Starting tips for new owners of diesel bobcats

Help Support SkidSteer Forum:

mbracewell

Member
Joined
Oct 22, 2005
Messages
11
I thought I would share some tips for new owners of diesel Bobcats. Maybe someone can learn something at my expense rather than their own. I bought a Bobcat 743B this summer. It was very hard to start first time of day but if it was warm it started without a problem. When starting it blew white smoke which if you have read other threads is a sign of unburnt diesel and possibly a glow plug problem. It would take me 5 -10 tries to start if I got the choke set just right. I should have just tested and replaced the glow plugs at $5.86 a piece. Instead I opted to put this off until I had to replace the starter at $190. So I pulled and tested the glow plugs and they were ALL bad. After replacing the plugs I am happy to report the Bobcat starts on the first try. Every diesel engine has it's own quirks but here is what works best to start my 743B. Set the choke at about the half-way setting. Glow for 20 seconds (at 50 F through 90 F; haven't gone through a winter yet) Start the engine. As soon as it sounds like it is starting to try to fire push the choke all the way down (off) and it should start. Moral of the story: If you are getting white smoke on startup or suspect a problem with the glow plugs take the time to check and replace them. They are a lot cheaper than replacing your starter. I hope this helps someone out. Mike
 

Tazza

Administrator
Staff member
Admin
Joined
Dec 7, 2004
Messages
16,697
Exactly, i posted that exact same problem yesterday. I had been putting up with the problem for a few weeks, then someone suggested the glow plugs (which i tested, but not out of the head) sure enough, i removed them and instantly could see they were shagged. Connected them to power and they only glowed rite at the thread, so basically they were useless. Without the plugs you rely on compression alone to get it to fire. I move the throttle up a little bit, glow for 30 seconds, then it fires up almost instantly.
 

pondfishr

Well-known member
Joined
Oct 11, 2005
Messages
215
Exactly, i posted that exact same problem yesterday. I had been putting up with the problem for a few weeks, then someone suggested the glow plugs (which i tested, but not out of the head) sure enough, i removed them and instantly could see they were shagged. Connected them to power and they only glowed rite at the thread, so basically they were useless. Without the plugs you rely on compression alone to get it to fire. I move the throttle up a little bit, glow for 30 seconds, then it fires up almost instantly.
It is mentioned setting the choke halfway. I have a 743 and am not aware of a choke adjustment. Is this something that was included on the 743B model and not the 743?
 

TriHonu

Well-known member
Joined
Apr 15, 2007
Messages
484
It is mentioned setting the choke halfway. I have a 743 and am not aware of a choke adjustment. Is this something that was included on the 743B model and not the 743?
On the newer loaders don't always believe the dash either.
My loader got hard to start. The display indicated it was glowing the plugs. I checked the resistance of each glow plug and they were all within specification.
I (finally) put a test light on the circuit and found that the relay that powers the glow plugs had failed. The dash indicated the glow plugs were getting power. I have to admit I was glad it was a $5 relay and not something more expensive. My loader has 5 identical relays attached to a bar below the air cleaner housing. I bought an extra and bolted it to the backside of the bar. Now there is one available if any go bad. I can just unplug from the bad and plug into the spare.
emotion-1.gif

Also for you guys running the Kubota engines. You shouldn't ever use starting fluid. I ran into a mechanic down at the CAT dealer. He tells me these engines are classified as High Compression diesels. You have a high probability of bending the rods when the starting fluid fires. He has seen a lot of Kubota's that were in for repair after someone used starting fluid on them. He told me if it is an EMERGENCY start cranking the engine then have a helper give a little puff of starting fluid into the air cleaner housing while you continue to crank the engine.
 
Joined
Nov 1, 2007
Messages
11
On the newer loaders don't always believe the dash either.
My loader got hard to start. The display indicated it was glowing the plugs. I checked the resistance of each glow plug and they were all within specification.
I (finally) put a test light on the circuit and found that the relay that powers the glow plugs had failed. The dash indicated the glow plugs were getting power. I have to admit I was glad it was a $5 relay and not something more expensive. My loader has 5 identical relays attached to a bar below the air cleaner housing. I bought an extra and bolted it to the backside of the bar. Now there is one available if any go bad. I can just unplug from the bad and plug into the spare.
Also for you guys running the Kubota engines. You shouldn't ever use starting fluid. I ran into a mechanic down at the CAT dealer. He tells me these engines are classified as High Compression diesels. You have a high probability of bending the rods when the starting fluid fires. He has seen a lot of Kubota's that were in for repair after someone used starting fluid on them. He told me if it is an EMERGENCY start cranking the engine then have a helper give a little puff of starting fluid into the air cleaner housing while you continue to crank the engine.
I've found that WD40 works well as a starting aid, I've used this many times on motors that I've dropped the filters on and could not get to fire up again. It doesn't give that nasty preignition knock that knocks the rings out of a motor like either does.
 

