What happened

[mikeintn]

Well went out to get some dirt on my 350B dozer today and didn't turn out good, after about 8 hrs. started pecking, pulled valve cover, front valve spring broke and about 1/2 inch broke off top of valve, bent pushrod.

I can understand a valve spring breaking, I"ve seen it on other engines, but there was 5 of the valve springs broke

When I got it it had been setting for along time only 1000 hrs. but it had started some rust in it, some on some of the springs, look more like it had just stained them, some rust in front cyl., bearings looked like new, so I put new sleeves and pistons in it, valve job using all old parts.

I got the head off and everything looks good under it.

So has anyone got any idles why the valve springs may have broken?
has anyone had them brake before?
is this something that is common?
should have they just been replaced because of age? [ never seen it on other engine]
looking under the valve cover you would think someone had ran the crap out of it but it was only ran between 1500-2000.

[LeonardL]

Mike,
Wow!! Not sure what to say or ask. Sorry it happened to you first of all, this is a real bummer!!
Refresh my memory... Is this a Gas engine or Diesel? The first two things I think of is... (1) This is an over reved situation... or (2) You may have put the wrong pistons in when you changed the pistons or got them in backwards.
The only experience I have ever seen something like this was on a couple of engines that had over reved or had went way beyond the max RPM for those particular engines. One of them was a 4 cylinder in a 450E and the other was in a 672B Motor Grader. Both engines had multiple broken springs and valves with either broken stems or bent really bad. The 672B had two pistons ruined and a hole big enough to throw a cat through in the side of the block! They also had several bent push rods.
Another thing that comes to mind would be the "Timing". If you had the front gears off of the engine you may have gotten them out of exact timing. However you should have had issues from the start if you had done that.
I don't know dude... you will just have to go back through the process and see what else turns up.

[Lavoy]

Lack of oil to the head?
Lavoy

[mikeintn]

Yell its got me also , if someone told me the same thing I would be thinking about the same Leonard, it is a diesel, 3-152, I've seen a spring brake on other things over the years, some on my race cars but you can understand that with big cams and 8000 rpms, but 5 out of 6 broke I'm not no diesel mechanic, but I would think a valve spring does the same thing, with all the stock parts [ except pistons ] should be no trouble and the pistons looks the same I got the head back off and everything looks fine, piston turned right nothing has hit piston or bottom of head or valves, everything under head look great, I ran it and never went over 2000 rpms most time around 1700 and I believe limit is like 2600 right? until that happened it ran perfect, start as soon as you hit the starter and lots of power was very happy with the way it ran, temp. never went over 190 oil pressure 40-60, I did look at it with the valve cover off and its getting oil Lavoy, I was thinking maybe same thing.

I guess if cant come up with anything I'll try to find new valves and springs
tomorrow and maybe pushrods have a valve job done and try it again

[LeonardL]

Wow... This one is going to bug me! After I wrote the first response I got to thinking like Lavoy and was wondering about Oil getting to the valve train but you should have a lot of gaulding and stuck rocker arms if oil wasn't getting to the head. I suppose the springs could have had rust issues but the way you described them it sounded like they were safe enough to use.
I've seen these springs collapse from over heating but never any broken except in an over rev. I don't know... maybe some of these other guys have seen something like this. It's got me puzzled for sure!!

[KenP]

deleted

[mikeintn]

Thought I post some pictures, worth more then 1000 words

I'm guessing the spring on the front cylinder broke first then it came off and somehow the rocker broke the top off the valve, chicken or the egg

[LeonardL]

I talked to a couple of friends of mine who are "Old" like me and have been mechanics as long or even longer than I have been. One asked the same thing Ken did about the springs being the right springs and or was the valve train set properly. The other guy brought up the timing issue. If you had the front gears off, did you get them back in exact time according to the marks on the gears? I am assuming you did or it would not have run right to begin with. He then stated if maybe it had jumped timing? Which is hard for a Deere engine to do. If it has, then there will be damaged gears or sheared keys or both. You can check this by simply rotating the engine over to the timing hole and pin on the flywheel and see if your number one piston is at the top. You could also pull the cover on the injector pump to see if the marks are lined up there. The thing here though is there should be some evidence of the valves hitting the pistons. And I don't see any marks or evidence of that in your pictures. Be sure you put some bolts and washers over the liners before you rotate the engine or you could push a liner up and out of the block. Been there and done that!!!
My additional thoughts are on the assembling of the valves and springs back in the head. How much did you collapse the springs to get the keepers back on the valve stems? I was thinking that if they were collapsed too much, it could have cracked them or strained them too much and they gave up after some running. If they were strained or even cracked, then the harmonic resonance Ken mentioned would have been multiplied. You wouldn't necessarily have to have an over rev situation to cause the failure. Make sense?
The broken valve stem still has me stumped. There should be some indication where and or why it broke the end off of the stem. Also you said it bent a push rod? Here again there should be some evidence to cause those to bend. I suppose it could have gotten between the rocker and something else to bend it but it is darned odd!
Just some thoughts to throw at you. I have another fellow I want to talk to but he is out of town for the week, so I will talk to him as soon as I can. You will probably have it back together before then but I will mention this to him anyway.

[Lavoy]

I'm thinking it was the high lift race cam that did it!
Lavoy

[LeonardL]

Yeah and he was pulling hole shots with it getting ready for the track!! Now we know!!! Probably using Nitrous as well!

[mikeintn]

Thanks everyone for a lot of good ideals and suggestions, you know you cant say anything much for a fact on these old tractors, lots have been changed, but I had just about everything apart on it and I'm as sure as I can be that it had never been apart, it didn't have many hrs. everything look original and the way you think it would with 1000 hrs. the bearings was original and very good with 1973 on them, only took it apart because it had set so long, it did need it because of some rust had started in #1 cyl. so I put a engine kit in it, the head was like everything else nothing showed any ware, I just took it apart cleaned it and lap the valves myself put it back the way it was, so it should have been the same as it came from JD.[ I don't know that for a fact just the best I could tell]. The tach and cable is new, it could be off, but I don't think it is, it just seems right by the engine sound, but a good point. I did have all the timing gears of it, again I think I put it all back right, I know you couldn't ask for one to run or perform any better before this happened.

I'm thinking a set of valves, springs, a pushrod [ maybe a set ] a spring retainer and a rocker or the adjuster that goes in it, if I can find something that's not China anyone has any ideals where to look?

That is what it looks like Lavoy, I ran 665 CI. engine with .850 lift cam with 350 lbs of set pressure and NOS at 8000 and never broke that many

I thought I was being easy on it, maybe it needed more RPMS

Would you have any of these parts I need?

[Lavoy]

I have never checked, but might have them available. E-mail me a list of what you want, and I will check.
Lavoy