burninggraphite

22re/5spd tapping/knocking started recently once the truck warms up and only at idle, the idle has gotten a little rough and i believe its associated, when putting my hand over the exhaust and the other on the bed of the truck i noticed that there is a stonger "puff" out the exhaust when the balance of the idle is thrown off. I am no guru but im learning and would say above average with people my age at diagnosing issues with engines but living on my own and getting back on my feet after a bout of homelessness from a cross country move in the truck im too broke for a mechanic at this time.

some research has lead me to believe that piston slap from high milage (175 thousand) may be a possibility bc the explanation makes sense... worn engine at idle wobbles and at speed smoothes out.

however, I think its something in the valve train like slack in a rocker causing an exhaust valve to stick but with the top end being rebuilt about 50k ago it doesnt seem likely that one rocker arm would wear with decent upkeep. I've changed the oil regularly and seafoamed from the vac line that goes to the brake booster a few times in the 50k I"ve put on it since the rebuild, so I dont understand how it would go out of adjustment so soon with good a maint. record.

any opinions on this will be considered and much appreciated so please dont be afraid to put in your 2 cents.

Thank you!

P.S. I dont really feel comfortable with pulling the valve cover because in my current situation only having one vehicle to get back and forth to work I simply cant afford to risk a fudge up or downtime OR a mechanic... so I am simply looking for opinions on possibilities to look into down the road when I can afford it, if the engine pops I'll get one of these and live in one of these

combatcarl

Check plugs n wires, then, I know you said you didn't want to risk taking the valve cover off, but you kind of have to, to check valve clearances. Sounds like a slight miss at idle. If you're hearing a rattle at idle it's "relatively" normal for the 22 series to have some valve clatter. It's kind of how you know you have enough clearance on your rockers/valves. Too much is a possibility, though, and might be noticeable at warm idle. But easy stuff first. Plugs, wires, cap, rotor. Also, find the EGR valve, and disconnect the vacuum line to it, see if it's working by applying vacuum to the EGR at idle, it should stall or nearly stall the engine. If not, it's plugged/inoperable, just plug the vacuum line and leave it disconnected. Check and adjust (if needed) your timing, while you're doing plugs/wires/etc.