Starting Gremlin

[6.5 Detroit Diesel]

Okay, so I sometimes swear my truck is possesed. It will sit there after being driven for a while and laugh it's evil little diesel, um, tailpipe off as I crank the motor over! The scary thing is that it is that bad. If the truck is cold, doesn't seem to matter how cold, it will start no problem. -15C not plugged in, good batteries within the first few cranks away she goes. When it is hot, not a problem, don't even wait for glowplugs to start it. The trick is when I have got the engine hot and then parked it for say twenty to thirty minutes. The engine temperature will just barely register. Sometimes the glows come on for a few seconds, other times they will just flicker. The truck has a really hard time starting like this. Extended periods of cranking are going to wear the batteries down. A few times I have had to get a push start or else sit there for an hour and let the engine get cold. What the heck could be the cause of this? Is there a reason why the glowplugs aren't coming on consistently?

[ccatlett1984]

your glow plug inhibit switch is failing.
i dont know its location on the 6.5L, but its a simple thread-in temp sensor.

[6.5 Detroit Diesel]

Is this a problem that can be fixed by wiring a switch to the glowplugs so that I could manually control them? I have been needing an excuse do up a switch for a while now.....

[DmaxMaverick]

If you are going to set up a manual glow, ignore your current temp sender. You won't miss it. It only "prevents" (or is supposed to, when it works) a glow cycle when the engine is warm. With a manual glow, you will have control.

[Robyn]

If the engine has even some warmth in it it should start without glow.
Now, when it does start do you get a huge cloud of smoke after cranking??

If there is no big cloud of smoke you dont have a Glow issue but instead an IP issue.
This being that the IP cant make pop pressure at cranking speed.

Try adding a couple quarts of plain old engine oil to the a tank of fuel.
(do it while you fill to mix it)
This will add some viscosity and allow the IP to build more pressure when hot.
My gut feeling is that things are right on the ragged edge here and to the point that they are starting to show troubles.

Also make sure the starter is really whipping that engine over. Slow cranking especially hot (and if the IP is getting tired) will show this sort of thing.

I have had 6.2 N/A engines that I could start without glow on a hot day and they had sat over night.

The IP and injectors may be on the way out the door.

Let us know about this and we can go futher.

Robyn

[JohnC]

The glow plug inhibit switch has been eliminated. If you buy a new one it's just a jumper. So, you can jump it yourself. That'll either fix the problem or eliminate the glow plugs as the cause.

Next step, worn pump head...

[6.5 Detroit Diesel]

Okay, injectors have around 23,000 miles on them. When it does start, there is a lot of smoke from unburnt fuel. The starter cranks the engine at full speed when the batteries are charged. Last summer when it was hitting from 25-40C in the shade, I didn't need to glow it either to start it. I think I will try to set up the switch. What are some of the setups that have been used? I don't want the switch install to be a hack job.

[6.5 Detroit Diesel]

Okay, so I wired in an over ride using 10 gauge wire and a 35 amp switch. Seems to make a difference, but the truck still cranks longer when warm then when cold.

[93GMCSierra]

I would check to make sure the lift pump is running, as supposed to, if the lift pump is working, but not when the starter first cranks it would be the IP pulling fuel rather then the lift pump.

[daustin]

Did you try the oil trick like Robyn suggested? I've done that on a 4911 that was "on the edge" and it worked for a little while IF i held the pedal full throttle until it fired. (a couple of turns of the engine) Also, when it won't start try pouring some water over the ip. Not cold water, just rool level temp water. If it starts after that, your in IP need. The 92-93's are notorious for that problem.
Don

[JohnC]

Okay, so I wired in an over ride using 10 gauge wire and a 35 amp switch. Seems to make a difference, but the truck still cranks longer when warm then when cold.

If you used a #10 wire for each bank you'll be OK, but if you have a single #10 wire feeding both banks you're under sized. The switch has to handle about 100 amps. Use the starter relay from an old ford.

[6.5 Detroit Diesel]

I have wired the lift pump as well so that I manually turn it on. Don't trust the OPS anymore. I will try Robins trick next time I fill it up. Otherwise I guess I am looking for a new pump

[6.5 Detroit Diesel]

Took the truck down to a big rig place I used to work at. Good for calling in favors. Had them check out the alternator and batteries. One battery does need to be replaced, but it was the alternator that I was wondering about. It was putting out 100 watts at 1,500 RPM. I thought it was supposed to be at 140 watts.

[JohnC]

Did you put an artificial load on it? Otherwise it puts out only enough current to bring the voltage up to the regulator set point.

[6.5 Detroit Diesel]

No load on it, so I am guessing that 100 watts with no load is okay then.

[ccatlett1984]

I am going to assume you mean 100amps???

[JohnC]

No load on it, so I am guessing that 100 watts with no load is okay then.

Amps? Yes. Fine. Keep an eye on the volt meter. If it's more than about 13, the system is charging and meeting current demand. (Verify the accuracy of the gauge first!)