My Cat 299D2 XHP blew a hydraulic hose that goes to the left track drive motor. I replaced the hose and most of the hydraulic oil. I could see that the old hose seemed to have been rubbing against the metal where it exited from under the cab to the left drive. The day after replacing that hose it appears to have blown a hose on the other side going to the right drive motor. The first hose blew just moving the machine with a grapple attached but I hadn't done any work yet. The second hose blew while I was mulching a stump with my Fecon mulcher so I was really stressing it. After years of never having a hose blow, this seems like an extreme coincidence. Do I have some kind of relief valve that is bad?
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Cat 299D2 XHP Blowing hydraulic hoses. Bad relief valve?
- Thread starter mjones35
- Start date
heymccall
Senior Member
Examining the rupture/ leak point is where to start.
Abrasion?
Corrosion?
Abrasion?
Corrosion?
The first hose that blew did seem to have some abrasion from rubbing against the opening leading to the drive motor. The second just seems to have a rupture. Both are the smallest of the group of hoses leading to the drive motors on each side and are only rated at 2250 psi.
Nige
Senior Member
Where did you get the 2250psi figure from, marked on the hose.? Are you talking about the case drain hoses by any chance.?
I had to guess at a S/No but which hoses are they on the illustration below.?
Nige
Senior Member
345-4633 is one of 4 hoses (2 each side) Ref #15.
#11 & #13 (1 of each) are handed LH & RH side of the machine.
Attached the drive system hose parts breakdown for DX2 machines from first built up to 1837.
I believe that the four hoses #15 are for the parking brake release and the 2-speed travel, and that the hoses #11/13 are for the travel motor case drain lines. If I am wrong I'm sure someone will correct me.
Remove your protective covers on each side and examine all your hoses. We just had the same issue and had to replace (2) hosed to the drives withing 40 hours (1400 hours on machine). After removing both covers and examining all the drive motor hoses we found several areas severely worn down to metal. One hose was under the cab and blew because it was rubbing against another hose by the hydraulic motor. When we replaced the hose I used plastic hose wrap where it exited the side. I'll be replacing another hose shortly, because it is worn and down to metal, but decided to wait until it blows. Each hose cost us $500 to have made at hydraulic shop.
I'm about to go back out to the machine and verify that the second line that blew is also the case drain line on the other side. Can anyone tell me if there is a filter on these case drain lines that could be clogged and causing high pressure? I just hope that the pressure didn't get so high that I've blown the seals on either drive motor. I'll check for any other worn hoses but it seems likely that it is a problem with excessive pressure in the case drain lines.
Nige
Senior Member
Based on the Part Number in your photo a few posts back I don't think that line was a case drain.
Nige
Senior Member
No I did not. What I said was "345-4633 is one of 4 hoses (2 each side) Ref #15”.
See post #7 above for full detail.
See post #7 above for full detail.
Nige, Sorry I misunderstood. #15 does appear to be connected to the motor at the location of the hose that failed. I can't tell from the diagram where the other end connects, but it was connected to one of the two t-connectors at the floor. I'm about to take a look at the second hose that failed. Thanks for your help.
Nige
Senior Member
The four hoses that go from the two t-connectors to the respective travel motors are all identical - Ref #15.
Hose #11 (LH side) and #13 (RH side) go all the way from the travel motors back to somewhere close to the hydraulic tank. That's what makes me think they are the case drain lines. If you open the attachment I posted earlier you can blow up the illustration for a better view.
Just finished looking at it and you are correct. There is one hose from each side that blew and both of them are part num 345-4633 and are both connected to the same t-connector. The other end of that t-connector is connected to the top of the main pump (I guess) with a hose with part number 345-4833. So they are not the drain lines.
In the picture above, the elbow at the top is connected to the t-connector with the two blown hoses. The second hose blew in a spot in the open with no abrasion. I'm hesitant to just replace the hose since there seems to be a pressure problem. Is there a relief valve for that port?
Nige
Senior Member
It depends if it is the 2-speed circuit or the parking brake release circuit, and I’m not sure which one is which.
Tones
Senior Member
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I'm not familiar with the 299 but if it's a closed loop circuit then the casedrain could very well return to the pump. If there's no obvious external damage to the hoses that causes them to blow then a casedrain flow test should be done ASAP. Worn hydraulic motor internals could be the cause and blown hoses are the symptom. Test each motor individually because they're interconnected and 1worn motor can damage the other side hoses.