Another Bobcat 435 Problem!

[DGODGR]

I was using my 435 to break frost the last three days. The attachment was an Ingersall-Rand hydraulic hammer. The hammer was rented from my local Bobcat dealer, and has been on my machine several times. As far as I know this hammer is what Bobcat currently offers for sale. My machine has a little over 2,500 hours and I have owned it since new. This machine has had, what I consider, a lot of issues in the time I have owned it (and I have several machines to compare, hence the title). During the second day of breaking I began to notice that the hammer was sluggish to start hammering. It would have a delay in activation (from the point of control input to start of attachment function), and would start out with very low BPM and then increase in speed. This was not due to incorrect bit loading or miss alignment/side load of the tool. At first I suspected it was (and I started trying to adjust alignment to get the tool to work properly- to no avail) but shortly there after I began to notice that other functions began to exhibit the same delay. It has progressed to a delay, then very slow cycle time, and/or slow at start of cycle then gains speed during the cycle. The lever is pushed to the stops but the function just creeps and/or speeds up without any change in lever input.This is an intermittent problem and appears in all functions accept the track drive, and I have not noticed it in the blade function either. Maybe this points to the pilot control circuit? As you can imagine the machine is pretty hard to modulate, when it is unpredictable in function, especially for detail work or work around exhisting utilites. This machine has exhibited similar problems before. The last time it did the issue was only on the boom and dipper functions, and this helped me to figure out that the pattern changer was the culprit. It is located near the operator's right heal and can sometimes get bumped. If it is between positoions it will exhibit these issues in the boom and stick functions only. Push the selctor back to the desired pattern position and the problem goes away. This is not the issue now as the pattern selector was fully seated in the desired position and the machine exhibits the problem regardless of the selected pattern (I checked it in both positions). I know that this machine has had a broken spool valve before. I think it was located on the side of the main pump. I have had so many issues with this machine, and the broken spool valve was a long time ago (probably back in '06 when the machine was still under warranty), that I don't recall what the symptoms were when the valve was bad. In the back of my mind I think the curent symptoms are similar or the same. Maybe, I just am not sure.
Has anyone had these symptoms before? Does anyone have any ideas as to what is going on here? Can anyone offer advice on how to isolate the issue so that I can make repairs myself? I have had a lot of problems with my local dealer, and I don't have much confidence in their current mechanic. I don't want to take it there. The machine is currently on a job that is close to a neighboring town and there is a different dealer located there. I may take it to them but I have not heard anything but "iffy" reports about them too.
Looking for help. Thanks in advance.

 

[B.U.S.I.]

So is this problem happening only when the hammer is attached and breaking? Or is the problem also occurring independently? I know some hammers are really sensitive to low nitrogen charge and/or improper hydraulic back pressures.

 

[Colorado Digger]

435

howdy, i know it sounds far fetched, whenver my machines get sluggish it is usually the inline fuel filter back behind the main fuel filter. then there is the pilot hydro filter and the hydro filter.
i have had great luck with my 435's and one actually has 6200 hours on it.
i am not a mechanic but that is what works for me.. not all the time... sometimes.
regards, cd:usa:usa

 

[DGODGR]

It continued to happen even once the hammer was removed. I think I have resolved the problem. As I mentioned in my OP I remembered that there was a previous problem with a spool valve that was located on the pump. I had the dealer look up my history and he found the repair I was thinking about. It was at 518 hours so it was still covered under warranty. According to the report my complaint was slow hydraulics. The problem was traced to a sticky valve (the one in question-on the pump). Report went on to say that they disassembled and cleaned the valve. No parts were paid for by Bobcat so I guess I was wrong about the broken spool. I remember seeing it broken but if Bobcat did not pay for the parts then who did? Anyway, I took it to the dealer (my local one as I asked some more questions about the one in the neighboring town but got negative feedback) so he could start trouble shooting on Monday. After reviewing the report and looking at the parts blow up I decided that since the suspect valve was so easy to get to (on the side of the main pump facing you when you open the engine compartment door) that I would investigate the valve in question. We took the spools out of the valve body and neither one was broken. The one closer to the pump was very difficult to remove (like it was stuck) so I think that maybe something came from the rented breaker and lodged itself in there. After reassembly of the valve the machine has not exhibited any of the symptoms it had before. As of right now I think the problem is fixed. Obviously we will be monitoring it closely. If it happens again I will take the valve apart again and see if that fixes it again. If it does I will start thinking that I need to cut open the filter and see if something has begun to come apart. If doesn't help then I will probably need to have the dealer trouble shoot the problem.

