Went to start up my '76 today and while it was idling I was revving the engine since it sounded like it was bogging a little. After a few revs I now hear this loud knocking coming from the engine when it runs. Car has oil in it and no fluids are pouring out of the car or anything like that, the engine just knocks really bad. What happened and how can I fix this?

Plugs and wires maybe?

If it sounds like a metal knock or tic that gets faster as you rev the engine......
I know how mad you get when the cars arent going right so I dont want to tell you any bad news. If its just a lifter, you may be able to get away with some fresh oil and some additive. Another thing you can look at is the flywheel, when it comes loose or cracks it makes a simular sound. The flywheel is a long shot but it happened to me on a caprice. An automotive stethoscope would be a big help.

If it sounds like a metal knock or tic that gets faster as you rev the engine......
I know how mad you get when the cars arent going right so I dont want to tell you any bad news. If its just a lifter, you may be able to get away with some fresh oil and some additive. Another thing you can look at is the flywheel, when it comes loose or cracks it makes a simular sound. The flywheel is a long shot but it happened to me on a caprice. An automotive stethoscope would be a big help.

It's a knocking sound that matches the speed of the engine, I guess it sounds like metal. Whatever it is I just wanna know. I wasn't even revving it that hard, just a few shots of the accelerator to stretch it's limbs so to speak.....

Worst case scenerio, its a bearings or a lifter. Either way the motor will have to be opened up. Lifters are not that hard but a bearing is a decent amount of work.

I did that once to an engine once - the ticking got worse and worse - ended up I had spun a connecting rod bearing

If it was a bearing that's on it's way out, wouldn't he have low oil pressure? Might that be a way to identify what it is? I hope it's nothing too serious, I really like that '76 of yours.

He'd still have oil pressure unless maybe the bearing material spun down into a main oil passage and clogged it but I've never seen that before.

racing a cold engine can and does cause lifter "hangup"
Im not sure id call that a knock, more of a clacking sound
which will normally go away after a mile or so of driving

if its a loud wrapping noise, that would make me think connecting rod big end

racing a cold engine can and does cause lifter "hangup"
Im not sure id call that a knock, more of a clacking sound
which will normally go away after a mile or so of driving

I've been wondering what that damn clicking noise is for the first minute or two after a cold start...Thanks :)

Is that something I should worry about?

My 472 was tapping really bad after a recent unrelated issue. It sat for a week or two prior to me starting it and the tap worked itself out after about 5 minutes or so of idling. How long did you have it running for? Chances are, if you haven't been driving it and you didn't do anything to harm it, it's probably nothing. Try some tranny fluid down the primaries when it's idling high, that should cure a carbon knock.

I've been wondering what that damn clicking noise is for the first minute or two after a cold start...Thanks

Is that something I should worry about?

No, mine does that, the oil just hasn't worked its way everywhere yet.

Lifter tick is a lot different than rod knock. No possible way to confuse the two.

Thanks everyone. Car's been sitting since this afternoon so what I'll do is do an oil change this weekend and start it up again. The car does do a lot of sitting so it might just be something that's stuck or hung up. For the time being I'll leave it alone and maybe it'll free itself up, if not it looks like I may be taking an engine apart at some point.... :(

Dope, before you do an oil change on the old beast, go to BGfindashop.com, type in your zip code, and when you find the nearest retailer, have them sell you a can of 105 (BG Quick Clean For Engines) and add that to the old oil and run it for 15 minutes and change the oil. What 105 does is eat away at the deposits that build up on lifters & rocker arms and washes it away with the oil. If you do this and the noise goes away, then it's just a noisy lifter or rocker arm. If not, then it's something more serious. Either way, a can of 105 runs about $7.00, so it's cheap insurance.

105 is described in further detail here:
http://www.bgprod.com/products/engineoil.html

Here's BG find-a-shop.
http://www.bgfindashop.com/locator/index.php


Let us know what happens!

Engine noises can be the hardest to diagnose, mainly because there are some many things that make similar sounds, but also because people have different way of describing the sound.

