Glow Plug Replacement (all?)

adrianmiura · **Posted:** Mon Mar 01, 2010 5:59 pm

Should I replace all my glow plugs or just the one that is bad (375 ohms) ?
Did some searching on the site and looks like there may be a slight chance that the plug will somehow break off and require head removal to confirm all ceramic material out of the cylinder.
Granted I have never worked with 7v ceramic glow plugs, but I have not had a problem removing them when I pre soak with PB Blaster. Has any here had a problem removing glow plugs ?

Thanks
Adrian

BVCRD · **Posted:** Mon Mar 01, 2010 6:05 pm

I haven't had the need on the CRD yet, but I have never broken one off in the past. If it were me, I would only replace the bad one. Wait till the other ones go bad IF they go bad. You can try the spray and soak method. Then, only back it out 1/4 turn, and then back in. Keep doing this a little more each time. Might want to spray more in between. Do this with a warm engine. Not hot, not cold. That will help with softening up any carbon buildup.

CATCRD · **Posted:** Mon Mar 01, 2010 10:59 pm

I wouldn't remove a glow plug if it wasn't bad.

CRDMiller · **Posted:** Tue Mar 02, 2010 10:12 pm

Pretty much the worst thing you can do to this engine is break a glow plug tip into the cyl, or mess up the threads.

I'd absolutely never replace a glow plug that was functional.

Unless you were going to use the crd to do something crazy where your life depended on it solely, and then i'd recommend a trailer and another crd.

dirtmover · **Posted:** Wed Mar 03, 2010 1:36 pm

#3 was done under warranty @ ~15months and I did #4 @ ~40months. #4 was cracked but both came out clean and without issue. I'm now at 46months and #'s 1 & 2 are still original.

The lifespan distribution would appear to be huge. I don't believe the longevity of these plugs can be predicted and failure of a single plug is not an indication that failure of the others is imminent. I've got three spares but will only use them to replace failed plugs.

Drewd · **Joined:** Mon Feb 06, 2006 12:24 pm **Posts:** 902

I personall would replace all 4. The plugs aren't as fragile in my experience. The only way I could break a glow plug was to drop it from 3 feet or snap it with a pair of pliers.

I don't know how removing a glow plug could break the ceramic? I just broke the torque on each glow plug and unscrewed them slowly and pulled them out slowly. Not an issue.

I replaced all 4 of mine becuase I had hard start issues and no bad glow plug codes. Starts like brand new now and I figure I'm good for another 70k miles.

MrMopar64 · **Posted:** Thu Mar 04, 2010 5:10 am

Even dropping a glow plug from just 3 or 4 inches up can potentially damage it. The impact can damage internally the inside of the ceramic or the pin inside which is transmitting the electrical current through the plug. The glow plugs are very fragile and should always be treated as such. Generally, a glow plug that would be dropped from any substantial height would be discarded and replaced with one handled correctly. To me, the potential to have engine damage certainly isn't worth the risk.

Drewd · **Joined:** Mon Feb 06, 2006 12:24 pm **Posts:** 902

I agree and I wouldn't intentionally mishandle new glow plugs. With all of the glow plug horror stories I've heard on tdiclub, I decided to see how much abuse the old ones I removed would take. I was pleasantly surprised to see that they were a little sturdier than what I had assumed.

ATXKJ · **Posted:** Thu Mar 04, 2010 8:31 pm

STAR told my dealership to change all 4 to troubleshoot a problem - they broke one - ended up pulling the head...

If it's working - it's best to leave it alone.

TDIwyse · **Joined:** Fri Aug 14, 2009 7:44 am **Posts:** 91

I'm curious about something. My two Cummins engines don't use glow plugs. They use an "intake grid heater" which is basically a heating element in the intake path that gets energized by the battery to create really hot air which gets pulled into the cylinders to aid starting in cold weather. Both of these engines start better than my glow plugged engines. And you don't have to worry about breaking tips off in your cylinders or the fussing around of changing each cylinders plugs as they slowly die. Is there some benefit to using plugs over the grid heaters? The only drawback I can see is it takes MUCH more current from the battery than the glow plugs. But I'd rather have the grid heaters . . .

adrianmiura · **Posted:** Sat Mar 06, 2010 10:17 am

Thanks for the feedback
Based on the replies im only going to chang the back glow plug.

nursecosmo · **Posted:** Sun Mar 07, 2010 5:13 am

TDIwyse wrote:

I'm curious about something. My two Cummins engines don't use glow plugs. They use an "intake grid heater" which is basically a heating element in the intake path that gets energized by the battery to create really hot air which gets pulled into the cylinders to aid starting in cold weather. Both of these engines start better than my glow plugged engines. And you don't have to worry about breaking tips off in your cylinders or the fussing around of changing each cylinders plugs as they slowly die. Is there some benefit to using plugs over the grid heaters? The only drawback I can see is it takes MUCH more current from the battery than the glow plugs. But I'd rather have the grid heaters . . .

