Vacuum Leak for Dummies

KINNEY201 · 03-18-2009, 05:38 PM

Hi,
I am in need of information on how to locate a vacuum leak. I've looked everywhere and can't find the "How to find a vacuum leak for dummies" version. Please help!

I have a 1997 Ford Explorer XLT 5.0 V8.

I am retrieving codes P0171 & P0174. (Lean banks 1 & 2).

I have already replaced the MAF sensor. Codes came back.

1.) How many vacuum hoses are there?
2.) Where are they?
3.) How do I check them for leaks? (I read somewhere something about ether?)

If someone can point me in the right direction. (Diagrams & actual photos would be great), I would seriously appreciate it.

Thank you.

JoeMahma · 03-19-2009, 10:19 AM

Well there are many hoses in different places. You can use a propane torch with a length of rubber hose on the end. Turn the propane on and with the engine running aim the end of the hose at the vacuum lines and if the engine idle rises you have found your leak. Sometimes it might be a gasket leaking as well so you'll want to run the propane around the intake manifold too. I believe you might have to unhook the Idle Air Control (IAC) valve when doing this or you might not get a change in idle but I might be wrong. Anyone else chime in?

reserved50 · 03-20-2009, 01:56 AM

call a shop and ask if they have an evap smoke machine, should find a leak if there is one in about 45min tops.

dynamite196 · 03-20-2009, 10:08 AM

Those codes are usually caused by leaking intake manifold gaskets. You can also use wd-40 to test for leaks, simply spray it around the suspected area and listen for a change in idle speed. When checking the intake manifold gaskets, make sure the engine is cold. The gaskets expand with the engine heat and can sometimes seal up the leak making it nearly impossible to find. You don't have to disconnect the IAC. good luck

KINNEY201 · 03-20-2009, 02:52 PM

Is there a vacuum hose diagram available for my truck? I've never had to mess with them so I'm not sure where to spray or look. Thanks for your time, it's really appreciated.

03-18-2009, 05:38 PM	#1
KINNEY201 Wannabe Elite Explorer 1997 XLT V8 Join Date: Feb 2007 Posts: 55 Vehicle Specs (Original Poster)	Vacuum Leak for Dummies Hi, I am in need of information on how to locate a vacuum leak. I've looked everywhere and can't find the "How to find a vacuum leak for dummies" version. Please help! I have a 1997 Ford Explorer XLT 5.0 V8. I am retrieving codes P0171 & P0174. (Lean banks 1 & 2). I have already replaced the MAF sensor. Codes came back. 1.) How many vacuum hoses are there? 2.) Where are they? 3.) How do I check them for leaks? (I read somewhere something about ether?) If someone can point me in the right direction. (Diagrams & actual photos would be great), I would seriously appreciate it. Thank you.

03-19-2009, 10:19 AM	#2
JoeMahma Wannabe Elite Explorer Pa. 1997 Mercury Mountaineer Join Date: Sep 2006 Posts: 282 Vehicle Specs	Well there are many hoses in different places. You can use a propane torch with a length of rubber hose on the end. Turn the propane on and with the engine running aim the end of the hose at the vacuum lines and if the engine idle rises you have found your leak. Sometimes it might be a gasket leaking as well so you'll want to run the propane around the intake manifold too. I believe you might have to unhook the Idle Air Control (IAC) valve when doing this or you might not get a change in idle but I might be wrong. Anyone else chime in? __________________ ~Jamie~

03-20-2009, 01:56 AM	#3
reserved50 Wannabe Elite Explorer mooo 1997 XLT SC'd 5.0/331 Join Date: Apr 2005 Posts: 654 Vehicle Specs	call a shop and ask if they have an evap smoke machine, should find a leak if there is one in about 45min tops.

03-20-2009, 10:08 AM	#4
dynamite196 Wannabe Elite Explorer Glastonbury, Connecticut 97 Sport Join Date: Sep 2006 Posts: 491 Vehicle Specs	Those codes are usually caused by leaking intake manifold gaskets. You can also use wd-40 to test for leaks, simply spray it around the suspected area and listen for a change in idle speed. When checking the intake manifold gaskets, make sure the engine is cold. The gaskets expand with the engine heat and can sometimes seal up the leak making it nearly impossible to find. You don't have to disconnect the IAC. good luck

03-20-2009, 02:52 PM	#5
KINNEY201 Wannabe Elite Explorer 1997 XLT V8 Join Date: Feb 2007 Posts: 55 Vehicle Specs (Original Poster)	Is there a vacuum hose diagram available for my truck? I've never had to mess with them so I'm not sure where to spray or look. Thanks for your time, it's really appreciated.