FA? Engine Knocks Loud on Startup...

have you checked the timing? adjusted the valves?

I had this noise on my '74 engine (start engine , goes bang bang bang ) also is there loss of power then over heating. Check endfloat on crank if you can feel loads of movement .... it the main bearings on the way out

sorry

John

piston slap maybe?

Low oil pressure ?

Randy

Just changed oil to 20w50...

OK, But hows the pressure the first few minutes after starting ? Did you have the knocking sound before you switched ?

Randy

Loose heads? Remove the valve covers and rocker assembly, and check the torque of the lower head nuts. If they are loose, you have to remove the engine and retorque the heads.

Bill, '67 Bug.

yes

-- Mel P.

Bill,

Wouldn't I leak oil if the heads were loose?

Not necessarily, or not much oil anyway. When I say loose I don't mean completely loose and rattling, just undertorqued. When the engine is cold, the pressure in the combustion chamber hammers the heads and the and the get banged back on the cylinders. When the engine warms up and the heads are beginning to expand, they get tighter against the cylinders eliminating the knock. This would much likely be your situation if the knocking continues for a minute or so, and then gradually goes away.

If the engine knocks loud just for a few seconds (2-6 sec) and then the knock suddenly just disappears, then the heads are not the problem.

Did you had the engine rebuilt recently? Are you using a full flow oil filter? What carb do you use? Any porting done on the heads? Does the outside temperature affects the knocking?

Bill, '67 Bug.

Bill,

thanks for your help... when I pulled the engine I found the flywheel 'nut' was loose. I got lucky...

thanks again