Deere X495 Rebuild Injection Pump Timing Gear Question

[scooter2]

Posting this question for two reasons:

1) Hopes to get answer to the unusual problem; and,
2) Hope the answer will help someone else in the future.

I'm in the process of rebuilding a previously badly abused John Deere x495 that I just acquired. It had obviously overheated before I acquired it. It would barely run and smoked a lot. So, I began to tear it down.

With the timing gear cover off, on a whim, I decided to check the tightness of four bolts located on the face of the injector pump cam gear. I gave each one a turn and found that they seemed loose for 12mm hex head bolts; just barely snug. I tightened them only slightly. I was using a torque wrench set to 15 foot pounds, so I did not over-tighten them based on normal standards for this size bolt. In fact, I didn't even make it to 15 foot pounds.

I looked in the service manual to find the torque setting, only to find this disturbing note:

"IMPORTANT: Avoid damage! Do NOT loosen bolts (H). If bolts have been loosened, the camshaft and gear must be replaced by AM880628 fuel injection pump camshaft kit."

Here's a larger picture of the timing gears:

Nothing further is mentioned in the service manual about why this entire assembly "must be replaced" if the bolts are "loosened." Neither, does it say what will happen if the bolts are tightened, as in my case. To make matters worse, this assembly is no longer available, anywhere.

It appears that the bolts go through slotted holes in the gear and are used to perform the rough timing of the injection pump cam; with fine tuning being completed via shims under the pump. It seems that once this is changed (by loosening the bolts) it is nearly impossible for a repair shop (or lay person) to reset the timing relationship.

Assuming that I didn't move the timing gear in relation to the injection pump cam shaft, I still don't know what the correct torque should be, or, what damage (or malfunction) might occur if I use this assembly now, after tightening the bolts. Anyone familiar with this type of injection pump cam gear with bolts?

 

[greentree]

IF you learn more, please post or PM.
I am considering the purchase of an x495 and I am trying to discover if this is a potential problem..........and cost to remedy.
Thank you for the photo.

Posting this question for two reasons:

1) Hopes to get answer to the unusual problem; and,
2) Hope the answer will help someone else in the future.

I'm in the process of rebuilding a previously badly abused John Deere x495 that I just acquired. It had obviously overheated before I acquired it. It would barely run and smoked a lot. So, I began to tear it down.

With the timing gear cover off, on a whim, I decided to check the tightness of four bolts located on the face of the injector pump cam gear. I gave each one a turn and found that they seemed loose for 12mm hex head bolts; just barely snug. I tightened them only slightly. I was using a torque wrench set to 15 foot pounds, so I did not over-tighten them based on normal standards for this size bolt. In fact, I didn't even make it to 15 foot pounds.

I looked in the service manual to find the torque setting, only to find this disturbing note:

"IMPORTANT: Avoid damage! Do NOT loosen bolts (H). If bolts have been loosened, the camshaft and gear must be replaced by AM880628 fuel injection pump camshaft kit."

Here's a larger picture of the timing gears:

Nothing further is mentioned in the service manual about why this entire assembly "must be replaced" if the bolts are "loosened." Neither, does it say what will happen if the bolts are tightened, as in my case. To make matters worse, this assembly is no longer available, anywhere.

It appears that the bolts go through slotted holes in the gear and are used to perform the rough timing of the injection pump cam; with fine tuning being completed via shims under the pump. It seems that once this is changed (by loosening the bolts) it is nearly impossible for a repair shop (or lay person) to reset the timing relationship.

Assuming that I didn't move the timing gear in relation to the injection pump cam shaft, I still don't know what the correct torque should be, or, what damage (or malfunction) might occur if I use this assembly now, after tightening the bolts. Anyone familiar with this type of injection pump cam gear with bolts?

 

[beenthere]

Assume this is the Yanmar diesel?

And as I read what you said, you didn't "loosen" the bolts, just tightened.

Or do you think someone else loosened them? and that is the cause of the engine problem? just wondering...

If me, I'd go talk with the mechanics at my Deere dealer. Don't know if that would work, nor if it would work for you.

Also, I'd try to reach out to Yanmar for info.

 

[scooter2]

IF you learn more, please post or PM.
I am considering the purchase of an x495 and I am trying to discover if this is a potential problem..........and cost to remedy.
Thank you for the photo.

I will keep this updated as I learn more.

The engine is still torn down. I honed the cylinders and installed three new pistons. Also installed new rod bearings. Started cleaning the head and found a crack at middle cylinder. Now, looking for a used head.

I have read that the X495 has a potential for the radiator screens to become clogged, sometimes resulting in overheating. Can't say whether this is due to owners failing to keep them clean, or if they are just inclined to get clogged due to the design. At any rate, something had caused this one to overheat -- which I knew when I bought it. One obvious clue was that the oil filler cap had melted. The external part, outside the engine, looked OK. But when you unscrewed it the threaded part of the plastic had dripped down into the engine. Looked like a dripping candle. I knew there was some engine damage, but had to tear into it to find out what was damaged. I was hoping that perhaps it would be only a head gasket, but now I've found the cracked head.

