, PTFE lined Polyester covered, crimped fittings. This hose costs $140.00.
There's a hose from the front damper to the fuel rail. This is the same hose that is pictured at the very first post in this thread. It is still available from Porsche and is less than $60.00. Great value! My version (made in 2014, using modern materials, and in lower volumes) costs $126.00!
The final hose, up front, is the pressure line that runs from the chassis to the front damper. Again, generally hard and brittle....but has generally been very stable for many years (due to old motor mounts.) New Mounts? Replace it. Volvo motor mounts? Replace it the week before you do the mounts! Moving the engine around for a clutch or torque tube job? Replace this hose. This hose is also NLA. I make another fantastic hose that is PTFE lined, polyester covered, crimped ends, with a lifetime guarantee. $165.00.
My hoses are available from 928 International, 928 R US, directly from me, and soon online from 928 Classics.
Hope this helps you guys!
07-24-2014, 04:11 PM
#27
Rennlist Member
That's some great info, thank you!
07-24-2014, 04:52 PM
#29
Rennlist Member
Done! :-)
07-24-2014, 04:52 PM
#30
Captain Obvious
Super User
Super User
My '85 hasn't burnt to the ground and the hose have been replaced with FI rubber hose (imperrial spec) and proper FI clamps over 8 years ago. Same time as the SC was shoehorned in. I have an FMU that pushes the fuel pressure to near 100psi when under full boost. The replacement hose show no leak what so ever. If they were supposed to fail months after installation, mine with having +2X the pressure should have failed in days. What gives? 