BMAN1113 Posted August 14, 2004 Share Posted August 14, 2004 My car runs fine, but recently I'm hearing more clattering of valves when shifting from 1st to 2nd, under semi-hard acceleration. Is this common among SC400's with 124k? Am I working towards a major repair? Thx Quote Link to comment Share on other sites More sharing options...
Zigzag Posted August 15, 2004 Share Posted August 15, 2004 Your "valve clattering" could be pre-ignition, especially in a higher mileage car, what grade gas are you using? 94 octane is recommended. Quote Link to comment Share on other sites More sharing options...
BMAN1113 Posted August 15, 2004 Author Share Posted August 15, 2004 I'm using premium Chevron. I can remember the octane. I thought it was like 91. I check. How does the age effect pre-ignition? Thx Quote Link to comment Share on other sites More sharing options...
lexxus Posted August 17, 2004 Share Posted August 17, 2004 When I push my 400, it does the same thing, if you're referring to pinging. In CA, we can only get 91. Here they have told me it might be carbon buildup, or it might need a tuneup. If it really is valves specifically, the obvious thing is a valve job, where they take the heads off and grind the valves and replace any that are bad. It might just be bad gas. Try a can of Techron, maybe that will clean things up. Quote Link to comment Share on other sites More sharing options...
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