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Broken 414 rocker arm -again and again, and again, and again!


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I have worked on the 414 engines in various tractors for 40 years and never had one like this.  The customer is the 2nd owner of this 1066 and does a good job with maintenance, although he does use John Deere 15-40 oil in the engine.

Every several years he will break a rocker arm or pushrod.  Sometimes he will go 7-8 years, the last time, only two years (233 hours).  It is not a main tractor anymore, yet the problem persists.

When he brought it to our shop in 2018, the camshaft was shot, as were the lifters and one rocker arm and it had several bent pushrods.  The engine was completely rebuilt except for the pistons and sleeves because it didn't use any oil.  We install all new valves, guides, 6 valve seats, new oil pump, new camshaft, lifters, pushrods, and cam bearings.  Also, new rod and main bearings, along with new rod bolts.

All passages were checked for debris and the injection pump timing was set correctly upon installation (and still is correct).  Injectors were overhauled.  Timing gears were installed correctly, etc, etc.

No stone was left unturned and yet 233 hours later, the #1 rocker arm has broke.  Note:  Whenever a rocker arm or pushrod breaks, it is not necessarily the same one.  

I haven't measured the lobe lift yet but I suspect there is a problem with the cam also because # 5 rocker arm has over .220 of gap.  The camshaft is the updated model which I bought from RF Engines.  It has the revised lobe ramp so the valve lash is set at .025 on all rocker arms.

This does not have the updated Valve Train Service package (1802464C92) because they are no longer available, although there appears to be an adequate supply of oil under the valve cover.  It also does not have the top-mounted breather on the valve cover.

The customer is super-nice about all this fuss, but I would like to get it fixed once and for all.

ANY help is much appreciated!!

Red Tech

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Valve guides installed too high and retainers contacting the guide? A shot in the dark. Height spec on intake guide from spring seat is 1.217 and exhaust is 1.297. 

I had a 1066 a year ago that kept breaking the #4 intake rocker arm and found a bad cam. The tractor only had 800 hours or so on an overhaul so he said replace the rocker arm only. Try to get by you know! 80 hours later the same one broke. He took it back to the shop that overhauled it and they couldn't believe the cam was bad so soon. 

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If it were mine I’d start with measuring lobe lift and go from there.  You might find that #1 is so worn that the rocker got too loose and the pushrod popped out.

         I believe the updated valve covers were installed with the top mounted breathers in order to get more oil mist up and across the cam/lifter area.   I might be wrong on that, but if I am someone will chime in.

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4 minutes ago, Mike56073 said:

If it were mine I’d start with measuring lobe lift and go from there.  You might find that #1 is so worn that the rocker got too loose and the pushrod popped out.

         I believe the updated valve covers were installed with the top mounted breathers in order to get more oil mist up and across the cam/lifter area.   I might be wrong on that, but if I am someone will chime in.

Also if you replaced the 3 rocker arm stands with bigger oil holes squirting down on the camshaft you needed the top breather. If you didn't replace the valve cover oil came out of the side breather. Don't ask how I know! Also if you had the wide gap rings it needed the airflow of the top breather. 

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Is it possible the head was planed and the valve clearance isn't there?

Ahhm...OBVIOUSLY, that JD oil is making the valves sticky, and then the rocker gets hammered until it breaks....😁

 

 

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Same exact issue I had on my 1460 combine with the 436 engine always broke the same rocker arm three times all valves set the spec .025 on intake and exhaust  its was the small lobe early style cam and small lifters cam shaft was junk engine was a reman from CaseIH  I'd never buy another from that outfit 

1460 rocker arm damage.jpg

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I have had this happen but on a different brand engine. (automotive) How much valve guide to valve stem clearance do you have? Curious what the valve stem looks like. (blue?) Is the guide still at the proper height or has it stuck to the valve and pushed up causing interference with valve keeper? Rocker arm looks black like maybe cooked on oil.

What horsepower is it running? Intake or exhaust rocker, or random?

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What part number on rocker arm.   Early engines had lighter rockers and many bent and over the years the ones that did not bend could still be in that engine.  Just a heads up. I don't have the part number if it was just advanced or different number completely 

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Check your timing also. This was actually a common problem back in the early 80s. Dad had a 815 combine he turboed . He advanced timing a bit. He would break a rocker about once a year. This wasn’t a high houred machine either. His 1066 broke a couple on a ihc reman from the early 80s. I think we swapped complete set of rockers. And no it isn’t the jd oil. Have run it for years in a 1066 never had troubles. I can’t  believe he was only one changing rockers. I chuckle reading this brought back memories of swapping one on the 815 in the rain when they were combining rye in 1981 or so.  An take you to exact spot in field we changed it. I was 11 helping Dad.

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IIRC neighbor had 1466 recalled for heavier rocker arms. Story I remember from him is early 400 engines were ok then they went to stamped rockers and first of these were too light. That is fence row conversation from about 1976 so don't hold me to it.  

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Truck rockers are stronger than tractor rockers ........ especially after you weld the "spine"  

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Could it be deflection? How many rps is it turning? I'm wondering if the valve guids are too tight, and sticking in the head. Cool down, they are free. Also, what about valve spring bind? Did you do the head, or did the machine shop? 

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43 minutes ago, Killer Red Mater said:

Truck rockers are stronger than tractor rockers ........ especially after you weld the "spine"  

Never paid attention have to keep an eye out for truck engines

 

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9 hours ago, Killer Red Mater said:

Truck rockers are stronger than tractor rockers ........ especially after you weld the "spine"  

What's the next weakest thing in the valvetrain, because that'll be the thing that starts breaking when the rockers can't anymore.

