The Stovebolt Site Forums The Shop Area Engine Shop The saga continues ( rockers)

Well guys' I broke another rocker arm. Intake again. Thats #4. About 20-40 miles and they give up. Valve is free. Hyd lifter is working and oil to the head. I'm stumped. This time it was #6 intake. Again. That should tell me something. God I hate to pull the head.

Glenn,

What type engine? Year? Factory rockers? Conditions under which rocker broke? Sounds like no oil getting to shaft and rocker seizing to shaft.

Glenn,

I just saw this post. I had to do some backtracking to figure out that this is a continuation of the "Sticking Valves" story.

You say it was #6...again, so this means it was a brand new rocker arm. This is very interesting, and bizarre!

Maybe someone will tell us if there is any chance for a intake valve to contact a piston top with a stock engine/cam setup.

Do all the valve springs appear to be stock, ie, single springs, not inner/outer hot rod stuff.

Does the truck run great right up until the rocker pops, or does it start to run differently, then drops the cylinder.

The only components in the equation are the cam, lifters, pushrods and rocker arms...seems pretty simple. If the cam starts to move the valve train and the valve refuses to move, something must let go! How could the valve refuse to move occasionally?

As my dear old cousin would say, "it'll develop". :confused:

Stuart

Just a thought, do you know if the engine had been apart before you aquired it? Maybe the head has been milled, if it was milled too much, or in conjuction with a milled block, the valve could be hitting the piston. Unfortunatly, you'll have to pull the head to find out.

would it have anything to with an incorrect gasket,, like one to thick............

Glenn,

I just can't help but think any valve to piston contact would bend the valve before it would break a rocker arm. Once the valve stem was bent, it would not "self heal" and you would sure as heck know it.

I have been on another forum where they talk a lot about guides that are varnished up...old gas and long term storage. I have never put much faith in the "varnish stories" I have heard.

Stuart

I'd invest the $30 +/- dollars in gaskets to pull the head and have a look at the piston, valve and valve guides. A set of valve guides and seals isn't that expensive. It sounds like either you've got a problem inside the head with the guides or the valve, or the valve is hitting the piston. If its hitting the piston, you should notice it.

In your other post you mentioned that the engine runs fine until the rocker breaks. Is it all old ones breaking and the new ones are doing fine? If that is the case I'd say metal fatigue is still a possible candidate and you should replace anything you havn't replaced yet.

Another thought, how does the shaft the rockers ride on look? Any chance the rocker is seizing to the shaft when it heats up and then breaking?

im begginning to wonder if you have something loose floatin around in the intake manifold, bouncing around and sticking under a valve, holdin the valve open piston hittin and bustin rockers? sounds like it would destroy a valve or piston first but maybe not... guess its a possiblility....stranger things have happened...about the only other possiblilty is the cam timing off a tooth or two... it could still run great untill certain rpm...

I had a 289 Ford once, fresh rebuild, new rockers from NAPA. They kept breaking one by one,no rhyme nor reason- finally pulled all of them & parts man re-ordered another set, never had another problem. Bad batch of rockers I guess,,brian

Are you valve springs directional, some springs are wound tighter at one end and I think that end must go down. If it is backward the spring will surely break.

Oh s$#t you did say rocker arm not spring.
NEVERMIND!!!!!

Are you getting plenty of oil to the rockers ? I still think your rocker shafts and oiling may be the link . I have some old 216 rockers if you need them.You pay for shipping and you can have them.I think one may be missing to the set.I hate for you to keep buying rockers and have them break.Seems like if the valve was hitting the piston,it would bend the valve and break the piston top.

What about coil bind of the springs? Or interference with valve stem seal? I would think that pushrods would bend first. What about rocker tip to valvestem alignment. I guess if it was off to one side, it may try to twist rocker end? Where are they breaking?

Glenn,

As far as noise, when you reassemble the lifters make sure the oil feed hole in the body and plunger aligned. The manual says to insert a suitable pin through both holes, fill assembly with oil and install pushrod seat and spring retainer. Press down on seat, remove pin and your ready to install.

Also I would pull the side cover, remove the spark plugs and turn the engine by hand and watch the lifters go up and down. I would then line the ball up at #1 TDC, watching #1 lifters to make sure they are on the base circle of the camshaft(both valves closed). At this point the push rod seat(plunger cap) on the lifter should be almost touching the lock clip at the top of the lifter. This is 0 lash + 1/4 turn. At 0 lash it would be touching the clip, at 0 lash + 1 1/4 turn it would be in the center of the lifter.

Also, is your block casting # 3835692 and your head # 3835908.

- Tom

Guys' I'm checking all these other points you have brought up. The springs do appear to be stock. The engine runs normal right up until one breaks. There is no indication that something is going to happen. No popping, backfireing or sluggish operation. The pushrods aren't bending. The valve train is real wet from oil. I've been told to remove guide seals. What do you think? OIlrag I'll take you up on your generous offer. I have the side cover off and am going to rebuild the lifters also. As much as I hate to, I think I'll end up pulling the head. Also OIlrag the eng is a 51 235 w/powerglide from a car that is now coupled to a man 3 speed. Block # 3692703, head 3835499, manifold 3835590.

