Because both lap bars do nothing, it could be something as simple as a broken belt or a belt that has come off. I would not junk it yet.
There is a possibility that a key on the hydro may have been sheared on the shaft that holds the pulley on. It is not usual that both hydros stop working at the same time if this is the problem.
The pulley could be spinning on the shaft so as to not transfer energy.
If everything that you have mentioned is good, Then just about the only thing we can see is that both of the hydros have gone bad. Make sure you take this to a good dealer for inspection before you buy new hydro's just to make sure that it really is the problem.
This is really a job for a good shop. I realize that "Take the mower to a shop" is not the kind of answer that you really wanted, but it is the CORRECT answer.
Feel free to contact me here at this question anytime ...even after you hit the "ACCEPT" button ...and I will try to help further.
If everything else on the mower is Good, it could very well still be worth fixing. I really do not think both hydros quit working because you did not say that your 15 year old son was hot rodding it, doing a mock tractor pull, or jumping buses. It could happen that they both quit simultaneously from normal mowing, but I seriously doubt it.
I really expect it to be something small like a sheer key on a pulley shaft or a belt. I hope this saves you lots of money.
The engine will be turning the pulley which will be moving the belt.
The belt must transfer the energy to another pulley which may be spinning on the shaft (if the key is broken).
It is also possible that at low speed the belt could turn the pulley and shaft with no load.
But when running, it may slip.
Also possible that the key is sheered off Inside the transmissions
It is very hard to say where the problem is.
I would need the model and serial number of your unit to give exact rather general help.
They are not all the same in design.
Some had the keys on the shafts under the pulley which is what kept the pulley from spinning on the shafts.
Some, the key was actually part of the pulley and when it sheered, the pulley had to be replaced.
Some, the key was actually INSIDE the transmission (a dumb place for it).
You can not tell, but I do not like the MTD equipment at all because it just is not made well. Cub cadet used to be a fantastic brand made by International Harvestor. But, they sold their NAME to MTD and they have put the name on the same cheap equipment they sell in the Discount stores. The same has happened to Yardman, Troy bilt, Bolens, White, And several other brands. They are all the same MTD Cheap stuff now.
In speaking with my brother on the subject He had very strong feelings about it (He is also an expert here and has 37 years running one of the largest shop around).
He thinks the best idea is to sell yours on craig's list as it is and buy a New one of quality. He suggested saying that it "Needs some work, and you just did not want to invest the time fixing it" People are so Hungry to buy used ZTR's that they are overpaying for junk. HE said you could expect to get $600 to $800 out of yours without fixing it. He also considered the fact that yours is MUCH too small for your yard, and you are going to have more and more problems with it as it gets older.
He said to me, on the phone, that he thinks buying a USED ZTR is a Huge mistake (but do not tell the prospective buyer. In his experience, no one ever sells a ZTR used until after it is already causing them problems. This is not the case with regular tractors, as they many times are sold just because someone wanted a New ZTR.
He said why would you spend $3600 on a used one, when you can pay $4600 for a New one. There is a Toro ZTR commercial design that sells for that much. It is made by EXMARK who is one of the best manufacturer of commercial equipment. Toro bought them out, and has them make ZTR's for them specifically for homeowners with yards your size.
Do not get me wrong, all the Toro Front engine Tractors are the same Cheap MTD junk that everyone else sells (yes MTD has even convinced Toro / Wheelhorse to allow the name to be put on the MTD cheap junk). But, the Toro Commercial ZTR's are fantastic.
I will be glad to provide specific information as soon as I get them model and serial numbers from you, but I wanted to share this with you before we went too far.
Also, fixing your MTD ZTR is not going to add much value to it on craig's list. Weird, isn't it. Just tell them you do not know exactly what is wrong with it, You checked and the belt was was good, but someone said there might be a pin or a key sheered somewhere, you just chose not to mess with it considering it was too small for your yard anyway.
I wanted to apologize for taking so long to give you the above response. I usually start at 6AM, and usually try to limit myself to working 12 hours per day. I am sure you understand. I saw your question come across just as I was leaving, so I called my brother to ask him to answer it for me. I was locked out of the question because I had left it up on my screen when I headed out to the Movies "Don't go see "Unknown" What a waste of a good idea and the price of tickets. Lucky I had a half price coupon.
Anyway, he sent me an email as if he was answering your question. I am going to send it to you in its entirety, partially because he took the time to respond out of respect for him and partially because I thought it might be nice to get another expert's opinion.
Warning, He can be blunt. But in doing so, he has your best interests at heart. Much may sound like what I already said, but he says it differently.
Please note: I wrote my answer before reading his, but after a short phone conversation on the subject.
