Hard Start Warm - Diesel Forum

eraser928 · 06-26-2005, 10:22 AM

I notice that when starting the engine once my engine is warm, it takes a few more seconds to get the engine started. It always starts immediately when it's cold. I notice that the glow plug light stays on the same length of time whether the truck is warm or cold.

I change my fuel filter every 10,000 and the oil and filter every 5,000 using Napa filters and Rotella oil.

I have about 115,000 miles on it and no DTC's. The truck has always and still does run great.

Any ideas?

[img]/ubbthreads/images/graemlins/shrug.gif[/img]

Spike481 · 06-27-2005, 02:01 AM

Hello, every time my alternator went out (3 times) the first symptom was, it seemed to crank over OK but took longer to start when warm. might not be your problem but it is easy to check by stopping by any auto parts store. SPIKE481

**klhansen** · 06-27-2005, 02:09 AM

If it's just a few (2-5) seconds, I wouldn't worry too much about it.

Probably has nothing to do with glow plugs, and by the way, the WTS light isn't connected to the glow plugs, they're independent. If it's cold (oil temp), the glow plugs will stay on up to 2 minutes.

It may have something to do with the oil temp input to the PCM for injection timing, when the oil is hot, the timing is more retarded than when the oil is cold. I once installed a resistor in place of the EOT sensor, and started it when cold. The timing was so far retarded that it took a LONG time to start, and filled the neighborhood with smoke. [img]/ubbthreads/images/graemlins/eek.gif[/img]

eharper177 · 06-27-2005, 09:18 AM

I asked a diesel mechanic this weekend about the warm start issue. He told me that since injection system relies on oil pressure to open the injectors, the thinner the oil, the longer it takes to build up pressure.
Hot oil=thinner oil=longer crank times.

**klhansen** · 06-27-2005, 12:51 PM

[ QUOTE ]
I asked a diesel mechanic this weekend about the warm start issue. He told me that since injection system relies on oil pressure to open the injectors, the thinner the oil, the longer it takes to build up pressure.
Hot oil=thinner oil=longer crank times.

[/ QUOTE ]

I don't think that's strictly true, as oil is basically incompressible whether it's hot or cold. All bets are off if there's air in the system however.

Cold oil would actually result in LOWER pressure at the injectors because of the increased resistance to flow that cold oil causes. The pressure would actually be a little HIGHER at the injectors when the oil is hot.

eraser928 · 06-29-2005, 08:21 AM

Thanks for everyone's input. [img]/ubbthreads/images/graemlins/warmsmile.gif[/img]

I have a volt meter in my truck and once I get out on the road, it pretty much always reads 14.3 volts.

Is there a chance that the cam sensor could be going bad or would I have other symptoms if that were the case?

Thanks again,
Jeff