Chrysler Repair: Sticking valve,Jeep 4.0L, jeep grand cherokee, valve lifter

Question
Hi Roland
I have a 2000 Jeep Grand Cherokee. I picked up a slight tapping sound that seemed to come from the engine, I drove it a little longer & now the noise got really loud. I took it to a local Jeep dealer who says that it's a "Sticky Valve" - he says that is a common problem on the 4.0 engines. What can I do to make the noise go away.

Thanks a stack

Sanjay


Answer
Hi Sanjay,
If it is indeed a sticking valve or clogged valve lifter you might be able to clear the problem by using an oil additive that produces a cleaning effect on built-up 'varnish' and deposits on internal engine surfaces. I don't have recent experience with these products but I believe that you add it to you engine oil (but don't overfill the crankcase, if necessary drain off enough oil to just fill to the full mark with the cleaner fluid) and then run it as described on the label. I believe that you don't want to drive the vehicle very far if at all with the compound in the crankcase, rather just idle it for the instructed time period, then drain the crankcase and replace with fresh oil. If that doesn't do it then I would take off the valve cover and inspect for a problem with the valvetrain which might have a displaced rocker as the cause rather than the 'sticking' theory (or you could do that inspection first, before the engine cleaner technique). If neither of those approaches work, then I would try to find an independent shop with experience on the Jeep engine and let them diagnose the problem. The ultimate solution may require the cylinder head removal to service the affected valve.
Roland