Will it start bending valves or bending pushrods?

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I caught a problem on a 986 that I rebuilt. The machine shop found the valve springs losing some tension. They used to put a washer under the spring to compensate. Instead they used keepers that put the retainer cap down farther on the stem. Within a few revolutions of the engine the valve seals were ruined from being smashed against the valve guide! I was none too pleased, but the shop sent a guy out to my shop to repair the problem with the head installed free of charge. Claimed they never heard of such a problem. That might be something for you to check.... clearance between valve guide and retainer at full stroke.

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28 minutes ago, Farmall Doctor said:

I caught a problem on a 986 that I rebuilt. The machine shop found the valve springs losing some tension. They used to put a washer under the spring to compensate. Instead they used keepers that put the retainer cap down farther on the stem. Within a few revolutions of the engine the valve seals were ruined from being smashed against the valve guide! I was none too pleased, but the shop sent a guy out to my shop to repair the problem with the head installed free of charge. Claimed they never heard of such a problem. That might be something for you to check.... clearance between valve guide and retainer at full stroke.

Biggest reason I just order complete valvetrain kits anymore and get everything new.  

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Thanks for all for the very insightful replies. 

I did put the complete valve train kit in the tractor.   The kit included springs, valves, guides.  I also had the machine shop put in 6 seats.  The updated camshaft, along with lifters and pushrods were also put in new.  I had a very good machine shop do the work as they have done for me for almost 40 years.

I started checking lobe lift and so far so good.

I think that I have an idea as to what could have caused this problem, based on some of the information that you have provided.  I'll report back after I have the tractor running, which may be a little while as I have to order parts and I am getting swamped with a lot of other repairs.

Again; thanks for the replies and if any of you think of something else for me to check, please continue to make suggestions.

As I stated earlier, this engine DOES NOT have the updated rocker arm towers and the top mounted breather.  How important are they?  Service manual states that they are not a mandatory change, but are "optional".

Red Tech

 

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Red Tech In my opinion the updated rocker towers are not that use full for your problem there are thousands of 400 series engines running around the country with old style towers and don't break rocker arms  the additional lube was more for cam shaft problems  in fact it will lower the lube volume to the rocker arms themselves when they first came out with that kit guys would put the new stands in when doing a camshaft but not install a the wider (back then you could get both widths) and run into rocker arm wear and valve guide problems.

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2 hours ago, Farmall Doctor said:

I caught a problem on a 986 that I rebuilt. The machine shop found the valve springs losing some tension. They used to put a washer under the spring to compensate. Instead they used keepers that put the retainer cap down farther on the stem. Within a few revolutions of the engine the valve seals were ruined from being smashed against the valve guide! I was none too pleased, but the shop sent a guy out to my shop to repair the problem with the head installed free of charge. Claimed they never heard of such a problem. That might be something for you to check.... clearance between valve guide and retainer at full stroke.

Oh man I forgot about valve spring shims. We used to keep a bunch around. Ground a lot of valves in my life.

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On 7/31/2020 at 6:58 AM, Matt Kirsch said:

What's the next weakest thing in the valvetrain, because that'll be the thing that starts breaking when the rockers can't anymore.

Will it start bending valves or bending pushrods?

I answered the question about "strength"   EVERY truck 466 has the "upgrade" stronger valve train ............ so there is that. Did I say it will fix any underlying problem ? NO However , ALL DT466 truck engines ALREADY have them sooooooooooooo 

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11 hours ago, Killer Red Mater said:

I answered the question about "strength"   EVERY truck 466 has the "upgrade" stronger valve train ............ so there is that. Did I say it will fix any underlying problem ? NO However , ALL DT466 truck engines ALREADY have them sooooooooooooo 

To be fair, you only mentioned rockers in your very short reply, nothing about the entire valve train. It kind of implied that putting the stronger rockers from a truck engine in was the solution to the problem of breaking rockers.

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check head thickness if it happened to be planed once in its life then the current machine shop planed it again could be the the head is to thin throwing off valve train geometry. then you would need different ratio rocker arms

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1 hour ago, hippy5488 said:

check head thickness if it happened to be planed once in its life then the current machine shop planed it again could be the the head is to thin throwing off valve train geometry. then you would need different ratio rocker arms

rocker arm ratio would not change push rod length would need to be shorter easy to do

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50 minutes ago, R190 said:

rocker arm ratio would not change push rod length would need to be shorter easy to do

Why would a planed head make any difference in the end it comes down to valve tappet clearance planing the head would be a mute point 

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The 1456's were known to have an exhaust valve guide come loose, work up until the valve went into a bind and then breaking the rocker or push rod.

This usually happened on the rear cylinders. More heat.

But, you had the guides redone so that should not be the case.

If #5 was at 0.220 then something is eating the cam, lifter or both or the push rod is bent or rocker is. But what is causing that to happen?

Look at that broken rocker?

That appears to be a fresh break and just think about the pressure required to break this.

The cam can do this.

But something had to prevent the valve from moving and the rocker was the weakest link and broke first.

The best may be to pull the head and cam, and check every spec that you can. 

Since this happens on any cylinder, it makes it harder yet to find and must be similar on all cylinders.

I have seen fuel and timing issues but none breaks things like this does.

I would first look at lift on the cam + rocker ratio to see if the valves are going into coil bind.

It takes serious pressure to break a rocker or to bend a push rod.

Are these intake, exhaust, or both that are affected.

Keep us up on what you find.

 

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