JCB 3C engine hard to start from a stall.

[brother100]

I hope some has an answer to this particular problem. After my 3C stalls from Hydraulics overload, the motor wont turn over to start. Generally you have to wait more than an hour before the motor will turn over. It seems that there is pressure in the cylinders or something like that. I relieve all of the pressure from the Hydraulics and pull the engine stop all the way out but that does not seem to make any difference. One point though, the engine turns over freely when the engine stop is pulled out but wont start. This is an annoying one because if it stalls, then you have an extended wait before you can get back to the job. Any ideas fellows?

[essexpete]

Does it stall easily without the relief valve blowing? I am not a hydraulic expert but pressure in any of the rams should not make any difference to the oil flow if the spool valves are not returning to neutral. It might stall to easily if someone in the past has tampered with the relief valve setting but on releasing the spool in question the flow should be enabled. Perhaps someone with more knowledge can expand or correct me.

On the second point do you mean if you stop with the pull stop when the engine is hot the engine will then spin over normally on the starter but not actually fire?

[brother100]

Yes thats right, the engine turns over but wont start with the stop fully out. After I posted yesterday, I had a play with it and slowly pushed the engine stop in as the motor turned over and it fired up. Im not sure if this was a fix or co-incidence as I usually have to wait well over an hour before the engine will turn over at all.

The stall looks as though, as you said, something to do with the relief valve and it stalls fairly easy when under load. I have had a search on this one and there is a good post that describes why and how to fix it. Thanks for your help on this one.

[essexpete]

Well I guess it could all be fuel pump related. The starting could be stop mech worn /not returning properly. It would also seem that worn pumps go further out of the working tolerances when hot. Have you got a rotary or inline pump, it is probably a rotary. There is a filter in the pump inlet and there are postings about that on this site. Also if the governor mech is not working properly it may not be responding to the sudden drag of the hydraulic system (if you see what I mean).