Rod Knock: Occurs when either the wrist pin bearing or the rod main bearing deteriorates to a point that it allows the piston to move in the cylinder bore (small end knock: commonly referred to as piston slap) or the end of the connecting rod to bang around on the crank shaft journal (big end knock: most common and is terminal). Rod Knock is most noticeable over 2500 RPM, but feathering the gas will cause a distinctive back rattle between 2500-3500 RPM.

http://www.youtube.com/watch?v=x9LJP1mw0es

Valve Train Noise: Gets louder with an increase in RPM, and is caused by Low Oil Pressure, Excessive Valve Lash, or Damaged Parts. If the noise goes away after the engine warms up, it could suggest a sticking lifter.

http://www.youtube.com/watch?v=48KGzC9RS5U

Good vid references. I will say that the rod knock that I have experienced is a deeper tone than that. Would probably have to do with the V configuration and much more block material than the boxer engine in the Subie...

Well, heck, Dope, November doesn't seem to be your month! Here's hoping things are just sticking a little from the car sitting so much. I'd really hate to see major engine work needed. Let us know what happens.

It sounds like the rod knock video...... :(

It sounds like the rod knock video......

That sucks dude, I feel for ya. Sounds like you may get to experience the joy of pulling and rebuilding an engine...

Well considering I can't drive it anywhere or tow it, I'm kinda screwed here. How hard is it to do something like this?

You can drive it to a garage. It may or may not seize up on the way.

If it were me, I would do the following. Pour in a quart of trans fluid. Run the engine, get it up to temp. If it is a sticking lifter, the trans fluid will free it up. If you have wiped a lobe off the cam, the tick will still be there. If it is rod knock, the noise will be there. Turn the engine off, jack it up, and drain your oil. Carefully examine the oil for metal particles or a "silver-y" sheen. This will be the remains of the soft bearing material. Remove the oil filter and let it drain. Cut it open, and unfold the filter material. Look for metal particles. If you find metal in the oil and/or filter, you have lost a bearing, and the engine will need a tear down. You can pull the pan (have to remove the engine mount bolts and jack up the engine a few inches) and check the rods on the crank. If you have wiped or spun a bearing, the rod will be loose on the crank. Engine must come out, crank must be turned, and new bearings go in.

http://i6.photobucket.com/albums/y250/DopeStar156/th_knock.jpg (http://s6.photobucket.com/albums/y250/DopeStar156/?action=view&current=knock.flv)

That sounds like exhaust leak, not knocking. I know, the audio is bad, and I'm sure it is much easier to tell in person...

It has that already hahahaha. It'd be awesome if that's all it is but I dunno.

I agree with Jay, it sounds a lot like exhaust. My '80 was without manifold gaskets and it sounded quite similar. It's tough to really tell with the video though...you may be lucky yet :)

You know what it really reminds me of?

Speed Buggy.

YouTube- speed buggy intro

Dope, engine knock on a cast iron V8 sounds like a 5lb sledghammer hitting a manhole cover. Does that make sense? It is really deep, no echo, low frequency.

that almost sounds to fast to be a bearing.

I agree, it sounds too high to be a main bearing. It does sound right to be piston slap, which isn't harmful to the engine, just really annoying. If you hear what sounds like a double tap when you feather the gas, then piston slap is the problem. Also if the noise goes away when the engine warms up, it be a sign of piston slap, because as the metal expands with the heat, the piston fits the bore better.

This is what low end rod knock sounds like on a real engine (be patient it'll eventually start):

http://www.youtube.com/watch?v=FksrdMc3lZU

So you think I blew a manifold gasket or something? How can I really be sure? I'll change the oil this weekend and let it run for a while and see if it straightens out. God i hope so, I don't have the heart to dump this car.....

Your '76 engine sounds more like a chuffing noise than a metallic clanking ... leastways to me. The rod knock sounds hideous, not at all like the muffled hiccup from your '76:Playdrv4me:

From the video you posted, Dope, it sounds like a manifold leak. The 425 in my '77 had a complete meltdown, and it sounded waaaaayyyyyy worse than that. I think Old Blue will live another day.

