Diesel is hard to start.

[DeepFrz]

What conditions indicate that it’s time to replace the glow plugs?

Answer
The following signs most likely indicate that it’s time to change a vehicle’s glow plugs. If any of these conditions
exist, be sure to check the vehicle’s glow plugs and if necessary, replace them with a new set of Bosch
Glow Plugs.
• Vehicle won’t start
• Vehicle starts only after excessive cranking
Excessive cranking can cause the engine oil to be diluted with fuel, which could adversely effect the life
of the engine.
• Vehicle idles roughly after initial start-up
• Excessive exhaust emissions after initial start-up

[DeepFrz]

Can only the worn or failed glow plug(s) be replaced, or should all glow plugs be replaced at the same time?

Answer
If one glow plug fails, chances are the others won’t be far behind. To minimize vehicle down-time and save on
labor costs, Bosch recommends changing all glow plugs at the same time.

[pbiJim]

Originally Posted by brankin

My manual states 2 sec at 68 deg, 3.5 sec at 32 deg and 5 sec at -15 deg F
I freely admit that I held my plugs for 20-30 seconds and burned them out. This is my experience with my Isuzu 3lb1

That is very different from my experience with German & American diesels. I did not know that the spec's on an Isuzu were that different. Thank you for expanding the range of my knowledge.

[sabray]

They did not burn out because you held them on for 30 seconds. More likely they could not dissipate the heat because they were coked up from improper use of the engine. You insulated the elements by allowing carbon build up.
Once they reach resistance they are as hot as they will get be it 5 seconds or 30.

[Steve Bean]

It's interesting that there's so much variation in recommended glow times. I admit I don't know everything yet, but I'm working on it... In the old Mercedes, switching the key switch to the "glow" position activates the plugs for 40 seconds. If it's quiet one can hear the relay click off, and if the dome light is on, it gets brighter. The owners manual for my boat's Universal Model 40 specifies "30 to 60 seconds, depending on temperature.". So I guess it comes down to: "Read your manual!"

[DeepFrz]

Once they reach resistance they are as hot as they will get be it 5 seconds or 30.

Not so, read the post about what causes them to fail. Applying voltage for to long a period of time is just one of the causes. Coked up wasn't mentioned.

[sabray]

Okay it wasn't mentioned. Maybe I am wrong but I have seen glow plugs all yucked up. Maybe it is because the injectors are off. But caking gunk on a glo plug will shorten its life. Not because you had it going fir 30 seconds but because it's not dissipating heat and it's all coked over with soot stuff that looks like carbon or it's coked up.
Bad term that coke perhaps. But they are sooted failed kaput. Not because of the occasional 30 second on. Usually these boats are not going hot out everyday. Many many long burns might decrease the life .
My engine doesn't need the damn things.

[pbiJim]

Originally Posted by sabray

But caking gunk on a glo plug will shorten its life. Not because you had it going fir 30 seconds but because it's not dissipating heat and it's all coked over with soot stuff that looks like carbon or it's coked up.
Bad term that coke perhaps. But they are sooted failed kaput.

Every failed glow plug that I have pulled from my current motor has been coated with soot. You may be on to something there.

[sabray]

They suggest in the article that the glow plugs can run up to three minutes . How ever poor timing, bad injectors etc.... Will cause the glow plugs to fail. Why do they fail because they get crap baked on them. They don't say why like I just did. The say these actions will lead to failure. Why they fail is conjecture on my part. Pretty sure though may be wrong its cause their is crap all baked up on them. Just my thoughts. The article is nice but it does not get to the root unless you cycle the glo plugs a lot or have a issue as described in the article by Bosch

[leadingedge]

I'd check the glow plugs, then the injectors, then the inj pump. You say it looks like it is not fueling correctly when running.... sounds like injectors.

I had injectors so bad that they were letting air back into the injectors when the engine was sitting stopped.... very hard to start.

[Raquin]

Brankin You are my new hero. I put a heat gun in the intake and it didnt even get a full turn and it fired up. On further investigation. I have found that all the glow plugs have been removed. That why I couldnt see any. I was looking for wires. At close look there is a threaded hole next to each injector. I would guess it must not go into the cylinder or it would be blasting out compression. Thank so much. Now I wondering if I should I just put one glow plug in the intake. There is a hole there as well. I have seen glow plugs there. Heat gun. COOL TRICK. I have been fighting this problem for about 3 months. Im a man and have never kissed a man but it you were here I might. lol Not really. Thanks again.

[brankin]

Originally Posted by Raquin

Brankin You are my new hero. I put a heat gun in the intake and it didnt even get a full turn and it fired up. On further investigation. I have found that all the glow plugs have been removed. That why I couldnt see any. I was looking for wires. At close look there is a threaded hole next to each injector. I would guess it must not go into the cylinder or it would be blasting out compression. Thank so much. Now I wondering if I should I just put one glow plug in the intake. There is a hole there as well. I have seen glow plugs there. Heat gun. COOL TRICK. I have been fighting this problem for about 3 months. Im a man and have never kissed a man but it you were here I might. lol Not really. Thanks again.

That is fantastic especially in light of all the grief I got about glow plugs. Now you need to get those injectors back in that engine because all that cranking will trash your started and that really is $$$$$. When I replaced my plugs, they were less than $20 each. Just get the make and model of your engine and call John Snyder at Diesel injection service, 2988 SE Monroe St Stuart, FL 34997 (772) 283-8999 and he can tell you exactly what you need and ship them right out. He was the one who taught me the heat gun trick so you can give him a big Kiss

[brankin]

What kind of engine is it?

[a64pilot]

Sometimes old timers will disable glow plugs because they like to use ether and ether and glow plugs don't mix well. But I've never seen anyone actually remove glow plugs.
Often the threaded plug in the intake port is where an ether injector is placed, although a few Diesels will have an intake glow plug and one in each cylinder, my Duramax Diesel in my truck is the only one like that I have experience with like that.
Glow plugs are usually wired in series which means when one burns out, the remaining ones get more current and that can cause them to fail pretty quickly one after the other.
Every glow plug I have ever removed had soot on it, which makes me think they were in the combustion chamber, which means if removed, you would lose compression, yours have been removed without plugs being installed where the plugs go? Or did I mis-read that?
I have a lot of Diesel experience, but almost no Marine Diesel experience, so take my post with a grain of salt.

[Snore]

Interesting thread! After reading all the posts, I read the manual on my Universal 5424 to see if I was making a mistake.

The Universal Diesel manual states, "Activate “Glow Plug” switch for 30 seconds to 1 minute, depending on the outside air temperature. It may be necessary to hold the glow plugs on during the time the engine is cranked in very cold outside temperatures. Turn key to full “right” position to crank"

I do not doubt that some manuals have shorter times, just never knew the times varied so greatly. Could it be an age thing? Older engines need a little help to get going??