vacuum solenoids

[6.2L Driver]

I have three solenoides on the drivers side valve cover. I see there first one has a line to the wastegate, and third or back on a like to the EGR valve. What is the second one for, and is there anyway to test then valves to make sure they are working?

Thanks

[ 03-02-2005, 08:02 PM: Message edited by: 6.2L Driver ]

[charliepeterson]

The rear two solenoids are for EGR function. If they don't work the SES light will come on. The front one is the waste gate solenoid for the Turbo. If this one fails you will most likely see lots of black smoke when you need lots of boost from the turbo.
A vacuum guage can help for diagnostics. A reading of 20"-25" to the front solenoid and 15"-20" to the waste gate at the turbo is good. Another way to quickly tell if the waste gate solenoid is working is to move the waste gate rod at the turbo with the truck running. You should not be able to move it. Now shut the truck off and the rod moves freely.

[6.2L Driver]

Thank-you,

I dont have any SES light on, but I know that when I pull the vacuum line off the waste gate it moves, and with the line hooked up I cant push the wastegate rod either.

Also if the truck has been shut down for a while, then when I go to start it, there is a clunk that seems to come from under the floor boards passenger side. This clunk or thump whatever you want to call it comes about 10 or 15 secs after start up? What would that sound be? could the converter or muffler be plugged?

[ 03-02-2005, 08:25 PM: Message edited by: 6.2L Driver ]