[pippintook]

My 77 TA 400 engine just started making an unusual noise.

Background: I don't know the complete history of the engine. I believe the engine is stock and has not been apart. It has stock exhaust manifolds and mostly stock exhaust. The engine has ran fine for me the last 4 years. Generally, runs good and no issues.

A few days ago I started up and engine seemed to be making a light tapping
or popping sound. It appeared to be coming from the driver's side of the engine. I shut the engine down after maybe 1-2 minutes.

I started today and when the engine first started there was no noise. Note, the outside temp is around 35-40 degrees when started today. After engine ran for about 10 minutes I started to hear a noise. It seems to be coming from driver's side. I have recorded a few videos of the noise. Check these links - sorry video is a bit shakey

https://www.youtube.com/watch?v=h53eeTS7Vss
https://www.youtube.com/shorts/09MvYGGIW60

Does this sound like a lifter ? Exhaust ? Something else ? When I crawl under - both the drivers and passenger down pipes look ok. I sprayed some soapy water on the drivers exhaust manifold to down pipe connection and can not see any bubbles. I guess I should pull the driver's valve cover and inspect ? Maybe also pull the drivers exhaust heat shield and check the exhaust manifold ?

Any ideas or advice is appreciated.

Thx

[Gach]

What you can do is, use a pair of plug wire pullers, while its running pull on plug wire at a time, the motor will start skipping , put it back on, go to next cylinder until you find, the cylinder that doesn’t make any difference once wire is off. this will tell you which cylinder it is, this will narrow down, once you pull valve cover off, you can look at that lifter rocker arm, it will at least tell you what lifter it is.

[Scott Stoneburg]

Sounds like a lifter to me

[Gach]

It could be adjustment but I doubt it, at least once you get into pulling it apart, you will narrow down what lifter it is, check cam lube also. But it sounds like a collapsed lifter. Who knows. Doesn’t sound like an easy fix but you never know until you check everything out

[pippintook]

Thank you for the replies.
.
I have been worried that a cam lobe (or lobes?) is maybe going flat I did a compression test with the engine cold and all cylinders were around 160psi. The tapping / clacking seems to be coming from the driver's side. I pulled both valve covers and I could not see anything abnormal. I started the engine (outside air temp was around 50F) and there was no tapping / clacking (or very minimal tapping/clicking). But, as engine warmed I started to hear the tapping / clacking and again it is driver's side. It seems to be coming from cylinder 1 and/or cylinder 3. I pulled the number 1 spark plug wire and the tapping / clacking did not appear to change much. I reconnected cylinder 1 wire and disconnected 3 and again the tapping / clacking did not change much. I had some heater hose and tried to listen to rocker stud on cylinders 1 and 3. They do seem noisier but not hugely noisier than other rocker studs. I tried squirting in some seafoam (down into engine - on and near the pushrods). That seemed to make the tapping/clacking a bit worse.
.
I am surprised this tapping / clacking noise started kinda out of the blue. The engine had been running fine for me last 4-5 years. No issues. When I pulled valve covers - it was very clean - no sludge. I have been good with changing the oil. But, I gotta give prior owner credit - it looks well maintained.
.
I am thinking I should likely do at least a partial tear down and inspect the cam lobes , lifters, rocker arms, balls on cylinders 1 and 3 (and likely all cylinders). I will also pull the oil filter and inspect. I am attaching few pics of the spark plugs - which look ok as far as I can tell.

[pippintook]

some pics of plugs

[Schurkey]

Ideally you would NOT pull plug wires off the plugs with the engine running. This is very hard on the insulation of the secondary side of the ignition system, including the windings inside the ignition coil, because the open-circuit you created drives the coil voltage sky-high.

The much-better method is to blunt the tips of eight small nails or pieces of wire, apply a touch of dielectric grease, and slide them between the plug wires and the boots at the distributor end. Point is, to NOT PUNCTURE the insulation--just go between the wire and the boot until you feel the nail contact the metal terminal of the plug wire. Then touch a grounded jumper wire, or grounded incandescent (NOT LED or neon) test-light to each nail in turn to short the spark to ground rather than create an open-circuit. Voltage drops to zero, which doesn't stress the insulation.

