Rocker failure

[Jens]

Last night I noticed a distinct lifting motion of one of my rockers during operation. After closer examination I also noticed lots of cast iron dust. I pulled the assembly today and there is about 80 thou wear on the pivot shaft and maybe 1/16" wear on the hole in the rocker itself. There is similar wear on the pivot shaft on the side that was still working ok.
Since water had made it up the head stud holes and was steaming off, I suspect that lubrication was lost and failure ensued.
I have not used grease for the rockers since day 1 and basically dribble oil all over (including the top hole) every time I lube the valve guides.

Questions:
Has anyone experienced failures of the rockers ?
What lubrication method did you use ?
How did you fix your issues ?

What I am thinking of doing is boring out the rockers themselves to get a true hole and inserting a bronze sintered bushing. I was also going to replace the pivot shaft with a solid shaft with springs on the end just like the original units.

Thoughts ?

[AdeV]

Sounds like a good plan to me. I think grease would be a better lube than oil in this instance, as it's got to stay in place. Oil, unless you're constantly dripping it on, will run out quite quickly.

I must say, you're having sweet FA luck with this engine Is there any part of it you haven't had to re-build?


BTW: The original CS's have hollow shafts with a grease cap; when the grease cap is given a tweak (once every 24h if I remember rightly), a bit of grease is squeezed out of holes around the pivots.

[sailawayrb]

I have not experienced this situation.  I just use the same oil as used for the valve guides.  You may want to consider switching to the "Gaskets-to-Go"
gaskets in lieu of using standard copper gaskets to eliminate any cooling water from coming thru the head stud holes:

http://www.gasketstogo.com/Listeroid.htm

My rockers came with bronze bushings like these:

http://www.generatorsales.com/order/Rocker_Arms.asp?page=Rocker_Arms

Bob B.

[Crofter]

I think that there would be meat enough to bore out for a thin bronze bushing but it will not be an easy job to get the alignment correct. Even the originals (listeroid) often need some fudging of holes in rocker shaft stand and shimming the rockers in and out to have them half azz line up centred over the valve stems. It will take some creative jigging to machine. Ideally the shaft should be fairly hard if you want to gain much over the original setup.
I think it will be much cheaper to buy an new assembly. There may be a closer source in Alberta but John F could likely fix you up fairly quick, being as you are the same side of the border.

[Crofter]

I had a look-see at jigging for boring. I think that alignment should be relatively easy if one was to assume the parts are not precision parts. In other words if one assumes that 'close' is good enough. I agree that ideally one should use a surface hardened, ground pivot shaft for best wear resistance.

Well you can certainly assume that there was no precision in their original conception! Some have pretty ugly misalignments that you could improve upon or conceivably make worse; that part is up to you, and your tolerance for "good enough", lol  How are you going to do the boring?

[Ian]

Yep, Jens - I also suffered the rocker arm wear....

I used (and still use) grease but, like you, found that more grease came out of the brass grease cup fitting than was being pumped into the rocker Shaft.

In my case, the rocker arm wear was completely through the bronze bush and into the cast arm itself; it was on the exhaust valve. There was absolutely zero marking to the rocker shaft.

I replaced the complete rocker assembly and fitted a hydraulic grease nipple in place of the brass screw cup. I now only apply grease when the engine is running and hot - in the belief that more grease is likely to find its way to the rockers rather than just oozing out of the biggest gap.

HTH

Regards,
Ian

[Ronmar]

I don't have any appreciable wear on mine, but not all that many hours either.  Oil holes on top of the rockers and grease cup are counter productive IMO.  I also think the grease takes the path of least resistance and exits too easilly instead of being forced where it belongs.  Rubber seals alongside teh rockers might improve this  I have an idea to use come small copper capillary tubing to take a little off the oil pump and send it up to drip into the rocker holes.  This would require drilling a drain passage in the head and the addition of a siphon tube to pull the oil level in the cups down to the proper point once oil starts to build up.  This however would give a source of oil to feed the end bearing of the camshaft in past the IP cam lobe...     

I use oil to lube my rockers, but not motor oil. I use 90 weight gear oil in my oil can for all the external lube.  A little more sticky and stays in place a bit better than motor oil does at op temp.  But I also make frequent rounds and oil the moving bits every couple hours in operation.  Another thing I have been looking at is I have not had the valve cover inplace for a little while.  I find the sight of a working valve train captivating:)  This kind of defeats the oil mist process, as any mist from the warm oil in the valvespring cups drifts away... 

[bschwartz]

How many hours are these rocker failures happening at?  I have about 1250 hours so far on my 6/1.  I haven't even considered checking for excess play..... maybe it is something I should investigate.

[bschwartz]

I use a rocker cover..... it's called the workshop roof 

[Ian]

Cannot remember exactly how many hours when I noticed the rocker arm issue. I probably noticed it about 1000 hours but I am sure it was a gradually operating process.

The exhaust rocker is the furthest away from the grease cup on my single. Considered putting a second grease cup on the other end of the shaft (closer to the exhaust rocker) but later decided to work on a single hydraulic grease nipple instead.

Probably another 2000 - 2500 hours since then with no OBVIOUS rocker issues.

HTH

Regards,
Ian

[veggie]

I like the idea of modifying to put a grease nipple at the end of the rocker shaft.
Then just keep a mini-grease gun hanging on the wall beside the machine.
Packing that grease cup and having 25% of the grease squeeze out in the wrong places is not optimal.

veggie

[Tom Reed]

After a bit of grease comes out of the hole on top of the intake rocker, I put my thumb on it and turn the pot until some comes out of the exhaust rocker too. I think I'm going to try and reverse the shaft so the holes point down and see how that works. I think there are notches in both sides of the rocker cover.

[mbryner]

Recently I'd just been using regular oil for the rocker assembly (because it was on hand).   Previously was using chain saw bar oil because it was thicker.   Great idea about a grease fitting!   Why not just drill out the grease cup and fit the grease zirc there?

[Ian]

The grease cup uses a 1/8BSP thread - the same as many grease nipples. No need to drill out anything - just take the grease cup and fitting off.

The shaft is keyed to locate around the stud but it is also left and right mirror imaged - so if you currently have holes in the TOP of the shaft - it is incorrectly assembled. Take the fittings off the shaft and turn it through 180 degrees so the notch is still in the right place but the holes (in the shaft) are at the bottom. Then reassemble.

Shaft holes pointing upwards (IMO) are about as much use as a chocolate teapot and WILL lead to rocker arm wear due to insufficient greasing of the arm bush.

HTH

Regards,
Ian

[Tom Reed]

Jens, I plan to do what Ian said.