JIM,Here is an answer for your ZTR QUESTION http://www.justanswer.com/small-engine/4n7x2-42-zero-turn-cub-cadet-wont-move-wife-went-start.html This particular ZTR is know for the hydrostat breaking and having to be replaced. If the belts are turning and the push/pull lever is in the proper drive position, then it is most probably that the hydro is bad and must be replaced. The size and quality of this unit is NOT proper for the amount of yard that you are using it on. It is quite undersized and wears out quickly under these conditions. If you are unwilling to spend the large amount of money that it will take to replace the hydro on this unit. Then I suggest that you buy a different ..... much better quality...mower. Even though the NAME cub Cadet "Used to be" a good brand name. It is no longer the case.... since they have been taken over by the DISCOUNT BRAND "MTD" Make sure that whatever you buy is a much better quality unit that has NOTHING to do with MTD. Also make sure that you get a large enough unit for your lawn.One that I would suggest is the TORO "Titan" Remember TORO has two different lines of ZTR's and you want the better line. The less expense line is probably the best unit for up to 1 acre or even up to an acre and 1/2 but NOT enough unit for your size lawn. The TORO "TITAN" 48" is a rugged unit with a commercial deck. It is actually built by "EXMARK" Toro owns "EXMARK" and they work together. Selling price for this unit BRAND NEW is only about $4500.00 and has a 3 year warranty. Yes there are several others you could buy but this is the best I have found for the money. My BIGGEST SUGGESTION is this !!!!!DO NOT EVER BUY A "USED" ZTR FROM ANYONE FOR ANY REASON !!!!!! ""EVER"" EVER !!!!!You will ALWAYS HAVE problems with the used unit because the prior owners usually have run it to death ! Most people do not know what "ZTR" Stands for!!! ZTR stand for "ZERO TURNING RADIUS" It DOES NOT STAND FOR "ZIP THROUGH AND RACE" !!!!! Most people drive the ZTR's very quickly because they think that it will save them money and time. They are WRONG!!! Going slower will make the unit last considerably longer and you will get a much better cut. All of the bouncing and bumping causes everything to wear out very quickly. Start with a BRAND NEW unit of good quality and you will use it for many years without a lot of problems....provided that you understand the concept of driving it slower to conserve it's life. This is true of ALL BRANDS of ZTR's regardless of what some other dealers want you to believe. Remember, they want to sell you a mower and will usually tell you anything they think you want to hear. I hope that this helps.
Also please note, that most used ZTR's are also from people that bought too small of a unit for their yard and upgraded to a larger unit as well. Some people have 5 acre yards and buy the one designed for your size yard and wear it out in 2 or 3 years.
I need the model number and serial number of your ZTR unit.
The model number usually is something like 13-112434 or 31-2134324 followed by a serial number.
Often it is under the seat.
I am Not 100% sure of the pin problem after speaking to my brother as he reminded me that often these units have two pulleys one on each hydro unit and it is unlikely that both of THOSE pins broke at the same time.
The in order to see any pins or keys, you have to remove the pulley.
I argued my point with him and we agreed that it is possible that the pulley mounted to the engine could have sheered a pin, but you would have noticed that the belt was not turning.
WHen you had it on the ground and tried to drive it, was the belt spinning normally. Were all pulleys spinning normally?
If the pulley on the engine is spinning with force, and the belt it is driving is moving with force and if it is spinning all the other pulleys with force.
Then you need to look for the error where the last part of the energy is not being transferred.
If all belts and pulleys are moving, then make sure the LAST pulley is not spinning on the shaft. It is a key that would make it Not spin the shaft we are after.
If the shafts on the hydros are both spinning, then the problem is Inside the hydros.
This gets very sticky
Also, there are rods that can be moved to allow the unit to be able to be pushed. You should not be able to easily push your unit without moving these.
Check to make sure they are in place and have not popped out of position.
You would then be in free wheeling mode. This is an easy fix, but I assumed that since it was working when being driven then suddenly stopped, that this was not the case. But I suppose that they could have not been engaged all the way. Check these.
Was it easy to push? It should not have been. Also, NEVER push a hydro with these engaged or you will cause permanent damage.
Many people Drag a hydro around with a truck when they won't working because they are too had to push and destroy the hydro simply because they are not away of the rods that must be disengaged in order to push it around.
Trust me, I fully understand "personal economic issues". That is why I was working so hard to try to save you money if possible.
If it is something simple, I say fix it, but do not replace the hydros. You will never get your moneys worth from the investment.
Also, Last I heard Toro had a 90 or 120 day same as cash program. Just a thought.
That was not an expected answer at all.
You said there was a pop, that the engine kept running and neither of the lap bars would do anything.
Yes, a broken piston would make a pop.
In a 2 cylinder engine, it could keep running.
BUT, if the engine is running, what the heck would that have to do with it not moving at all when a lap bar was moved?
Not saying it could not have a broken piston.
But, be careful about trading it in.
You might end up seeing it on their showroom floor 3 days after you did.
When you said it kept running, was it running right?
With a broken piston, it would Never sound right again.