rattle in motor

[jin3000]

hi. i have what seems to be a big problem.my 97 240sx w/ka at 100,000 miles has a rattle or a knock.it does it inthe morning for about5 to 10 secs then also at 3000rpm .ive taken it to a few shops and have been told its my rods going bad but have also been told it my valves needing adjustment.im hoping its not the first one .i know its hard to determine the prob without the car being there but any ideas?also i would like to know what the average cost of repairing these would be,or should i just have it rebuiltand if so what could i expect to pay .btw do you know a good shop in san antonio ,tx.

thanks in advance.

[navysnail]

is it like a dry start rattle?

[NISTECH]

like you said its really hard to tell especially after you have had different opinions from different shops. But the valves are technically not adjustable in a manner that they could loose their adjustment . They are adjusted using shims. typically you never have to change those shims through the life of the car. is the knock hear when you bring the engine right off idle? if so I would guess its a rod or main bearing.