Bobcat 721

[MS1080]

Hi all, I bought a bobcat 721 for private use in our garden. I changed all filters and fluids and the hydraulic runs really good. But when i push through both handles for full speed the engine stalls and will nearly quit until i release the handles for nearly half speed. So i think it has Quite half of the rated Power it also is really Hard to Start. Its the deutz f2l411 engine, dies anyone know which engine can bei replaced? Some kubota or other deutz f2l Best regards Matthias

 

[mmsllc]

I am not familiar with the smaller machines. What engine is in your 721? Gas or diesel?

 

[MS1080]

I am not familiar with the smaller machines. What engine is in your 721? Gas or diesel?

It is a Small 2 cylinder deutz Diesel with the Name f2l411. Original about 28 hp But Mine feels like 10 HP.

 

[Tazza]

It is a Small 2 cylinder deutz Diesel with the Name f2l411. Original about 28 hp But Mine feels like 10 HP.

Sadly it isn't as easy as slapping in a kubota, the deutz is air cooled, the kubota is liquid cooled.
You said it's hard to start, do you use the excess fuel button the in the injector pump when starting the machine?
Just how hard are you pushing and how high are the revs?
Try pushing into the pile of dirt slowly, you still have the same torque at lower speed, if the engine bogs down too much, ease off the sticks.

 

[mmsllc]

Sadly it isn't as easy as slapping in a kubota, the deutz is air cooled, the kubota is liquid cooled.
You said it's hard to start, do you use the excess fuel button the in the injector pump when starting the machine?
Just how hard are you pushing and how high are the revs?
Try pushing into the pile of dirt slowly, you still have the same torque at lower speed, if the engine bogs down too much, ease off the sticks.

To better understand what you saying = are you pushing into a pile as far as you can & then curling the bucket back & then lifting after the bucket is curled back all the way? I've seen this as being the proper way to fully load up the bucket as a way to maximize the capacity of the bucket. It might also help to know the size of your bucket & if it is meant for your machine, too. I've seen huge buckets (meant for lighter mulch or just to push snow) I've bought a 751 that came with a 78" mulch bucket. It was an obvious mis-fit!!

 

[gearbox]

To better understand what you saying = are you pushing into a pile as far as you can & then curling the bucket back & then lifting after the bucket is curled back all the way? I've seen this as being the proper way to fully load up the bucket as a way to maximize the capacity of the bucket. It might also help to know the size of your bucket & if it is meant for your machine, too. I've seen huge buckets (meant for lighter mulch or just to push snow) I've bought a 751 that came with a 78" mulch bucket. It was an obvious mis-fit!!

If there is a button on the pump make sure that it is not stuck in as it will hold the pump rack from going to full fuel

 

[MS1080]

If there is a button on the pump make sure that it is not stuck in as it will hold the pump rack from going to full fuel

I tested to lift some stuff around 600kg it was no problem for the lift and tilt. But the Problem is, when i drive without any load and push the handles for maximum speed the engine goes down and out when i dont release the handles to drive slower. i cant reach the maximum speed even on a flat road. I think the engine is worn out, especially with this slightly blue smoke when torque is needed.

 

[SkidRoe]

I tested to lift some stuff around 600kg it was no problem for the lift and tilt. But the Problem is, when i drive without any load and push the handles for maximum speed the engine goes down and out when i dont release the handles to drive slower. i cant reach the maximum speed even on a flat road. I think the engine is worn out, especially with this slightly blue smoke when torque is needed.

Here is a test to try: Drive up to something really solid, like a concrete wall, make contact and then slowly push your sticks forward. If everything is healthy, you should be able to break traction and spin the tires. Let us know what you get as a result.
Also, I believe that the 72X models were available with a 2-speed option, which was facilitated through the use of variable displacement drive motors. Are you stuck in high gear or have the swash plates over travelled, allowing a top speed that is higher than normal?
HTH - SR

 

[Tazza]

Here is a test to try: Drive up to something really solid, like a concrete wall, make contact and then slowly push your sticks forward. If everything is healthy, you should be able to break traction and spin the tires. Let us know what you get as a result.
Also, I believe that the 72X models were available with a 2-speed option, which was facilitated through the use of variable displacement drive motors. Are you stuck in high gear or have the swash plates over travelled, allowing a top speed that is higher than normal?
HTH - SR

You may not be able to get both to spin at the same time, but you should be able to get one side to break traction easily.
Blue smoke isn't great, it is sounding like the engine is worn, hopefully not too worn.

 

[MS1080]

You may not be able to get both to spin at the same time, but you should be able to get one side to break traction easily.
Blue smoke isn't great, it is sounding like the engine is worn, hopefully not too worn.

