6.2L Maintenance

[tieoneon]

The forums have given me some great information so far. I just purchased a 1991 GMC Suburban with a 6.2L in it. I am new to the diesel world and wanted to find out if the Quick Heat plugs will make a difference over the AC Delco plugs in a generally warm area, I am in Virginia Beach, Va. I want to replace them as a preventative maintenance measure and can get the AC Delco plugs locally. I also wanted to know if you should replace the leads that goto the glow plugs and the controller ? Is this a good thing to do ? I appreciate your help on this. I am a total newbie so any information would be greatly appreciated. thanks.
George

[tieoneon]

Should this go in another forum ?

[argo]

While I am by no means an absolute expert on these engines, I can tell you that a good set of AC Delco 60G plugs will work well. When it gets really cold (which it may not in your area) you may need to cycle them twice (turn the key on, wait until the glow plug light goes out, shut off the key, turn it back on, wait until the glow plug light goes out, then crank). If you aren't scared of a slight wiring project, you can also add a resistor to the lead that the glow controller uses to monitor the glow plugs when activated. I put a 10 ohm resistor in mine which gives me 15 second glow times on cold startup. The Quick Heats I have no experience with, but many other people on this and other diesel forums have used them, and with great success. By using those you would not have to do the glow controller mod I just described. Many with 60G plugs also run without the mod as well. I only did it since I just finished a conversion into a gas Suburban, and I didn't want to have to gut the harness again if it proved to need the extra glow time, so I just went ahead and did it while I was there. I love that year of Suburban, BTW. It has the four small headlights and that bold grille on the square body. I love my 93, but the 88-91 are my favorites. Good luck, and welcome to the forums!

[DmaxMaverick]

Welcome aboard!

No. This forum is as good as you'll do.

Unfortunately, you've brought up a somewhat controversial topic. Much like asking about brands and types of engine oil, synthetic vs. traditional, tire brands, and such. The best you'll do is get a collection of opinions, then go with what makes the most sense to you. The opinions aren't necessarily wrong, but may reflect the personal experience of the contributor, and may be in conflict with the experience of others.

Here's my opinion:

Replace the wires/connectors if they appear to need it. If they are brittle, broken or burned, replace them. If they appear to be in good working order, a replacement may be worse than what you have now, not to mention the extra effort (and possible double extra effort, if you have to replace them again soon).

I like the QH plugs from Kennedydiesel.com. There was a short time period he sold a bunch of bad ones (failed quickly), but that was the cause of a bad lot, and John took care of his customers. The sets I've bought from him were before and after the period, so I can't comment on personal experience of that, only what I've heard. If I were buying GP's today, I'd buy Kennedy's, unless I found a local source for 11G plugs for a steal. The AC plugs (assuming you mean AC-60G) are good plugs, but don't get nearly as hot as previous OEM plugs, or the QH's. 60G's are a marginal gain in warmer climates, and often require modification in cold to really cold climates (Midwest - Great White North). The 60G plugs are good, but require 2-3 times the glow time to reach heat similar to a 11G or QH plug. Glow times, for me, have not been an issue for a long time (20+ years). All my controller-equipped Diesels have manual activation. The later models are PCM controlled, and do well if the serviceable parts of the system are healthy (wires, plugs, connectors, etc.).

In any case, stay away from the Ebay plugs if not sold by reputable retailers. There are a bunch of clones, including that batch of bad QH plugs, being sold. None are worth the risk, IMO. Poorly designed plugs can and do swell the tips when they fail, possibly leaving you with a major repair job, or worse.

[argo]

Replace the wires/connectors if they appear to need it. If they are brittle, broken or burned, replace them. If they appear to be in good working order, a replacement may be worse than what you have now, not to mention the extra effort (and possible double extra effort, if you have to replace them again soon).


Good point. If the glow plug wiring is weak, no glow plugs will work well.

[tieoneon]

Thanks guys that is great information. Thanks for the tip on the ebay plugs, I was looking at those but will probably go with the AC 60G plugs so that I can get them this weekend and replace them. I will look at the leads and figure out if any of them need to replaced. Thanks for the information. I actually have a bigger problem right now. I replaced the alternator belt because it was squealing and I was getting black dust on the alternator fan and the upper alternator bolt from the belt. I put the new belt on and took it around the block and that belt broke. So I have something out of line or the water pump or alternator are not spinning properly. I think it is the alternator because of where the belt dust is showing up. But I am going to have to figure that out this weekend. It is always something. I really appreciate the input. I might just put a new alternator, water pump and glow plugs in it this weekend and then hopefully not have to worry about anything for a while.

[Robyn]

The glow plug wires (green ones) are a fusible wire. Unless the wires are burnt through or have bare spots, keep them.

You might wish to crimp on some new connectors on the ends and add new little heat resistant covers on them too.

I like the 60G plugs myself. Had zero issues with them.

The older 11G plugs were good. The others such as the 9G would fry and swell. :eek:

I stick with Delco plugs

Robyn