Leaking PSCV Flared Fittings
Thread Starter
Burning Brakes
Joined: Dec 2005
Posts: 1,164
Likes: 224
From: Pawleys Island, SC
Leaking PSCV Flared Fittings
Is there a trick anyone can share for getting flared fittings to seal? Replaced my PSCV and it seems to be leaking from the fittings. The tubing flares seem to be in descent shape, not cracked. The PSCV is a fresh rebuild from Lonestar. I torqued them to spec and then when they leaked, I untorqued them slightly and retorqued with a little more force. Still yet to determine if that worked. Is there a technique for dressing the flared tubes that would smooth and remove any imperfections, assuming that's the issue? Would I have a more reasonable chance of success by just replacing the hoses?
Thread Starter
Burning Brakes
Joined: Dec 2005
Posts: 1,164
Likes: 224
From: Pawleys Island, SC
Burning Brakes
Joined: Jan 2001
Posts: 1,219
Likes: 448
From: Loir Valley Sarthe, France
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2024 C3 of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
I rebuilt my PSCV back in the spring. One of the new hoses just would not seal! I tried about 6 times, ensuring it was seated properly, everything was clean and in-damaged - all to no avail.
In the end I remembered a conversation I had had with a friend many years ago about the same subject. He'd done a few PSCV changes (at the time, a part-time Vette mechanic!) and said he'd used PTFE tape. I'd followed his advice and used it on the hoses going to the pump. I recalled that years later I had put a turn or two when I changed the rest of the hoses, and had forgotten about it. So, I put a couple of turns of PTFE tape on the offending flare nut, tightened (not very tightly in fact) and hey presto, no leak!
A long winded way to say "Try PTFE tape"!
Many will say it should not work, many will say it's a "bubba trick", but the hoses have been sealed up with it for at least 20 years.
In the end I remembered a conversation I had had with a friend many years ago about the same subject. He'd done a few PSCV changes (at the time, a part-time Vette mechanic!) and said he'd used PTFE tape. I'd followed his advice and used it on the hoses going to the pump. I recalled that years later I had put a turn or two when I changed the rest of the hoses, and had forgotten about it. So, I put a couple of turns of PTFE tape on the offending flare nut, tightened (not very tightly in fact) and hey presto, no leak!
A long winded way to say "Try PTFE tape"!
Many will say it should not work, many will say it's a "bubba trick", but the hoses have been sealed up with it for at least 20 years.
Thread Starter
Burning Brakes
Joined: Dec 2005
Posts: 1,164
Likes: 224
From: Pawleys Island, SC
I rebuilt my PSCV back in the spring. One of the new hoses just would not seal! I tried about 6 times, ensuring it was seated properly, everything was clean and in-damaged - all to no avail.
In the end I remembered a conversation I had had with a friend many years ago about the same subject. He'd done a few PSCV changes (at the time, a part-time Vette mechanic!) and said he'd used PTFE tape. I'd followed his advice and used it on the hoses going to the pump. I recalled that years later I had put a turn or two when I changed the rest of the hoses, and had forgotten about it. So, I put a couple of turns of PTFE tape on the offending flare nut, tightened (not very tightly in fact) and hey presto, no leak!
A long winded way to say "Try PTFE tape"!
Many will say it should not work, many will say it's a "bubba trick", but the hoses have been sealed up with it for at least 20 years.
In the end I remembered a conversation I had had with a friend many years ago about the same subject. He'd done a few PSCV changes (at the time, a part-time Vette mechanic!) and said he'd used PTFE tape. I'd followed his advice and used it on the hoses going to the pump. I recalled that years later I had put a turn or two when I changed the rest of the hoses, and had forgotten about it. So, I put a couple of turns of PTFE tape on the offending flare nut, tightened (not very tightly in fact) and hey presto, no leak!
A long winded way to say "Try PTFE tape"!
Many will say it should not work, many will say it's a "bubba trick", but the hoses have been sealed up with it for at least 20 years.
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
Thread Starter
Burning Brakes
Joined: Dec 2005
Posts: 1,164
Likes: 224
From: Pawleys Island, SC
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Le Mans Master
Joined: Mar 2001
Posts: 6,640
Likes: 287
From: Ann Arbor Michigan
A flared tube is suppose to seal on the cone of the mating part. What usually happens is that there is so much friction between the threads in the housing and the tube nut that most of the torque applied never gets to the joint. You can try a little antiseize on the nut. I suspect the Teflon tape does the same thing and doesn't actually seal the joint because it can still leak out between the tube and the nut ID.
Thread Starter
Burning Brakes
Joined: Dec 2005
Posts: 1,164
Likes: 224
From: Pawleys Island, SC
That's a good point, I'll try anti seize if (when) I have the hoses off again. Probably when all else fails and I just replace them. They weren't installed dry. I would have thought that the PS fluid would have been enough of a lubricant.
Burning Brakes
Joined: Jan 2001
Posts: 1,219
Likes: 448
From: Loir Valley Sarthe, France
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2024 C3 of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
Yes, a couple of turns.
As Duke94 said above, given how a flare nut joint seals, it shouldn't work. I don't quite know why, but it does. I'm guessing the nut seals with it's piece of pipe, but the pipe end doesn't quite "seat" with the base of the joint in the PSCV. So, the fluid gets round that and seeps into the threads.
I've stuck with the "normal" white tape and only a couple of turns, so it's a minimal thickness.
As Duke94 said above, given how a flare nut joint seals, it shouldn't work. I don't quite know why, but it does. I'm guessing the nut seals with it's piece of pipe, but the pipe end doesn't quite "seat" with the base of the joint in the PSCV. So, the fluid gets round that and seeps into the threads.
I've stuck with the "normal" white tape and only a couple of turns, so it's a minimal thickness.
