Engine issue tap, tap, tap tap, tap, tap

[brown7373]

Developed a continuous tap on my stock untouched 72 350. Using a mechanics stethoscope, I am 98% sure it is coming from number 2. I tried the magic potion (Risilone) hoping it was just a gummed up lifter, but no help.

I am pretty sure I have a bad lifter. It starts and runs fine at light load, but hates even moderate acceleration and increased rpm. Any thoughts about anything else it might be?

My plan is to replace the lifters and pushrods and hopefully nothing else unless I find something when I get into it. Will driving it gently do any other damage until I get time to take it apart?

[harpo231]

Could be rocker arm worn

[dirish]

I had a detonation issue. New crate tapped under load. It sounded like valve ticking. Vacuum advance adjustment helped. If you adjusted timing, or a new distributor it may be timing. Mine would not do it unless driving. Never at idol, even under throttle. Just a thought.

[Jcfcamaro]

Have you pulled the valve cover. Might be a loose rocker arm. But to figure that out you will need to turn the the engine over to top dead center and check half the valves as the Chilton manual then turn the engine over another full turn with the timing mark back at zero then run the other half of the valves.

[demian5]

Pull valve cover and ID the culprit.

I dodged a bullet by adding about half a pint of marvel mystery oil to the engine and poured right down onto the lifter.

I then started the engine every few days and let it get almost to operating temp.

Then one day it free'd itself, I adjusted the rocker and we live happily ever after.

the cause of my issue on my rebuilt low-mile 327 (that gets driven once every couple of months) was lack of oil changes (since the car sits). It was about 3 years since the last one. Ill have to do it for time and not miles from now on.

[demian5]

Oh and I've heard of guys snaking a single lifter out using magnets through the distributor hole...

[brown7373]

It taps at ALL engine speeds, but gets very bad under load and loses power. Obviously it speeds up as the rpms increase. Also, I don't want to push it because it sounds like it may really break something.

[D.PASSMORE]

You could be washing out your CAM. When you get the vave covers off. Look for glittering metal particles in the coners of the head. After it colls, dip your finger in that oil, the bigger the particle, the quicker its going out.
Im suggesting this, but it could be few other things.

[Big Block]

I had a rocker arm snap in half. The push rod was tapping the valve cover. It ran but not good. I parked it immediately and pulled the cover. Had t handles on the valve covers. Called a friend to pick me up and bring a socket set with him. Picked up a new rocker arm at the part store and replaced it where I parked it. Had it back on the road good as new. Good luck.

[hamjet]

sounds like a broken valve spring or rocker.. maybe the tip of the push rod also.

[demian5]

I thought the worst case scenario...

(never considered detonation... even with the power pack heads)
Broken rocker
Pulled rocker stud
broken valve spring
flat cam

...untill I pulled my valve cover. Just a stuck lifter, but it sounded like the motor was broke.

[brown7373]

My engine runs fine at idle and light driving, other than the sound of tap, tap, tap. At light throttle, 35-40 mph, windows up and A/C on, you wouldn't know anything is wrong.

I'll pull the rocker cover and check the springs & rocker arms. If they look OK and no evidence of metal filings, I will probably need to pull the intake and check the lifters.

[demian5]

Originally Posted by brown7373

My engine runs fine at idle and light driving, other than the sound of tap, tap, tap. At light throttle, 35-40 mph, windows up and A/C on, you wouldn't know anything is wrong.

I'll pull the rocker cover and check the springs & rocker arms. If they look OK and no evidence of metal filings, I will probably need to pull the intake and check the lifters.

Your issue will be obvious. Even with a collapsed lifter, one will be loose. Everything will not be OK. Look for metal like D.PASSMORE says.

[SuperChief]

I guess us amateures only get grief instead of encouragement to post

[jeffahart]

Originally Posted by brown7373

Any thoughts about anything else it might be?

X2 on the exhaust leak.

[demian5]

Originally Posted by SuperChief

Sounds like an exhaust manifold leak Not kidding, worked for me.

Muffler bearing going out.

[Coley]

Originally Posted by demian5

Muffler bearing going out.

...lol....or maybe a torqued out bindel rotor.....

Coley

[57taskforce]

The fact that it looses power under load makes me rule out an exhaust leak. Like said above pull the valve covers and I bet the problem becomes relatively obvious.

[SuperChief]

Originally Posted by demian5

Muffler bearing going out.

Actually you may be correct and I missed the exhaust leak...."The canooter valve is a part of the exhaust regeneration assembly on new diesel engines. The canooter valve usually fails due to overheating of the exhaust bearings.

It's spelled "Canuter" not canooter. Over use of this valve is caused by faulty friggate switch wiring. When this happens, the muffler bearings become hot and can seize. Eventually, the catalytic converter fluid will become tainted with halogen bulb fluid due to canuter valve blow-by.

At this point, it's best to scrap the vehicle..."
Thanks for the astute observation. I did not intend tp hi-jack this thread. I will now only observe answers and refrain from comment.

[GASoline71]

It was a joke... relax mang!

Gary

[brown7373]

I replaced the muffler bearings when I changed the muffler oil!

[67 chevelle]

This is common nowadays , hope its not whats happening ,but is a possibility , especially if you are low on power .

Originally Posted by D.PASSMORE

You could be washing out your CAM. When you get the vave covers off. Look for glittering metal particles in the coners of the head. After it colls, dip your finger in that oil, the bigger the particle, the quicker its going out.
Im suggesting this, but it could be few other things.

Broken valve spring is also likely , much easier to fix , big blocks break them frequently , small blocks less often , remove your valve covers and hopefully the problem will jump out at you

[Money_pit]

Are you using oil with the zinc stuff in it? Or just conventional oil?
These ole girls like the old oil not any of the new garbage.

[brown7373]

Zinc additive

[demian5]

Originally Posted by brown7373

Zinc additive

Did you pull the valve covers yet????