Have you felt to see if all the manifold bolt heads are still there? I bet there is at least one missing at the back...

From the video you posted, Dope, it sounds like a manifold leak. The 425 in my '77 had a complete meltdown, and it sounded waaaaayyyyyy worse than that. I think Old Blue will live another day.
I hope so, can't bring myself to send the monster to his death..... :( You really think I blew out the exhaust by revving in park? I know the 500 is a monster but...... wow....

Have you felt to see if all the manifold bolt heads are still there? I bet there is at least one missing at the back...
I'll have to check tomorrow. My first day off in 6 days.... ugh....

You'd be surprised how much backpressure these cars have because of their emissions-strangled exhaust. It's also much more noticable in cold weather, and NJ isn't exactly a bikini paradise this time of year. And let's face it, the car is, how shall we say, well used.

Took a new video today, maybe the sound quality on this one is better.
http://i6.photobucket.com/albums/y250/DopeStar156/th_knock2.jpg (http://s6.photobucket.com/albums/y250/DopeStar156/?action=view&current=knock2.flv)

I noticed by feel that the vibrations are worst if I place my hand in top of the air cleaner and not the valve covers. My dad thinks I might have threw a rod.....

That ain't no exhaust leak dude. It doesn't sound like lower end knocking to me either. I would say it is a valve train issue. I would pull the valve covers and see if everything is working normally. I hope you can save her.

I'm with Al on this one, maybe one of the rocker Ts snapped. Did you get the automotive stethoscope yet, you will be able to hear which side is bad before removing the valve covers. But like Al said, I have never heard a bearing knock that sounded like that.

Makes a lotta sence. I was racing it cold and the valves are pretty dry when the thing first fires up. Not to mention I checked the dipstick yesterday and it was down a quart of oil.....

FML..... Hopefully I can fix this myself....

Definitely something to do with the top end, not an exhaust leak. As you seem to have a lot of room where you live, this will be the perfect opportunity to learn how to do a top-end rebuild. Remember, the goal was to restore the car slowly, over time, as a hobby. There's no deadline here, it's not your DD, you have all the time in the world to work this out and fix it at your leisure. It's a nice feeling, if you stop to think about it. ;)

I do have a complete rocker setup off a 425 that is the same. Maybe someone should chime in just to reassure that the rocker assemblies are the same.

Definitely something to do with the top end, not an exhaust leak. As you seem to have a lot of room where you live, this will be the perfect opportunity to learn how to do a top-end rebuild. Remember, the goal was to restore the car slowly, over time, as a hobby. There's no deadline here, it's not your DD, you have all the time in the world to work this out and fix it at your leisure. It's a nice feeling, if you stop to think about it. ;)

No, you're right. Sometimes I forget this and I look to get the thing up and running too quickly. My concern at this point is the fuel lines freezing from a long sit if that's what happens. A friend of mine has offered to come over and help me with diagnosis and if I gotta do it, I've got my shop manual so, shouldn't be too hard. I hear the 500 is an easy engine to work with......

If you're worried about the fuel lines, just drain the gas and put her up on blocks for the winter. Obviously, you can't drive her in this condition, so you could pull the engine, put it on an engine stand in your nice, warm garage, and work on it at will. I'll give you something to do over the long, cold NJ winter.

Well I've got some news about the situation. My friend came over with the automotive stethoscope, and this is what we heard from my '76 DeVille....

"**** that. I ain't goin' down that easy......."

The repping came from the valve cover on the driver's side. We poured a bit of Dex/Merc tranny fluid down the intake while the monster was running. We then fed it gas and watched the smoke show as the rapping dound disappeared. My friend made some much needed choke adjustments and the monster runs just as well as it used to minus the bogging that was present before. I owe a ton of graditude to my friend for comin' out to my place and ressurecting my vicious monster. I'm ashamed for thinking my 500 was that easy to kill, however I'll be sure to be more careful with revving in the future.....