Even though grid heaters are more reliable, glow plugs give cleaner, more complete fuel ignition in small displacement engines. Glow plugs also allow a slightly lower compression ratio in smaller displacement engines. Larger displacement combustion chambers such as in the Cummins, aren't as picky about how the ignition begins because there is much less thermal diffusion from the charge air to the cylinder walls. Duramax trucks have intake heaters as well as glow plugs for superior emissions performance. There have been a few guys who have retrofit small diesel engines like ours, such as Toyotas and Pajeros, but I don't know how well they turned out. They might smoke a little more at startup but that is what makes diesels cool, isn't it?

The biggest hurdle to overcome in installing a grid heater into a CRD would be the incredible current draw. Cummins engines use two 120 amp heaters for a total draw of 220 amps, or 2640 watts. Of course Ram trucks have two BIG batteries. My little mule barely has enough juice to turn the engine over @-30F, much less power a 120 amp grid heater, and that is with an after market Red Top. I would certainly want to have second battery if I were to go this route.

racertracer · **Posted:** Sun Mar 07, 2010 8:10 am

The question is, will we ever see a metal Glow Plug to replace the existing fragile ceramic one?

TDIwyse · **Joined:** Fri Aug 14, 2009 7:44 am **Posts:** 91

Those are interesting points, thanks.

Although, the Cummins 6.7L has been 2010 emission compliant since its introduction in 2007. I'm pretty sure it's only using a grid heater. The Duramax, even with a grid heater and glow plugs, wasn't meeting those emission standards. And both the Duramax and the Ford engines going forward will be using urea tanks while the Cummins doesn't need them.

My little 3.3L Cummins with a manually operated (I push a button which triggers a high power relay which stops when I release the button) grid heater starts better and smokes less in cold weather than my 2.8L Liberty with the glow plug system. And it's using the same single conventional battery my VW TDI uses. Although I believe this is likely due to having a starter that spins the engine faster than the CRD is using. I personally believe finding a faster spinning starter would be the best cold-start aid improvement for the CRD.

I just prefer the KISS method (Keep It Simple Stupid) whenever possible . . .

nursecosmo wrote:

Even though grid heaters are more reliable, glow plugs give cleaner, more complete fuel ignition in small displacement engines. Glow plugs also allow a slightly lower compression ratio in smaller displacement engines. Larger displacement combustion chambers such as in the Cummins, aren't as picky about how the ignition begins because there is much less thermal diffusion from the charge air to the cylinder walls. Duramax trucks have intake heaters as well as glow plugs for superior emissions performance. There have been a few guys who have retrofit small diesel engines like ours, such as Toyotas and Pajeros, but I don't know how well they turned out. They might smoke a little more at startup but that is what makes diesels cool, isn't it?

The biggest hurdle to overcome in installing a grid heater into a CRD would be the incredible current draw. Cummins engines use two 120 amp heaters for a total draw of 220 amps, or 2640 watts. Of course Ram trucks have two BIG batteries. My little mule barely has enough juice to turn the engine over @-30F, much less power a 120 amp grid heater, and that is with an after market Red Top. I would certainly want to have second battery if I were to go this route.

Drewd · **Joined:** Mon Feb 06, 2006 12:24 pm **Posts:** 902

Besides the founder of LostKJS, who has lost an engine from our "fragile" ceramic glow plugs? As long as they are handled carefully, they are a sound product. My last 2 diesels besides the Liberty CRD had ceramic glow plugs and never had an issue other than one going bad always around 65k miles.

How many ceramic glow plugs failures have occurred with the Liberty?

ATXKJ · **Posted:** Tue Mar 09, 2010 8:55 pm

I think Darby's last post on that it wasn't clear if the glowplug killed the valve - or the valve killed the glowplug.

MrMopar killed one - but a dyno's not always gentle, and his stuff is only sometimes stock.

I think everyone over about 50K has killed at least one - I took out 12 and it looked like the head was killing the plugs - not the other way around.

I think the biggest issue is possibly breaking one when you pull it.

flash7210 · **Posted:** Tue Mar 09, 2010 10:22 pm

So how do you know if a glow plug is bad if there is no CEL?
Where is the best place to buy new ones?

I have 60K miles on my '05 and am wondering if I should replace mine just to be safe.
But then I'd hate to break one off in the head upon removal. :oops:

baddabing · **Posted:** Wed Mar 10, 2010 2:16 am

I have 45,000 miles on mine. Sometimes when I go start the Libby, it starts fine. Other times it cranks over and over, more than usual. I am not sure if that is a glow plug issue or a fuel delivery problem? If you have a glow plug problem, do you always get a cel indicating such?

I to would like to know where the best place to buy glow plugs for these rigs?!

nursecosmo · **Posted:** Wed Mar 10, 2010 5:21 am

flash7210 wrote:

So how do you know if a glow plug is bad if there is no CEL?
Where is the best place to buy new ones?

I have 60K miles on my '05 and am wondering if I should replace mine just to be safe.
But then I'd hate to break one off in the head upon removal. :oops:

If it is bad there "should" be a CEL. I have 98k on mine and all the original plugs.

BVCRD · **Posted:** Wed Mar 10, 2010 9:47 am

I'm a little over 65,000 miles and all of mine still work. You'd know it, if it were cold out and one wasn't working.

Glow Plug Replacement (all?)

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