Jd 300b hard to start when hot

Mallard1 · Jun 17, 2020

Is the red arrow where the solenoid screws in?

Tx Jim · Jun 18, 2020

Your tractors hyd pump appears to be the non-serialized type which would require a more expensive electric controlled valve(RE40463 @ $871.66). From viewing your photo it appears that your tractor's hyd pump has a manually operated destroking screw(see photo below)

Mallard1 · Jun 18, 2020

Tx Jim said:
Your tractors hyd pump appears to be the non-serialized type which would require a more expensive electric controlled valve(RE40463 @ $871.66). From viewing your photo it appears that your tractor's hyd pump has a manually operated destroking screw(see photo below)

Thank you for your help. I didn't mind spending the $250 for the solenoid but for the $850 and as little as the backhoe is used I think i'll give the screw a try. I think i read somewhere the process is to screw down until resistance is felt then a couple turns to get it started. after started back it back out. is this correct?

Tx Jim · Jun 19, 2020

Mallard1 said:
Thank you for your help. I didn't mind spending the $250 for the solenoid but for the $850 and as little as the backhoe is used I think i'll give the screw a try. I think i read somewhere the process is to screw down until resistance is felt then a couple turns to get it started. after started back it back out. is this correct?

Yes that's correct.

Mallard1 · Jun 20, 2020

Tx Jim said:
Yes that's correct.

Thanks Jim, I believe this fixed my issue, I went down there Friday and it was slow to start. I used a 1/2 wrench to tighten it down. After that it spun over fast and cranked right up. Once I backed the bolt back out the hydraulics came back. Now I just need to find a good spot to keep a 1/2 wrench stored on the backhoe.

Tx Jim · Jun 21, 2020

You're welcome

finn1 · Jun 21, 2020

Hot start problems on a Diesel engine are usually caused by a worn out injection pump. The clearance between the plunger and barrel increases as the pump wears, and the viscosity of diesel fuel drop as fuel temperature increases. Net result is that the pump leaks internally such that there is insufficient fuel delivery hot to start the engine.

By reducing hydraulic pump pressure, you are reducing parasitic loads at cranking speed. The result is higher cranking speed, which masks the high leakage from the worn pump.

A bandaid solution, but it doesn’t fix the root cause of hard hot starting....a worn out injection pump.

Tx Jim · Jun 21, 2020

finn1
Many JD tractors built from '61-'92 with the closed center hyd system are difficult to start due to the hyd system not just worn inj pump. I'll bet you wouldn't be a happy camper if you had a JD tractor with a freshly rebuilt inj pump was still hard to start after it had been operated long enough to get hyd's to operating temp.

PS: After serving as a JD dealer service manager for 13 yrs I'm very familiar with the symptoms of IP that has a worn head & rotor just as I am with hyd problems on the previous mentioned JD tractors