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76 Posts
Okay, so like the title states, my engine has developed a knock. But first here's a little background on the engine:
a few weeks ago i let my dad borrow my 95 firebird (lt1 150xxx miles) since he was having vehicle issues himself, and it was running in fine condition at this point. when i got it back, it ran like garbage. it had an awful sounding knock and it felt like it wasnt running on all 8 cylinders, so i instantly thought "oh great...another head gasket blown" (i have had bad luck with head gaskets in previous cars) so i just drove the car about two blocks to get home and parked it. next day i went out to get an idea what was wrong with it and started it up and the knock mysteriously went away but it was still running like crap. so i read a TON of threads on here and alot of my symptoms matched that of a bad opti, so i went and replace the whole opti, plugs, wires, serpentine belt, waterpump, crankshaft seal, thermostat, fresh 10w30 synthetic oil, (was no metal shavings in oil) and thought i was in the clear. started it up, and it ran much better, but that "knock" came back. its strange because it is ONLY at idle or low rpm and kinda smooths out when driving, but if you take your foot off the gas and cruise the car runs rough (slight vibration) and you can hear the knock. same thing when parked, it will knock until you hit the gas and pick up the rpm's and then it smooths out. after reading through a whole ton more threads, only two things have come up that seem similar to my issue, 1: collapsed lifter or some sort of lifter issue,, 2:i have a "dead" cylinder.
so after throwing a decent chunk of money at this issue already, i was hoping someone on here could help me diagnose this before i just start throwing random parts at it and wasting money? i will try to get a video and upload it tomorrow. sorry for the mega long post, and thanks for reading :LS1LT1flag:
a few weeks ago i let my dad borrow my 95 firebird (lt1 150xxx miles) since he was having vehicle issues himself, and it was running in fine condition at this point. when i got it back, it ran like garbage. it had an awful sounding knock and it felt like it wasnt running on all 8 cylinders, so i instantly thought "oh great...another head gasket blown" (i have had bad luck with head gaskets in previous cars) so i just drove the car about two blocks to get home and parked it. next day i went out to get an idea what was wrong with it and started it up and the knock mysteriously went away but it was still running like crap. so i read a TON of threads on here and alot of my symptoms matched that of a bad opti, so i went and replace the whole opti, plugs, wires, serpentine belt, waterpump, crankshaft seal, thermostat, fresh 10w30 synthetic oil, (was no metal shavings in oil) and thought i was in the clear. started it up, and it ran much better, but that "knock" came back. its strange because it is ONLY at idle or low rpm and kinda smooths out when driving, but if you take your foot off the gas and cruise the car runs rough (slight vibration) and you can hear the knock. same thing when parked, it will knock until you hit the gas and pick up the rpm's and then it smooths out. after reading through a whole ton more threads, only two things have come up that seem similar to my issue, 1: collapsed lifter or some sort of lifter issue,, 2:i have a "dead" cylinder.
so after throwing a decent chunk of money at this issue already, i was hoping someone on here could help me diagnose this before i just start throwing random parts at it and wasting money? i will try to get a video and upload it tomorrow. sorry for the mega long post, and thanks for reading :LS1LT1flag: