1992 - 2002 GM OBS Trucks Vans 6.5L Diesel V8 Glow Plugs & Wiring Repair & Replacement (Chevy & GMC)

[@willdrivesu7914]

This is probably the best video I've seen for replacing glow plugs. I'm new to the 6.5 and have been trying to figure out why it just won't start after the outside temp drops below 50, (checked the controller and harness, all tests out fine) was really hoping it was not going to be a plug issue...as I have a hummer, reaching number 8 is going to take some serious gymnastics, I could barely get my hand in there to touch the connector. But...going to have to, because I'm not paying someone 1,000 bucks to replace them. (Yeah that's what I was quoted, lol )

[@mtebaldi1]

I agree.

[@Randy1290]

I have quickly fallen in love with this channel!

[@1966cambo]

Very detailed, thank you for your efforts!

[@mtebaldi1]

Great video DrShock

[@austonstromberg1347]

Thanks for the video I'm looking to do this on a 98 Savanah with a school bus body. The dog house in the van gives great access to 7 and 8 plugs. Whish me luck on not breaking one those shield studs.

[@ADEMONTE09]

Best KZbin video, lots of info thank you!

[@curtiskelly6724]

Great DIY video and great info.

[@jcfields3762]

DR. Shock How do you check optical sensor in IP ?

[@coreygood86]

I have an 82 K10 with a 6.2 diesel. If you have a factory glow plug controller the 60g plugs do not heat up quick enough to properly start the engine without excessive cranking. I used Kennedy quick heats and she starts up every time

[@eedom69]

I am tugging on these white connectors like mad and they aren't budging. Should i spray penetrating oil in the connector? I sprayed around the nut like part of the glow plug but wondering if spraying in the wire end would help?

[@DrShock]

It would not harm the wiring or connector to spray some penetrating oil into them to free up corrosion. It may help, the male spade end of the glow plug has a small square cut out of it (you can see this in the video thumbnail photo). The female end of the wire has a connector that grasps onto the spade, and into this square cut out. So it does take more force than a typical electrical connector to separate. I'd suggest moving onto another cylinder to get the feel for the force required with one that is less bonded together.

[@eedom69]

@@DrShock I've tried tugging on 4 or 5 and they are all tough. I will try the oil now. Thanks!

[@eedom69]

@@DrShock I think that little spade thing broke off in the connector. No idea how'd I get that thing out of there and I guess I need a new connector or wiring?

[@DrShock]

Yeah, as old as these 6.5Ls are it can happen. This is why I covered how to repair the wiring in this video. ;-)

[@eedom69]

@@DrShockRight so I just watched how you replaced that wiring and the initial test light will tell you if it needs replacing or just a visual inspection? It was quite a struggle but I removed all the connectors and only 2 spade heads (on the more rusty side) broke off in the connector. Really hoping removing the plugs will go better.

[@eedom69]

Any tips on getting the broken spade out of the connector? Been trying to push that tab down with various tools but getting close to just breaking it and u said u could get a new one from aptiv?

[@DrShock]

There are links in the description for the parts I identified in this vid. You need a special tool to separate the connector from the housing, I list that in the description too.

[@eedom69]

Well I got 7 out and one had to break. It broke right at the hex head. Impulse is to use a small drill bit but then not sure what after that. Any ideas?

[@DrShock]

When you say _broke at the hex head_ then if that means flush with the head with the hex part now gone, I'd say stop and drive it into a shop after buttoning up the other 7, as it will require specialized tools to address that I doubt you have given our previous thread of discussion (like using a MIG welder to put a nut on it). Don't attempt to use an extractor on a stuck plug remains as if the extractor breaks off then it's a pull the head off to remedy situation. If you mean the upper portion of the plug broke off, but the hex head threaded base of the plug is still there - then you might be able to continue by applying some heat to the hex head to further break up corrosion at the top threads.

[@jrm4408]

I have a 99 suburban with the 6.5 as well - I've changed all the glow plugs before but suspect a couple had failed again and was going to change them, then all of a sudden I stopped hearing the glow plug relay buzzing while the wait to start light was on initially. Very hard starting so clearly the glow plugs hadn't been powered while the light was on but once it started the light flashed on and off for a few seconds normally, at which point I could see the volts dip each time so that tells me the plugs were being powered at that time. Is this an indication of a bad glow plug relay/controller?

[@DrShock]

The voltmeter dipping does indicate that one, or more, glow plugs are drawing current. If that's not happening in the wait to start sequence it could be the controller, or it could be a problem elsewhere in the wiring harness. Would require a bit of diagnosis with the shop manual schematic to confirm which.

[@jrm4408]

@@DrShock At this point I'm going to roll the dice and replace the controller. As far as I know it's factory and new parts are always good insurance in an old vehicle IMO. If it's still doing it I'll have to investigate further, if not I have a spare.

[@jrm4408]

@@DrShock I just replaced the controller and got the same result. No buzzing from the relay but once it starts or after a certain time the key is on it will blink intermittently like normal and the volts dip each time the light comes on indicating the plugs are drawing power. Not sure what's next in line to check? I don't understand the circuit enough to know what tells the controller when/how long to power the glow plugs when the key is on (pre start) and the wait to start light is on. I know it's temperature related but not sure what sensor it's using. Coolant temp? A different one?

[@jrm4408]

Do you know where I can get a wiring diagram and/or troubleshooting info for the glow plug circuit? I'm still having issues even after replacing the controller. Don't have a shop manual.

[@DrShock]

Shop manual is the only source. Either hardcopy from the search link in the video description, or thru service information (SI) at www.acdelcotds.com

[@emso0105]

The wiring going to the glow is a fusible link. Any idea how to replaced it? Who sells it and what guage is the wiring?

[@DrShock]

There's a link in the description for a seller on eBay that has just that short length of baby blue fusible wire. Same gauge and manufacturer as original.

[@ESLinsider]

I got a 2003 p42 with a 6.5 are the glow plugs all the same part number? Like are the ones I need the same ones u used in this video?

[@DrShock]

The ACDelco part number I went over was the last and only 6.5L glow plug design released by GM (I showed this in the GM service bulletin during the video). GM stopped shipping these 6.5L engines in their own vehicles after MY 2002 (Express vans were the last to have them). Your Workhorse P42 (aka P van) that came with the GM 6.5L engine originally would have called for a Workhorse W8000549 glow plug (which I believe is actually the same GM ACDelco 60G plug we covered in this video rebranded by Workhorse).

[@ESLinsider]

@@DrShock Yeah Workhorse marks up a lot of stuff 2X what I can find on other sites. So looks like it is the same.

[@eedom69]

Mine are looking super rusty and I got a p0380 code I got a multimeter. I read some say to spray these down with a wd40 or pbblaster and let them soak for a few days before trying to remove them. Any advice? That part of my engine is rusty was there something I could put like paint or oil to stop rust in this area after changing the glow plugs or is it too hot?

[@DrShock]

If you are in the rust belt, then, yeah, I would definitely recommend a penetrating oil overnight first. Something like Kroil or PB blaster.

[@js1451]

How to remove glow plugs if very rusty? Pb blaster ? Heat them?

[@DrShock]

Penetrating oil overnight indoors (in a garage/shop) if cold out. Try with a 3/8" breaker bar after. I like to _escalate_ from there to a few _short_ bursts with a 3/8" impact wrench with a torque stick (to limit the force) and deep socket. The vibration is what I'd be after to breakup rust bonds not to actually remove the plug. Then back to the breaker bar to actually attempt removal. Regular maintenance intervals usually prevent the rust bond on the plug threads from becoming too much trouble. But if the truck has been neglected in this regard, be prepared for the plug(s) to break off flush in the head. Not the end of the world, just pull the head(s) and have a machine shop extract what's left. Even if you overcome the rust bond, if it's been neglected too long, the plugs electrode (aka tip) can be swollen and still not come out of the head. For this situation a special tool linked in the video description is required.

[@js1451]

How many f/lbs max on the torque stick?

[@davidneumann6231]

Great video. What crimping tool did you use? An Amazon link would be great. Thank you!

[@DrShock]

Thanks, the tool I used is an MSD ignition 35051 pro crimp. I have a link in the video description for the jaws that fit a series 56 terminal, as well as all the other parts I showed in this vid.

[@donaldlong9649]

what kind of book is that. that shows the glow plug diagram?

[@DrShock]

That would be the GM factory service manual. Last rev for OBS trucks would be 1998 second edition.

[@donaldlong9649]

@@DrShock ok thanks!!

[@whoopwhoopler8612]

You said to check the glow plugs every 100,000 miles. What is the upper end or range of the 6.5 in mileage before you have to rebuild the motor and heads?

[@DrShock]

GM unfortunately doesn't publish any maintenance interval information on glow plugs for the 6.5L diesel engine. So 100K is just _some best practice advice_ to avoid letting them go too long and become either defective, or damaged and thus difficult to remove. As far as engine lifespan, this really varies and I've not heard any consistent guidance in this regard. Diesels are far more robust than gasoline engines, but they also at some point will need to be rebuilt. For me personally, I'd go down the rebuild route when I encountered a major engine repair (e.g., new head gasket needed) rather than based off mileage alone.

[@eedom69]

@@DrShock I've got 66k and a P0380 code. Mine look rusty. I am going to get in there this week and test them out. Otherwise starts fine.

[@stephanburgess2805]

What does a glow plug do ?

[@DrShock]

Diesel engines do not use spark for ignition, but rather compression of the fuel. This type of combustion is most efficient at a particular temperature range. When cold, warming the combustion chamber eases starting, and that is the function of a glow plug. A glow plug is essentially a heating element. On a 6.5L diesel engine, they are cycled on and off until the appropriate temperature is reached for optimal starting.

[@lynchcreekmuzzy5759]

I am getting ready to purchase the Aptiv series 56 terminals from your Amazon link and it's asking for gauge....is it a 14-16 or 10-12 gauge. Just making sure before i order all this stuff...fantastic video!Sub'd - thank you 1993 C3500 Chevy 6.5L (150k original miles.)

[@DrShock]

Thanks. I seem to recall these were 14-16ga for that part number I used, but you should double check what you have already (just use your wire stripper to measure the outside glow plug wire insulation diameter). It's possible that different body styles, years may have gotten something different wiring size wise. Or that the wiring has been replaced/repaired in a past life altering it in that regard as well. Also if you have trouble locating them, they may be listed under the older name Delphi instead of Aptiv.

[@lynchcreekmuzzy5759]

@@DrShock will do....thank you 👍

[@eedom69]

I can't remove the connector

[@DrShock]

Likely corrosion has bonded them together, you'll have to pull more firmly straight out in line with the glow plug (not at an angle). I have a pair of pliers with plastic jaws for this purpose. Be sure to pull only on the connector, not the wire.

[@eedom69]

@@DrShock right thanks.

[@eedom69]

@@DrShock I sprayed them down in the wires ran the engine for awhile but they still don't budge. I can wiggle them but idk try pliers next? I don't have plastic ones but thought I could duck tape them. :/ Idk.

[@mtebaldi1]

DR Shock, are those Bilstein's your original shocks?

[@DrShock]

Those are the originals on this truck (not mine personally tho) yes. Great brand that I'm a big fan of, this set still passes the GM service manual tests just fine after a quarter century.

[@craigberube9890]

Have you ever work on a California emissions relay controller module? Any videos?

[@DrShock]

I'm not aware of any such module employed by GM on the 6.5L diesel powertrain during its production run. That's more likely for the later 6.6L Duramax engine.

[@ESLinsider]

Afraid I'll break this white connecter. You just pull it straight back? Penetrating oil help? These are Fairly rusty

[@DrShock]

The light colored plug housing to the end of the glow plug electrical connector? Yeah, just pull straight back grasping the housing *not* the wire. They are a friction fit at the spade connector of the glow plug. Depending on how many decades old your setup is, these may crumble or break unfortunately. I cover in the video a suitable replacement that is still temperature compatible. Now I'm talking about the tip of the glow plug wiring harness here, those short intermediate wiring harnesses on the passenger side that route thru the exhaust manifold shields are a different two piece design but the ends are the same.

[@eedom69]

@@DrShock Yeah I think like the one you showed in the vid. Accessing these is also tough right side looks like i can almost do it through the doghouse but the left driver side I got to take the wheel well apart and of course when they made these things they weren't thinking of that. Hidden bolts under the floor rubber. I'll guess i'll try again tomorrow.

[@davidneumann6231]

Did you use antisieze on the glow plug threads?

[@DrShock]

No, living in a southern area of the USA this has never been a thing, nor is it called for in the GM service manual. Though I will use Permatex Anti-seize on some exhaust fittings where torque isn't as much of a concern. But you shouldn't need it on a glow plug if you are using a torque wrench to install them. If the previous person didn't, yeah that could make you wish they had put anti-seize on the threads first . ;-)

[@davidneumann6231]

@@DrShock Thank you. I did not think you had used it but I was unable to confirm via the video as my wifi reception was sketchy during my install. I installed them without antisieze :). I used heat and candle wax to remove the heat shield nuts so there is residual wax on the nuts and studs so next time should be easier

[@eedom69]

You did a good job making the video but I Think I am giving up. Those plugs won't budge with a socket wrench putting most of my strength in it and I don't got an impact as I've seen others advise to use on a low setting to vibrate loose so I don't know what else to do. Called the dealership although for $160 an hour I could probably get an impact.

[@DrShock]

If this service has never been done, or the truck spent any time driving in Winter in a rust belt state, the glow plugs can be really bonded to the cylinder head due to corrosion. Even if not there could be swelling of the tips on the inside, requiring special tools to dislodge them without them breaking off. Rather than impact tools, you could instead try a sharp rap with a _small_ hammer mid-way against a breaker bar on the socket to try and dislodge the corrosion. I wouldn't recommend taking an older vehicle to a GM dealership if you decide to farm out the work. I'd instead recommend finding a diesel mechanic who will have the right special tools for anything that may go wrong. Preferably an individual who is on the older age side, and thus some experience with the 6.5L engine.

[@eedom69]

@@DrShock Thanks I am trying to understand what you said here: "try a sharp rap with a small hammer mid-way against a breaker bar on the socket to try and dislodge the corrosion."" A sharp rap is like hitting it? So something like placing the socket on the plug and striking it?

[@DrShock]

Use your same socket with a breaker bar, instead of a ratchet wrench (this is just a tool that does not ratchet so is stronger at the socket attachment point). You hold it with your left (unless you're a lefty) and strike the middle of the tool handle with a small hammer to drive it in the unscrew direction (lefty loosey). The shock of such a _rap_ can often dislodge corrosion at the exposed top threads where you can then get it going by hand the rest of the way with penetrating fluid. You might still run into a swollen glow tip, but it will mostly unscrew even in that situation so you'll be past the rusted threads challenge.

[@eedom69]

@@DrShock Okay I see I just don't have a breaker bar.