Hi, i tested to drive against a concrete wall, and the tires couldnt spin, the engine RPM goes down till its out. So i have to handle a rework or replacement of the engine i think. But where could i find some informations which motor could fit ?

 

[flyerdan]

Hi, i tested to drive against a concrete wall, and the tires couldnt spin, the engine RPM goes down till its out. So i have to handle a rework or replacement of the engine i think. But where could i find some informations which motor could fit ?

The 700, 720, 721 and 722 are all the same frame, just different engines. A Wisconsin VH4D and a Ford 98 cid industrial, can't find a model number in the book for it. Probably the easiest retrofit would be the Wisconsin, but sourcing one might be more expensive that overhauling the Deutz.

 

[SkidRoe]

Hi, i tested to drive against a concrete wall, and the tires couldnt spin, the engine RPM goes down till its out. So i have to handle a rework or replacement of the engine i think. But where could i find some informations which motor could fit ?

That does not sound good, but before you completely throw in the towel, do a compression test on the engine to be sure that it is shot.
As far as what to put in, do you want to keep it a diesel, or would you be open to converting it to gas? You may be able to graft in a 35 hp Briggs & Stratton Vanguard engine.
If you are hooked on diesels, your best bet would be to stay with the Deutz and rebuild it. Anything else would be water cooled and would require you to put in an entire cooling system, which could be more trouble than it's worth.
FWIW - SR

 

[Tazza]

That does not sound good, but before you completely throw in the towel, do a compression test on the engine to be sure that it is shot.
As far as what to put in, do you want to keep it a diesel, or would you be open to converting it to gas? You may be able to graft in a 35 hp Briggs & Stratton Vanguard engine.
If you are hooked on diesels, your best bet would be to stay with the Deutz and rebuild it. Anything else would be water cooled and would require you to put in an entire cooling system, which could be more trouble than it's worth.
FWIW - SR

Silly question, but have you changed the air filter?
It may still be worth checking up what it will run you to replace rings, pistons and possibly even the cylinders.

 

[bobbari123]

Silly question, but have you changed the air filter?
It may still be worth checking up what it will run you to replace rings, pistons and possibly even the cylinders.

that deutz engine is very reliable, way better than kubota. i suggest that you change new fuel filter and send injectors to diesel shop, so they can check them. bad injectors could make it hard to start and cause lack of power and also smoke from exhaust

 

[bobbari123]

that deutz engine is very reliable, way better than kubota. i suggest that you change new fuel filter and send injectors to diesel shop, so they can check them. bad injectors could make it hard to start and cause lack of power and also smoke from exhaust

and check that throttle linkage so it will apply full throttle

 

[MS1080]

and check that throttle linkage so it will apply full throttle

I changed all filters and fluids and installed also a new electric diesel pump. the trottle is at max, there is a screw at the engine which will block. So i have to open the engine to see its condition. Has anyone a few hints how the compression could be measured on this engine without spark threats or anything else?

 

[SkidRoe]

I changed all filters and fluids and installed also a new electric diesel pump. the trottle is at max, there is a screw at the engine which will block. So i have to open the engine to see its condition. Has anyone a few hints how the compression could be measured on this engine without spark threats or anything else?

You need a diesel compression tester, like so:
http://www.princessauto.com/en/detail/pro-point-diesel-compression-tester-set/A-p8428062e
http://www.amazon.ca/Performance-To...383&sr=8-1&keywords=diesel+compression+tester
You may be able to borrow/rent one from a diesel/truck shop.
Cheers - SR

 

[Tazza]

You need a diesel compression tester, like so:
http://www.princessauto.com/en/detail/pro-point-diesel-compression-tester-set/A-p8428062e
http://www.amazon.ca/Performance-Tool-W89731-Diesel-Compression/dp/B00EDEEHRG/ref=sr_1_1/186-2285526-6958101?ie=UTF8&qid=1454331383&sr=8-1&keywords=diesel+compression+tester
You may be able to borrow/rent one from a diesel/truck shop.
Cheers - SR

It is a bit more difficult on this engine, no glow plugs to screw into. As you will know, the injectors do not screw in, so finding an adaptor may be a little difficult.

 

[SkidRoe]

It is a bit more difficult on this engine, no glow plugs to screw into. As you will know, the injectors do not screw in, so finding an adaptor may be a little difficult.

What holds the injectors in? Our old Ford tractors on the farm did not have screw-in injectors, or glow plugs, neither does the Cummins in my pick-up, but we could still test compression.
There has to be a way, even if you have to have an adapter machined.
Food for thought - SR