F935 cranks but won't start, has run perfect

[pmsmechanic]

I wouldn't ordinarily suggest this but you might try a little squirt of starter fluid. Emphasis on little.

I thought of the same thing but before I used a little bit of starter fluid I would check and see if the glow plugs are getting any power. With the lead of the test light on a good ground the light should come on when held on a glow plug terminal while the glow plugs are on. Individual glow plugs can be tested by attaching the lead to the positive in the battery and touching the post on each glow plug individually. If the glow plug is good the light will glow.

A little bit of starter fluid means about a half to 1 second shot into the air cleaner housing before the air filter while cranking the engine over.

 

[radios1]

If you have unrestricted air intake, fuel and compression it should start.

Compression Pressure
3TN75, 3TN78, 3TN82,
3TNA82, 3TN84
(870 CUT, 955 CUT) . . . . . 2448 kPa (355 psi)
3TNC78 (3011 OEM),
3TN84 (3014 OEM). . . . . . 2158 kPa (313 psi)
Maximum Difference Between
Cylinders . . . . . . . . . . . . . . . . . . . 490 kPa (71 psi)

some engines need working glow plugs, though..

 

[TractorGuy]

I have to admit I am basing my comments on my experience from owning a JD 855 CUT. The F935 has a similar engine or so I'm told. My 855 never needed the glow plugs to start unless it was freezing weather. In fact I think it just had a air intake heater and it never even activated above 60 degrees.

Here is the JD check list if the engine doesn't start.

Troubleshooting

 

[pmsmechanic]

My F935 needs glow plugs every time it's started cold. when the engine is a operating temperature it starts ok without the glow plugs.

 

[pclose]

I guess you have verified it is fuel at the injectors and not water?

Yikes! I've been thinking about the water possibility. I don't think there was enough water, but when I changed the fuel filter and shook all the excess out I noticed some beads in my oil change bucket. It wasnt more than I would expect though. I'll check glow plugs with tester later and probably compression over the weekend. Not sure I want to go the starter fluid route yet. Younger me wouldve tried that already lol!

 

[i7win7]

I guess you have verified it is fuel at the injectors and not water?

Yikes! I've been thinking about the water possibility. I don't think there was enough water, but when I changed the fuel filter and shook all the excess out I noticed some beads in my oil change bucket. It wasnt more than I would expect though. I'll check glow plugs with tester later and probably compression over the weekend. Not sure I want to go the starter fluid route yet. Younger me wouldve tried that already lol!

Used to drive semi's, road service mechanics would test start diesels with wd40.

 

[radios1]

check if the glow plugs are getting voltage!..

 

[pclose]

Thanks. I hadnt checked glow voltage. I just did and there is 12+ volts at the glow wire. Battery tests at 12.9. I got a compression test kit yesterday. I also got starter fluid but I havent tried it. I'll test compression later through the glowplug ports. I cleaned up and loosened the glowplugs. . I pulled out each to get a look. They had some carbon built up on them, but not too bad. They smelled like fresh fuel. I don't know if they work. I'll test them electrically too. I'll post the compression results later. I plan to test each cylinder dry, then wet, for comparison.

 

[beenthere]

I also got starter fluid but I havent tried it.

From what I read and have heard, you best put that starter fluid away somewhere, as it can cause some damage to your engine.. Evaluate the risk, just sayin...

 

[TractorGuy]

WD-40 is a safer alternative. I have also used it looking for intake leaks.