65silververt

This is not on my car, but my father's 66 427. It's a driver and while it smoked a little bit at start up and under hard acceleration, it ran really well until last week. however, that all changed last week. The engine has developed a loud clacking/ticking noise, which at first i thought was coming from the valvetrain, but after investigating the rockers, it actually appears to be coming from somewhere deeper inside the engine. There is also a loud squealing noise that is most audible at the rear underside of the engine. I told my father that I thought it was either the pilot bearing or one of the rear main bearings. Im not sure if the clacking/ticking noise is coming from exactly the same area or not, but it doesnt sound good.

I know in the video it sounds like the chatter is coming from the valvetrain, but all of the rockers are tight and i see nothing going on in the engine valley. The chatter is more audible on the passenger side of the engine.

I'm not sure if there is a way to embed the video. Click the picture and it will play the video in my photobucket album.
Thanks

Also, one other thing i noted is that not all of the rockers are getting the same amount of oil. Some spray, while others barely have oil dribbling out. This is the case on both sides of the engine. It also took around a minute for oil to even start pumping out of the rockers after initial start up. Pressure is around 60psi at start up, but drops to 20psi once oil is warm.

hedgehead

Good time for a fresh rebuild before it's too late.

Tampa Jerry

I am no expert by any means, but it sounds like a dead lifter or wiped cam lobe. In that light, it could be a pulled rocker stud or stripped adjustment nut. What type of lifters are in the motor? Jerry

65silververt

A rocker would be loose if it was a wiped lobe. Everything is fine in those regards. Valvetrain is totally intact and functioning correctly. I checked all rockers, studs, pushrods, etc.

I know it sounds like it is coming from the valves in the video, but it's not...it's deeper. When i put my ear to the oil pan while the car is running, i can hear the chatter, but it sounds more menacing, especially with the combination of the loud whine, which is not audible in the video.

OldKarz

I had the same sound in my 66 427. Pulled the engine and I had a bad piston. Currently at machine shop, I am going to rebuild with a roller. I decided to rebuild the muncie at the same time, finished with it yesterday. Now if I could only get the machine shop to hurry up.......

midyearvette

i hear nothing but rocker noise like one is too loose or other valve train issues
i don't hear anything deep inside the mill but tough to diagnose with this video
if it is piston slap, sometimes it will mask like valvetrain, also a bad valve guide will create extra lash too
i just don't hear anything that sounds like it's very deep, but again, hard to say with the video.....good luck....

Nitrodamus

The 427 in my 66 developed a sound similar to that and started to get smoke on the right bank. Pulled the engine and found a broken piston skirt and scored cylinder wall. Also discovered the previous owner had rebuilt the engine as a L-88. That was a surprise!

Westlotorn

I hear only a tapping that has the rythm of the rocker arm but the engine did not sound strong.
Any time your oil pressure drops from 60 cold to 20 hot you have internal leaks. If it has done this for a long time the engine may have been built loose. If it has been getting worse lately it may be the cam bearing mentioned in prior post or worn Main and Rod bearings.
The squealing mentioned I did not hear in your video but I have heard spun rod bearings squeal. The noise on your tape did not sound like a rod bearing though.
If a cam bearing has been wiped the lead cam bearing material may have blocked the oil hole in one cam journal giving you weak or no oil in that journal. Lead Tin cam bearings were the standard for years.
Does your oil pressure rise with RPM when Hot?

65silververt

Again, there are no loose rockers. I even went over all of them just to make sure that everything was adjusted correctly. When i put my ear down near the valves, the sound is coming from somewhere in the valley or below. I really thought the valvetrain would be to blame, but everything is adjusted properly, no slack or slop, no excessive adjustments required, etc.

Also, it has the really loud whine in the rear lower portion of the block, which started at the same time the clacking noise became present.

Yes, the pressure rises with RPM when hot.

Thanks for the replies.

INMYBLOOD

I agree with everyone else it' a valve train noise. My brothers 402 had a broken valve spring. It was very very hard to find. That tap is a loose adjustment, collapsed lifter or broken spring.

midyearvette

or....i hate to say it, a lobe going south....i listened again and maybe hear a faint sound of an errant exhaust valve, or spring, or lobe......

65silververt

1. Can't be a lobe failure or at least im almost 100 percent sure it had nothing to do with the lobes on the cam and this is why.
I went over the valves twice and readjusted them. If it were a lobe, that particular lifter would be adjusted down further on the rocker arm NOT to mention, the rocker arm would be loose and the cause of the chatter.

2. Again, Nothing is loose or requires more adjustment than any of the other valves/rocker nuts. I guess a broken spring would cause temporary looseness and chatter while being depressed?

3. There is a loud whine coming from the rear bottom of the engine. This whine started when the chatter started. It's either a main bearing or the pilot bearing. I think it is the pilot bearing because the clutch pedal rattles violently when i depress it.

thanks

JohnZ

With that symptom, it's more likely to be the throwout bearing.

Nitrodamus

With this latest symptom I'll go with JohnZ and the throwout bearing

65silververt

-Perhaps both concerning the whine and pedal chatter. The pedal chatter has always been present since he purchased the car 4 years ago, but the whine is new. The whine is constant, the pedal shake becomes very noticeable and worse when depressed.

-The chatter at the valvetrain or near the passenger valvetrain remains a mystery currently. The engine was running great before the chatter, but since the chatter began, it runs pretty rough at idle, which i agree, would indicate that it is something going on with the valves. Since none of the rockers are loose or require adjustment, i will take a close look at the springs as soon as i have a chance.

Anyway, due to the engine burning oil and given the array of different issues, i think its time for a rebuild. It burned a quart of oil in under 20 miles of driving.

Procrastination Racing

This is not burning it; it is pumping out straight out.

The roughness, the vibration, the noise all add to one thing - pull the engine out and apart.

I had a 350 that began using oil about a quart every 100 miles roughly. I didn't have much choice about driving it, as I was pulling a trailer from Florida to Chicago at the time and a very pregnant wife. When I got to Chicago and pulled the engine, the block was ruined as it had two cylinders with grooves an eighth inch deep in them from broken rings and ring landings.

Granted if it had been a rare original engine in a Corvette I could have sleeved it, but a plain 350 in a Suburban just meant new engine.

Don't wait.

street62

It is not a rod or maine bearing. If the oil presure is ok and there is no loose rockers, check the fuel pump, the fuel pump rod rides on its own lobe just like the lifters. It could also be a stuck lifter from varnish on the lifter. If a lobe was wiped out you would not have full lift at the valve.

Mr D.

You say burned, unless there is evidance the engine leaked a quart of oil in 20 miles you have no choice but to pull this engine and tear it down.

Railroadman

You have been given a whole bunch of "it might be..." here and about 80% of them would involve a teardown anyway. I vote go for it, you may catch something which is getting ready to grenade, and will gain the peach of mind that things are right once it's all done.

65silververt

It's not my car, so i just went by what my father said on the oil before and after measurements. I dont see any major leaks and it certainly does not appear to be burning enough oil to factor in 1 quart per 20 miles. I should have thought about that statement before posting it...i would think that the car would be like a smoke machine if it were burning that much oil. However, it does blow out a good amount at start up, it smells like burning oil while running, and it definitely puts out a nice plume of smoke under acceleration.

I wont have time to help him pull the engine until next month, so unfortunately, the car will be hanging out on his lift until then. However, i will post back as soon as i have a chance to start pulling it apart.
Thanks again for all the replies!