Broken rocker arm adjuster screw

[Jflr]

I was adjusting the valves yesterday on my 1985 SP135 Lehman and the adjusting nut for valve #1 broke off. I don’t believe any of the broken pieces fell into the engine. I have attached a picture. I finished adjusting the rest and started it briefly and it ran smoothly.

Should I be concerned if some small fragments got into the engine?

I have ordered a replacement from AD. Does anyone have any ideas on the best way to remove the broken nut? Brian at AD suggested vice grips and if that failed I would need to remove the rocker arm. Can I heat it up in some way or use penetrating oil to loosen it first?

Thanks for any suggestions.

 

[RT Firefly]

Greetings,
Mr. J. Hmmm....Just a few thoughts.... It already had a hole down the center so you might try an Easy-out although I don't know how much you could tap it in without damaging the push rod.
Heat works 99.9% of the time for me. The problem is how much heat? In this application, very hot, very small tipped flame for short periods of time alternating either side of the rocker arm. The rocker arm is possibly hardened? so you don't want to destroy that.
IF you resort to vice grips, I would suggest a snug fitting steel rod in the hole to minimize collapse of the nut when you clamp down.
I don't know if penetrating oil would be any better than the oil the nut has been sitting in for the last X years unless it has rusted somehow.


Edit: IF you took the arm off, it would be a LOT easier to work on, "on the bench".

 

[Jflr]

Thank you RTF. How difficult is it to remove the arm?

 

[RT Firefly]

Greetings,
Mr. J. Sorry. I haven't got a clue how to remove the arm. I saw a mechanic remove the whole rocker arm assembly on one of our engines and I don't recall it being terribly involved.

 

[twistedtree]

Can you account for the missing fragments? I don't know the construction of a lehman, so can't guess where any fallen fragments might end up. Hopefully they find their way to the oil pan and drop to the bottom.


Is the adjuster screw just a friction fit, or is there a lock nut? I've always had adjuster screws and a lock nut.

 

[mvweebles]

Thank you RTF. How difficult is it to remove the arm?

I dont know Ford Lehmans, but do know old school pushrod engines peetty well.

The entire rocker assembly must be removed to replace a rocker arm. There are a series of bolts that hold down the assembly, one of which was visible in your original picture. You will need a decent torque wrench to reassemble, and I would re-torque after 20-hours of run time. I don't know the torque specification but should be easy to find.

Personally, assuming you can account for large fragments, I wouldn't worry about smaller fragments. They would stick to the oily surfaces, and the large shoulder of the rocker would prevent it from defending the pushrod gallery anyway.

Any chance of a pic of an unbroken adjuster nut? Like TwistedTree, I am used to nut and locknut assemblies. The broken part looks like a cast item which I am having a hard time visualizing.

Good luck. I hate when stuff like this happens.

Peter

 

[av8r]

The rocker shaft assembly is easy to remove as a unit. Loosen the bolts that hold it to the head and lift it off. The rocker arms and support towers are then free to slide off the shaft. Be sure and keep the rocker arms, springs and towers in order. To reinstall set the assembly in place, fit all the pushrods into their socket, and tighten the tower bolts progressively. Torque the bolts and check the valve clearances.
If you have not checked the injectors this would be the easiest time to get them out. Some mechanics remove the shaft assembly to remove the injectors.

 

[Marco Flamingo]

Good time to run a little rare earth magnet around the area. It can pick up little shards from crevices. Have you found any piece(s)?

 

[C lectric]

--Have you actually talked to American diesel about your problem?

--yes, try some penetrating oil. Any thing may be better that what you don't have.

--I read some time ago that a 50/50 mix of acetone and auto trans fluid is one of the best penetrants. Now more than a few have vouched for that.

--Some heat may be usefull. I would not use a big torch, rather a good mini torch so the heat can be directed at the rocker arm socket that the broken nut is stuck in.

You do not want it red hot, just good and warm.

It may not need a lot of heat. It just needs enough to expand the arm socket slightly to release the grip. I learned a lesson a long time ago about stuff like this. DO NOT play the torch all over the arm socket , rather play it in one spot quickly to expand that spot slightly and try removing the nut. If there is any thread locker the heat should also help to release the grip.

But talk to American Diesel first specifically about this if not already done.

 

[Jflr]

To answer some questions:

The adjuster screw is a friction fit. I have attached some pictures that Brian at AD sent me. I did have an email conversation with him.

 

[mvweebles]

To answer some questions:



The adjuster screw is a friction fit. I have attached some pictures that Brian at AD sent me. I did have an email conversation with him.

New one on me. Anyone know why the bolt is hollow? What keeps it from backing out (or perhaps tightening) if no lock nut?

Peter

 

[Comodave]

New one on me. Anyone know why the bolt is hollow? What keeps it from backing out (or perhaps tightening) if no lock nut?

Peter

Maybe so you can use an easy out when they break???

 

[Larry M]

I’d try what Brian suggested but I would bar over the engine first so that rocker arm is at it’s lowest contact point (adjustment screw at its highest point). That way you wouldn’t be loading that valve. If it doesn’t work then you could still use an easy-out or remove the rocket arm.

 

[Jflr]

Thank you for the suggestions. Does anyone see any problems in continuing to run the engine as is until the end of the season? I plan on pulling it out in mid-September.

 

[KnotYet]

Well, you did mention that you were adjusting the valve(s).
Did you attain the correct clearance on that one?
These adjusters may have an interference fit on the rockers that is
sufficient to keep them tight so if the clearance is within the specs
you could use it. Maybe check it after a run or two.

 

[mvweebles]

Thank you for the suggestions. Does anyone see any problems in continuing to run the engine as is until the end of the season? I plan on pulling it out in mid-September.

If it's adjusted correctly, should not be a problem to run it.

Good luck.

Peter

 

[Jflr]

I wasn’t able to adjust it before it broke. It is about.016” instead of the correct .015”.

 

[mvweebles]

I'm not the best mechanic in the world, but if that happened to me, I wouldn't worry a bit for at least a 50 hour run. And even that's conservative.

Enjoy.

Peter

 

[RT Firefly]

Greetings,
Mr. J. .001" isn't too much and too loose is preferable to too tight. At least that's the case for air cooled VW Beetle engines. Too tight and you burn valves.


Edit: I'm having second thoughts about the use of an Easy-out (EO). Tapping an EO into the existing hole will increase the pressure on the threads (expand the adjustment screw). Hmmm....

 

[Ox76]

I've been turning wrenches for over 30 years including rebuilding diesel engines. .001" over is nothing. You can run it for hundreds of hours and it'll be fine. Heat the cast part that the adjuster screws into. Use MAPP gas - it gets hotter than propane. Then try to turn out the screw with some vice grips. If all that fails you can simply pull the rocker shaft off and change that one rocker for a new one and a new screw, but then watch it because the tolerance might change quickly as it breaks in. Hope I'm clear as mud.

 

[Mischief Managed]

I wasn’t able to adjust it before it broke. It is about.016” instead of the correct .015”.

Valve lash tightens with use so you can run the thing for at least the duration of the valve adjust interval before you need to address it.

 

[Jflr]

I tried the vicegrips and heat without luck. The remainder of the bolt head broke off. I checked with Brian and I should be able to remove just the first pedestal and take off the rocker arm fairly easily. I’ll likely take it to a local machine shop to extract the rest of the bolt. I will try that in a few weeks once the boat is out of the water for the season.

 

[kchace]

I had the same engine and broke an adjuster nut exactly the same way you did. I bet you were using an open end wrench to turn it? One should always use a socket wrench to turn those.

Ok, so here’s the deal. Those screws are purposely a very tight friction fit so that no locknut is needed. (For you folks who are trying to help but don’t know the Lehman, they are a VERY tight friction fit only) The easiest way to fix it is to replace the entire rocker arm which would include a new adjuster nut. If one knows engines reasonably well it’s an easy job to pull the entire rocker arm assembly off, and remove and replace what’s necessary to replace the arm. Depending on the location, it may be possible to remove just one rocker arm assembly “mount” and slide things off the end.

As far as using it as is for now, it appears that the nut broke off above the rocker arm. If so, you should be ok as long as there are no cracks in the nut extending down into the arm.

Ken

 

[mvweebles]

I had the same engine and broke an adjuster nut exactly the same way you did. I bet you were using an open end wrench to turn it? One should always use a socket wrench to turn those.

Ok, so here’s the deal. Those screws are purposely a very tight friction fit so that no locknut is needed. (For you folks who are trying to help but don’t know the Lehman, they are a VERY tight friction fit only) The easiest way to fix it is to replace the entire rocker arm which would include a new adjuster nut. If one knows engines reasonably well it’s an easy job to pull the entire rocker arm assembly off, and remove and replace what’s necessary to replace the arm. Depending on the location, it may be possible to remove just one rocker arm assembly “mount” and slide things off the end.

As far as using it as is for now, it appears that the nut broke off above the rocker arm. If so, you should be ok as long as there are no cracks in the nut extending down into the arm.

Ken

I guess that solves the problem of gap changing slightly when lock nut is tightened.

Good tip about using a socket vs open end wrench. I'd add that a 6-point socket would be best possible.

Peter

 

[Jflr]

Update. The engine ran fine until haul out. I was able to remove just the one rocker arm as it was #1. Took it into a machine shop and they had to drill it out. It’s now back on with a new adjusting bolt and gapped properly. Oh, and I used a six point socket this time. A lesson learned. Thanks for all the comments.