 

[DGODGR]

howdy, i know it sounds far fetched, whenver my machines get sluggish it is usually the inline fuel filter back behind the main fuel filter. then there is the pilot hydro filter and the hydro filter.
i have had great luck with my 435's and one actually has 6200 hours on it.
i am not a mechanic but that is what works for me.. not all the time... sometimes.
regards, cd:usa:usa

My 435 seems to be hyper sensitive to fuel filter condition. I have had so much filter trouble (with Bobcats) that we carry an extra set in each of the crew trucks. Actually both of my Bobcats will plug filters before any of my other machines. When this happens the engine will lug down and even die if you let it. Of course this will slow down the hydraulics some but it is definatley not the fuel filters in this scenario. Thanks for the advice though.

 

[Colorado Digger]

yeah, i get a problem similar to that on my 300's. when we run the broom, something happens and it will normally only run one direction.
i have also ridden idaho. it is excellent. we are losing, or are close to. alot of our coveted single track through this new bill called "hidden gems"
has not passed yet, i don't know the details.
good luck.
regards, cd

 

[DGODGR]

yeah, i get a problem similar to that on my 300's. when we run the broom, something happens and it will normally only run one direction.
i have also ridden idaho. it is excellent. we are losing, or are close to. alot of our coveted single track through this new bill called "hidden gems"
has not passed yet, i don't know the details.
good luck.
regards, cd

I'm sorry, I must be forgetting something. Have we spoken before about riding? Please remind me. I am involved in San Juan Trail Riders (our local club) so I've heard about this initiative. It directly impacts some of our trails as well. We have had direct discussions with the Honorable Mr Salazar (sp?), or rather his staff, regarding our position in the matter. So far he seems more interested in creating his "legacy" than in doing things that are beneficial to the public, or at least, that make sense. We already have MILLIONS of acres set aside as wilderness in the state of CO alone. More area than the size of half the individual states on the Eastern seaboard. Most of the areas proposed for the wilderness designation DO NOT EVEN QUALIFY for wilderness as defined by congress when they passed the laws that allowed public land to be classified as wilderness in the first place. Our local club has been pretty fortunate (relatively speaking) in the recent travel management planning. We have lost some, in recent proposals, but we have gained some as well. Hell, the local tree huggers have appealed the decision. They won't rest until nobody but hikers can use public lands. After that they won't rest until every one follows a dress code or something of similar nonscense. On a positive note, there were over 100 protesters that recently gathered at the local USFS offices. Unlike most would be led to believe they were not there to protest how the OHV community is destroying Mother Earth with reckless abandon. They were there to protest how they feel that the USFS is bowing to the pressures, of the special interest groups and the politcians who want to find some way to be labeled as having a "green" platform, rather than follow the mandates, set forth by Congress, as to how to establish rules and close/open trails.
We are probably getting off topic a bit (is it OK when you are the OP?). I would be happy if you PM me to discuss futher all things dirt bike. Maybe you would like to see some of our high country trails some time.

 

[Colorado Digger]

trail riding

10-4. i knew you rode so i figured i'd let you know i did as well. i will pm you later and pass on my info.
good luck with that 435. i know it has been a p.i.t.a.

 

[DGODGR]

I look forward to it. BTW, you must know Kelly Geselle (SP?). He is up your way. He has done a couple of hot taps for me.

 

[Colorado Digger]

the ol'fart

yeah, i know him.. he's a great guy. funny as hell,always does a great job/

 

[Ryanrb25]

My 435 seems to be hyper sensitive to fuel filter condition. I have had so much filter trouble (with Bobcats) that we carry an extra set in each of the crew trucks. Actually both of my Bobcats will plug filters before any of my other machines. When this happens the engine will lug down and even die if you let it. Of course this will slow down the hydraulics some but it is definatley not the fuel filters in this scenario. Thanks for the advice though.

I have found a very simular problem with our 435's. One of them would idle fine and free rev but as soon as you placed any load on the thing she had no power...starving of fuel from a few gummy filters. Apart from that the 4 435's we have are brilliant.

 

[landtekk]

Never had a problem with the filters. 1800 hrs knock on wood.

 

[landtekk]

6200 hrs, cool.

 

[landtekk]

howdy, i know it sounds far fetched, whenver my machines get sluggish it is usually the inline fuel filter back behind the main fuel filter. then there is the pilot hydro filter and the hydro filter.
i have had great luck with my 435's and one actually has 6200 hours on it.
i am not a mechanic but that is what works for me.. not all the time... sometimes.
regards, cd:usa:usa

Sorry, forgot to add a quote with the last post.