New Glow Plugs Improve Cold Start, But Still Not Perfect..

[David_Jennings]

I recently replaced the glow plugs on my 99 6.5 and it helped tremendously with cold starting, but I still get a cloud of smoke when I start her in the mornings. (Smoke is always ominous.) She runs very well, and always starts after a second or two when cold, but the smoke give me concern. Is it possible my glow plug regulator is going bad too? (If you are going to suggest that I need new injectors, please lie to me about how easy they are to replace.) Thank you.

[DennisG01]

If the engine has been sitting over night, it's not uncommon to get some white smoke. Did the truck ever start better than it does now? What kind of ambient temps are you referring to?

How does it start if you cycle the glows a couple of times?

How does it start if you plug it in?

Are you positive that all plugs are getting power? Just use a test light or a volt meter to verify power at each spade when the WTS light is on.

Are you positive that all plugs are good? Just being newer doesn't mean they're good.

[DmaxMaverick]

Your result may be predictable, and possibly typical. If you replaced original OEM type plugs with AC60G plugs, and it is cold enough, there will be less glow plug heat than before. The 60's require twice the glow time to get as hot as older type plugs.

No lie. The injectors are an easy job. A little tricky at #6 and 8, but not a bad job by any means. Most complaints occur after the replacement, with improper/incomplete bleeding of air in the system. No biggie, though. If they have over 100K, or unknown miles, they are probably (past)due for replacement.

[David_Jennings]

I should probably say "colder" rather than "cold." I am on an Island in the Puget Sound, and the temp is usually in the high 30's at night.

I didn't test the plugs before or after. I will do so.

Less than 90K miles. I'd like to wait until it gets "warmer" and "lighter" before I tackle the injectors. Of course, leaning into that engine bay and working in a car port over wet gravel makes me appreciate going to work on Mondays.

[DmaxMaverick]

Well....Winter is just starting, and injector performance is more critical as the temperature drops. Good idea to do them during warmer weather, but they don't complain (as much) then, so get put off until it's inconvenient. Just works out that way, with most things. 90K is close enough to consider them "due". A new set will likely be a noticeable improvement, in about all respects. I suggest having them rebuilt and balanced, or replaced with new/reman's. No point in wasting time/money on testing, IMO.

I hear what you're saying about the island. I lived in Oak Harbor (Whidbey Is.) for several years. It isn't very cold now, and doesn't usually get very cold, or not for long, but it'll be a while before it warms up again. Pick a weekend with some sunshine predicted, and gitterdone.

[David_Jennings]

Now it's worse. I'm back to where I started. It's almost as though the new glow plugs worked for only a short period and went bad. I know there is fuel because I get clouds of smoke when starting it first thing in the morning. Once it's warm, it starts easily. It's not that cold here, only in the high 30's at night. Not sure where to turn next.

[DennisG01]

What type of plugs are they? What about how it starts when plugged in?

Did you test them, yet?

[rustyk]

Check your battery grounds at the engine/chassis. I had a similar problem, made worse by a lift pump failure. After checking/replacing/repairing everything on the "hot" side, all that was left were the grounds, and they were truly cruddy. Cleaned up, it starts right away. A puff of smoke is normal.

[DaveBr]

What is your wait to start light doing from the time you turn the key on? Should stay on about 7 - 10 seconds then give quick flashes every couple of secs four or five times.

[JTodd]

I just changed my plugs because they were obviously bad. Even with an almost immediate start, there is a plume of smoke as startup. Always been there. If the truck is starting fast, you are not having a problem other than perhaps leaking injectors.

Personally, I wouldn't worry about them. If there are no other issues, such as poor running, hard starting, etc, go have some turkey and spend the money on Christmas presents for your family

[David_Jennings]

Now it won't start at all. Just tried to get her going, and there is nothing happening. I get white smoke and can smell fuel, but it is gradually declining. I tightened all the grounds, and I can hear the lift pump working. I replaced the old plugs with Delphi HDS309. I will test the new plugs, but if they are suddenly bad after only a few days, then something else is causing the problem. My "wait" light is coming on and asking me to wait before starting, so everything seems normal. Once started, it runs great.