Last edited by Stephen Irons; Nov 28, 2017 at 05:11 AM.
Burning Brakes
Joined: Jan 2001
Posts: 1,219
Likes: 448
From: Loir Valley Sarthe, France
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2024 C3 of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
Drifting
Joined: Dec 2011
Posts: 1,743
Likes: 289
From: Chardon Ohio
interesting - never heard of them
Race Director
Joined: Mar 2016
Posts: 14,406
Likes: 8,212
From: Napa Valley California
Make sure the tubing and flare are straight on the fitting. Hold the tube as you finger tighten the nut to keep everything lined up. Snug the nut and watch that the tubing and flare remain straight and don't move and make sure the tubing does not begin to twist as you tighten the nut. Many people over-tighten the nut and distort the flare or tubing. If you get seepage use some scotchbrite pad to clean up the mating surfaces on the flare, tubing and the fitting.
Most manufacture's will put a note in their instructions to not use any tape or sealants.
Also, try to match the fittings, flares and nuts with the same manufacturer. I have found that some manufactures use a slightly different angle cut on their parts than others and mixing parts from different manufactures could cause sealing issues that can't be overcome.
Most manufacture's will put a note in their instructions to not use any tape or sealants.
Also, try to match the fittings, flares and nuts with the same manufacturer. I have found that some manufactures use a slightly different angle cut on their parts than others and mixing parts from different manufactures could cause sealing issues that can't be overcome.
Last edited by OldCarBum; Nov 28, 2017 at 02:34 PM.
Thread Starter
Burning Brakes
Joined: Dec 2005
Posts: 1,164
Likes: 224
From: Pawleys Island, SC
Finally got the leaks stopped. I replaced all four hoses with new. Ordered an AC Delco hose set from Rock Auto but they were different enough from the originals, length and shape, to make me nervous about using them. Got another set from Willcox (the packaging is actually labeled Corvette America). They were somewhat different from the originals also but I went ahead and used them.
I also used copper gaskets at all seven fittings, got them from Grainger, and put anti-seize on the nuts. Didn't use a torque wrench but being the third time I mess with these fittings I've got a pretty good feel for it. I'd say they're torqued somewhere around 75-100 in-lbs. If I wind up having to tighten them I'll put a torque wrench on them but for now I'll just enjoy my leak free power steering - while it lasts.
I also used copper gaskets at all seven fittings, got them from Grainger, and put anti-seize on the nuts. Didn't use a torque wrench but being the third time I mess with these fittings I've got a pretty good feel for it. I'd say they're torqued somewhere around 75-100 in-lbs. If I wind up having to tighten them I'll put a torque wrench on them but for now I'll just enjoy my leak free power steering - while it lasts.
Last edited by revitup; Dec 11, 2017 at 10:26 AM.
Burning Brakes
Joined: Jan 2001
Posts: 1,219
Likes: 448
From: Loir Valley Sarthe, France
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2024 C3 of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
Finally got the leaks stopped. I replaced all four hoses with new. Ordered an AC Delco hose set from Rock Auto but they were different enough from the originals, length and shape, to make me nervous about using them. Got another set from Willcox (the packaging is actually labeled Corvette America). They were somewhat different from the originals also but I went ahead and used them.
I also used copper gaskets at all seven fittings, got them from Grainger, and put anti-seize on the nuts. Didn't use a torque wrench but being the third time I mess with these fittings I've got a pretty good feel for it. I'd say they're torqued somewhere around 75-100 in-lbs. If I wind up having to tighten them I'll put a torque wrench on them but for now I'll just enjoy my leak free power steering - while it lasts.
I also used copper gaskets at all seven fittings, got them from Grainger, and put anti-seize on the nuts. Didn't use a torque wrench but being the third time I mess with these fittings I've got a pretty good feel for it. I'd say they're torqued somewhere around 75-100 in-lbs. If I wind up having to tighten them I'll put a torque wrench on them but for now I'll just enjoy my leak free power steering - while it lasts.
Thread Starter
Burning Brakes
Joined: Dec 2005
Posts: 1,164
Likes: 224
From: Pawleys Island, SC
The open end crow's foot worked fine, vs a flare nut type (which I don't have - two sizes required, 7/16 and 5/8). Tightening torque is low enough that the open end wrench slipping isn't an issue.
Race Director
Joined: Mar 2016
Posts: 14,406
Likes: 8,212
From: Napa Valley California
This is a bit of information I'm passing along to those who may not be aware.
When you use a crows foot on a torque wrench, you are increasing the torque value you apply to the fastener.
The torque value on a torque wrench is calibrated from the center of the handle to the center of the ratchet head.
Increasing the distance between the two points increases the leverage and torque applied to the fastener. Only slightly, but it's something to keep in mind.
Even adding an extension between the socket head and ratchet head changes the torque value.
Torque wrenches need to be calibrated routinely and stored properly by turning the dial back to 0 after each use. I've found mine to be off a few ounces/pounds when they have not been used in awhile.
There are numerous web sites and UTube videos on calibrating your torque wrenches yourself.
When you use a crows foot on a torque wrench, you are increasing the torque value you apply to the fastener.
The torque value on a torque wrench is calibrated from the center of the handle to the center of the ratchet head.
Increasing the distance between the two points increases the leverage and torque applied to the fastener. Only slightly, but it's something to keep in mind.
Even adding an extension between the socket head and ratchet head changes the torque value.
Torque wrenches need to be calibrated routinely and stored properly by turning the dial back to 0 after each use. I've found mine to be off a few ounces/pounds when they have not been used in awhile.
There are numerous web sites and UTube videos on calibrating your torque wrenches yourself.
Last edited by OldCarBum; Dec 23, 2017 at 11:55 AM.