JD744 w/noisy Yanmar 24hp Diesel

[Gary Clark]

Wife & I bought a JD x744 with Yanmar 24hp diesel about a6 wks ago as a replacement for a JD445 she cuts our 7 ac grass with. In the time we've had it, besides a few minutes of running to attach/detach johhny bucket & JD snow blade attachments, it has been parked. My wife remarked at that time she thought it was noisy.
For the 1st time last wk, my wife took it out to cut our 7-8 acres of grass; 5 passes & the neighbor hiked out to talk to her & remarked that the engine was "very noisy, didn't sound right". We took it to the dealer Saturday, svc mngr said it "sounds like a diesel"; we started a JD 2305 in the lot with same engine & compared, our JD x744 Yanmar had a much louder mechanical rapping noise than the JD 2305 Yanmar, same engines. Svc mngr said they'd check it out. Dealer left voice mail yesterday saying nothing found, machine ready for pick-up.
Any good advice out there on next step to A) confirm (or not) there is a problem or potential problem? & B) get JD/dealer to do something about it if confirmation? I am going to record our JD x744 Yanmar 24 hp diesel at 3 speeds, idle - 1/2 & full throttle, & record 3-4 other new JD XXX Yanmar 24 hp diesels same way for comparison. Also taking it to local small engine repair shop (not JD dealer) for advice. Thanks for any suggestions.

 

[jcmseven]

I cannot answer your question well, but I can say I have had four different Yanmar's in this sized engine, and they all have sounded differently. The engines will also sound differently between an X series and a 2305 due to how the engine mounts are and the shape of the hood, etc. The cavernous hood style of the X series tends to magnify sound even though it is fully enclosed. I also will say that among the engine I have used, three of them were on X series tractors, and again they all sounded differently. They all also ran well. My advice would be that unless your dealer (or another JD dealer) can find something mechanically wrong with the engine, or muffler (a common source of tone differences) to not bother the engine. Yanmar has a history of making very solid engines. Every now and then, one will be bad, but it is incredibly rare and a case report. One thing I would not advise is to allow a non-JD small engine shop to begin working on this engine. These engines are complex and JD offers a pretty comprehensive warranty on your machine, unless someone else messes with it--then its voided if they find out. Yanmar warranties its own engines in these machines, but they will abide by the JD warranty in most cases. If one has to buy one of these engines, they are several thousand dollars. My advise would be to have your current dealer or a nearby JD dealer re-look at the machine and if nothing is found, continue to use it with ear protection. There is some engine to engine variability on the sound, so long as the exhaust is appropriately sealed, which would be my bet if there is a problem. These engines are loud, especially at idle and many times people are not used to this and do not like that aspect. My father is an example of that. I am letting him use my 850D Gator, which is much better than his previous machine and a real stump puller, but he does not like it because the engine is "too rattley". I am no expert, but if you could process a high quality file of the engine at those differing speeds I and others on this forum who have them would be happy to listen in for you.

John M

 

[AKfish]

Welcome to TBN, Gary.

Lucky man - has a Yanmar diesel - and a wife that likes to run it! :thumbsup:

Does your dealer have another JD744 on the lot or a couple of them with the Yanmar?

If so, any chance that you and your wife could fire them up for a look/hear? That might ratchet back some of your concerns.

AKfish

 

[joes_427_vette]

Gary;
Welcome to diesel land. My 455 had over 2,000 hours on it when I bought a new 4110. The 4110 from day one has the loudest sharp crackle noise I have ever experienced. The dealer said I could buy a new muffler ( $240.00 and no return if mounted ) to see if it cured the problem but to them it was within normal range. My brother has a new diesel Gator which is quieter than mine with basically the same engine. I wear ear muffs and hope when it gets a couple hundred hours on it mellows out. My 55 hp New Holland is very quiet and I can speak with people while it runs without adjusting my ears.
I wanted to design another extension on the exhaust system to experiment with the noise level but haven't come up with a plan. I don't want to put more back pressure on the valves by restricting the outlet. I don't mind noise but the sharp tone without ear protection would be unbearable.

 

[LBrown59]

we started a JD 2305 in the lot with same engine & compared, our JD x744 Yanmar had a much louder mechanical rapping noise than the JD 2305 Yanmar, same engines.

Trade the X744 for the 2305.

 

[joes_427_vette]

While your trading buy a gasoline model zero turn. Faster, quieter, and turns on a dime. Course the newness hasn't worn off in six weeks. Radio headphones come to mind. Entertainment while tending the lawn.

 

[jcmseven]

ZTR, not that much faster and you can't till the garden with it. OK, I will take that back, they are some faster on lawns that are smooth, pretty flat, and that have a lot of turns, none of which I have on my property, sadly. My 757 60" cut ZTR was only a few minutes faster on what I mow than my X595 (the precursor to the X748), and I am decent at using a ZTR.

John M

 

[joes_427_vette]

JCMSEVEN;
Were just interjecting a little humor. Don't get upset. We really try to help on occasions although it doesn't sound like it at times. I'm living with the same problem you are. Haven't come up with the perfect fix but it is rolling around in my head someplace. I also like the flexability of a lawn tractor vs a ZTR. I have more ways to get into trouble.
Hang in there... we will find a cure.

 

[Gary Clark]

That's some very helpful commentary here & later regarding comparing tonal differences of yanmar in our 744 against the 2305, never considerd effects of engine compartment cowling/space, engine mounts & muffler. Good advice re: passing on getting local small engine shop commentary. I'll find another dealer with x700 yanmar & get recording(s) & forward. Need to compare apples & apples is clear. Local dealer has no x700 w/yanmar so I'll find nearest one that does to do just that. Thanks much for the advice.

 

[Gary Clark]

Don't have that much experience with diesels in this size range so the commentary on differences in sounds even for same exact yanmar 24hps is interesting & helpful, alleviates some concern ... I would (& did) expect identical behavior sound wise, even between different chassis, ie, our x700 vs 2305. We have a Kubota Z21 ztr & neighbors Kubota CUT diesels to compare our JD 744 yanmar to, both husky diesel sounds but quieter in that there is very much less mechanical ping/rattle compared to the yanmar (I liken/guess that sound to be result of valve/lifter noise), both kubotas comparably quieter. btw, the kubota ztr is ~11-12mph in the wide open stretches while the JD 7xx is ~7-8mph, I generally xcatch & pass the wife on the JD every 5-6th loop when we're cutting the same 3-4ac field as an oval. The JD with AWS however is superior around our landscaping around house & fruit tree grove ... easier on grass in tight turns. You can't have any fun with the attachments with the ztr like you can with the JD 744, but it does cut a lot of grass fast.