I have a 93 4runner 3vze with automatic 4wd, I just got it last night and it appeared to have a rod knocking on start up and when reved over 2000 rpm,
today I started it and got a slight kickback and a hissing noise coming from the drivers side around the exhaust manifold area, it went away immediately and started, running rough and missing, until it cleared out, then it smoked out of the tailpipe for a short while and cleared out, Im thinking possible head gasket, I guess my question is will a head gasket problem appear to be a rod knock intermittently, like maybe the piston is free floating and knocking while in a no compression state, or maybe full of water?
I will try to compression check it and figure it out this weekend, thanks for any input
Happy New Year!!

 

a blown head gasket will not cause a rod knock... unless coolant has entered the crankcase and caused a rod bearing to wear inordinately.

 

What color was the smoke? It could have just been condensation in the exhaust. Or, if it's black, could have been unburned fuel. Or, if blue, then oil....which could be a couple of things.

Anyway, are you sure the hissing was from the manifold and not the airflow meter?

I will say in my experience if a motor has trouble making initial combustion, the motor can knock. Particularly if you have trouble firing on any one or more cylinders. This would also included normal running conditions.

 

I compression checked it and found 2 low cylinders 4 and 6 and those plugs were caked up with deposits, Im not going to chance it I think it will be best to tear down and inspect it all, crank included, thanks for the input guys!