fiatslug87 Posted February 22, 2013 Share Posted February 22, 2013 Is the 4.0 an interference engine, i.e. is the valve travel lower than the highest piston travel? Link to comment Share on other sites More sharing options...
Geonovast Posted February 22, 2013 Share Posted February 22, 2013 Yes. Link to comment Share on other sites More sharing options...
Biotex Posted February 22, 2013 Share Posted February 22, 2013 I'm going to disagree. It is not an interference engine. To my knowledge mostly only overhead cam engines which run a timing belt are interference. IE. if the belt breaks, you can destroy a piston and or valves. If the timing chain breaks on a 4.0L or realistically slips a few teeth, the valves would not hit a piston with a stock cam installed... In fact, if you install a high lift cam, you usually run dished pistons to clearance the valves. I have never seen a 4.0L any other way. Link to comment Share on other sites More sharing options...
Geonovast Posted February 22, 2013 Share Posted February 22, 2013 I could have sworn I read a few articles back in the day that said it was, but it appears I was incorrect. Link to comment Share on other sites More sharing options...
Minuit Posted February 22, 2013 Share Posted February 22, 2013 Nope. If the timing chain breaks (it won't) or slips the only thing that will happen is the motor will stall. Bet it's a fun job getting the timing right after that happens. Link to comment Share on other sites More sharing options...
cruiser54 Posted February 23, 2013 Share Posted February 23, 2013 Nope. If the timing chain breaks (it won't) or slips the only thing that will happen is the motor will stall. Bet it's a fun job getting the timing right after that happens. Easy to get it right. Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 23, 2013 Share Posted February 23, 2013 The Jeep (AMC) 4.2, 4.0, and 2.5 are all non-interference designs. However, the big Rotax single engine on my bike is not. Well, it is in stock form, but if you're running a high-lift cam and the timing belt breaks, you're in a world of hurts. It grenades real fast. :eek: Link to comment Share on other sites More sharing options...
54bobby Posted February 23, 2013 Share Posted February 23, 2013 not interfierance engines. i drive an 86 3 series bmw and they are interfierance engines. if you break a timeing belt on those cars, you're f'd valves slam into pistons and you're looking at major engine work or replacement. our trucks you just coast to the shoulder, replace the chain and back on the road. Link to comment Share on other sites More sharing options...
jeepsouth Posted February 23, 2013 Share Posted February 23, 2013 good info to know. Link to comment Share on other sites More sharing options...
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