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Discussion Starter · #1 ·
Need some help and ideas troubleshooting this problem. I have a 2014 brutus hd pto. I'm having an intermittent issue where driving normally it will suddenly lose engine rpms down to a bare idle. The machine will slow down, sometimes to a stop, then the rpms will come back up and it will drive normal again. The dealer changed out the fuel filter but that didn't fix it. Today the problem reappeared and this time the engine actually stalled completely. It would restart but not easily. The rpms were erratic and when I tried to go it was sluggish and stalled again. So I loaded it on the trailer and brought it back to the dealer about an hours drive away. When I dropped it off it was running fine again. Interestingly too is that if I used the hand throttle I could run the engine and rpms at full throttle with no issues. But when I used the treddle peddle to drive forward is when it would have the problems. Any thoughts on what may be causing it or things to check would be appreciated. Thanks, Jeremy.
 

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My Bobcat 3650 was running erratic at startup last fall, the new fuel filter fixed that, but now that it's winter, it works great in low snowblowing, but if I try to drive down the road in high it is very sluggish and will get up to about 20mph and then just die out like the engine is lugging. It feels like the hydrostatic drive is fighting it, there just isn't any power while driving fast, but all kinds of power for snowblowing. Also the snowblower chute swings left real fast, but just creeps when swung to the right, in warm or cold weather, although it's slower in cold weather.
 

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Ive found that my machine will sometimes bogg down and that letting up on the treddle a bit would bring the rpms back up. Bogg is maybee not correct its more like idle down as i dont feel the rpm drop is caused by a load but more a throttle controll problem. I'm trying to nail down more of a pattern on what conditions cause this but I think its related to hyd oil temp or flow or lack thereof.

perhaps there's some sort of govenor that relates flow, rpms and throttle position. if the hyd flow drops for some reason the engine idles down to prevent damage to the pump.

I don't think its a "normal" condition but I have had others describe the same thing on other hydrostatic machines like tractors.
 

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Try unscrewing the hydraulic fluid cap and equalizing the pressure. Had a similar issue last winter and unscrewed the hydraulic fluid cap. There was a rush of air into the tank as the pressure equalized - I guess the fluid level dropped over time and simply opening the cap eliminated the problem. Maybe it's driven by big temp changes?

One thing I noticed is that I could run the brutus at wide open throttle while still, and the bogging down issue only happened when I was moving. That's what pushed me to check that cap.
 

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Discussion Starter · #6 ·
Thanks for the thoughts and ideas. Keep them coming. It seems that I'm not alone in this issue. Collectively maybe we can find the cause. Mine is exactly as each of you have described. I think its just a difference in how we're describing what's happening. As Jorts pointed out, mine was the same in that sitting still I could run the engine at full throttle either with the hand throttle or by pressing the treddle peddle while it was in park/neutral, but the problem presented only when it was in low or high gear and moving. TheRealbuzz mentioned something I read also about some sort of governing system to where if the hydraulic pressure drops the computer will take over the engine rpm and regulate it to prevent pump damage. Maybe someone can add some more information on this system and how its supposed to work and how to possibly bypass it temporarily to be able to rule it out. And as Ketchn said, I used mine all day yesterday with the snowblower with no problems. Again it was in low gear moving forward slowly with the hand throttle set up to about 2000rpms for the snowblower and it ran fine all day with no issues. Then the problem presented today when I was trying to go forward at full speed. Seems logical to suspect there's something going on with the computer systems management of the engine rpms relating to the hydraulic flow when the machine is moving.
 

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When you experience the loss in RPM what was the outside air temp? I had a similar problem and it turned out to be water in the diesel. It happend twice to me, both times the outside temp was less than 5 degrees. I used Diesel 911 additive and have not had a problem since.
 

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Discussion Starter · #10 ·
Its still at the dealer so I haven't been able to try anything myself yet. I'll let you all know what they find and say. The first few times it happened the outside air temps were 30's to 40's. At that time the dealer suspected water in the fuel filter / water separator so they changed it out. Seemed to run fine after that for a few weeks. When it happened again the other day temps were in the teens. It's only been 3 weeks since the filter was changed. I've only used it about twice a day to run to the bus stop since then and a few hours plowing the driveway. Then I used it for about half a day blowing snow on Tuesday. It ran fine all day Tuesday but it was high rpms set with the hand throttle and slow speeds as I was blowing snow. Then Wednesday morning when I went to the bus stop, high gear and high rpms using foot tredle peddle, is when the problem reappeared and this time worse then the first times it happened. I turned the drain lever on the bottom of the filter/water separator and checked what came out. All fuel and no water. Drained the entire filter. Then tried driving again. The problem was still there. I'm only using good clean fuel from a reputable gas station. I did treat the fuel with Bobcat brand diesel deluxe fuel additive. I used to use it with my t300 and had a bottle left over. I can't imagine that would cause any issues. In fact it should help.
 

