Ducman82

just went and checked. bushing is whole and looks good, no strange movement... hummmm

Shark_Week

doesn't sound like it's coming from the engine

Fabio421

Cut open the oil filter. If it were a knock and sound that bad you should see some metal in the filter. It sounds like something is loose to me.

Bill Ball

OK, so I would describe that as a rattle, not a knock. It's a vibration, not a rhythmic knock that matches RPM, so, I don't think it's anything like a rod or other part of the rotating mass. It sounds like a loose bracket, say, for the air pump diverter valve, rattling against the block. It sounds like a broken cat coverter core rattling in the exhaust, although you have tracked it to the block rather than the exhaust. Perhaps it is the shield plate above the AC compressor - at least my 89 has one. Perhaps it is the heatshield near the motor mounts. Whatever it is, it doesn't sound internal or rod knock-like. I wouldn't be cutting any filters unless it's time for an oil change.

Stromius

Does an 81 have the exhaust sampling ports/hose off the exhaust headers? Or how about airpump plumbing?

Ducman82

No ports or emission stuff on the car anymore. Getting it up in the air (rack) and delv a little further today. It's more constant now, compared to that video.

Cosmo Kramer

Sounds to me like a metallic vibration, not a rod knock. Doesn't follow the rpms. Get it in the air again with it running and see if you can find something loose.

Ducman82

sound is mostly coming from driver side exhaust...... but not really the block. we think its a broken valve spring. so this week/weekend I'm going to take the drivers cam box off and take a look.

SMTCapeCod

missing any wrenches/sockets?

;-)

vze2jshn

Listen with stethoscope from top side of cam tower also.

17prospective buyer

Does the sound occur at engine speed or half engine speed?

Ducman82

all tools are accounted for. with scope you can Really hear it on numbers 5-6. at speed it barley makes any noise, so the valve likes to float... going to take a plug out when she is cold and take a look......

namasgt

Have you ever had the oil pan off? GTS baffle?

Are you saying that it makes the sound regardless of revving it or not as of today?

Ducman82

makes the sounds more when hot. and is specific to the head area around 5-6.

Ducman82

last night i took the driver side cam gear cover off, moved the belt a little and saw this....... wow its worn... some oil seeps and everything under that cover.. ugh. now my debate is this,

take apart and fix the springs (if that is indeed the case)
or remove the old girl, and clean up the engine bay while building up the hybrid..