Flex hone

[Feedbag]

Hello, I have a 743 with a Kubota V1702 4 cylinder diesel engine it. I am putting in new piston and rings due to low compression. The cylinder walls are 3.25” and are within spec with no scaring or scratches. I was planning on using a flex hone for cross hatching the walls. Should I use a 3.25” flex hone? Or use a 3.5” one? Never used a flex hone before, Thanks...

 

[SkidRoe]

Hello, do you have some information on the hone? Make or website info? Thanks - SR

 

[Feedbag]

Hello, do you have some information on the hone? Make or website info? Thanks - SR

I talked to a machinist and he said the 3.5" hone would be fine. The name of the hone I bought is "Flex-Hone" and I purchased it at NAPA Auto Parts.

 

[Feedbag]

Hello, do you have some information on the hone? Make or website info? Thanks - SR

http://m.brushresearch.com/product-flexhone-tool.php

 

[Tazza]

http://m.brushresearch.com/product-flexhone-tool.php

As they are flexible, the bigger one would be fine.
Do let us know how it goes, they are good engines, but they are prone to cracking heads when they over heat.
I have made a good running engine from 3 parts ones, it started and ran awesome.

 

[Feedbag]

As they are flexible, the bigger one would be fine.
Do let us know how it goes, they are good engines, but they are prone to cracking heads when they over heat.
I have made a good running engine from 3 parts ones, it started and ran awesome.

The head was cracked because it over heated. My oil cooler got clogged up with debris from the fan and that blocked the air flow across the radiator. I did not know the head was cracked and it was starting hard, so I used engine starter. I replaced the head and it ran, but not very good. Took it apart again and found that the #1 and #4 pistons were damaged, probably from the starting fluid. Cylinder walls were OK and within spec, so I honed them out and they all came out pretty good with the flex hone. Have 4 new pistons and rings sets on order.....

 

[Feedbag]

As they are flexible, the bigger one would be fine.
Do let us know how it goes, they are good engines, but they are prone to cracking heads when they over heat.
I have made a good running engine from 3 parts ones, it started and ran awesome.

I read not to use starting fluid in diesels, but I thought it was because of the glow plugs or grid heaters. Only later did I learn that it can damage rings and pistons. Never again, I learned my lesson with starting fluid.....

 

[Feedbag]

As they are flexible, the bigger one would be fine.
Do let us know how it goes, they are good engines, but they are prone to cracking heads when they over heat.
I have made a good running engine from 3 parts ones, it started and ran awesome.

Also, I fabricated an “air wand” that I can use to clear both the oil cooler and the radiator of debris that has accumulated on their surfaces. Hopefully, by doing this, I can avoid the same problem in the future....

 

[Tazza]

Also, I fabricated an “air wand” that I can use to clear both the oil cooler and the radiator of debris that has accumulated on their surfaces. Hopefully, by doing this, I can avoid the same problem in the future....

Starting fluid can be hard on diesels, but i heard that if you use it right, it isn't too nasty. No glow plugs and ensure it's spinning before giving it a shot of starting fluid.
I assume the piston damage wasn't there when you replaced the head? Water from a cracked head can damage it, even bend con rods, ensure you check them when you put your new pistons and rings in.

 

[Feedbag]

Starting fluid can be hard on diesels, but i heard that if you use it right, it isn't too nasty. No glow plugs and ensure it's spinning before giving it a shot of starting fluid.
I assume the piston damage wasn't there when you replaced the head? Water from a cracked head can damage it, even bend con rods, ensure you check them when you put your new pistons and rings in.

Although it should have been obvious, I never considered the coolant as the cause of the damage to the pistons. Thanks for pointing that out. The piston damage was the spaces in between the grooves for the rings, they broke away in some sections. This only happened on the #1 & #4 pistons, the other 2 were fine. Amazingly, the cylinder walls are fine, the pieces of the piston fell apart as I removed them from the engine. Everything else was fine, 4 new piston and ring sets going in soon.

 

[Feedbag]

Starting fluid can be hard on diesels, but i heard that if you use it right, it isn't too nasty. No glow plugs and ensure it's spinning before giving it a shot of starting fluid.
I assume the piston damage wasn't there when you replaced the head? Water from a cracked head can damage it, even bend con rods, ensure you check them when you put your new pistons and rings in.

I did not see the piston damage when I put on the new head as the damage was on the sides of the pistons. Everything looked good at the time of the installation. I mistakenly assumed the head was the only problem when the diesel shop confirmed that the head was indeed cracked. Cost me an additional head gasket, education isn't cheap..... ????????????

 

[Tazza]

I did not see the piston damage when I put on the new head as the damage was on the sides of the pistons. Everything looked good at the time of the installation. I mistakenly assumed the head was the only problem when the diesel shop confirmed that the head was indeed cracked. Cost me an additional head gasket, education isn't cheap..... ????????????

