engine rattles

[nitroxsteve]

I just got my mj on the road this week and I'm working the bugs out. The engine runs good and pulls strong but has a rattle in the top end at higher rpms (around 3,000 up). And only while on the gass if you let up and let the engine slow the truck down it stops. It does not sound like a bearing or a piston slapping. It sounds like the valves are loose. Has anyone had a similar problem or have any ideas? I have run seafoam thru the engine and changed the oil to 10w40 penn. As far as I can tell from the shop book you cannot adjust the valves. When I have time I plan on pulling the valve cover to check things out. Thanks

[89comanchesleeper]

have you cheked the timen? could be spark knock if its only under loads.

[nitroxsteve]

have you cheked the timen? could be spark knock if its only under loads.

 

Good thinkin Ill check it tomarrow. It does sound like a spark knock.

[jimoshel]

You can't adjust the valves but you can tighten loose hardware. My rattle was caused by rocker arm bridge bolts working loose.