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

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?

Re: Engine issue tap, tap, tap tap, tap, tap
 

Could be rocker arm worn

Re: Engine issue tap, tap, tap tap, tap, tap
 

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.

Re: Engine issue tap, tap, tap tap, tap, tap
 

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.

Re: Engine issue tap, tap, tap tap, tap, tap
 

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.

Re: Engine issue tap, tap, tap tap, tap, tap
 

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

Re: Engine issue tap, tap, tap tap, tap, tap
 

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.

Re: Engine issue tap, tap, tap tap, tap, tap
 

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.

Re: Engine issue tap, tap, tap tap, tap, tap
 

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.

Re: Engine issue tap, tap, tap tap, tap, tap
 

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

Re: Engine issue tap, tap, tap tap, tap, tap
 

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.

Re: Engine issue tap, tap, tap tap, tap, tap
 

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.

Re: Engine issue tap, tap, tap tap, tap, tap
 

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.

Re: Engine issue tap, tap, tap tap, tap, tap
 

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

Re: Engine issue tap, tap, tap tap, tap, tap
 

X2 on the exhaust leak.

Re: Engine issue tap, tap, tap tap, tap, tap
 

Muffler bearing going out.

Re: Engine issue tap, tap, tap tap, tap, tap
 

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

Coley

Re: Engine issue tap, tap, tap tap, tap, tap
 

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.

Re: Engine issue tap, tap, tap tap, tap, tap
 

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.

Re: Engine issue tap, tap, tap tap, tap, tap
 

https://cdn-files.apstatic.com/climb...1494310801.jpg

It was a joke... relax mang! :) :)

Gary

Re: Engine issue tap, tap, tap tap, tap, tap
 

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

Re: Engine issue tap, tap, tap tap, tap, tap
 

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


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

Re: Engine issue tap, tap, tap tap, tap, tap
 

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.

Re: Engine issue tap, tap, tap tap, tap, tap
 

Zinc additive

Re: Engine issue tap, tap, tap tap, tap, tap
 

Did you pull the valve covers yet????

Re: Engine issue tap, tap, tap tap, tap, tap
 

Worth mentioning here is the mechanical fuel pump can peck too and sound just like a lifter. In my many years I have had two pumps do this. The spring inside gets weak on some allowing the slack at the pushrod causing the peck. Since the fuel pump is located directly under #2 cylinder it is easily missed as the cause. AC pumps usually last longer than others.

Re: Engine issue tap, tap, tap tap, tap, tap
 

I had the same issue and like Boog already wrote, it was a worn out fuel pump. After replacement the problem was solved. I did put in an edelbrock pump since my carb is also edelbrock.

Re: Engine issue tap, tap, tap tap, tap, tap
 

I've had brand new fuel pumps knock too, very annoying, when you're a mechanic and have to replace a part twice. The old one (original) leaked.

To the OP- use a stethoscope or a wood dowel and try to find the closest location of the noise.

Re: Engine issue tap, tap, tap tap, tap, tap
 

I pulled the right rocker cover and see no evidence of any metal shavings. I turned the engine to #1 position and the #2 intake rocker is loose and there is way too much play in the push rod. I need to make sure the rocker stud didn't pull out, but my next step will be to pull the intake to get to the lifters.

Re: Engine issue tap, tap, tap tap, tap, tap
 

Slow your roll!

Before doing all of that work, see how much it takes to pull the push rod out of the lifter. If its more than 1/8" then it is a collapsed lifter. You can't really see in there, but you can try. Maybe a borescope.

You can visually see if the stud is pulled out. It's gonna be higher and there will be a witness mark at the bottom where it meets the head.

Re: Engine issue tap, tap, tap tap, tap, tap
 

The rocker studs are all exactly the same height, so no stud pulled out. With the engine in the #1 firing position, #2 intake rod has about 1/8 to 1/4 up and down play. Rocker arms and tips look fine.