Photo attached of nails in a Chevy TBI application, Pontiac similar.

[dataway]

There are times when a leak/crack in an exhaust manifold will not start making noise until it warms up and the leak/crack expands. But usually the process of shorting an ignition wire will show up and exhaust leak pretty quick.

[PDC]

Based solely on the video, this does sound more like a lifter and less like exhaust. If the tapping does not start until the engine begins to warm up, that could mean when cold, the oil has sufficient viscosity to slow the bleed rate and add a bit more cushioning for that lifter. As the oil warms up and thins down, the symptom reveals itself. Not sure what viscosity oil you run. Most folks with bone-stock engines gravitate toward 10/40. Joe Gibbs offers a synthetic 15/50 that may help quiet that lifter down by slowing the bleed rate as the temp climbs. The ‘cold’ flow rate of a synthetic 15 wt shouldn’t be much different than the cold flow rate of a conventional 10 wt. This is not an alternative to a proper tear down / inspection / repair - but could help if a proper repair is not in the immediate budget.

FWIW - I had a 455 with one clacky HFT lifter after a full rebuild. No amt of adjusting cured it. But with Gibbs 15/50 synthetic, it was noticeably quieter than with any other oil I had tried. I honestly could have lived with it, but swapped in a set of USA Johnson Hylifts, and that solved the problem. Lifter faces and cam lobes were fine, but a couple lifters were bleeding down more quickly than the rest.

[400 Lemans]

That's also the same sound that a broken spring on the fuel pump arm makes when it gets that slack in it. You would think it would also do it when the engine is cold though. Worth a check if you don't find anything else. It has happened to me before.

[phil400]

I've used a long screw driver to listen for noises, usually will be pretty evident which one it is. If you think it's cylinders 1 or 3, just pull the Valve cover and try wiggling the rocker any excessive slack will be pretty evident to make a clacking sound that pronounced,or to check for a collapsed lifter just push down on the push rod side of the rocker it'll be spongy and you'll be able to push it quite abit till it bottoms out in the lifter.

[Half-Inch Stud]

Alt bearing noise; remove belt, then run engine.
Might well remove PS belt too to remove doubt on pulleys.

You will fell better knowing without doubt. Check rocker looseness. Re-lash on base circle.

[nUcLeArEnVoY]

My car makes the exact same sound on occasion during a cold startup, and it's probably a lifter. It disappears as it warms up for me, though; which tells me it's just an intermittent sticky lifter. I've driven the car near 5k miles since I've got it and have had no problems so I just figure it takes some time for that particular lifter to pump.

Run the car for a bit without revving it up too much and see if the tick settles down.

[Kenth]

20w50 viscosity engine oil is the usual cause for ticking lifters.

Recipe is 10w30 as the manufacturer recommends for viscosity.

[pippintook]

Thanks for all the replies

Note, I have not yet tested with alternator and PS belts disconnected. I have also not yet checked the mechanical fuel pump. For oil I am using Rotella 10w-40.

I had some old romex house wire (14-3?). I stripped off the jacket and cut the copper wire into maybe 5" pieces. For each 5" piece, I made a bit finer tip to the wire using a very light touchup with my angle grinder. I dabbed the wire in some di-electric grease and then inserted into HEI cap. I only did 1-3-5-7 as there is minimal (none?) tapping/clicking coming from the passenger side cylinders.

I had the valve covers off. Outside temp was approx. 50 degrees F. A friend had a listening ear that I borrowed. See pics attached. I started the engine and there was some light ticking / tapping. Again, noise coming from driver's side. Just from standing beside engine it again seemed to come more from cylinders 1 and 3. I used the engine ear and the noise seemed to be coming from cylinders 1 and 3. The engine was still on fast idle around 1600 rpm. I had a vacumm gauge attached and the reading was pretty steady around 20-21. I used the test light and started grounding cylinders 1-3-5-7. I could see the spark jumping from the copper wires I had inserted into the HEI cap and the test light tip. It was hard to tell if RPM was dropping - though I could see the reading on vacuum gauge become more erratic. Shorting 1 and 3 seemed to lessen the tapping a bit - though I could still hear it.

