Evap Purge Solenoid
Thread Starter
Instructor
Joined: Oct 2000
Posts: 177
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From: Laguna Niguel, CA
Evap Purge Solenoid
I need some help about an intermittent tapping sound that I am getting lately. I had this problem about a year ago it was very brief and it went away until just the other day. The car runs fine but every now an then I get a loud Tapping sound from the driver side valve train or close to that area. The car is usually at operating temp always has good oil pre and then it just shows up last for about 3 minuets +or- and then fades away. Is this the Evap Purge Solenoid and how do I convince the dealer when chances are it wont happen when in their procession. Could I be looking at internal problems such as lifters? The car runs quiet at start up except the piston slap and when the tapping starts it seems to fade away slowly like its loosing presure that started it. Let me know if you can help.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Re: Evap Purge Solenoid (bigwave)
Not real familiar with the C5 system, but on others that I am familiar with the solenoid is either running or not and generally doesn't "fade". Best way to find it is with a hose in your ear or stethoscope if you can get your hands on one.
Pro
Joined: May 2001
Posts: 553
Likes: 5
Re: Evap Purge Solenoid (bigwave)
First of all, I'm fairly sure that you don't have lifters in a pushrod engine. You have a cam, pushrods, roller-rocker arms, and valve springs, but no lifters.
How's your oil pressure? Any hesitation?
How's your oil pressure? Any hesitation?
Thread Starter
Instructor
Joined: Oct 2000
Posts: 177
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From: Laguna Niguel, CA
Re: Evap Purge Solenoid (David Lively)
David Oil pressure is good and there is no hesitation. I get some pinging close to red line but I think that is bad gas 91 oct. and Delco plugs (soon to be changed NGKTR55). As for the fading of the tapping it’s the volume that fades but the speed is always consistent with the engine speed. Like it is getting easier for it to breath after time and then begins to work better making the noise fade.
Burning Brakes
Joined: Jan 2001
Posts: 985
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From: Palm Desert, CA , USA
Re: Evap Purge Solenoid (bigwave)
Usually the only time you will get a lifter noise is on warm up. It may take a few seconds for them to pump up. You didn't say how many miles you have on the engine, mods etc. An exhaust leak could sound like that (at the header) but I doubt that it would be intermittant.
Team Owner
Joined: May 2001
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From: Dear Karma, I have a list of people you missed.
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16
Re: Evap Purge Solenoid (bigwave)
The evap purge solenoid clicking thing has been something that I think a lot of folks may have mis-diagnosed as "lifter noise". I noticed an improvement when I did a little light bending (er, sorry..."forming") of the bracket where the solenoid is mounted to ensure that the solenoid and/or bracket were not resting against anything nearby such as the intake manifold , head, valve cover, etc. I have even considered wrapping the solenoid in a high temp insulating material just to prevent the sound from being noticeable but since I've made sure the solenoid isn't resting against anything, it seems to have helped a bit. JMHO :)
Thread Starter
Instructor
Joined: Oct 2000
Posts: 177
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From: Laguna Niguel, CA
Re: Evap Purge Solenoid (Tx99FRC)
tx99frc I'll try that tonight as for the miles I have 18K on her now. All well above the speed limit :yesnod: I took her for fast lunch and there was no tapping noise go figure.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Re: Evap Purge Solenoid (David Lively)
First of all, I'm fairly sure that you don't have lifters in a pushrod engine. You have a cam, pushrods, roller-rocker arms, and valve springs, but no lifters.
How's your oil pressure? Any hesitation?
How's your oil pressure? Any hesitation?
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Heel & Toe
Joined: May 2001
Posts: 23
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From: Korea
Re: Evap Purge Solenoid (bigwave)
I have posted this many times before on the f-body boards. I dont know for sure if the C5s have a purge valve, but I certainly would check it anyway. I would bet it is the same for the C5s.
If you have a tapping sound, piston slap is a very good possibility, but before you convince yourself that you indeed have piston slap, bent pushrods, noisy injectors, etc, at least try this first:
Start your cold engine in the morning. After about 1 minute, does it start “tapping”? Tapping lasts until the engine warms up and then stops? You may just be a victim of the “Purge Valve From Hell”. Your fuel vapor purge valve is located right next to the #1 fuel injector. That’s the most forward injector on the driver’s side.
Now that you have identified the purge valve, start your [cold] engine and let it idle. As soon as the tapping sound starts, unhook the electrical connector to the valve (while engine is still idling).
If the tapping sound stops, you have found the problem. Your warranty will replace the valve, but it’s just a crapshoot whether you get a quiet one or not. If you are not under warranty, I believe the valve costs under $50.
If you have a tapping sound, piston slap is a very good possibility, but before you convince yourself that you indeed have piston slap, bent pushrods, noisy injectors, etc, at least try this first:
Start your cold engine in the morning. After about 1 minute, does it start “tapping”? Tapping lasts until the engine warms up and then stops? You may just be a victim of the “Purge Valve From Hell”. Your fuel vapor purge valve is located right next to the #1 fuel injector. That’s the most forward injector on the driver’s side.
Now that you have identified the purge valve, start your [cold] engine and let it idle. As soon as the tapping sound starts, unhook the electrical connector to the valve (while engine is still idling).
If the tapping sound stops, you have found the problem. Your warranty will replace the valve, but it’s just a crapshoot whether you get a quiet one or not. If you are not under warranty, I believe the valve costs under $50.
