Engine noise
 

This morning, when I started my '51 Ford with the '51 Merc engine, I noticed a slight tapping sound. It varies with engine speed, but is not there at idle. After the engine warms up, it goes away completely. The car has good oil pressure (idles at 20 psi hot, and runs down the road at 55 psi or so).

I suspect a wrist pin. Anyone got another opinion? As I understand it, this is not a serious problem until it happens all the time.

Re: Engine noise
 

Piston slap goes away as the piston warms up and expands a little.

I I had a wrist pin ticking in a y-block. I didn't know what it was until it weakened the rod and broke it in two, wiping out the block. When I disassembled the engine I could feel the slack in the wrist pin bushing.

Re: Engine noise
 

Could be fuel pump rod. Do you have a stethoscope handy?

Re: Engine noise
 

Re: Engine noise
 

does your engine light come on? ha-ha just kidding. Could be a valve. I had a tap tap tap on a new rebuild & I was waiting to readjust them & setting at a traffic light. The light turned green & I started to go, not hot but like you would normally take start off & all of a sudden there was this loud noise & the engine started missing. I was only a couple of blocks from home so babied it home & pulled the heads off. Found a valve head laying on top of the piston, lucky me it didn't hurt anything. Replaced all the springs & valves.

Re: Engine noise
 

Same symptom in the '53 Merc engine in my 34 pickup. My theory was that one valve lash is set a little loose and it quiets down after the engine heats up and the valve stem and lifter elongate to tighten the gap.

I did the math and the elongation would be less than .001. Probably not enough to quiet a loose lifter. Just shot down my own theory. So I will just continue to drive and be glad that by the time I get out of the subdivision the little tapping is gone.

Re: Engine noise
 

I'm with you (for now).

Re: Engine noise
 

Your problem seems to be opposite of mine. Mine taps at start-up and goes away after a short warm-up. Plus, it's more of a tap, not a metallic "ting, ting". Right now, I'm at the "If it ain't broke, don't fix it" stage.

Re: Engine noise
 

Stethoscope is a good idea, or just a long extension(s) with one end on your ear and the other touching the block along the intake manifold. Unlikely to be the fuel pump push rod because it is under constant spring pressure from the pump lever.

Re: Engine noise
 

More likely a piston noise than a wrist pin. Pins don't tighten up like the aluminum piston does as it warms. That's just assuming it's in the piston/pin area of course and we know how assumptions can go.


Terry