After about 10 of the engine running - all of a sudden I started hearing a
more pronouced ticking / tapping and again it seemed to be from cyl 1 and cyl 3. The rpm was perhaps around 1000 at this point. I used the engine ear and it
definitely seemed that the intake on cylinder 1 was clacking. The intake on cylinder 3 seemed to clack - though not as loud as cyl 1. I was not sure if maybe I was just hearing the clacking on intake cyl 3 just because it is right beside cyl 1 intake. Cyl 5 and cyl 7 were making minimal noise and again almost no noise from pass side cylinders. This is video I recorded after around 12-14minutes of the engine idling.
https://youtu.be/uVaps9sGzlA?si=yUQRu9sXGKNX-Dd1

Shorting the 1-3-5-7 showed similar results. I would see the vacuum gauge become more erratic as each cylinder was shorted and tapping seemed to lessen a bit when shorting cyl 1 and cyl 3.

Strangely, after about 17-18 minutes of idling the tapping started to go away. This was video is where the tapping was getting less apparent
and showing the vacuum gauge reading - a bit under 20 and a bit erratic. See https://youtube.com/shorts/rNlBF5zRZ...CGHTGhmkAtI-st
Then, after maybe 20 minutes of idling, it was very hard to hear any tapping. The engine was now fully warm and idling around 750-800 rpm.

Note, to catch the oil splashing, I placed tin foil on top of exhaust manifolds beside the head and then placed some cloths on top of tin foil. I checked the rockers on all cylinders. The rockers on cyl 1 and 3 were maybe a tiny bit looser than other cylinders - but , all cylinders seem close to the same.

[pippintook]

Here are few pics of the engine ear. This device definitely helps to hear and isolate some engine noises.

Just to repeat - this is video I recorded after around 12-14minutes of the engine idling. https://youtu.be/uVaps9sGzlA?si=yUQRu9sXGKNX-Dd1
Tapping noise was still there.

This video is where the tapping was getting less apparent and showing the vacuum gauge reading - a bit under 20 and a bit erratic.
See https://www.youtube.com/shorts/rNlBF5zRZEA

[yellow1098]

I would also change the oil and inspect it for any metal …having a magnetic drain plug helps…ask me how I know

[steve25]

To confirm good , bad or going bad cam and lifters pull your valve covers , wipe the oil off of the tops of the push rods such that you can make a mark with white out on them.

Start the motor and look for the needed rotation of each push rod.
Every time a valve opens and closes the push rod should spin because the lifter spins.


If at any given rpm some of the push rods spin slower then the others or hardly at all, then you have a Lobe and or lifter going bad.

Nothing last forever, and once a certain level of ware takes place the self adjustment of a hydro lifter can no longer compensate, although you might find that the expansion of a warmed up motor might quite things down some.

[4dblnkldude]

The much-better method is to blunt the tips of eight small nails or pieces of wire, apply a touch of dielectric grease, and slide them between the plug wires and the boots at the distributor end. Point is, to NOT PUNCTURE the insulation--just go between the wire and the boot until you feel the nail contact the metal terminal of the plug wire. Then touch a grounded jumper wire, or grounded incandescent (NOT LED or neon) test-light to each nail in turn to short the spark to ground rather than create an open-circuit. Voltage drops to zero, which doesn't stress the insulation.

Photo attached of nails in a Chevy TBI application, Pontiac similar.[/QUOTE]

This is a great troubleshooting method, I never thought of it! I learned something today and its only 830 EST. It sounds like a rocker to me. Bring the engine up to cylinder #1 and #3 on the compression stroke and wiggle around for rocker looseness. The factory nuts do lose their holding ability. I am hoping you have an easy one here.

[steve25]

At TDC ( both valves closed) rocker arms that are ball mounted will always rock side to side some.