1986 t/a with an 88 gta 5.7 tpi did the radiator water pump thermo planning to get a lower fan temp switch as i have been having problems prior to this with over heating. now for the question at hand. my engine knocks for a while i thought it was my clutch cause i know im gonna need a new one soon but when i press the clutch and rev up the engine i dont hear the knock even to 4000 rpm i dont take her much past that just cause ive had no need to so when i go to pull out from a light sometimes ill hear the knock right away other times i have to be really demanding of her to get her to knock 2nd gear to 2000 2200 rpms nothing but slightly hear a knock ....maybe not sure though yet 3rd gear yet again being demanding of her shell knock up a storm but if i take my foot off the gas and am light with her till shes up to speed no knock 4th gear same and 5th gear same all of these gears have a variable though if im going up the hill and accellerate a bit demanding of her she will knock all gears but if i milk her up the hill keep her under 2000 rpm i can get her up the hill no knocking now when im dead stopped i hear nothing even to suggest that she may be knocking dont know where to go from here please if im not clear with anything just ask i depend on this car its my daily driver

 

A " solid " knock like a bad lifter or connecting rod?

Does it sound like it has a slight " rattle " more like pinging?

Does itdo this only when up to operating temp, or even when cold?
Do you have an air dam?

Check your oil level. Loook at all the exhaust connections for blown gaskets-- you will see black soot around bad exhaust connections.

If it sounds like it's coming from inside the motor, look for ANY metalic reflections on the dip stick.
Get a new oil filter.
Take off the old oil filter, drain it & CAREFULLY cut it in half. Look at the filter material for metalic reflections. The thin metal will cut flesh easy--get some old gloves.
Put on the new filter per directions.

Metal in oil **can** be from a bearing.

 

Also check motor mounts, trans mount, & all
suspension mounts, exhaust hangers.

IDK torque specs, but at least make sure nothing is obviously loose.

 

Are you describing mechanical, or combustion knock?
If you think it's combustion, you should also be experiencing power loss.

 

I ran her this morning and no knock so I presume its when she is hot . Rattle is a good word for it cause I couldn't describe it. Like I said if I take it easy and let her build the speed use hills to my advantage she won't rattle I thought when it first started that it was my clutch cause it would seldomly do it in 5th gear going up a hill.

 

are you running cheap gas or are you using 89 or higher?

 

By hot do you mean; normal operating temperature, or is it overheating, hot enough to overflow with steam, if not overflow, boiling noise when the engine is shutoff.
If it's getting really hot, it will also be losing power.

 

thank u ur advice about the air dam worked beautifully shes cold now im almost sure she is too cold though all i did was put that air dam on

 

Hopefully that's it!

As torque_is_good mentioned, try the 89 octane. Keep vigilant on the gauges & sounds, as well as any power loss for awhile.