Hello, i have 1966 chevelle 327 single 4 barrel, motor was rebuilt 3/4 years ago by a professional machine shop. It only has maybe 300 miles around town. I pulled it out of shop this week andit started miss firing kicking back and stopped running. After checking spark, fire ,distributor I heard something rattling when I cranked it over ?? I PULLED VALVE COVER AND A PIECE OF PUSH ROD WAS LAYING NEXT TO A BENT AND STUCK OPEN EXCAUST VALVE. then I pulled manifold and lifter was laying in valley not damaged . Does anyone have any Ideas what could have happened . MOTOR WAS NEVER RUN HARD OR OVER REVED , NEVER MADE ANY NOISE AND ALWAYES RAN FINE, I WOULD APPRECIATE YOUR THOGHTS ,MIKE
Guess 1 1 Valve stuck open 2. Piston bent valve 3 loose pushrod got jammed 4 cam spit lifter out of bore Guess 2 1Retainer let loose or spring broke 2 valve dropped and got bent 3 piston pushed bent valve 4 loose push rod and lifter got ejeccted Guess 3 Someone fed or didn’t feed gizmo and the damn gremlins got all pissed off and tore your shit up Guess 4 Will be as good as any
Like Squirrel said, guesses is all you'll get. Pull the head and have a look. My first thought is a dropped seat if the spring is still attached to the valve.
Sounds like maybe a lack of oil to the valves, or at least that one. Seized, bent and broke the pushrod. But as noted above, without seeing all the details, including the valve stem, it's impossible to tell definitively from a few thousand miles away. Mike
How old is the gas? Old gas will burn but when it cool causes the valves to stick like molasses. Ask me how I know. Sent from my LG-K550 using The H.A.M.B. mobile app
Press in rocker studs? Could have pulled out, loosening up everything on that valve. Sent from my SM-G965U using The H.A.M.B. mobile app
Had a perfectly running 235 neighbor had a 280z with old gas he drained it said he didn't know what to do with it I dumped it in my old truck ran ok stunk a little next day started it and 2 valves stuck and push rods came out from under rocker sprayed it down with marvel unstuck it drained the gas ran the clean gas through it never happened again. Happened on another car of mine. Sent from my LG-K550 using The H.A.M.B. mobile app
I'm thinking that is what you will find. Bad gas leaves hard carbon around the exhaust valve that makes them stick.
Check the valve height with others. If it's low, smack the top of the valve stem a few times with a soft hammer and see if it changes height. If it comes up, it's probably sticking. If it is driven lower and sticks, squirt some penetrant on the stem through the plug hole and smack it some more to see if it will free up. It may not be bent.....guesses.
I HADN'T THOUGHT ABOUT VALVE STICKING I JUST FIGURED SINCE IT WAS DOWN LOWER THAN THE OTHERS IT WOULD HAVE TO HAVE GOTTEN BENT, I TOOK AS BRASS PUNCH AND TAPPED IT TO SEE IF WOULD COME LOSE BUT IT JUST KEPT GOING FURTHER OPEN . SINCE FOR THE LAST FEW YEARS I HAVE BEEN MOVING IT IN OUT OF GARAGE WITH OLD GAS PUTTING SOME NEW FROM TIME TO TIME that MIGHT HAVE CAUSED THE CARBON BUILD UP. I GUESS THE ONLY WAY TO CLEAN IT WOULD BE TO PULL THE HEAD. THANKS,MIKE
Before pulling the head, MMO or Deep Creep/ Sea Foam is your friend. Get some and try to get it on the stem. It will work on the carbon that is causing the issue. Spray, spray, spray, smack, smack, smack. It may free up. Put a cup or two of MMO in the fuel tank and run it to help clean things up with the rest of the valves.
Intetesting..and scary, got a lot of engines sitting. Wonder how old is old, or if stabilzer helps. Their ad department should be all over that.
I've noticed I can get away with 3 -4 months before it smells sour I have several I leave the gas low and burn it down low and put fresh in on top. I also dump marvel in the gas. Sent from my LG-K550 using The H.A.M.B. mobile app
Pull the head. while your at it have a look at the timing chain and gears maybe? Sounds like it had a tight guide possibly. Better have a look at the rest of them too. JMO Lippy
Corrosion in the valve guides. We had a similar problem in brand new engines. They were all run on a test stand at the end of the assembly line. Procedure was to mount them to the test stand, fill with coolant, do three snap accells against an inertia weight to calculate horsepower, remove, and ship to the vehicle assembly plant, install in the chassis, and drive to the transport. The transport would drop the chassis at the body builder where they would sit until the body was scheduled, maybe three or more months. Total run time prior to storage was less than an hour, I would estimate. Upon startup there was a rash of stuck exhaust valves that ended up being caused by micro corrosion of the guide, seizing the flash chromed valve stem. Fixed the issue by going to a chromed and polished valve stem, which had a much smoother surface finish, so there were no irregularities in the stem for the rust to fill and seize the stem. The kicker is that tho problem only appeared after we changed the piston ring pack to clean up an oil consumption problem. The old ring pack passed so much oil on initial run in that the stems were wet enough to prevent the guide corrosion problem on engines that went into storage at the body builders.
I had a fresh SBC in a motor home. It ran good for 6 months or so. New bronze guides, bigger SS valves, new seals, piston, rings, bearings, etc. Ran hard one day in the heat. Pulled in a rest area that night and when I woke up in the morning and fired her up, a couple of exh valves were stuck. Of course, it popped the rockers off and bent the push rods on 2 valves. I pulled the bent push rods and limped to a fairgrounds near by and pulled the heads. The machine shop guy said the valve guides were a little too tight and when shut off hot, they had crushed and gripped the valve stems. Honed them all out, replaced the 2 valves and we were good to go! We had it running again in 2 days. Looser is better!
not to get off track, but i get free gas from a friend who owns several marinas. they have to drain the tanks when going in for service. i get about 2 55 gallon drums per summer, and run the shit in my old cars. think about it, many reasons for a boat to go in for service. some have sunk, some have been sitting for years, some 2cycle, it all goes in the same drum, and i love it. i do not run it in my modern fuel injected stuff, but the old cars burn it up just fine, no side effects what so ever, been doing it for 10 years. now, good luck with your broken valve
Now I'm wondering..we have a 1966 International fire truck that doesn't get driven a whole lot, gets a gas fill up about once a year. Sometimes when started it has what I have always thought was a bled down lifter, but maybe it's a sticky exhaust valve. Not a low mileage engine though. Sometimes it takes a minute then suddenly all quiet.
Todays gas....It's a crap shoot when starting up our old cars after they have sat for weeks/months. 2 engines I know of : ...Intakes... One a sbc in a 40 Ford not ran for a winter, took it out for summer, running OK got on it a bit to clean it out and bent a pushrod pulled the rocker stud. Upon pulling the head, found the intake valve stuck hard with a snot yellow parafin like substance clinging to the stem. Had to drive the valves out of the guides. Other engine was a 235 6 cyl that had the same issue and broke the rocker arm. Pulled head stuck valve. Oh..also a 223 Ford...bent the pushrods but the guy sold the car as is and never investigated it..
OK I soaked valve and it wouldn't budge , so I pulled head and there was a small spot on piston were valve hit it. The valve would not push out so I I had to cut stem off to get it out . So I wouldn't damage guide. There is a lot of carbon on stem so I guess I should pull other head and clean them both up ?
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