Possible wiped cam lobe

[87geeinn]

Was just cruising to work around 65mph last night on the interstate and felt the car buck very slightly a time or two. I looked over and then the Scanmaster knock display started going ape****. I pulled the car over immediately and popped the hood. There was a tapping coming from the motor, so I jumped in and shut it down. I didn't lose any oil pressure so I'm thinking a wiped cam lobe. Pehaps I'll get lucky and it's just a rocker arm but I doubt it.

One question: If the cam is indeed toast, ss the motor ruined with all that metal ciculating through the motor or will I be okay if I do a roller cam and heads upgrade, clean up the oil pan, etc?

[kenmosher]

A wiped lobe usually isn't a sudden event ... it just gets steadily worse over time until it's really bad. My guess is it's a rocker arm or pushrod ... maybe lifter?

Fingers crossed!

[87geeinn]

Yeah, I'm hoping it's something minor too.

The only thing I've noticed as of late is that there has been a decent amount of "chatter" on cold start ups because the oil psi takes about three seconds to build. It's just as if there is no anti-drainback valve or start up was done after a oil change without filling the oil filter prior. I've tried different brands and sizes of filters and they all do the same.

The "chatter" that I was hearing last night sounded very similar, so it could indeed be a sticking lifter that finally petered out. I'm not sure because I didn't want to keep running the car on the side of the interstate at 1:30AM.

[87geeinn]

I think I may be dealing with a failing or sticking lifter.

Started the car this morning, verified oil pressure, and noticed the noise was coming from the passenger side. Shut it off, popped the valve cover off and re-started the car. All of the pushrods were spinning away and all of the rockers seemed to be travelling their full range of motion. I used a mechanic's stethescope and pinpointed the noise as definitely coming from the #4 intake area. I had the stethescope rod right on the rocker shaft just behind the nylon retainer and could hear a definite "tap-tap-tap" that was substantially louder than the rest of the others.

I shut the car off, smacked the back of the rocker arms on the pushrod sides with a hammer and restarted the car. After 2-3 minutes the noise started subsiding and then it sounded fine after that.

I did overfill the crankcase by about 1/2 quart by accident on my last oil change but didn't think it was an issue. I'm wondering if maybe the crank was churning the oil up into a froth and some air got into the system. Gonna drain a bit of oil out and drive it around and see what happens.

[kenmosher]

That's excellent news! Hope it doesn't come to that lifter failing, but even so, that's better than the alternative...

[87geeinn]

UPDATE:

Drained 1/2 quart of oil to bring the crankcase to exactly the full mark. Took the car for a spin and car drove like a dream...for now. Gonna start saving for heads and a roller cam (finally). :drool: