Help with diagnosis

[jstaples2]

Hi all -
I need some help troubleshooting a new engine noise. A couple days back during a drive I noticed the engine was surging a bit while at a stoplight and idling really rough. Up until then the engine ran like a top.

Tonight I head out to take her for a drive and I decided to check the plug wires before getting started. One plug wire at the dist. was a bit loose and I got it seated back down firmly. I started the car up and she went back to idling really rough. I figure it would warm up, but I noticed there was a new sound coming from the passenger side.

It sounded like a typewriter - taka-taka-taka-taka. Not loud, but noticeable. Nothing on the driver side. I pulled the throttle back a bit and the chatter seemed to go away, but returned at idle. I shut things off and was about to pull the valve cover - but thought I'd check in with the resident experts before doing so.

Thoughts?

Edit:
It's a 383 motor, never been rebuilt to my knowledge, stock heads, valve-train.

 

[oldcigarette]

I'm not an expert by any means but surging sounds more like a carburetor problem to me. A little bit of valve train noise is pretty normal, are you sure it's a new thing?

 

[commando1]

taka-taka-taka-taka.

Valve train clatter.
Starting with...
a. wiped cam lobe(s), then
b. collapsed lifter(s), then
c. bent pushrod(s), then
d. broken valve, valve spring, a/o valve spring retainer, then
e. broken rocker arm.
That all comes after you take a stethoscope to see where the

taka-taka-taka

is coming from, hopefully from an exhaust manifold leak, but not likely since you said it runs like crap.

 

[sczuylevch]

i'd put a timing light on it and see, a couple weeks ago i was on some really bumpy roads, one minute the car is fine next minute it ran like crap. went home checked all the plugs they were perfect, checked the timing had retarded itself to 10 atdc. ran great after i reset that. guess i didnt have the holdown tight enough. trust me it wasnt loose. Hope its something easy good luck!

 

[detmatt]

Vacuum leak maybe? I'd give the engine room a once over to make sure it's nothing obvious. Fuel flow maybe? Check filter, the ethanol in today's fuel reaps havoc on rubber hoses and steel lines and can cause a gelatinous gunk to build up in the carbs fuel bowl(s). I have 2 engines with fresh valve trains and neither of them are perfectly quiet but if you think you have a lifter collapse then you better go in for a closer look. How's your oil pressure?

 

[jstaples2]

I went out this morning and saw I was about a quart low, so I added a quart of oil, changed the fuel filter, rechecked the plug wire connections, vacuum hoses.

I fired it up and it idled a bit rough through warm up, but the noise was almost gone. Once it was warm I checked the timing, bumped up the curb idle and things smoothed out.

Oil pressure: 25 at idle, ~50 WOT

I can still hear the noise a bit, but am thinking it might be the alternator. Hard to tell, but I went out and got a stethoscope. I'll try it out later tonight once it cools off out here. I wouldn't notice it if I didn't know what the engine sounded like before.

I've been thinking the alt may be dying on me for a couple months now. I can't seem to idle with headlights, ac, radio, brake lights all at the same time. The draw dims the headlights and will kill the radio. Since I don't drive much at night I don't ever have the headlights/ac on and draw that much juice. I'm hoping the issue here is a dying alt and not the valve train. I'll try out the stethoscope tonight.

 

[MYSINBIN]

I went out this morning and saw I was about a quart low, so I added a quart of oil, changed the fuel filter, rechecked the plug wire connections, vacuum hoses.

I fired it up and it idled a bit rough through warm up, but the noise was almost gone. Once it was warm I checked the timing, bumped up the curb idle and things smoothed out.

Oil pressure: 25 at idle, ~50 WOT

I can still hear the noise a bit, but am thinking it might be the alternator. Hard to tell, but I went out and got a stethoscope. I'll try it out later tonight once it cools off out here. I wouldn't notice it if I didn't know what the engine sounded like before.

