Any Diesel gurus out there?

I need to go to the diesel knoledge koledge ASAP. One of my customers has a forklift with a 4 cyl N/A perkins diesel w/ mecanical injection, built in the late 90's, It is having a hard start/ no start problem every couple of days. The glow plugs work, the fuel filters are new and the battery is new, and the injection pump was recently rebuilt or replaced. What happens is that if it doesen't light up on the first or second try, it won't start at all, even with starting fluid. But what is realy wierd is that if I jump start it from a running engine/battery it usualy starts right up ,some times even w/o starting fluid. once its warmed up a bit it restarts fine.

So it seems that that little bit of extra voltage from the running engine spins the starter just a little bit faster and thats what it needs to light off.

So my non diesel edumaked brain thinks that this is indicating worn rings, when the starter is cranking at any thing less that 100% speed the compression is leaking past the rings before it can combust from the compression ignition. It also sems to have alot of blow-by gasses in the crank case after it does start, if I remove the oil filler cap on the engine a steady flow of blow by gass and pressure comes out. I don't know what amount of blow by would be considered normal for a diesel engine? Do diesels have a pcv system or any other way to evacuate the blow by gasses from the crank case? I need to figure out what is going on with this engine ASAP, three other techs have already worked on it and come up with nothing.

Weak fuel cut off solenoid or air cut off solenoid that requires extra juice to open? Check that.

Old NA diesels have no PCV, except on boats.

Did you do a compression test? That will tell you the rings deal.

HappyAndy wrote: The glow plugs work, the fuel filters are new and the battery is new, and the injection pump was recently rebuilt or replaced.

"The glow plugs work."

Sounds like glow plugs. They may "work", but your description makes them sound weak to me. How old are they?

Low compression is a good possibility.

mcp001 wrote:

HappyAndy wrote: The glow plugs work, the fuel filters are new and the battery is new, and the injection pump was recently rebuilt or replaced.

"The glow plugs work." Sounds like glow plugs. They may "work", but your description makes them sound weak to me. How old are they?

+1. Just because the light comes on and they are dragging down the volt meter doesn't mean they're working. Test the resistance of each one. If they're not within about 5% of each other, I would be very suspect. Also test the GP relay to make sure it has a clean closed circuit when energized. No more than 0.2v drop across the big side.

And starting fluid is a bad idea. It ignites way to easily for diesel use.

Don't use starting ether on a diesel. Diesel folks say the motor becomes dependent on it and won't work without it. I don't know- that's what I'm told. You can use a gasoline soaked rag over the air intake, but DO NOT let the rag get sucked in.

Is there a pre-heater?

Smoke on start-up is fairly normal for a diesel.

Is it stored outside? How cold is it being subjected to?

A cold diesel needs A LOT of cranking power to fire it up. While a gas engine may start on 40% cranking power, a diesel will not. One 80% capacity battery will not even be enough- it would need something like 95% of it's full cranking power through the entire cranking cycle. Does it have 2? Are they both very strong? (Note- they will balance each other. 1 weak one will draw down the other)

The simple temporary fix is a dipstick oil heater. Plug it in when not in use, it will fire right up. Or store it inside.

Warm diesels will always fire.

Check: cold cranking amps, glow plug resistance, fuel pre-heater, in that order.

Probably not compression. But that is pretty easy to check.

It's not direct injection, is it?

derekshannon wrote: BTW, Diesel should start with a capital D!

not this one

ignorant wrote: Weak fuel cut off solenoid or air cut off solenoid that requires extra juice to open? Check that. Old NA diesels have no PCV, except on boats. Did you do a compression test? That will tell you the rings deal.

The fuel cut off soleniod is also new, I don't have a diesel compression tester, and for as infrequently as I have to service them I don't plan to get one, but if I can get the boss to pay for it as a shop tool.....

Funny this came up. For years i have worked part time in the winter for a large snowplowing outfit. We use starting fluid by the case. Some of the older machines simply wont fire without it when its very cold out doesn't seem to hurt em one bit. Never had to use it on my 6.5 chevy I personally have seen diesel machinery come through with the wrong battery, resulting in a no start condition, not enough cca's. I seem to see more batteries that are junk even when new.

SVreX wrote: Is there a pre-heater? The simple temporary fix is a dipstick oil heater. Plug it in when not in use, it will fire right up. Or store it inside. It's not direct injection, is it?

pre-heater. no I will run the idea of a dip stick heater to the customer aren't all relitivley modern diesels direct injection?

I'll bet she is indirect injection, just from the way you are talking...

http://www.difflock.com/diesel/troubleshooting.shtml

http://www.aa1car.com/library/diesel.htm <--- according to that, there is a minimum cranking speed required by a diesel to light off.

So the fact that you might not be achieving min crack speed could be typical charging issues? Any way to check spec min crank speed on that bad boy and see if you are achieving it with current battery?

did ya check the alternator?.. charge much?

HappyAndy wrote:

SVreX wrote: Is there a pre-heater? The simple temporary fix is a dipstick oil heater. Plug it in when not in use, it will fire right up. Or store it inside. It's not direct injection, is it?

pre-heater. no I will run the idea of a dip stick heater to the customer aren't all relitivley modern diesels direct injection?

A forklift from the '90's is not a modern machine, in diesel terms.

aren't all relitivley modern diesels direct injection?

Yes and no.

When we think of direct injection we typically think about the difference between gasoline being injected before the intake valve or directly into the chamber.

With diesels, direct or indirect injection is different, since all of them inject fuel directly into the chamber. With diesels, direct injection squirts fuel straight into the combustion chamber from the injector nozzle. Indirect injection squirts fuel into a pre-chamber that is connected to the combustion chamber. The former requires huge injection pressures and very fine atomization. The latter can get by with lower pressures and the pre-combustion swirl chamber takes care of the atomization.

The Perkins you have should be IDI (indirect injection). That has very little to do with your problem, just thought I would clarify that little tidbit

Curtis is right, it has very little to do with you problem, only perhaps indirectly.

The reason I asked is that direct injection systems are finicky, require higher pressure, and frequently more electricity to get them fired.

Keep looking at your electrical.