That's the thing, you don't know if there is damage further down till the head is on. You can't get a compression test with a cracked head, so don't be too hard on your self.
I guess the fact the pistons are aluminium, they shouldn't scratch cylinder walls, so it makes sense that no damage was done as it wasn't run this way too long.

 

[Feedbag]

That's the thing, you don't know if there is damage further down till the head is on. You can't get a compression test with a cracked head, so don't be too hard on your self.
I guess the fact the pistons are aluminium, they shouldn't scratch cylinder walls, so it makes sense that no damage was done as it wasn't run this way too long.

I have the engine resembled and I tested the compression, all 4 cylinders came in around 420 PSI. I put the engine back into the machine, bleed the air out of the fuel system, powered up the glow plugs and fired it up. Started right up and once the residual air worked it's way out of the system, it idled perfectly with approximately 54 PSI of engine oil pressure. Very happy

 

[Tazza]

I have the engine resembled and I tested the compression, all 4 cylinders came in around 420 PSI. I put the engine back into the machine, bleed the air out of the fuel system, powered up the glow plugs and fired it up. Started right up and once the residual air worked it's way out of the system, it idled perfectly with approximately 54 PSI of engine oil pressure. Very happy

Awesome job.
They are quite a simple engine, as long as the wear limits are within spec, you really can't go wrong.

 

[TimberHole]

I have the engine resembled and I tested the compression, all 4 cylinders came in around 420 PSI. I put the engine back into the machine, bleed the air out of the fuel system, powered up the glow plugs and fired it up. Started right up and once the residual air worked it's way out of the system, it idled perfectly with approximately 54 PSI of engine oil pressure. Very happy

If you don't mind me asking, how expensive were the parts for the Kubota? Are there any aftermarket parts available? I did a top end in frame overhaul on a 30hp Yanmar diesel and spent about $1,500. I did a full overhaul (which required splitting the tractor) on another engine of the same type and spent close to $3,000 in parts, including the head and machine work. I've wondered about the Kubota parts but thankfully haven't had the need to research it. The Bobcat S150 I bought has about 2700 hours so hopefully it will last me a long time.

 

[Feedbag]

If you don't mind me asking, how expensive were the parts for the Kubota? Are there any aftermarket parts available? I did a top end in frame overhaul on a 30hp Yanmar diesel and spent about $1,500. I did a full overhaul (which required splitting the tractor) on another engine of the same type and spent close to $3,000 in parts, including the head and machine work. I've wondered about the Kubota parts but thankfully haven't had the need to research it. The Bobcat S150 I bought has about 2700 hours so hopefully it will last me a long time.

I got the new head, with the valves from Kumar brothers. I also got the new pistons and ring sets from them. I will have to look back and see what I paid for them and get back to u. I did not think the asking prices for these items were unreasonable tho...... U can see the prices I paid here; https://www.kumarbrosusa.com/kubota/kubota-parts.html

 

[TimberHole]

I got the new head, with the valves from Kumar brothers. I also got the new pistons and ring sets from them. I will have to look back and see what I paid for them and get back to u. I did not think the asking prices for these items were unreasonable tho...... U can see the prices I paid here; https://www.kumarbrosusa.com/kubota/kubota-parts.html

Thanks for he link. I looked up the engine in my S150. Parts seem fairly reasonable in comparison to the Yanmar diesel parts for my tractors. When I bought this machine I wondered if maintaining one was beyond the average guy. Hopefully I won’t need to go to the dealer for much stuff. I bought a few window parts from the dealer and paid lust price plus shipping. I can’t think of another time I had to pay a dealer shipping.

 

[Feedbag]

Thanks for he link. I looked up the engine in my S150. Parts seem fairly reasonable in comparison to the Yanmar diesel parts for my tractors. When I bought this machine I wondered if maintaining one was beyond the average guy. Hopefully I won’t need to go to the dealer for much stuff. I bought a few window parts from the dealer and paid lust price plus shipping. I can’t think of another time I had to pay a dealer shipping.

Some of the dealer pricing in this area are insane. I went to the local Bobcat dealer for a glow plug and they wanted $30.00. The same exact NGK glow plug was $11.00 at NAPA.

 

[Hotrod1830]

Some of the dealer pricing in this area are insane. I went to the local Bobcat dealer for a glow plug and they wanted $30.00. The same exact NGK glow plug was $11.00 at NAPA.

My local dealer is always trying to stick me for shipping. ALways ask for the parts to be shipped on the stock order. If Overnight shipping you WILL pay shipping, but regular stock order shouldnt. I have caught them more than once trying to sneek a shipping charge onto the bill. I always ask them what that charge is and remind them it was on the stock order, and the charge disappears. I am almost 100% certain that bobcat doesnt charge them shipping for stock orders. they dont in the automotive industry. gotta watch those dealers and your invoices.