[DennisG01]

OK. Before you get ahead of yourself, still got to check some of the basic stuff, as noted above. Namely, if you're getting juice to each plug and how do the plugs test out?

[David_Jennings]

I need to test two things--whether the plugs are getting power, and whether the plugs are good. I thought I saw a couple of threads on how to test, but I did a search and found a ton written on glow plugs, but no easy to follow procedure. I'm assuming I can use my voltmeter, set at 12 volts, to test whether I am getting power. How about the test for the plugs? Could I use the same tool to test for resistance? I.e., touch the tang and touch the block, and if there is zero resistance, I have a problem, no? THanks.

[DennisG01]

Yup, you're on the right track. Check out post #6 on the link below. By no means am I the only one that has stated on this forum how to test them. It's just quick and easy for me to find it (using the search) by using my own name as a qualifier.

The best way is to test them using an amp-draw test. But, you'll need a meter with 20-amp setting. Most inexpensive ones only have 10 amps.

I *think* it was a member named Mark Rinker that showed how to do this using a battery charger. You might find this with a search (using his name).

http://www.thedieselpageforums.com/tdpforum/showthread.php?t=24395&highlight=test+glow+plug

[David_Jennings]

I used the test-light procedure and found that three of the plugs on the driver's side were already bad. Not sure how that can be. I didn't pull the wheel off to test the others, but I assume they are bad too. I tested the old plugs that I removed, and found two that still worked. I stuck them in and it made a difference. Okay, my new glowplugs failed after only a week. I thought glow plugs went out gradually. The big question is; what would cause my plugs to go out? Is there such a thing as bad plugs? Would the regulator cause the plugs to go south? I would like to figure this out before i shell out again for new plugs. Thanks again for your help. (The new plugs were Delphi.)

[6.5 Detroit Diesel]

did you use anything to start the truck? ether or something like that? it is easy to fry plugs that way if you aren't careful.

maybe you got a bad batch. i had something similar happen with plugs on one of my trucks. they were bad almost right away.

[DennisG01]

Usually plugs do last a while. Maybe you just got a bad batch. Unless the GP controller is throwing more volts at the plugs than they're spec'd for? Are you getting 12v at the plugs? You don't need to test each plug to verify if the Controller is bad since it only has 2 outputs. But, verifying if the GP's wires are good/bad means, or course, testing for 12v at the wire end.

Also verify that when the WTS light is off, that there is indeed 0 volts going to the plugs.

How about your grounds and battery cables? Good and clean? Also, is the plug making a good contact with the engine?

To completely verify a good plug or not (with it on your workbench), use the truck's battery or a portable jumper and put 12v right to the plug. You can use jumper cables or the porta-pack's cables. The plug should light up nicely from tip to about half-way down within about 5 seconds.


I'm just about out of ideas - hopefully some of the experts can chime in if none of this works for you.

[David_Jennings]

Can I test the output at the spade with the plug hooked up, or should I pull the hook-up and run the other end of the tester to ground? (Will this fry my little tester?) Thank you for all the help.

[David_Jennings]

What a nightmare! One of the glow plugs just disintegrated and started blowing combustion gases out the glow plug hole. It's the second to last one the passenger side. The clip is still attached to the spade, but the rest of it is gone! Talk about a bad batch of glow plugs. Now I have to worry about the parts that didn't get blown out.

[DmaxMaverick]

Unless your entire electrical system is "overcharging", you can't have too much voltage at the plugs. They get full battery voltage when engaged. You can, however, have too much time applied, and that can fry plugs. On the 1999, the GP cycle is controlled by the PCM, so it's unlikely unless you have a bad relay that's not disengaging when power is removed, but the WTS lamp will stay on as long as there is power at the plugs.

Just FYI, the plug ratings vs. the vehicle voltage is misleading. In most cases, including all GM 12V applications, 6V plugs are used. The reason is time. A 6V plug with 6V applied take 30 seconds to a minute to come up to heat, and the same is true for a 12V plug in a 12V system. HMMWV's use 12V plugs, in a 24V (actually a 28V military standard) system.

It is possible to get bad plugs right out of the box. I've had dozens over the years, and some in batches. I have fried whole sets of plugs in older (pre-OBD) systems when the voltage regulator failed during afterglow (system charge volts can exceed 20V). It can happen, but it's very rare. Not at all likely in a late model OBDII vehicle (glow plugs would be the least of your worries). It is also possible during jump starting or boost starting (with boost chargers).

As mentioned above, the use of ether (starting fluid) or other fuel starting aid can cause GP burn-out. Pouring fuel into the intake to help a start can also cause GP failure.

[6.5 Detroit Diesel]

make an adaptor for a vaccum and try to suck that crap out of there. sounds like you got a bad set.

[David_Jennings]

I pulled out the remnants of the glow plug and I lucked out: none of the heating element had detached. Very strange, however, to have it blow out and release compression like that. I put in one of the old non-working plugs and it fired up and sealed the hole. Now to the next step. I beleive I will replace the plugs and the glow-plug regulator. I don't beleive I am over-cycling, because the light is not staying lit for more than the usual time. Maybe my adventures on eBay led me to some crappy plugs. I am thinking about going to Pensacola Diesel (on line) for my parts. I got my PMD and cooler from them. I won't be buying Delphi plugs, that is for sure.

[David_Jennings]

Great idea with the vacuum.

Based the post by Dmaxmaverick (#20), I don't think my bane can be anything other than really cheap plugs. My WTS light functions normally, so I don't think my plugs are getting power for too long. However, to save the cost of a third set of plugs, I will replace the relay/regulator/controler. I can't think of any other variables that would cause plugs to go. And no, I have not used starting fluid of any kind. I got the plugs from a Canadian outfit that is now selling eDam plugs. Lots of noise about those plugs on the web.

[JohnC]

I'm not that familiar with the '99 wiring, but I'd guess the "controller" is really just a relay and the control is in the PCM. Also, the wait light is in parallel with the glow plugs, so if it's not on neither are the glow plugs. Based on what you've said, I doubt if the relay is part of the problem. My bet is the "Delphi" plugs are counterfeit.

[enormiss]

Guess I've learned one thing, avoid Delphi HDS309 plugs on Ebay
If the OP or JTodd could comment on duration of smoke and actual temps it'll help me (and others searching down the road)

I've been having issues with startup smoke since I bought my rig last winter.
This cannot be normal, I'm afraid of asphixating my neighbors. :D
Yesterday mornings temp was mid 40's, normal glow cycle, immediate start.
Had large amounts of smoke for around 40seconds.
Obviously not running on all cyl
This is typical (for me), with only the time of smoke varying with tempature.
Above 60deg and I'll have no smoke at all.



I just changed my plugs because they were obviously bad. Even with an almost immediate start, there is a plume of smoke as startup. Always been there. If the truck is starting fast, you are not having a problem other than perhaps leaking injectors.
Personally, I wouldn't worry about them. If there are no other issues, such as poor running, hard starting, etc, go have some turkey and spend the money on Christmas presents for your family

[DennisG01]

Sounds like a bad plug or two. Or, maybe some that are "not so hot". Test them all. At 40* you shouldn't be getting that much smoke.

PS: If you end up needing more help with this one, start a new thread. 'Ya don't want to be a "hi-jacker"! ;)

[JohnC]

Or poor spray pattern on some or all of the injectors...

[DaveBr]

I agree with John - your injectors could be spewing instead of spraying. You might want to do a compression test to see if low compression is contributing to the fog.

[David_Jennings]

This is interesting. I contacted the seller in Canada, and they admitted to having problems with plugs. They offered a refund, but may have backed off from actually giving one. I plan to send the plugs back. It is fair to assume that they may have been unaware that their supplier was slipping them counterfeit or bad plugs.

I have the supplier's name and address, but I am hesitant to post it until I know how he deals with the problem. If he ignores me, wouldn't it be fair and helpful to post the situation here?

I am about to install the new plugs and a new controller. I know it will fix the starting problem, because the plugs fixed it the last time; it's whether it will stay fixed that remains to be seen.

Thank you all again for your support. I have said many times that I would never own one of these trucks without this website. With the help from this website, I don't know why more people don't take advantage of the low price on these trucks. People are truly frightened of them. Another example of how GM shot itself in the foot.

[Plattman]

Reading this post brought back some very recent memories of a very bad experience. I purchased a set of (8) new AcDelco 11Gs on ebay a few weeks ago. First time cycling the new plugs, I was watching current with my clamp-on DC ampmeter and noticed that two were not firing. I went to pull them and couldn't due to swelled tips. After busting the two plugs and digging out the tip through the injector hole, I decided to remove the rest. 7 out of 8 were swelled. It took me an entire Saturday to remove the 7 bad plugs. I contacted the ebay seller and he refunded the money with out any hastle and just said he's never seen this before. These were either counterfit AcDelco plugs (although they did say AcDelco on them) or from a batch that the manufacuturer threw away which someone had dug out of the garbage. It was suspicious that the sellers name had "international" in it. His/her typed english was not good. The plugs came in sealed bags, not AcDelco boxes. He/she would not tell me were the plugs came from. As I understand, 11Gs have been out of production for a while and shouldn't swell, even if powered continously.
Picture below of 6 out of the 7 swelled plugs.
http://www.thedieselpageforums.com/photopost/data/500/medium/glowplugs_001.jpg

I purchased a set of 60Gs from RockAuto which I should have done the first time. I only "saved" $5 by using ebay. It still hurts recalling the memory. Needless to say it has been a learning experience.

[David_Jennings]

I replaced the plugs and the controller and it works perfectly. Time will tell now. I have never read anywhere that poor injectors would foul glow plugs, the way bad gas can foul a plug on a two-stroke motorcycle. Can glow plugs foul, after only a couple of week's use?

All of mine but one failed, but the strangest thing was that one melted and allowed the compression in the engine to blow through. You can actually see down the hole left by the tip that blew out. I've never heard of plugs coming apart on the outside. At least it didn't swell.


I took pictures, but I cannot figure out how to attach them.

[DmaxMaverick]

Reading this post brought back some very recent memories of a very bad experience. I purchased a set of (8) new AcDelco 11Gs on ebay a few weeks ago. First time cycling the new plugs, I was watching current with my clamp-on DC ampmeter and noticed that two were not firing. I went to pull them and couldn't due to swelled tips. After busting the two plugs and digging out the tip through the injector hole, I decided to remove the rest. 7 out of 8 were swelled. It took me an entire Saturday to remove the 7 bad plugs. I contacted the ebay seller and he refunded the money with out any hastle and just said he's never seen this before. These were either counterfit AcDelco plugs (although they did say AcDelco on them) or from a batch that the manufacuturer threw away which someone had dug out of the garbage. It was suspicious that the sellers name had "international" in it. His/her typed english was not good. The plugs came in sealed bags, not AcDelco boxes. He/she would not tell me were the plugs came from. As I understand, 11Gs have been out of production for a while and shouldn't swell, even if powered continously.
Picture below of 6 out of the 7 swelled plugs.


I purchased a set of 60Gs from RockAuto which I should have done the first time. I only "saved" $5 by using ebay. It still hurts recalling the memory. Needless to say it has been a learning experience.

Those aren't 11G's. If they only had AC Delco stamped on them (no part #), they are either 9G's or counterfeits (likely). 11G plugs will not swell like that. They just quit when they fail. I prefer 11G plugs, but they are getting scarce. I would buy used plugs before any off Ebay unless I knew the seller. I look for NOS (New Old Stock) at parts stores, and many of them still have 11G's on the shelf, although you may have to blow off the dust.

[DmaxMaverick]

I replaced the plugs and the controller and it works perfectly. Time will tell now. I have never read anywhere that poor injectors would foul glow plugs, the way bad gas can foul a plug on a two-stroke motorcycle. Can glow plugs foul, after only a couple of week's use?

All of mine but one failed, but the strangest thing was that one melted and allowed the compression in the engine to blow through. You can actually see down the hole left by the tip that blew out. I've never heard of plugs coming apart on the outside. At least it didn't swell.


I took pictures, but I cannot figure out how to attach them.

Glow plugs won't foul like 2 cycle (or oily 4 cycle) plugs. They don't require on a spark gap to operate. They heat internally, and will easily burn off any oil build-up. They can come out with a bit of soot caked on them, but it doesn't hamper the function much, if at all. Bad injectors can cause them to fail if they are in the flame path (which is non-existent with good injectors), but you'd likely have other serious issues before the plugs fry. A visual inspection of the plug should be obvious if this has happened. In your case, sounds like you had another demon at work. I have seen 9G plugs blow out the insulation and pass compression through it. This can happen if they are overheated, by one way or another.

There is a tutorial sticky on picture posting at the top of the photo forum. If you pics are too large, you can upload them to your TDP Photo Album (http://www.thedieselpageforums.com/photopost/index.php), or have them hosted off-site (Photo Bucket, WebShots, etc.), then link them into your post.

[David_Jennings]

I posted a couple of pictures in the photo albmum. I hope they show.

[DmaxMaverick]

I posted a couple of pictures in the photo albmum. I hope they show.

They are there. You can either link you album, like this (this will include all the images uploaded to your album, including those added later): http://www.thedieselpageforums.com/photopost/showgallery.php?ppuser=1326&cat=500 (you can use this link at any time, it won't change)

Or, link the individual images into your post. Below each image is a link you can copy/paste into a forum post using the instructions in the tutorial.

[David_Jennings]

So far, so good. The new regulator and plugs (wellmans) are working great. 24 degrees this morning, and she started up with no smoke. I was finally able to convince the eBay seller to make good on the glow plugs: he is sending me a new set. I don't need a second set, not for many miles, so guess where I will be listing them?

[DennisG01]

Uh-Oh. Someone correct me if I'm wrong, but doesn't Wellmans = WAP's? There was a wide rash of bad plugs by them. They kept burning out quickly. They're of the "quick heat" variety, which in and of itself isn't bad. But these were problematic. Hopefully you got them from a good place that has new stock of them and hopefully the new stock is good. I went through 2 1/2 sets of those myself... all in less than a year.

[David_Jennings]

You have to be putting me on. Wellmans are problematic too? I would really like to complain, but in light of the other postings under the 6.5 heading, most of what I'm going through is an owner and not a mechanical problem. Anyway, the seller of the Wellmans has excellent feedback, and they offer a one-year guarantee. But then, so did the last guy. By the time the weather heats up, I will have three spare sets of plugs, none of which I will feel confident to actually use, and I will be the fastest guy in the West at replacing glow plugs.

[DennisG01]

You have to be putting me on. Wellmans are problematic too? I would really like to complain, but in light of the other postings under the 6.5 heading, most of what I'm going through is an owner and not a mechanical problem. Anyway, the seller of the Wellmans has excellent feedback, and they offer a one-year guarantee. But then, so did the last guy. By the time the weather heats up, I will have three spare sets of plugs, none of which I will feel confident to actually use, and I will be the fastest guy in the West at replacing glow plugs.

I know, I know. I wish I was putting you on. Did you get them from SS Diesel? IIRC, Walt used to have a 2-year warranty on them - maybe not, but that seems to ring a bell - back when I had got them, anyway. Lots of guys have gone the route of trying the quick-heats or even just buying based on cost (not saying that's your reasoning - just a general statement). Sometimes it's better to just pay a few bucks more.

Oh well, like I said, hopefully the bugs have been worked out of those plugs... but unfortunately I have yet to hear anything good about them. Maybe they'll at least get you through the winter... Hope for the best!:)