D722 to D902 engine swap?

[LanceM]

I've had a BX1850 that I picked up dirt cheap with a cracked head on its D722 engine. I'm finally looking into fixing it, and found a D902 engine locally. Is it possible to make this swap fairly easily? Or would it require a lot of changes? From what I can see, they look very similar and the dimensions are within 1.25" any direction. Are there any downsides or other considerations I should have in mind?

Also, I know the engines vary depending on what they were designed for... tractor, generator, UTV, etc. Is there a way to identify which was designed for tractors? Are there other models (maybe from a UTV) that would be acceptable to use? I believe the engine I'm looking at is a D902 ET03. Where can I find information on what that came out of?

Thanks!

 

[Workerbee]

You should be able to find a new head and gaskets required for around 6-700. Unless you like the aggravation of swapping something different in there, that seems like a reasonable alternative to me.

 

[LanceM]

You should be able to find a new head and gaskets required for around 6-700. Unless you like the aggravation of swapping something different in there, that seems like a reasonable alternative to me.

Unfortunately it's looking like around 1000 for the head and valves as suggested on another thread on this site. I'm not totally against it, but there's a 902 listed for under $200 locally.

I'm mostly trying to feel out how much aggravation would be involved in that swap... bolt patterns, belts, cooling system, etc., as well as the differences in the versions of the 902 that would potentially be suitable (generator, mower, tractor, UTV, etc) and how to identify which is which.

 

[Workerbee]

Ive done swaps before on mowers primarily, and it seems there are always little things that require a lot of time and fabrication to get past. Firstly, are you positive there’s no issues with the 922, hidden or otherwise? Excessive hours? If your 922 was longer will it fit in the frame? Or is the engine block the frame? How will a different length affect your driveshaft for the front axle? Is the exhaust manifold in the same location or will you need to modify the exhaust system or cut up your cowling to get that to go? Double check your mounting bolt patterns as a little off can be a pain. Lots of things to consider. But I see why yould attempt this and I likely would too. Theres information online about Kubota engine dimensions and possibly mounting patterns. Its been a few years since I needed to look those up, but by googling I did find that. Good luck on your project!

 

[North Idaho Wolfman]

The D722 and the D902 are of the same family so a swap "should" be pretty straight forward, The real plus is your mounting to the front of the engine so no bell housing or clutch issues.

I would be highly suspect of a Good $200 D902 as they normally go for way more.

I would want to hear it run before installing it, this would also answer the issue is it a 1800 RPM gen motor (that can get pretty pricey to change the internal parts needed to run it up to the proper RPM needed for your tractor).

 

[LanceM]

Ive done swaps before on mowers primarily, and it seems there are always little things that require a lot of time and fabrication to get past. Firstly, are you positive there’s no issues with the 922, hidden or otherwise? Excessive hours? If your 922 was longer will it fit in the frame? Or is the engine block the frame? How will a different length affect your driveshaft for the front axle? Is the exhaust manifold in the same location or will you need to modify the exhaust system or cut up your cowling to get that to go? Double check your mounting bolt patterns as a little off can be a pain. Lots of things to consider. But I see why yould attempt this and I likely would too. Theres information online about Kubota engine dimensions and possibly mounting patterns. Its been a few years since I needed to look those up, but by googling I did find that. Good luck on your project!

All good things to consider. Thanks for the input!

 

[LanceM]

The D722 and the D902 are of the same family so a swap "should" be pretty straight forward, The real plus is your mounting to the front of the engine so no bell housing or clutch issues.

I would be highly suspect of a Good $200 D902 as they normally go for way more.

I would want to hear it run before installing it, this would also answer the issue is it a 1800 RPM gen motor (that can get pretty pricey to change the internal parts needed to run it up to the proper RPM needed for your tractor).

I know they're both part of the "super mini series", but wasn't sure how much that affected swapping. I'm very suspect of the engine myself- still trying to gather information on it at this time. I have seen several used 902's since I bought this, but have yet to find a 722 locally. So whether or not this particular engine is good, it's worth the research in case another pops up.

Are the RPM's the only real difference between a generator motor and the tractor motor? I believe this came off a Kubota RTV, so I'm assuming the RPM's shouldn't be an issue.

Thanks!

 

[Workerbee]

Lance I see theres a brand new d722 listed for 2000 here on CL. Im not sure of any details and just passing it on as food for thought. No affiliation.

 

[5-th-times-a-charm]

From what i noticed while swapping 902 in kubota rtv with 722 and I'm sure theres many other possibilities with other 722 with different spec numbers.

!.Cam 722 lacks spur gear to drive hydro pump #2 for power steering.

2. engine mounts had to be welded differently. it didn't bolt right up.

3. The exhaust manifold was mounted to the head differently and couldn't be swapped. which didn't allow the stock exaughst setup to bolt back on without reconfiguring cutting welding.

4.I think its 18% less powerful

5. The thermostat housing doesn't come off without removing the front cover (or something like that coolant

Of course, there are workarounds for all these things but there is a risk of something not going right on each workaround, and then you are back where you started. and My opinion is its better to just rebuild your 902 if possible. That way you know what you got. It all being done proper and takes the same amount of time. I can be cheaper also. unless you find a 722 for next to nothing.

 

[Henro]

My BX2200 uses the D905, and the BX1800 uses the D722. I believe they are essentially the same tractor and only the engine differs.

So the question may be, how different are the D905 and the D902 engines?

I have no clue, but maybe this data point may be of some help…