QuestionQUESTION: Hi Roland. Thanks for offering up your expertise. My LHS is running a little erratic. A friend who used to be a Mercedes tech troubleshot my issue with a hand-held analyzer to be my EGR valve. I've found them for ~$115 and have located the device on the car. Is this something I will need specialized tools for or can a shade tree mechanic like me do the job? Anything unusual I should be careful for or watch out for? Thanks.
ANSWER: Hi Ken
It may be the case that you won't have to remove and replace it. Here is how I have previously described a quicker correction of what may be the problem. It is not too difficult to R & R, so if this doesn't work please write back.
"the exhaust gas recirculation valve which is located behind the engine near the air intake throttle valve. It is mounted in a pipe that runs between passenger side exhaust manifold and the air intake manifold. The valve is mounted horizontally and has a valve stem between its round vacuum actuator top and the body of the valve attached to the pipe, inside the flange that connects the two parts. The stem has a slot into which you can insert the tip of a flat-bladed screwdriver so as to lever the stem back and forth against spring action which should move freely and close tightly. If the stem seems to be sticky so that stem doesn't close all the way by spring action, then you can try spraying some penetrating solvent like WD-40 on the valve stem to freeup its motion.
If the valve is sticking slightly ajar it will make for a rough idle and poor acceleration such as you describe because the mixture is too dilute. It is one of the most common causes of this symptom. So see if you can find the valve and check/lubricate the stem. To check it in motion you can rev the engine from idle to 2500 rpm and back to idle and watch to see if the valve stem moves freely in both directions to the extreme open and closed positions. It may be that the interior of the valve is cruddy so that might require that it be unbolted from the pipe where it it attached and cleaned. But chances are good it will only be a sticky stem. Feel free to write back with the results and other questions you might have."
Roland
PS May I ask a favor? Please use the 'thank/rate' tab below to offer me a nomination to be the 'expert of the month' which I am in competition for in December. Just answer 'yes' to that question.
Thanks very much in advance.
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QUESTION: To gain visual access, will I need to disconnect the (2) radiator system hoses? One runs to the overflow tank and the other runs into ??? I forget. It's dark outside and I looked at it this afternoon. As you can see, all secrets are safe with me. Can't remember squat:( Ken
AnswerHi Ken,
I don't believe that any significant dismantlement is required. Nothing in any manual speaks of having to deal with coolant hoses. Perhaps the air intake hose from the air filter to the throttle body might get in the way, but that is about all.
Begin by looking for the small pipe that branches off the right exhaust manifold toward the throttle body at the rear of the engine. None of the manuals mentions any removals to examine the valve and its stem. There are some testings that can be done but those require one of the vacuum-drawing hand-operated testors. In my experience the most common issue it just a gummy valve stem action.
I can xerox copy and postal mail you some pages that show it. Use the the 'thank/rate' tab below where there is a comments section where you can tell me a postal mailing address. And please, consider a 'yes' at the 'nomination for expert of the month question'. Thanks again.
Roland
