engine and drivetrain Daily driver - need HELP

[OZ2002]

I fear the worst and hope for the best. My '71 02 started making a prounounced metallic tapping last night about a mile from home. I was driving normal and had just shifted into 2nd. It was so bad that I could feel it through the clutch pedal. About a block from home the noise subsided somewhat and I didn't feel it though the clutch pedal any longer. It was kind of like a no spark condition in a cylinder, except that the car acclerated well.

I checked the plugs, plug wires, distributor cap, rotor, and valve clearances. All seemed in order. I drove to work this morning, and the car still has good accleration and doesn't seem to be missing (I think the timing is good). The noise is still there, and got worse again after I got near work (after about 10 miles). I can tell that it's not the tranny (noise is there in neutral and the frequency of the tapping increases when I depress the accelerator). The noise seems to be coming from the head or the block. There was no indication of any oil in the coolant or coolant in the oil. I have an older engine and get some blow-by on deceleration from higway speeds.

Any and help is very much appreciated.

[TobyB]

Pull the valve cover-

could be as easy as a lash adjuster that's slipped.

Could also be a blown exhaust gasket- they sound like a 'tap'

more than anything else.

I'd look under the valve cover before I even drove it home.

hth,

t

[DavidLMM]

Check your plugs, too. I used to have a Honda that would back out the #3 plug every 6 months or so. After the first time, I knew what it sounded like, but that first time was pretty stomach-churning.

Might it also be the fan whacking something due to a weak or broken motor mount? Could be lots of things - and many of them relatively minor.

David in Nashville

[c.d.iesel]

. . . . ? LEAKING EXHAUST MANIFOLD GASKET

leaking header pipe to front muffler joint ?

if you say you checked valve adjustment ? -

any rocker arm really loose ?

you didn't remove the cam cover ? - take it off now and

inspect for a loose rocker, broken valve spring,

loose rocker arm locating spring . ? ? ? ?

[jmiller]

I once had that happen on my old Datsun 510. Sudden loud tapping, but car still ran fine. Drove it 10 miles home, no problem except for the LOUD tapping. Pulled the valve cover, turned out that one side of the timing chain broke and was rapping against the valve cover. Can't believe the whole thing didn't break, considering how far I drove it like that. It was a good excuse to leave it at my folks house for a few months while I had to go back to school. I planned on fixing it during Christmas break, but Dad was sick of looking at it so he paid for a complete valve job. Woo-hoo!

Jeff

[OZ2002]

Thanks all. After a quick inspection, it tooks like I have to get a little deeper into. The plugs are good and the valve clearance is adjusted properly. What is puzzling is that the noise is intermittent, anything from non-existent to very loud (at idle or speed).

Brice