Here's one thing to be aware of for anyone rebilding one of the Yanmar 3TNA72 (as in the 455) or 3TNE74 (as in the X495) engines. The service manual is wrong concerning the tightening torque for the oil pump fasteners. The screws are m6x1 thread. The manual says to torque the three socket head cap screws to 221 inch pounds. When I rebuilt my 455 a few years ago, I stripped these bolt holes trying to achieve the stated torque. Had to drill and tap the holes and use m8x1.25 replacement bolts. This time, on the X495, I again tried to go to 221 inch pounds, and again stripped the holes. Again had to drill and tap, and use the larger size screws.

Before someone tells me how dumb I was to try to tighten m6 bolts to 221 inch pounds, yes, I now know! I've since looked up the recommended torque for m6x1 machine bolts going into alloy and it is more like half that, or less than 100 inch pounds.

As for the injection pump cam gear bolts, I do not believe the engine had been torn down to this level before. All of sealant on the timing gear case cover looked like it would from the factory. It is possible that the bolts may have loosened some when it overheated. The reason I checked them is that, when I was torquing the oil pump bolts, on a whim, I just decided to check the timing gear bolts.

At this point, I'm not overly concerned. I do believe they are set at the factory and that it would be very difficult -- if not impossible -- for someone to get the cam shaft-to-timing gear relationship correct if it were ever maladjusted.

I have already reinstalled the timing gear cover. So, I'll find out after I get a new head and complete the reassembly.

 

[scooter2]

Assume this is the Yanmar diesel?

And as I read what you said, you didn't "loosen" the bolts, just tightened.

Or do you think someone else loosened them? and that is the cause of the engine problem? just wondering...

If me, I'd go talk with the mechanics at my Deere dealer. Don't know if that would work, nor if it would work for you.

Also, I'd try to reach out to Yanmar for info.

Discovered them to be what I considered "loose" just by chance. Had a torque wrench in hand and decided to just check them. Torque wrench was set very low, like around 15 foot pounds, but they turned just a little. I tried all four and they all turned some.

I did not loosen them, only tighten. Almost certain that no one loosened them before I got the tractor. The engine looked like it had never been cracked open before.

Have not had great luck trying to talk with John Deere mechanics. They seem a little protective. By chance, there is a large Yanmar importer/dealer reasonably close by. I could ask them and may, but thought it would be helpful to post this here for the reasons stated in the original first post.

 

[beenthere]

Thanks for the additional info.
As to the debris plugging the radiator, my 425, and 455 are a much better design than the one-piece hood Deere went to with the X series tractors. Very little dust and dead grass debris gets past the side panels of the 400's, whereas considerable debris gets past the one-piece hood. To the point, I don't use my X485 for lawn mowing (another reason is the poor design of the mowing deck).

 

[Coyote machine]

Try this independent diesel IP specialist shop and see what they can tell you. They work on many brands and have specialized knowledge:
Joel Shenk at Conestoga Diesel, in PA. fuel injection injection pump injection pump rebuilding injection pump repair, Conestoga Diesel Injection Fuel Injection and Turbocharger Rebuilding. The Moose Pump people! Willow Street, PA Home Refer to Sticky at top of Kioti Owner/Operator forum for more info.
Post back results.

 

[Zebrafive]

Thanks for the additional info.
As to the debris plugging the radiator, my 425, and 455 are a much better design than the one-piece hood Deere went to with the X series tractors. Very little dust and dead grass debris gets past the side panels of the 400's, whereas considerable debris gets past the one-piece hood. To the point, I don't use my X485 for lawn mowing (another reason is the poor design of the mowing deck).

Which deck? (x485) I am guessing different on the 455, what does it have? Reason I ask is looking to get a newer JD, thinking 455 or x495/x744

 

[scooter2]

Thanks for the additional info.
As to the debris plugging the radiator, my 425, and 455 are a much better design than the one-piece hood Deere went to with the X series tractors. Very little dust and dead grass debris gets past the side panels of the 400's, whereas considerable debris gets past the one-piece hood. To the point, I don't use my X485 for lawn mowing (another reason is the poor design of the mowing deck).

I could call the John Deere dealer or specialty shops, but thought this would be a good topic to have posted in the forums for future re-builders. I don't like to ask businesses for free advise. If I'm going to take up their time I feel like I should pay them for their knowledge. Hopefully, at some point someone will come along who is familiar with this rather esoteric problem.

Interesting comments about 455 vs X495. I'm on my second 455. Bought one that was ready for the dump. Did a complete restoration and engine rebuild. Ran great. Thought I wanted a zero turn, so bought a JD 757, used. Went through it to make sure everything was perfect. Ran it for about two months and decided (along with my wife, who likes to mow) that the 455 (which I still had) was better suited for our 3 acres. Listed the 757 and, of all things, had a guy call wanting to trade me a.... JD 455! His had around 900 hours and was in good condition all around. We completed the trade and I ended up with two 455 mowers. Decided to sell the one I restored, with plans on going through the newly-acquired one at some later point in time.

That's when I came across the X495 that I'm working on now. A little disconcerted to hear that you prefer the 425/455 to the X4xx tractors. Oh well, guess if I get this one running I'll have a chance to compare them. I'll post some pictures later of how the tractors looked when I acquired them.

 

[beenthere]

Both 54" decks... the X485 I believe is 54C. Just does not do the fine job mowing grass nor with the leaf PowerFlow unit as the older 54" decks. Again, my opinion. The 54C blows grass out from under the deck whereas the old 54 does not.