clacey Posted December 29, 2003 Share Posted December 29, 2003 I just bought a 91 LS 400 with 213,000 mi. I just replaced the Starter, & PCV Valve. The engine makes a tapping noise when under acceleration. When I replaced the PCV Valve, I noticed that it seemed pretty sluggy in there. Would it help to remove the valve covers and clean the valves and lifters? If so what should I use? I know that in 97 the dealership ran some GM Top Engine Cleaner through it to remove a tapping sound. I wonder if I should try that again? Has anyone used this stuff on thiers? The three causes of this seem to be: 1. Sticky valves 2. Valve adjustment 3. Exhaust leak 4. Timing advanced Do you have to reset the timing when you replace the timing belts? I have a lot to do to this thing. Any input is appreciated. Thanks, CL Quote Link to comment Share on other sites More sharing options...
SKperformance Posted December 30, 2003 Share Posted December 30, 2003 WHy waste all that time ,just buy a bottle of engine flush and run it then replace the oil (and filter) with cheap stuff for a week then replace with synthetic to make sure all the flush is gone. Quote Link to comment Share on other sites More sharing options...
clacey Posted December 30, 2003 Author Share Posted December 30, 2003 Does the flush stuff really work? If so what's the best brand? Thanks, CL Quote Link to comment Share on other sites More sharing options...
SKperformance Posted December 30, 2003 Share Posted December 30, 2003 They work amazing i have used tehm on my wifes sunfire my civic ,lexus and the list goes on. I use the penzoil one they all are pretty much the same The lifters getting unstuck makes the biggest power and noise difference. Quote Link to comment Share on other sites More sharing options...
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