Won't start in cooler temps

[Melissa C]

I have a 1997 Suburban 2500, I live in southern California. It doesn't get seriously cold here, we hit freezing only a few nights a year. And yet, now that the nights are cool (40's Fahrenheit) my burb will not start in the morning. If I plug in the block heater for 25-30 minutes it will start, with a nice cloud of white smoke coming out the exhaust pipe. The smoke does not last long, but it's worse if the engine is colder.

I am shamefully, horribly ignorant about engines, which is why I joined up here - to learn. I plan on taking it in to my mechanic, but would like to have some idea of what might be the problem. I actually trust my mechanic, but he's not a diesel specialist. A friend thinks it may be a compression problem. He first suggested the solenoid, but that was replaced just a year ago.

I'm very grateful for any and all suggestions.

[Robyn]

This issue sounds like a classic glow plug issue.

Does your glow plug wiat to start light come on when you switch the key on ???

Does it cycle correctly ?? (should stay on for about 10 seconds then go off.

Now if the glow timer is cycling then the issue is either the timer/controller is bad or the glow plugs have failed.

If the light does not come on then the issue is likely the glow controller has failed.

More info please.

Missy

[Melissa C]

Mechanic SAID the glow plugs were good, but like I said he isn't a diesel expert. The "wait to start" light comes on, and I hear a very quiet kind of ticking noise which stops when the light goes off. I am not sure if it's 10 seconds, I think it's a bit longer than that, even more so when it's cold.

Thank you. If I can give any more information, just ask.

[JohnC]

The "wait to start" light comes on, and I hear a very quiet kind of ticking noise which stops when the light goes off.

Hmmm, it shouldn't be ticking...

You may hear a click when they turn on and another when the light goes out, but not a regular ticking. (You may be hearing the fuel lift pump, on the frame under the driver's side door).

The only way to test the glow plugs without removing them is to remove the wire from each plug and test its resistance. This is a fairly reliable test, although not 100% conclusive.

Each bank of cylinders has a separate harness with a fusible link. With the glow plugs connected and the wait to start light on, confirm that there is 10 or so volts present at the glow plug connector. If they have power and the plugs test around 1 ohm then they should work. If they still don't, pull out some of the plugs and test them to see if they get (red) hot.

Bottom line, however, is that if plugging the block heater in helps then it is almost certainly a glow plug issue.

[ronniejoe]

The ticking that you hear is probably the fuel lift pump on the driver's side frame rail. The 96 and up trucks run the pump with key on to prime the system before start.

The glow control is all done inside the PCM. It sounds like the system is trying to function as designed.

Each plug needs to be checked for continuity and each lead wire needs to be checked to ensure that voltage is being supplied to each plug. Disconnect all the lead wires and use a test light connected to B+ and probe the terminal on each plug. If the light doesn't come on, the plug is open and no good. Next, attach the test light to a good ground and probe a lead wire terminal. Switch the ignition to "Run" and see if the light comes on. Repeat this for each lead wire cycling the switch each time to ensure that the PCM is calling for glow. If the light doesn't come on on any of the leads, you have a problem. Find the break in the wiring and repair as required.

If none of the leads have voltage, probe the large post on the glow plug relay at the driver's side rear of the engine. The post near the driver's side is connected directly to the battery (B+). The post on the passenger's side of the relay is connected to the wire harness for the glow plugs. When the key is off, the driver's side terminal should cause the test light to come on when probed, but the passenger's side one will not. Just after turning the key to "run", the passenger's side post should turn the test light on when probed. When the PCM timer runs out, the light will go out and you should hear a click as the relay drops out.

If the light doesn't come on when probing the passenger's side post just after ignition on, then the relay is bad or the control wiring on the connector at the back is bad.

[Melissa C]

Thank you all so very much. I'm going to see if I can find some diagrams or any applicable videos on youtube so I can get a visual feel for what you are all telling me. I will feel a lot more confident in discussing this with my mechanic - thank you!

[Kennedy]

For the cost of a good set of plugs (we have them at $69) this is where I would start. The facts point to plugs anyhow.

[65-f100]

Melissa - I live in SC and had the exact same symptoms. I got a set of the glow plugs from Kennedy and just installed them yesterday. Fires right up without block heater plugged in and it was in the 40s here this morning. Almost certainly the glow plugs. Call Kennedy.

[Melissa C]

I wish very much that I could give Kennedy my business, but since I don't know how to replace them myself, was lucky enough to come down with the flu at the end of last week (I still have it, oh joy), and I need the 'burb fixed and ready to go before sunrise on Monday I bit the bullet and took it in to the nearest diesel shop (http://thedieselshop.com/). I can only hope that I'm not being hideously ripped off. That will teach me to put repairs off for too long. So far you have all been proven correct - the plugs are all mostly dead. Hopefully there are no surprises on top of that, as I doubt I could afford any more repairs. Thank you all.

[More Power]

Melissa,

Welcome to The Diesel Page!

Aside from a glow plug(s) replacement, be sure to run any other diagnosed problem by the guys/gals here before authorizing the work. I agree with others here that enough of the eight glow plugs might have failed.

Jim

[93GMCSierra]

Been a while since I was on here but I have a question regarding glow plugs.

How long do a set of kennedy plugs usually last?

about 2 to 4 years ago my dad and I replaced all the glows, among other work with a kennedy's as well as pcm
Now recently it has had trouble starting cold. This is on my dads 97 I dont have access to it so I can only go by what he tells me.
I am thinking the relay may have gone bad.

[ronniejoe]

I am thinking the relay may have gone bad.

Does the "Wait to Start" or "Glow Plug" light come on in the dash? If it does not, the relay is probably bad.

[93GMCSierra]

Does the "Wait to Start" or "Glow Plug" light come on in the dash? If it does not, the relay is probably bad.

My dad never mentioned it, I will be asking him soon as I can.

[93GMCSierra]

spoke to him he said the wait to start light does come on

[ronniejoe]

The relay is probably ok then. To confirm, check voltage at the two large, threaded terminals with the key off. There should be twelve volts at the one on the left (truck left, viewed from rear) and none on the one on the right. Have someone turn on the key, and check voltage on the right terminal again. There should now be twelve volts. You should hear it click when the key is turned on and you should hear it click again when the PCM timer shuts it down. Voltage should read zero again on the right post.

[93GMCSierra]

The relay is probably ok then. To confirm, check voltage at the two large, threaded terminals with the key off. There should be twelve volts at the one on the left (truck left, viewed from rear) and none on the one on the right. Have someone turn on the key, and check voltage on the right terminal again. There should now be twelve volts. You should hear it click when the key is turned on and you should hear it click again when the PCM timer shuts it down. Voltage should read zero again on the right post.

Thank you for your replies, he found his fuel filter was not up to the task, Should have looked into the cold weather thread first :D