Scag Tiger Cub Hyro Line Bursting

[lawnphysics]

Hello, I am just putting this out here to see if any of you have had a similar experience. My right hand pump on my Scag Tiber Cub recently bit the dust. I took the liberty of taking the pump apart and noticed that the bearings had worn out and shredded. Thus scaring up and taking the pistons out with it. So I flushed the lines with air compressor hose, then ordered a new hydro pump. I got the new hydro pump on the mower. It runs great, pulls great for about five minutes and boom! There goes the hydro return line. I can not figure out what is causing the lines to build up enough pressure to blow them out. Anyone got any ideas or suggestions? I need this machine to work. I have changed the filter, but am considering changing it again in case something is wrong with the one on it.

At a loss here so let me know what you think could be causing it.

I am planning on pulling all the return hoses off and the reservoir off and thoroughly cleaning them and putting back together. I am tired of fighting with this thing so any suggestions, advice would be appreciated.

[LawnMastersTN]

have you flushed the whole hydro system?

[lawnphysics]

Yes. I thought I did, but I looked over the part diagram blow outs last night and think I missed one line coming into the filter. Going to reflush the system this morning and change the filter again, (changed once already) and see if that makes a difference.

[lawnphysics]

Okay, thanks LawnMastersTN.

I replaced the filter (again) just in case there was an issues. I took all the return and supply lines loose and took the air compressor to them. She ran for an hour and no problems yet. I think I may have it fixed now. Going to work it to death Monday so I shall see if it holds up under a good workload.

[lawnphysics]

The return line that comes off the right hand pump and feeds into the left hand return line at a "T" keeps bursting before the "T". This busrt happens before the metal stiffner part of the "T". I do not have a clue what to do to this thing at this point.

[LawnMastersTN]

You are building some serious pressure to do that. The pressure has to be way higher than the other side. At first I though you missed a piece of metal and it cut the inside of the line and it made it weak, but now I am stumped... Ill ask a buddy of mine that is a mechanic at a scag dealer. Ill get back to you.

[lawnphysics]

Hey LawnMastersTN,

I finally went down to NAPA and they gave me a scrap piece of 4000 PSI hose about 18" long for free. I put that hose on and began to mow. Hasn't blown yet. However, I looked down at the hose and noticed a small little pin hole getting started. I knew there was no way that pump could be generating over 4,000 psi...so I started looking around for something that could be rubbing against it.

Well the solution, I think, was my fat butt was causing it, every time I sat down. The little metal pin that holds the springs next to the seat safety switch was pushing into the line. Now I am not 100% sure this was what is causing it, but I am pretty sure I was ripping a small hole into the hose and every bump I hit was causing a bigger rip into the hose. Since the 4,000 psi hose was reinforced with steel and not the wool it was able to take more abuse so I was able to see what caused it. Just my assumpution.


My solution was twisting the pin to a long ways position with the mower opposed to width ways which gave it clearance to not hit the hose.


Would still like to hear what your buddy thinks if you get to talk to him.

Thanks again!

[LawnMastersTN]

Originally Posted by poplarcreeklawn

Hey LawnMastersTN,

I finally went down to NAPA and they gave me a scrap piece of 4000 PSI hose about 18" long for free. I put that hose on and began to mow. Hasn't blown yet. However, I looked down at the hose and noticed a small little pin hole getting started. I knew there was no way that pump could be generating over 4,000 psi...so I started looking around for something that could be rubbing against it.

Well the solution, I think, was my fat butt was causing it, every time I sat down. The little metal pin that holds the springs next to the seat safety switch was pushing into the line. Now I am not 100% sure this was what is causing it, but I am pretty sure I was ripping a small hole into the hose and every bump I hit was causing a bigger rip into the hose. Since the 4,000 psi hose was reinforced with steel and not the wool it was able to take more abuse so I was able to see what caused it. Just my assumpution.


My solution was twisting the pin to a long ways position with the mower opposed to width ways which gave it clearance to not hit the hose.


Would still like to hear what your buddy thinks if you get to talk to him.

Thanks again!

The thing that I would want to know is why the pin was hitting the orignal hose when it was fine before the pump replacement. The first hose that blew would be my concern, unless you removed the seat or moved that pin. I'll call him now BTW

[lawnphysics]

The part that was affecting the line was taken off the mower for ease of access to the pump. In fact it has to come off to get to the pump. When I put it back on I am assuming something shifted the pin in the process of putting it back together.

[LawnMastersTN]

I talked to my buddy and he said it would be really hard for a pump that size to bust that hose. I would tear the wheel motor up before it bust the hose. He said that with the orignal hose that if it was hit with something sharp while under pressure it would put a pin hole then burst open. I think your seat pin is your issue JMO