Hello everyone, new to the forum although I have been skulking around for a while researching. Came upon the site while googling my problem. I have a bobcat 853 from the early 90's, or so I was told when I bought it. Not sure which engine it is... guy said it was a Deutz, but not sure. When I bought it it started fine for the most part, battery seemed to drain when shut down but not a big deal. Sometimes I would have to hit one of the solenoids to coax it into starting as well. As time went on, over the last two years it progressively got harder to start. By harder to start I mean that it would turn over but wouldn't fire off until I put a booster on it. I changed the battery, still getting harder to start. I put in a bigger battery. Still getting harder. I fixed the ground and replaced the solenoids and made sure good contact at each connection point in the electrical system. Still getting harder. So hard in fact that the starter will engage, but it isn't strong enough to roll the engine over... even with the battery charged and assisted with my truck. So I thought the starter might be going, pulled that out and inspected. It looks fine, haven't put it on a bench yet but will soon. I can bar the engine over by hand, no wierd noises. What I did notice was that the engine seems loaded. Could it be and from where? I have no manual so am not to familiar with all the components and construction of the machine. Is there a tally plate somewhere that I can look for to get particulars on it? Thanks for any help, wife wants it moved out of the driveway soon lol.
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I guess it could be a starter issue, it may look good, but doesn't have the power it should.
The aux hydraulics on this machine is controlled with the right hand stick thumb control. If the electro-mechanical solenoids stick, they can load the engine down like this.
Another way to confirm this is to remove the drive belt, see how it starts without the pumps attached.
The aux hydraulics on this machine is controlled with the right hand stick thumb control. If the electro-mechanical solenoids stick, they can load the engine down like this.
Another way to confirm this is to remove the drive belt, see how it starts without the pumps attached.
Yeah, I will be benching that starter here soon. I don't have a thumb control on this one... just two sticks with the right stick able to go right and left for the aux hydraulics. I moved it around to make sure it was lose and not stuck. The drive belt... I lifted the seat to have a look under there... to be honest I never saw a belt, but will look again... it looked almost like the engine was directly coupled to the pump, but I wasn't looking too hard there, was poking around trying to see how the starter came out. Thanks
antfarmer2
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You may have somthing else is your engine lined up with the pump or sideways
Ok, so I didn't have a lot of time last night to look around inside but I did get the starter bench tested. It's fine. Also, the Bobcat is an 843 not an 853 as I previously stated. Serial number is 503750351 if that helps. I am still sifting through google to find any pertinent info and a manual that applies to that model and serial number. So now I am thinking the problem is in the hydraulics somewhere... maybe a relief valve?
That makes more sense. There are no thumb controls on a 843, it's done with the steering lever.
I wonder if anyone has ever experienced the problem I am having, I will describe it a bit better here. When I go to start the engine (with a fully charge battery hooked up to a 200 amp start assist pack) I can hear the bendex engage and the engine will crank very slow for maybe half a revolution then stop. When I bar the engine by hand I can turn the engine as much as I want, no expensive crunchy sounds, but it feels like it is coming up against some serious resistance. When I turn it slow it feels liek it could just be the compression, but when I turn it fast the resistance is enough to stop me in my tracks. I hold it and slowly I get over the "hump" for lack of a better term. Then it spins for maybe 170 degrees and then that same resistance. I think it is that resistance that is stopping the starter. I am going to uncouple the engine from the pump, (found a parts book and it looks like a simple enough job, maybe a u-joint in there) That will tell me what system I am having the issue with, engine or hydraulics, but if anyone has experience with a similar problem I am all ears. Thanks.
antfarmer2
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Duezts it might be your timming belt
Pretty sure 843 had either a Perkins or an Isuzu engine depending on serial number break. Uncoupling the engine isn't a bad idea. First I'd try starting it with it up on blocks. The steering is always worn out on those and if it is trying to creep forward, that would put a hefty load on the starter. Also, your starter is probably about fried from trying to start it like this. If you haven't already, put a new positive battery cable on it. That could be sucking a lot of juice up. If it still turns over hard with the pump uncoupled, I'd say the engine is junk.
I was just thinking of a hard starting 843 I had one time. Customer brought one in with a laundry list of crap wrong with it. One was hard starting which it was. Once running, it ran like crap and I noticed a sweet smell. Checked, no coolant in the radiator. I pressure tested the unit. No visable leaks and pressure drop was very slow. Tried to start it. 100% hydro locked. Check oil, more coolant then oil. I advise the customer of the problem and we agreed he would have somebody else look at since $75 an hour would quickly exceed the value of the machine. The machine had hydraulic and many other issues, it wasn't really worth fixing.
William Munney
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I would go over the electrical connections again. If one is dirty/corroded no amount of boosting will get it to spin fast.
Opened up the Bobcat to have a look at the scope of work required to get the engine uncoupled... and found that it was a bit beyond what I can devote to it time wise at the moment, (looks like the gas tank has to come out?) so looked at the electrical again. Start system has new battery (only a couple months old) two new solenoids, new battery cables, cleaned up all the connections. Checked the impedance through the start system wires, seems good. Starter was bench tested at the start of all this. Just doesn't want to go. Can hear the bendex engage and the starter hum a bit, but no movement. Engine bars over by hand smoothly, just gets tough every 180 degrees, which I assume is just the compression, but feels pretty tough, could by hydraulics. Put a meter on the starter terminal and the negative post on the battery and saw the voltage drop to 2 volts on startup. Is that normal, doesn't seem right to me...? Thanks.
OldMachinist
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Have you looked at the flywheel ring gear to make sure its not damaged and hanging up the starter?
When I had the starter out I did have a look at the ring gear yes... I didn't see anything out of the ordinary.
2 volts will cranking concerns me. A battery at worse, maybe down to 9.5v under extreme load. Either a bad cell on the battery, or extreme load the starter can't over come. Pulling a battery down to 2 volts, that kinda voltage drop, something getting real hot real fast.
Why did I think you had a 843, I see now its a 853. 853 are belt drive, just pop the drive belt off and the engine is free of any outside load.
Yeah, I would have thought so too... but nothing seems to be getting hot... none of the battery terminals, wires, solenoids, or the starter itself... I guess I will get the battery looked at... not unheard of for a new battery to have a bad cell so soon I guess.
It's an 843, see 5th post down, I made a mistake originally.
antfarmer2
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Try pulling the glow plugs and try turning it if the battery checks out good
