Convertible Vehicles Enthusiasts | Information | Maintenance

top pump bypass valve leaking

Thread Tools
 
Search this Thread
 
Old May 12, 2013 | 01:18 PM
  #1  
george88gta's Avatar
Thread Starter
TECH Apprentice
20 Year Member
iTrader: (3)
 
Joined: May 2004
Posts: 366
Likes: 2
Default top pump bypass valve leaking

Was going thru the car for spring cleaning and I found the bypass valve in the "bypass" position. I moved the valve to the "operate" position and it started to leak at the base of the valve handle, actually more like seeping. I operated the valve a few times and cleaned up the leaking fluid ( looks like Dexron III). Leak looks like it has stopped. I placed some shop towels around the valve just in case. Top operates fine and fluid doesnt spray out. I recently purchased this car so I have no idea as to why the valve was in the bypass position. Anyway, as I read thru a few threads, I see reference to using mineral oil instead of Dexron III. Is mineral oil thicker and less prone to leaking and does the system need to be flushed to change to mineral oil? I did some research and the valve is part of the motor/pump assembly and does not appear to be available separately, so if the leak persists, I guess I need to change out the entire pump assembly. Any thoughts?
Reply
Old May 14, 2013 | 10:44 AM
  #2  
JohnnyBs98WS6Rag's Avatar
TECH Addict
Photogenic
Shutterbug
Liked
Community Favorite
iTrader: (1)
 
Joined: Jul 2005
Posts: 2,498
Likes: 369
From: NE Indiana
Default

My guess is the previous owner wanted to operate the top manually, which is what the valve allows when opened.

As far as the leak goes, yeah this happens, in various places too. You might be able to disassemble the pump assembly and replace just the valve, I believe the nylon hoses are just simple compression fittings.

Dexron III was the original GM recommended fluid to use in these pumps. Later a TSB was issued that recommened a change to mineral oil. Not sure why (less likely to stain when it leaks maybe??). The recommendation did not mention the need to flush the Dex III out first, which I had not done either w/ no issues mixing the two. I've also heard of people using hydraulic jack oil, although I would stick to GM's recommendations. You can find mineral oil in the pharmacy near the laxatives.

Good luck.
Reply
Old May 14, 2013 | 04:31 PM
  #3  
george88gta's Avatar
Thread Starter
TECH Apprentice
20 Year Member
iTrader: (3)
 
Joined: May 2004
Posts: 366
Likes: 2
Default

Originally Posted by JohnnyBs98WS6Rag
My guess is the previous owner wanted to operate the top manually, which is what the valve allows when opened.

As far as the leak goes, yeah this happens, in various places too. You might be able to disassemble the pump assembly and replace just the valve, I believe the nylon hoses are just simple compression fittings.

Dexron III was the original GM recommended fluid to use in these pumps. Later a TSB was issued that recommened a change to mineral oil. Not sure why (less likely to stain when it leaks maybe??). The recommendation did not mention the need to flush the Dex III out first, which I had not done either w/ no issues mixing the two. I've also heard of people using hydraulic jack oil, although I would stick to GM's recommendations. You can find mineral oil in the pharmacy near the laxatives.
s
Good luck.
Near the laxatives!!! I wont touch that line. LOL. Anyway, its been a few days now and no leak, maybe the seals at the valve just needed exercise. Think I will purchase some mineral oil and just remove some of the Dexron III and refill with the mineral oil. The area near the pump is spotless, so I doubt that there were any serious oil leaks in the area. Thanks for the info.
Reply
Old Nov 12, 2016 | 06:04 AM
  #4  
NitrOmm's Avatar
TECH Enthusiast
iTrader: (1)
 
Joined: Apr 2009
Posts: 567
Likes: 6
From: Wellington, FL
Default

I'm resurrecting this from the dead because I have the same issue as the OP.
After having issues with the switch I used the pressure release valve for the first time (to lower the top), after which the valve started leaking/ seeping in the exact location described.

Any body know if these valves can be taken apart & rebuilt OR a part # for replacement ?
Reply
Old Nov 17, 2016 | 02:48 PM
  #5  
JohnnyBs98WS6Rag's Avatar
TECH Addict
Photogenic
Shutterbug
Liked
Community Favorite
iTrader: (1)
 
Joined: Jul 2005
Posts: 2,498
Likes: 369
From: NE Indiana
Default

My guess is that there is "packing" around the ****'s shaft that prevents leakage up the shaft (similar to old-school faucets), and that packing is either dried out or has compressed to the point it no longer seals. IIRC, the ****'s shaft goes through the center of a "nut". If so, you might try tightening the nut which should compress the packing and might seal up the leak, or you could remove the nut and see if there is any packing that could be replaced under it. You should be able to find new packing in the plumbing section of a hardware store.

As a last resort, you might be able to find a new valve with similar compression fittings in the plumbing isle at the hardware store. This should be similar in size to what is used on the water line going to a refrigerator w/ an icemaker.

Post up if you find a solution.
Reply




All times are GMT -5. The time now is 05:45 AM.

story-0
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?

Slideshow: We take a close look at the ONE and Artidiag 800BT2 diagnostic tools from Topdon and the reasons to buy one over the other.

By Pouria Savadkouei | 2026-05-28 11:05:11


VIEW MORE
story-1
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine

Slideshow: The controversial Ferrari F6 swaps its original flat-12 for a Corvette Z06-derived LT4 V8 and sends power to four rear wheels through a custom-built drivetrain.

By Verdad Gallardo | 2026-05-26 18:23:54


VIEW MORE
story-2
7 Most Reliable High-Performance Engines GM Has Ever Built

Slideshow:These GM engines didn't just make huge power, they survived abuse, boost, track days, and six-digit mileage with a reputation for refusing to quit.

By Verdad Gallardo | 2026-05-21 16:45:27


VIEW MORE
story-3
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-4
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-5
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-6
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-7
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-8
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-9
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE