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Author Topic: JD engine problems  (Read 1225 times)

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Offline tacks Y

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JD engine problems
« on: February 03, 2019, 04:58:39 PM »
I have a 440C skidder with a 4239T engine.  I had crank done and sleeves and pistons. Now I dropped a exhaust valve ( spring is broke). Banged up head and piston and cracked sleeve. I shut it down at first sound then started again to listen with doors open, big mistake. Is this common? Will a broken spring do this much?  

Offline bushmechanic

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Re: JD engine problems
« Reply #1 on: February 03, 2019, 06:21:26 PM »
Oh for sure it can do that and much worse. I did a International BD144 that the springs got weak enough to drop the valve to where the piston hit it, broke it off then smashed the piston and bent the rod which broke the liner and ruined the block. Good luck in the repair!

Offline Firewoodjoe

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Re: JD engine problems
« Reply #2 on: February 03, 2019, 07:22:41 PM »
I used to play around with Chevy engines. 4x4 trucks. Blew one up where the valve hit the piston. Bent the push rod but worst was it destroyed the piston bent the connecting rod and went out the block. Actually out the side of the engine massive hole with a rod swinging in and out 🤣 drove it home on 7 cylinders. That may have been a rpm issue lol like 7500!

Offline mike_belben

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Re: JD engine problems
« Reply #3 on: February 03, 2019, 08:24:07 PM »
I had a buddy who won his sled pull class on 7 holes with a BBC.  Pulled the plug and rocker arms of the piston with a hole in the dome and ran it.  It was a keith black block with more welds on it than u could shake a stick at, and a collection of mashed parts dangling off the bumper.
Revelation 3:20

Offline tacks Y

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Re: JD engine problems
« Reply #4 on: February 04, 2019, 08:33:15 AM »
I only had about 20 hours it since rebuild. Changed all bearings in tranny also. I was not running hard at all, died 60 yards from garage so I guess there is a bright side. Took me 5 hours to get backhoe running in the cold to move in shop. So do I buy a new springs now? Not sure if I can save head, beat it up between valves at the injector. Will pull valves and look at seats, took end off exhaust valve. If I had not restarted ? ? ? I had to drop the hitch, and never thought this would happen. 

Offline kiko

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Re: JD engine problems
« Reply #5 on: February 04, 2019, 09:08:07 AM »
With idle speed about 700 rpm or so, in 15 seconds that piston has hit the busted valve just short of 200 times. Can go from fine to trashed real quick. It is hard to find out exactly what happened first when a valve drops.  However, when the head if the valve snaps off it is usually because of improper valve adjustment (loose) that is allowing the valve to slam shut instead of easing down and when the valve gets hot off it comes.  To verify the theory( that is all it is from where I am at) check the rocker adjust mentioned on the valve that dropped and compare to the like valves ( intake or exhaust) to see if the adjustment is close to the others, it should be.  The adjustment on the rocker where the valve dropped may be loose. Or the the spring just failed creating the same scenario. The engines I work on regularly would be newer, but addressing the head is always part of the rebuild process.

Offline tacks Y

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Re: JD engine problems
« Reply #6 on: February 04, 2019, 07:11:22 PM »
Kiko, that would not explain the broken spring. It broke in the middle and the one half broke in half. The adjusters are all tight.

Offline kiko

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Re: JD engine problems
« Reply #7 on: February 04, 2019, 08:10:35 PM »
This kind of failure is a chicken or egg kind of thing.  The spring could have failed. Interference when the valve dropped could have caused valve train damage.  And from here i am speculating

Offline mike_belben

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Re: JD engine problems
« Reply #8 on: February 05, 2019, 11:08:55 AM »
That is a hard shot to call.  One piece i will say is that valve seals on my old engine that shoulda had oil SHIELDS, little plastic splash deflector clips.. Caused the brand new guides to wear right about to the casting in 4,000 miles.  The valves floated so much from sticking in unlubed guides that they ate the top of the liners, and finally a pushrod hung up and got munched.  While changing a pushrod i accidentally dropped a lifter under the head into the galley sideways, forcing a very angry michael belben to pull the head off a new gasket. And by gods grace and divine sense of humor, discovering the whole mess before it was too late.  New valves and guides yet again but its still running.  


Anyway lack of lube up top will cause valves to stick in the guide and then stuff snowballs until it hits the fan. Look at your guides and valve stems for galling.  If you find it look at oil supply. 
Revelation 3:20

Offline tacks Y

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Re: JD engine problems
« Reply #9 on: February 06, 2019, 07:08:41 PM »
Update. My engine is a 4276T not the 239, which I knew but forgot. Took the head and parts to the machine shop. Same one that ground valves, head and crank. I had put the valves, lines and the rest together. He thinks the spring just broke (one in a million) keep running until the spring broke again. Then doom and gloom. I looked at the spring parts and I could see where is was rubbing. He said I might have been able to hear it but I did not notice. I got the rod and liner out with the motor in, I did not think I would get the pan off in the machine but I did. So waiting on parts, hope to put it together next week. The head is a little banged up but he thinks it will be fine. 

Offline tacks Y

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Re: JD engine problems
« Reply #10 on: February 15, 2019, 08:29:01 PM »
Update again. Put new piston and sleeve in, injector, had the head checked another valve and spring. Put it back together Wed, ran 5 hours Thur, rain today. Went to retorque head today found another broken exh spring on #3 this time. Did not drop valve so lucky there. Changed all springs now, retorqued head now back up and running. Not sure why they broke but there is no way to screw up a spring that I know of. Did hear a different sound when running but no tapping and only at a idle. Was lucky to be able to change springs with out removing head. 

Offline mike_belben

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Re: JD engine problems
« Reply #11 on: February 15, 2019, 09:25:30 PM »
Sorry to hear of your bad luck on that.  
Revelation 3:20

Offline Randy88

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Re: JD engine problems
« Reply #12 on: February 17, 2019, 09:28:59 AM »
Whenever a head comes off, it gets checked over and we usually put all new springs on, for as cheap as they are, its good insurance all the same.    In all the engines we've got and had, and in all the hundreds of thousands of hours, never YET dropped a valve, had many other issues over the years, but not a dropped valve.    I'm sure my day is coming, as they say its only a matter of time.

But curious, did the put new valve guides in when they checked over the head and did you have the rockers checked and ground as well, sounds like to me the rockers have a wear pattern in them and when the head was done, they switched valve location and you have an issue with uneven wear on valves and rockers??     Might be wrong, just a suggestion and something to ask or think about, if this is the case, your problem may not go away even with new springs??

Offline tacks Y

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Re: JD engine problems
« Reply #13 on: February 17, 2019, 08:19:14 PM »
I do not think new guides. The valves run a cap on top, not sure of the name. And no wear there. The shop did the head, he grinds his own cranks (not sent out). Seems to know his stuff, claims the only JD valve problems are with the smaller stem valves. Mine I think are 8mm and the smaller are 7? Still no idea what would make one break, so i gave the rest the 3lb hammer test. I could not get any to break. I trust my mach shop, but he does more with race engines. He is also in to making winch drive shafts for the JD skidders. All and all I hope this problem is now gone. I had someone looking at my 440a for sale and they wanted to buy the C, I told them I could not sell until I had ran it more. I am glad I did, if it had went out on someone else I would have felt like crap. 

Offline Randy88

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Re: JD engine problems
« Reply #14 on: February 17, 2019, 09:27:04 PM »
I forgot the stem caps on JD's, those should eliminate the problem of worn valve stem ends to a certain extent.   The last JD I did was last winter, a 466 and the valve's were pretty bad, along with the injection pump and injectors, the pump needed a new rail in it.  

My thoughts on the springs is this, they are constantly moving and flexing, everything has a fatigue factor and eventually they will fail or get weak from heat and flexing, just like a head itself, they can develop small fractures or cracks you can't see, its why they magniflux heads to find cracks not seen with the naked eye.    

Some shops go by the pound test on springs, others use hours as a means to replace them, some still ask about broken springs and just replace them all once one breaks, it just depends on who's doing it and how they learned over the years. 

You changed them all, which is good in my opinion, if you any further issues in the next while, there is something else wrong somewhere in the valve train.     I'd run it some, not hard by any means and pull the valve cover again just to see and recheck the valve lash before pouring the coals to it much.    The 466 is supposed to have the valves set, then warmed up and reset warm, not sure on that model of JD though.   I've got a 239t to rebuild myself sometime, but it won't be this winter, not enough time nor enough spare cash on hand to do that along with everything else on the list. 

Here's hoping you got it solved and your problems are behind you.    

Offline tacks Y

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Re: JD engine problems
« Reply #15 on: February 18, 2019, 06:14:00 PM »
I had a JD loader  with the 239T to go in instead of reworking my engine, but seller backed out. Have you ever heard of a JD spring breaking?


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