kelly_b

Active member
Joined
Nov 14, 2007
Messages
31
Sounds like buying a crappy old car. Fuel, air, and fire is all it needs to start. All you have to do is check these three things and you will usually figure it out. :)
 

perry

Well-known member
Joined
Aug 22, 2006
Messages
869
Sounds like buying a crappy old car. Fuel, air, and fire is all it needs to start. All you have to do is check these three things and you will usually figure it out. :)
I local BC mechanic told me that my 853 had a 'direct' injected diesel engine and are usually much easier to start, so far he is correct. I'm not sure how many BC's came with direct injection.
 

skidsteer.ca

Well-known member
Joined
Jan 20, 2006
Messages
3,853
I local BC mechanic told me that my 853 had a 'direct' injected diesel engine and are usually much easier to start, so far he is correct. I'm not sure how many BC's came with direct injection.
The 853 uses the Isuzu diesel and they start great even in our climate, don't even need the glow plugs until it get down to 0 far or -15 to -18 C with 10/30 oil
with 0-40 motor oil you could likely get down to -10 or -15 f
They are right in there with the best of diesels I have seen, including 3208 Cat, 6068t JD
The 2203 Kubotas start good too, with glow plugs, the Isuzu is equal with them imo.
Ken
 

Tazza

Administrator
Staff member
Admin
Joined
Dec 7, 2004
Messages
16,697
The 853 uses the Isuzu diesel and they start great even in our climate, don't even need the glow plugs until it get down to 0 far or -15 to -18 C with 10/30 oil
with 0-40 motor oil you could likely get down to -10 or -15 f
They are right in there with the best of diesels I have seen, including 3208 Cat, 6068t JD
The 2203 Kubotas start good too, with glow plugs, the Isuzu is equal with them imo.
Ken
Direct injection is the best for starting but they are genearlly a bit louder. My old 731 with a Deutz was great starting no matter what the temperature was. Just hit the excess fuel button on the pump and it would spin over once and burts into life. The engine didn't come with glow plugs and i never knew about the excess fuel button. I would flatten the battery winding it over in the cold then i was told by a buddy that works on injectors to hit the button. One flick of the key woke the sleeping beast. With in-direct injecton engines, they loose heat when the air goes into the pre-comp when cold.
I agree with ken on the 2203, the newer style engines seem to start fast, i'm not sure if the plugs heat faster or its the way the air is swirled with the new design but i found they do start easier.
 

skidsteer.ca

Well-known member
Joined
Jan 20, 2006
Messages
3,853
Direct injection is the best for starting but they are genearlly a bit louder. My old 731 with a Deutz was great starting no matter what the temperature was. Just hit the excess fuel button on the pump and it would spin over once and burts into life. The engine didn't come with glow plugs and i never knew about the excess fuel button. I would flatten the battery winding it over in the cold then i was told by a buddy that works on injectors to hit the button. One flick of the key woke the sleeping beast. With in-direct injecton engines, they loose heat when the air goes into the pre-comp when cold.
I agree with ken on the 2203, the newer style engines seem to start fast, i'm not sure if the plugs heat faster or its the way the air is swirled with the new design but i found they do start easier.
I meant to say the Isuzu start equal to the Kubota withOUT the use of glow plugs. Modern diesels seem to have made great strides in cold weather starting.
Also important for cold weather is a good thermostat that warms the engine quickly, diesel hate running cold, thinner oils like 5/30 or 0/30 or 40. Warm up time. Give the engine and the hydrostats time to warm up. 5 minutes of idling can save you alot of grief. Plug the engine in whenever you can. Electricity is cheap.
Ken
 

perry

Well-known member
Joined
Aug 22, 2006
Messages
869
I meant to say the Isuzu start equal to the Kubota withOUT the use of glow plugs. Modern diesels seem to have made great strides in cold weather starting.
Also important for cold weather is a good thermostat that warms the engine quickly, diesel hate running cold, thinner oils like 5/30 or 0/30 or 40. Warm up time. Give the engine and the hydrostats time to warm up. 5 minutes of idling can save you alot of grief. Plug the engine in whenever you can. Electricity is cheap.
Ken
Ken, I read your post a few months back where you recommended motor oil over hyd. fluid. Problem is, I read it after I flushed the system and filled with hydraulic!. Is this something you've done for some time? and, have you experience any problems with motor oil?.
Thanks
 

skidsteer.ca

Well-known member
Joined
Jan 20, 2006
Messages
3,853
Ken, I read your post a few months back where you recommended motor oil over hyd. fluid. Problem is, I read it after I flushed the system and filled with hydraulic!. Is this something you've done for some time? and, have you experience any problems with motor oil?.
Thanks
Perry
The manuals for both my NH and Bobcat call for motor oil. So that what I have always used. I have never had a problem, and some of the guys are saying bobcat now recommends hyd oil. I'm staying with what I have always used based on the manual,and that NH wants motor oil and I switch attachments between loaders.
Further , our local heavy equipment mechanic that takes on our work I don't want to do in my shop feels that motor oil have better lubrication properties over hyd oil. He had us switch 2 of our skidders from A.T.F. to 15/40 (for use only in the summer) and this resulted in 15 to 20 degrees cooler hyd tank temps.
I have just choosen to stay with what has worked with my skidsteers.
Ken
 
Top