Glow Plugs

[Jimma]

Another stupid question, sorry. I'm new to the diesel world and got a problem with the glow plugs. What would cause the following problem? Sometimes, I depress the prewarmer before starting and it starts right up and I release the prewarmer and it runs fine. But then it stalls suddenly, even after running for some time and is obviously running warm. But if I depress the prewarmer it will start immediately but stall as soon as I let up on the prewarmer,. I may have to depress it for several minutes to keep it running. (runs fine if I do that) but stalls when I let up, then it seems to correct itself and runs fine when I let up on the prewarm button. Sometimes takes 4 or 5 minutes, other times 30 or 40 seconds. Any thoughts on whats going on? My other diesel burns very dirty when the pre warmer is depressed and clears up after I release it, but this one seems to run perfectly clean with the buttom depressed.

 

[Jimma]

If there are any deisel mech. out there or anyone who has an idea, I could use some thoughts. The machine runs fine after a cold start. I depress the manual pre heat button for the glow plugs and it starts right up. I release it after a few seconds and it runs fine for a time, sometimes a long time. Then it just stalls and won't start, even if it has been running for hours, unless I depress the preheat button. Then it will stall as soon as I release it. If I hold it depressed it will remain running and then after several minutes, I can release it and it will run normal for a while then repeat that same thing later. I don't kinow anything about the glow plugs except what I have read the last few days. They seem to work like a pre ignition on a gas burner. After the initial start and they have heated enough to burn what is in the ignition chamber, they shut down and don't have a purpose until you need to start the engine again cold. if that is the case, then my problem must be fuel, maybe water in it or clogged injectors. I just bought the machine so the fuel may have been sitting a while. I'm just a hacker trying to eliminate stuff. Can I rule out electrical if the engine is producing enough spark to keep it running with the pre heat button pushed?

 

[ChoppyChoppy]

What is the engine?

 

[Eq Broker]

Does the machine have a Murphy switch that you press to start the engine? If so, the Murphy is sensing that something is wrong with the engine and it will shut it down in order to save the engine from blowing. It could be either low oil pressure, high water temp, or low voltage. When the motor shuts down you need to identify which problem it is by looking at the gauges.

Hope this helps!

Dave
Global Equipment Exporters
770-420-6400

 

[Jimma]

The engine is a 34HP diahatsu deisel on a SC352 Vermeer stump grinder. And no it doesn't have a Murphy switch. If there was something else happening in the engine, I wouldn't think that it would start right up immediatley by pressing and holding the pre-heat. Wouls there be any situation where the engine would loose spark during operation and then operate only with the pre-heat button pressed then for mysterious reasons, regain spark and operate normally? This happened about 5 or 6 times yesterday in a 6 hour period.

 

[wood4heat]

. If there was something else happening in the engine, I wouldn't think that it would start right up immediatley by pressing and holding the pre-heat.

If it has a safety switch to cut fuel in the event of low oil pressure or anything like that the pre heat button would likely override it as there will be no oil pressure until it is running.

 

[Eq Broker]

I hate to say this as the Daihatsu is the worst engine Vermeer ever put on a machine. I have 13 years experience with the SC352 and many who owned this machine had to install a new engine with less than 700 hours. Daihatsu has left the US market due to the problems that they were having with their engines. I wouldn't recommend this machine to anybody. Diesel engines don't have a spark. I would take this to a diesel mechanic and see what they say.

Sorry, I couldn't help.

Dave

 

[Jimma]

Hi Dave, thank you for responding. I have another 352 with a Diahatsu motor and I have heard a lot of bad things about them. But I try and run it on a lower RPM than normal and keep an eye on the oil situation and hope I can keep them running. It does have an oil sensor/switch, but they oil doesn't seem to be the problem and the fact that it corrects itself while running even longer baffles me. It actually runs and cuts excellently when it behaves. I originally thought it was an electrical thing because the alternator went, but I replaced it and thought all was well.

 

[Eq Broker]

I don't think it would be a bad key switch and I'm sitting here trying to figure out what is causing the shut down. When a fuel solenoid goes bad it stays that way and needs replacing. I would contact Dave Hudson, as he's the Daihatsu rep to Vermeer. You can contact him at 913-669-6648 and he might be able to help you and get you to a tech. I believe he works for Briggs and was distributing the Daihatsu engines.

If I think of anything, I'll get back with you.

Dave

 

[Jimma]

Thanks for the info Dave, I'll give him a call. I think it is beginning to narrow down to a fuel problem. The machine sat for over 8 months and the fuel may have reacted badly and clogs or won't burn except with the excessive glow plug heat until the bad stuff is sufficiently burned. Sounds reasonable to me, but than again, I'm just a hacker. Im hoping someone smarter than me will read this and tell me that sounds right or that I'm a boob it's got to be this or that.

 

[Eq Broker]

I would replace the fuel filters especially if it has an inline fuel filter. They do have a tendency to clog. We had a machine in here last week that also had a cracked fuel filter housing. I would check that as well. When it's running, does it blow any smoke?

 

[Jimma]

Thanks Eq Broker, thats was what I was thinking but haven't had enough time to take a look and change it yet.

 

[Knobby57]

If you are sure you don't have a murf switch about all you need if fuel to keep it running once it's started . Most the newer diesels have a electric solenoid that is normally closed . Throw voltage at them and they open up to let fuel to the motor . Some will have 2 powers and one ground . Both are energized at startup then just one will have power when running . My gut feeling is you have a sticking solenoid. But before I did anything drain the fuel and make sure the tank is clean . Replace the fuel filters and make sure the fuel line is in good shape . If the fuel line is at all cracked , replace it , they can suck in air but not leak. I found that out the hard way .
Your fuel solenoid will probably look like this

Also running your glow plugs for that long is really really really bad . You can melt them into oblivion and not be able to get them out . I pm you my cell if you feel the need o may be able to help


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[Knobby57]

Sent from my phone when I should be working

 

[Jimma]

Thanks Knobby, The engine does have a gas shut off solenoid that is energized when the key is in the on position. I thought of that but couldn't figure out why it would suddenly shut while the machine has been running then re-energize when the glow plug preheat was pressed and shut down again every time the pre heat is released. Unless there is some type of short in the wiring which I will check. In the mean time, I will change the fuel filter and drain the remaining fuel and see what happens. By the way, on my way in a few minutes ago, I turned on the ignition, pressed the preheat and it started right up. Released the preheat and it ran perfect.. Thanks again, I really appreciate it

 

[Knobby57]

There is a good chance that when you energize the glow plugs you are engaging the pull wire on the solenoid


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[Jimma]

that would explain why I can restart the engine. But what makes it cut off mid stream? I'm a loosy mechanic but a pretty good investigator and not much makes sense to me except contaminated fuel. I guess the easiest way to check the solenoid would be to wait till it happens again and without turning the key to the off position after it stalls, see what the solenoid is doing. If it is the solenoid or an electrical problem, it should be closed. Otherwise it should be the fuel. Does that sound right?

 

[Knobby57]

You should have a ground . A hold open power and a pull open power . Pull open should only be hot in start up and the hold should be powered up key on . The hold power is not enough to open the solenoid just keep it open . And dont try to use the pull powered up all the time you will smoke the solenoid in short order


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[Jimma]

So when it stalls, if I test it before shutting the key off, the hold should still be pulling power? Lt. grey/black according to your diagram?

 

[Knobby57]

That diag is a generic . May not apply to yours but they are all mostly the same . If it stalls and you unplug it while the key is still on and it clicks then it's not likely your issue because it was still open . That solenoid is probably less than 100 bucks . Probably easier just to throw one on


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