Diesel Place banner

1 - 8 of 8 Posts

·
Registered
Joined
·
704 Posts
Discussion Starter #1
With a pressure system it is easy to see a fuel system leak because when you turn on the pump, fuel will drip out any leaking fitting. With the Duramax being a vacume system, it will just suck air in, and you will not see the fitting leaking.


I just finished installing the Racor primary filter kit, and I want to make sure I don't have any leaks. What is the best method to achieve this. When the truck is parked, none of the fittings drip, but the power seems down since the install. Perhaps it is just my imagination.
 

·
Registered
Joined
·
12,262 Posts
Short of pressurizing , good luck .... You also will prolly accumilate a air pocket perhaps at the OEM .... Check after a few days for air ...


You are prolly fine and it's just a figment of imagination ...


Mac
 

·
Registered
Joined
·
663 Posts
Armric,

The Helms manual details a procedure to check for leaks that includes installing clear tubing to look for bubbles and a leak down test using the Kent Moore Gauge connected to the Schrader valve test port. For the leak down test the system is pressurized by pumping the primer until hard. Pressure that bleeds off to quickly (through the return) as measured on the gauge indicates a leak. With out checking the manual I can't be sure but I seem to remember that if the pressure bleeds off in less than 10 seconds it's a problem. Vacuum leaks are tough to find. I think A bear had the best test.. Early on in the TDP "air in fuel" discussions when we were looking for the cause of the vapor accumulating in our Mega Filters, a bear performed both a pressure and vacuum test directly at the tank sender's feed and return lines. IIRC, he put the whole system under a vacuum and let it sit overnight and found no vacuum change. Then he pressurized the whole system using propane and again found no change in pressure after sitting overnight. A bear proved his system had no leaks yet his megafilter was accumulating vapor. This was the test that convinced me that the Duramax OEM fuel system normally produces and circulates vapor do heat/vacuum induced out gassing of the fuel.
 

·
Registered
Joined
·
1,309 Posts
Amric, you can check for leaks with an oil squirt can with any type motor oil you have handy. Start the engine and put a few drops around the threads and hose to barb area. I used to find intake manifold leaks and I recently found one on one of my Racor installations. You have to watch close but it works. Later! Frank
 

·
Registered
Joined
·
1,124 Posts
Man Frank, you are old.
I haven't heard that method in 20 years, still works though. My Uncle taught me that one in the 60's.
 

·
Registered
Joined
·
1,309 Posts
I was working on hot rod Fords in 1960 and that is how old I am. Later! Frank
 

·
Registered
Joined
·
1,048 Posts
Frank, you aint old, you're seasoned! You're experienced. Old? Naw! Me too niether!


I was taught to use ether for vacuum leaks. Thats a no brainer! VRROOMM, yep that's it!
 

·
Registered
Joined
·
1,309 Posts
Hi Mitch! I used ether to when I didn't have to buy it. Later! Frank
 
1 - 8 of 8 Posts
Top