I've been thinking the alt may be dying on me for a couple months now. I can't seem to idle with headlights, ac, radio, brake lights all at the same time. The draw dims the headlights and will kill the radio. Since I don't drive much at night I don't ever have the headlights/ac on and draw that much juice. I'm hoping the issue here is a dying alt and not the valve train. I'll try out the stethoscope tonight.

Start with the simple things: Is the belt tight enough?

Check the alternator output with a meter.

And then there is the smart *** answer that my friend gives me for mechanical issues:

"You could wash it"

John

 

[jct]

voltage regulator?

 

[tbm3fan]

Valve train clatter.
Starting with...
a. wiped cam lobe(s), then
b. collapsed lifter(s), then
c. bent pushrod(s), then
d. broken valve, valve spring, a/o valve spring retainer, then
e. broken rocker arm.
That all comes after you take a stethoscope to see where the
is coming from, hopefully from an exhaust manifold leak, but not likely since you said it runs like crap.

My wife's Sable has a very loud slap sound in her car. Definitely from the lifter valley and probably a collapsed lifter for whatever reason. Ready to open it up and replace. Tried to clear it out while running the oil with some Marvel's but didn't work. However, the engine itself runs very smoothly despite that.

 

[Dobalovr]

My wife's Sable has a very loud slap sound in her car.

My wife's van has the same sound but I traced it to her hand striking my head every-time I smiled at the pretty girl in the drivethru....the noise went away fairly quickly...

 

[65sporty]

i'd put a timing light on it and see, a couple weeks ago i was on some really bumpy roads, one minute the car is fine next minute it ran like crap. went home checked all the plugs they were perfect, checked the timing had retarded itself to 10 atdc. ran great after i reset that. guess i didnt have the holdown tight enough. trust me it wasnt loose. Hope its something easy good luck!

Sczuylevch it sounds like your timing chain jumped a tooth, have you ever changed the timing chain and gears? The factory timing gear is a aluminum gear with nylon covered teeth when they get old they get brittle and will strip off.

 

[detmatt]

My wife's van has the same sound but I traced it to her hand striking my head every-time I smiled at the pretty girl in the drivethru....the noise went away fairly quickly...

Lmfao!

 

[70bigblockdodge]

My wife's van has the same sound but I traced it to her hand striking my head every-time I smiled at the pretty girl in the drivethru....the noise went away fairly quickly...

I hate that noise.

 

[jstaples2]

voltage regulator?

So I ended up taking the fury down to advance auto and the guy hooked it up to some tool and told me the voltage regulator was shot. I pulled the old one off thinking if it was original maybe I could clean the points and get back on the road. Once I opened it up, I discovered it was an electric/solid state unit. So.... I ordered a replacement from RockAuto and it came in today. I cleaned all the connection points, hooked it up and still have the ammeter bouncing all over and can't get lights/ac/radio to all run at the same time. The ammeter drops way down and the radio cuts out, lights dim, etc.

It looks like it's the A/C that is the big draw on voltage. I was hoping this group might have a suggestion? Alternator? Back to Auto store for another reading?

Did it work before?
Yes, less than a month ago I was cruising regularly with lights, radio, A/C. Headlights dimmed a little at the stoplights, but everything seemed fine.

What have you done recently?
I swapped out my old 7mm spark plug wires for new 8mm ones.
Bought a brand new battery
replaced voltage regulator

 

[65sporty]

Sounds like your alternator can't keep up at idle. Works ok at cruise speed? You need to check the voltage output at idle. Most old alternators were only about 50 amp max and only charged about 10 amp at idle. They are not like modern alternators that put out 40amp at idle.

 

[70bigblockdodge]

If it is pulsing I would bet the diodes or rectifier are crapping out.

 

[jstaples2]

Ok, yep things work fine when driving, but it's at idle when the voltage drops. So, it sounds like a new or rebuild might be in order.

 

[65sporty]

Is yours a single or dual field alternator?

 

[Zwap]

Is yours a single or dual field alternator?

With that voltage regulator on the picture it's the "single output" alternator (actually both the single and dual output alternators are single field alternators).

 

[70bigblockdodge]

If by sending chance it is a dual field alt check the grounded brush for a good /consistent ground