Still, while we were loading the engine to clear the carbon and Dex/Merc, the roar from under the hood was the most beautiful sound I've ever heard, I love my big block V8.....

Here's some pics of my driveway tonight after we were all done. My newly revived '76 DeVille, my friend's '78 DeVille, and of course my '05 STS.....

http://i6.photobucket.com/albums/y250/DopeStar156/PB120117.jpg
http://i6.photobucket.com/albums/y250/DopeStar156/PB120118.jpg
http://i6.photobucket.com/albums/y250/DopeStar156/PB120119.jpg

Glad to hear that the Glorious Blue Tank of yours is fine and up and running again. It's always a worry when they start making noise, but I've heard that the Caddy big-blocks are hard to kill. Can't get enough of your DeVille, Dopestar!

Happy to hear some good news, glad to know that the Blue Giant is well & kicking! :-)

Me too. I think I'm gonna take this as a lesson in not letting the thing sit for massive amounts of time. I need to get this thing on the road.....

You've made my day, Dope! :) So it turned out to be a sticking valve lifter or some such? Hell, probably good for another 200K! Now get her registered and drive that mother!

Wish I could! Insurance is my problem right now, last time I tried Hagerty turned me down......

Try JC Taylor. They insure my two older Cads.

I just use progressive... :S

I'll have to look into JC Taylor, ultimately I'd like to take the Fleetwood off my regular insurance and have both cars insured with collector companies, but have the DeVille wear the Historic plates, then leave the STS on with 21st Century. Should end up being cheaper overall. I'll prolly wait until March to get this rolling since I'll be 24, and I'm sure a few scratches on my record will disappear by then. Don't see much of a point insuring a car so close to the winter when I wouldn't be driving it anyway. For now I'll just try not to let it sit around for weeks on end like that and make sure it gets a good gallop around the block every so often. I'm gonna get some Stabil and pour it in the tank, then fill the tank up about halfway. I usually leave it a little under a quarter of a tank so I can consume it before it has a chance to turn........

Adding Stabil is a good idea if you're not planning on running the car enough to use a tank of gas in about a month. However, I'd fill 'er up all the way to avoid condensation build-up in the tank and lines, which can damage the tank, lines, and gas.

Well I added more gas to the tank today, ran the engine with half a quart of transmission fluid in the oil, then dumped and changed the oil. My engine is officially de-gunked. Fresh 10 W 40, Lucas, and a filter and the engine is running happy. I'm gonna go grab a bottle of Stabil today and dump it in the gas. Thanks for the advice and love guys......

tranny fluid in the oil? does that help clean it out or something? I've never heard of that

tranny fluid in the oil? does that help clean it out or something? I've never heard of that

Transmission fluid is exactly the same as motor oil, except it has tons of additives, because of its long term use. The additives give the fluid great cleaning properties and putting small amounts into your crankcase will clean out the sludge. You can run a 1/2 quart of ATF in the crank case for the entire oil change cycle, but most people change the oil and filter after 500 miles because the sludge can can cause blockages and clogs in the filter.

Transmission fluid is exactly the same as motor oil, except it has tons of additives, because of its long term use. The additives give the fluid great cleaning properties and putting small amounts into your crankcase will clean out the sludge. You can run a 1/2 quart of ATF in the crank case for the entire oil change cycle, but most people change the oil and filter after 500 miles because the sludge can can cause blockages and clogs in the filter.

good to know man, thanks for the info. I'll definitely give that a try.

Transmission fluid is exactly the same as motor oil, except it has tons of additives, because of its long term use. The additives give the fluid great cleaning properties and putting small amounts into your crankcase will clean out the sludge. You can run a 1/2 quart of ATF in the crank case for the entire oil change cycle, but most people change the oil and filter after 500 miles because the sludge can can cause blockages and clogs in the filter.

Yep.... Car runs like a champ now.....

Just like people....the right diet and plenty of exercise can do wonders!