Vacuum leak detected

MI0706 · 06-04-2009, 02:54 PM

On my wifes 01 Dodge Ram, we keep getting the service engine soon light. When I pulled the code with my scanner, at first it came up as a small vacuum leak. Now it comes up as a gross vacuum leak.

I've changed the gas tank cap (to rule that out). What is the proper sequence in tracking this problem down?

When running, I can't hear anything that sounds like air being sucked in (except at her cold air intake). The engine does not idle at high rpm's and does not idle rough.

I think I'm going to have to start changing parts on the system. I would like to know the logical sequence of part changing.

Thanks for the help.

semocoachworks · 06-04-2009, 08:43 PM

Take some carb cleaner and start the engine. While engine is COLD(so it dont catch fire), spray the carb cleaner around your vacuum lines, fittings, etc. If the vacuum sucks this in, your engine should stumble and then you can look where you sprayed for a cracked line or bad hose. Hope this helps!

MI0706 · 06-05-2009, 10:45 AM

Wow... That's a good idea... Never thought of that before. Thanks!!!

semocoachworks · 06-05-2009, 05:44 PM

No problem, hope it helps!

gmctrucks · 06-06-2009, 09:39 AM

Quote:

Originally Posted by MI0706

Wow... That's a good idea... Never thought of that before. Thanks!!!

I agree with you he gets rep points for that.
GMC

MI0706 · 06-21-2009, 02:48 PM

Well, the carb cleaner idea didn't work (but it still is an outstanding idea).

The code that is being given is P0455 (vacuum leak, gross leak detected, atleast that what my scanner says it is). It appears that this is directly related to the A/C system. In our attempts to isolate the problem, it only happens when the A/C system is turned on (even then, it is an intermittent problem). But when the problem does happen, a weird sound is emitted inside the cab. Kind of sounds like a light "roaring" sound for about 5 minutes (when the blower is turned on, the higher the speed of the fan, the louder it is). Then the code will come in and the sound will stop. The A/C system never seems to function inappropriately (other than the roaring sound). After the code is reset, it will not happen again during that driving period.

I've located the tiny (appears to be specially made) lines that penetrate the firewall. These lines are directly tied to the vacuum system via some T's and maybe a check valve or two. I'm not sure as to exactly what they do. I'm guessing that they use the vacuum system to change damper positions for climate control? If anyone has some knowledge of their function, please enlighten me.

Anyway, I'm having a hard time finding a supplier for these lines (other than Dodge). My first guess is to start changing these lines and see what happens. That is, unless someone else has ran into this specific problem before and would be kind enough to step me through a logical sequence of further isolating the problem. Does anyone know of any other suppliers for these lines?

Thanks for the help. I do greatly appreciate it.

Would anyone be interested in seeing pics of my wifes show truck?

leolkfrm · 06-21-2009, 07:10 PM

pics of you wife showing her truck are always welcome!!!

MI0706 · 06-22-2009, 03:53 AM

Leo: LOL... My wife is very camera shy... Although she shouldn't be (she's smokin')... Anyway, I will get some pics of her truck...

leolkfrm · 06-23-2009, 04:27 AM

is it vac, or evap? big differance

MI0706 · 06-24-2009, 08:38 AM

Leo: I believe it's vac... Upon some further investigation, I found what appears to be a tiny bad spot in the supply line (downstream of the check valve) that goes to the damper position control switch in the cab (switch that changes between defroster, floor, head, etc.).

So far, I put some tape over that bad spot and the problem hasn't came back yet. I hope like **** that was the problem!

06-04-2009, 02:54 PM	#1
MI0706 Senior Member Join Date: Dec 2007 Location: Crawfordsville, Indiana Posts: 84	Vacuum leak detected On my wifes 01 Dodge Ram, we keep getting the service engine soon light. When I pulled the code with my scanner, at first it came up as a small vacuum leak. Now it comes up as a gross vacuum leak. I've changed the gas tank cap (to rule that out). What is the proper sequence in tracking this problem down? When running, I can't hear anything that sounds like air being sucked in (except at her cold air intake). The engine does not idle at high rpm's and does not idle rough. I think I'm going to have to start changing parts on the system. I would like to know the logical sequence of part changing. Thanks for the help.

06-21-2009, 07:10 PM	#7
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 4,300	pics of you wife showing her truck are always welcome!!! __________________ 4 wheels move the body 2 wheels move the soul B.W.A.I

06-23-2009, 04:27 AM	#9
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 4,300	is it vac, or evap? big differance __________________ 4 wheels move the body 2 wheels move the soul B.W.A.I

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06-04-2009, 08:43 PM	#2
semocoachworks Senior Member Join Date: May 2009 Location: rapid city, sd Posts: 420	Take some carb cleaner and start the engine. While engine is COLD(so it dont catch fire), spray the carb cleaner around your vacuum lines, fittings, etc. If the vacuum sucks this in, your engine should stumble and then you can look where you sprayed for a cracked line or bad hose. Hope this helps!

06-05-2009, 10:45 AM	#3
MI0706 Senior Member Join Date: Dec 2007 Location: Crawfordsville, Indiana Posts: 84	Wow... That's a good idea... Never thought of that before. Thanks!!!

06-05-2009, 05:44 PM	#4
semocoachworks Senior Member Join Date: May 2009 Location: rapid city, sd Posts: 420	No problem, hope it helps!

06-21-2009, 02:48 PM	#6
MI0706 Senior Member Join Date: Dec 2007 Location: Crawfordsville, Indiana Posts: 84	Well, the carb cleaner idea didn't work (but it still is an outstanding idea). The code that is being given is P0455 (vacuum leak, gross leak detected, atleast that what my scanner says it is). It appears that this is directly related to the A/C system. In our attempts to isolate the problem, it only happens when the A/C system is turned on (even then, it is an intermittent problem). But when the problem does happen, a weird sound is emitted inside the cab. Kind of sounds like a light "roaring" sound for about 5 minutes (when the blower is turned on, the higher the speed of the fan, the louder it is). Then the code will come in and the sound will stop. The A/C system never seems to function inappropriately (other than the roaring sound). After the code is reset, it will not happen again during that driving period. I've located the tiny (appears to be specially made) lines that penetrate the firewall. These lines are directly tied to the vacuum system via some T's and maybe a check valve or two. I'm not sure as to exactly what they do. I'm guessing that they use the vacuum system to change damper positions for climate control? If anyone has some knowledge of their function, please enlighten me. Anyway, I'm having a hard time finding a supplier for these lines (other than Dodge). My first guess is to start changing these lines and see what happens. That is, unless someone else has ran into this specific problem before and would be kind enough to step me through a logical sequence of further isolating the problem. Does anyone know of any other suppliers for these lines? Thanks for the help. I do greatly appreciate it. Would anyone be interested in seeing pics of my wifes show truck?

06-22-2009, 03:53 AM	#8
MI0706 Senior Member Join Date: Dec 2007 Location: Crawfordsville, Indiana Posts: 84	Leo: LOL... My wife is very camera shy... Although she shouldn't be (she's smokin')... Anyway, I will get some pics of her truck...

06-24-2009, 08:38 AM	#10
MI0706 Senior Member Join Date: Dec 2007 Location: Crawfordsville, Indiana Posts: 84	Leo: I believe it's vac... Upon some further investigation, I found what appears to be a tiny bad spot in the supply line (downstream of the check valve) that goes to the damper position control switch in the cab (switch that changes between defroster, floor, head, etc.). So far, I put some tape over that bad spot and the problem hasn't came back yet. I hope like **** that was the problem!