Glenn,

dude buy higher quality rockers

Hey GEC52, You mentioned its #6 again, have any other ones broken? If it is only #6 here is a theory I have come to. The valve stem or the guide is either burred or slightly deformed or bent. What happens is that the valve will turn slightly as the engine runs a while and this causes the valve to lock intermittantly when it does it breaks the rocker.

Did you do some engine work to this truck like a valve job just before this started? Could it be that your guides were damaged when they installed them. If the machine shop has a defective installation tool and didn't go back and check the bore, it could effect more than 1 valve. As the engine warmes up expansion and contraction of the valve and guide will be differant. This would explain a 20 to 40 mile drive before problem occures.

I would blame it on a stuck lifter on the #6 hole.
If there are no performance issues prior to breaking I would think a lifter is sticking.
Just a thought.

wilbur

Was thinking on rocker shaft some of those are right hand and some are left hand, cylinders 2,4,6,are left hand angle, not interchangable.
not sure how far off from center on valve or push rod if assembled wrong. check rocker arm shaft for bend in it. binding, could be valve seem free but at certin point binds enough to break rocker. could be you got 11 hydralic lifters and one mechanical. I think what I would do is repair the broken lifter, assemble rocker shaft and adjust rocker arms as if they were mechanical lifters, .06 intake .13 exhaust. if they make noise adjust for hydralic. Maybe the car engine was a truck engine in a car.hope this helps
jbennett
40 burb

Wilbur,
Your right about the lifter being stuck.I took the lifters out and the #6 was frozen with the plunger all the way up. I found a parts store that carries them so I ordered acouple. Hope it solves the problem.

Glenn,

Great,this is one post that i have been watching daily.The rockers are on there way,good luck !!!

I once had a very low mileage 235 ,it wouldn't even start and seemed very "tight". I removed the rocker arm assembly,and discovered all the rockers were very stiff. I carefully dissassembled it,laying out all the parts on a table in order of removal.The "shelac build up on the moving surfaces was incredibly bad.I systematically cleaned all the surfaces with SOS (wire soap) pads from the kitchen.After cleaning all the soap and residue off each part, I oiled every part and reassembled the rocker arm assembly.Every rocker moved easily and smoothly.It was a complete success and that low mileage 235 purred like a kitten. Lothar

Glenn,

53 Moneypit surmised it was the lifters in the other thread back in July....yea Dave. I hope this is the final chapter of the Rockin-Rockers!

Stuart

Glenn,

I hope you have found the problem. You wouldn't have had as many questions on this post if you had just posted the new information on your old post.

Timx writes "dude buy higher quality rockers". Well dude if you know where to get higher quality rockers why don't you say so. I've serched this country for every valve train part and I'm telling you that parts for a 51, 235 with hyd lifters are not easy to come by.
Badly-Your right I should have kept it on the original post (sticking Valves). But, I know from experience that people stop reading a post after about 15-20.

Glenn,

Here we go again. I rebuilt or replaced lifters. Replaced rocker shafts and push rods. I inspected piston tops and found them to look normal. She ran like a champ for 25 miles. Then, #4 intake rocker arm broke. Thats 5 intake arms now. Not a single exhaust rocker arm. This makes no sense. I guess the head is coming off now. If it were one or two of the same ones I'd say its a valve or guide. But,it's a different one each time. I'm stumped.

Glenn,

Glenn,

Grab a wooden stake and drive it through the distributor on your truck!

Can you list the rocker arms that have broken, and indicate if they were replaced with new items and broke again! Although it doesn't seem like it to you now, you have made progress. You know a few more things that AREN'T causing it!


Stuart

Glenn,

Drop me an E-mail if you need a full pressure 235. I have one that is complete, fan blade to tranny. It came out of a 58 and is supposed to be in good shape. In theory, all it needs is a new coat of paint.

Your patience must be wearing thin!

John

Stuart,
2,3,4,5,and six intake rocker arms have broke. # 1 has not so far. #6 broke twice. It was replaced with an old arm. I did find #6 lifter frozen with the plunger in the up position. So, I can see how 6 broke twice. The rest of the lifters worked properly. I did however replaced a couple of lifters that where abit scraped up. Bizarre. I had earlier talked about the noisy valve train. Well after going deaf from using a rubber hose to listen to everything, I now think that all the noise is coming from the water pump (new) or more likely the timming gears.I drain the cooling sys and replaced. Then I put water pump lube in. It didn't make any difference. Does anyone else have real noiy timing gears?

Glenn,

Probably everyone with the aluminum timing gears has some noise. The fibre gears are quiter but don't hold up as well, naturally.

I assume that all your push rods are good and the same proper length. I think you covered that in the earlier thread. Check them again if you will, and replace all those lifters.

Did you solve your problem ??