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Need some help and ideas troubleshooting this problem. I have a 2014 brutus hd pto. I'm having an intermittent issue where driving normally it will suddenly lose engine rpms down to a bare idle. The machine will slow down, sometimes to a stop, then the rpms will come back up and it will drive normal again. The dealer changed out the fuel filter but that didn't fix it. Today the problem reappeared and this time the engine actually stalled completely. It would restart but not easily. The rpms were erratic and when I tried to go it was sluggish and stalled again. So I loaded it on the trailer and brought it back to the dealer about an hours drive away. When I dropped it off it was running fine again. Interestingly too is that if I used the hand throttle I could run the engine and rpms at full throttle with no issues. But when I used the treddle peddle to drive forward is when it would have the problems. Any thoughts on what may be causing it or things to check would be appreciated. Thanks, Jeremy.
Drain the water from the fuel filter. This fuel filter has a water separator. There is a drain on the bottom of it. Mine I had to replace. I was having this same issue.
 

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Discussion Starter · #12 ·
update

I picked the machine up from the dealer on Saturday. Unfortunately they could not get it to duplicate the issue. When I loaded it in the trailer to bring it to them is was having the issue. It took me a couple tries to actually get in into the trailer as it kept stalling. It took about an hour to get to the dealer. When I started it up there and unloaded it had started running fine again. The next day they got to it and ran it up and down the road numerous times but could not get the issue to show up. So they put some diesel fuel additive in the fuel just for good measure and gave it back to me. I've been running it for 2 full days now and haven't had the issue show back up. I'll post back if it loses rpm's again and I try a few of the suggestion.
 

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I picked the machine up from the dealer on Saturday. Unfortunately they could not get it to duplicate the issue. When I loaded it in the trailer to bring it to them is was having the issue. It took me a couple tries to actually get in into the trailer as it kept stalling. It took about an hour to get to the dealer. When I started it up there and unloaded it had started running fine again. The next day they got to it and ran it up and down the road numerous times but could not get the issue to show up. So they put some diesel fuel additive in the fuel just for good measure and gave it back to me. I've been running it for 2 full days now and haven't had the issue show back up. I'll post back if it loses rpm's again and I try a few of the suggestion.
The only thing the additive would do might help it not gum up. Is it cold where you are? Are you running the right mix of diesel? Otherwise, someone drained the water in that filter and boom, issue fixed.
 

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Mine is getting real bad now. I was snowblowing yesterday the temp was +10 Fahrenheit, used the block heater for a couple of hours before starting, but it still took 3 tries to start it.
The water temp after using the block heater was 135 deg. At that temp the glow plugs don't even come on.
My problem is like the others here, if I'm snowblowing at anything over 3000 engine rpm's it will just die out and almost quit, if I don't immediately stop moving forward, I wasn't going fast just creeping thru 8-10 inches of snow. I removed the cap on the hydraulic tank and got a small whoosh of air, but it didn't help at all, I tried it several more times during my snowblowing time but didn't get anymore whooshes. It feels like the hydrostatic drive is the issue, but towards the end of my hour and a half of blowing, it would start dieing off if I had it in park and ran the and throttle to 3600 rpm's. That sounds like a fuel issue.
I also early on dumped about twice as much diesel anti freeze stuff in the tank accidentally as I was supposed too, but it didn't help a bit over the next hour. I also use Irving diesel as their refinery is in Canada and every big diesel truck owner and the local schools love Irving diesel as they don't have winter problems with it. That and I already had some of the winter fuel treatment in it.
I noticed that someone else had about the same problem and replacing the fuel filter didn't help them.
Any one have some more suggestions?
 

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No I haven't, I need to try that as mine seems to be fuel related, seems odd that so many are having about the same problem. We shouldn't all be having fuel problems. This is the first diesel problem I've had in any of my truck or tractor stuff I've had in the past 17 years.
 

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fuel filter icing?

Did you use Diesel 911 or another treatment? Not all diesel fuel treatments are equal. Some have deicers, others have solubilizers, demulsifiers, etc.

No I haven't, I need to try that as mine seems to be fuel related, seems odd that so many are having about the same problem. We shouldn't all be having fuel problems. This is the first diesel problem I've had in any of my truck or tractor stuff I've had in the past 17 years.
Maybe it's a design flaw, making the unit more prone to fuel filter icing?
 

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right now it is -40 c will turn on block heater for two hours and see what happens, I have been putting three ounces of kleen flo in each 25 litres of diesel and it seems to be working.
 

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Diesel 911 worked for me. Seems like we are all having the same issues in cold weather. I wonder if it has something to do with the way the fuel is returned to the tank?? Diesel 911 (red bottle) is hard on injectors but gets rid of any water in the system. I keep a bottle in the door pocket just in case. Its going to be -30 windchill here this weekend, I'll probably add a splash tonight.
 

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......had some time to give the brutus a quick look over this weekend, I'm very happy with the shelly rotella synthetic. Has not burned a drop of oil and still looks clean. I have about 30 hours on it.
 
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