bobcat 743 - v1702 4 cyl missing one cylinder

[chuckwsh]

I have an old play toy, Bobcat 743 with this Kubota engine. Last year I noticed it running on 3 cylinders. To figure it out, I loosened the caps on each injector slightly and watched the rpm fall on each except #3, towards the back of the engine. I re-bled all of these at the top, still missing. with FULL rpm for a while, still not clear. I changed the Injector with new from Bobcat, still missing. It has 2300 hours on it, I have babied this motor 3/4 max working throttle most of the time. I wanted to check the compression so went to ugg, harbor freight for a tester, but its not fitting (supposed to) into the injector hole. Any other easy checks I can do? I guess compression is probably the next deal. Someone mentioned the glow plug if its junk the cylinder will not fire? I'm thinking this is incorrect...? I looked inside for dirt but it looks pretty clear on the air intake, always had filters on it! Always! Changed the fuel filter when this all started to no avail.
any help appreciated.
Chuck-

 

[Theekillerbee]

Sounds like you are on the right track, it's likely bad compression. A missing glow plug will only affect the motor for cool/cold starts. Once she warms up, there is no need for them. In fact once you get the thing started, the glow plugs do not come back on.

 

[chuckwsh]

so do you think pullin goff the valve cover and checking the play on the rocker whatever is in there will be of any use? I guess if they all look OK then its pull the engine and finish the job, kind of odd with 2k hours on it..

 

[Theekillerbee]

You can pull off the valve cover and have a look, as it isn't that difficult to do, but a compression test is where I'd go to next.

 

[chuckwsh]

well, about 400-450 across the board on the compression, finally got a chance to check it. Now I guess its bring the injectors someplace to look at. I would suspect anything around 400psi is OK give or take. cheap harbor freight guage but it worked fyi for 30$, has a lot of adapters with it but one fit the v1702.

Chuck

 

[chuckwsh]

oh yea, first thing I was lookin for...compression was real good there suprisingly..I checked for tightness in the valve train plus movement..they all seemed to be OK by eye. clicked over the engine and checked them all about the same - thanks - seems i'll go for the fuel delivery system at this point.

 

[kuboman]

Bad injector or delivery valve I'll bet.

 

[chuckwsh]

I bought a new injector...first thing I did, didn't work, have them all in separate bags. Going to find someone to check them..but...whats a delivery valve?
I need learnin on that one...! also...how difficult/harmful can it be to take out the injector pump? if I leave the shims on it and use dust caps
on all the inlets outlets..perhaps there is a clog or dirt on one of the valves there? is this easily servicable?

thanks.

 

[chuckwsh]

runs! 4 hours of sequential troubleshooting paid off, it was a nice day out yesterday here in MASS. Took out all the injectors and was going to have em tested, but decided that I wanted to do it myself and test the system. Pryed the fuel lines up and around on each injector and attatched them all back on out of the cylinders. Had the wife crank the thing over and watched them all, #3 not producing. Swapped it with another, still not producing on that cylinder. Decided to go for the pump and the valves on top of it. One at a time I dismantled the tops, delivery valves? and cleaned them with canned air, put them all back together and bled the system, same deal, wife cranked the starter, only this time 2-3-4 worked but not 1! opened that again and watched the fuel run out the top for a second or two then sealed it, bled it and cranked it over, all 4 producking good streams of fuel. Assembled them all back in the block and it runs great, either dirt or a terrible vapor lock airbubble-whatever. Regular seasonal maintenence this weekend, sandblasting cleaning painting and its ready for the "Farm"! thanks for all the hints, keep the forum up, these things really save time and $ for folks who use them!
Chuck

 

[aquaforce]

thanks for all the hints, keep the forum up, these things really save time and $ for folks who use them!
Chuck

Glad you found it without a bucket of money spent.


I gotta ask............do you use Kubota fuel filters???

 

[madbobcater743]

Glad you found it without a bucket of money spent.


I gotta ask............do you use Kubota fuel filters???

Do kubota filters work or are the bobcat ones better?
or are they both made by the same company.

 

[Tooljunkie]

Im betting kubota fuel filters are cheaper.

Bobcat utv/yanmar powered thermostat was astronomical.
Its a polaris in bobcat colors. Yanmar was much less than half.

Bobcat is notoriously overpriced.

 

[North Idaho Wolfman]

I've found that most Bobcat branded parts are cheaper than Kubota branded parts.

madbobcater743,
Read your other post for more information.