Glow plug temp sensors - 4005, 1047, ???

[BadDog]

I've got another question that I haven't been able to answer with searching (sites or Google).

Some time back I have read that there was a change to the glow plug post-heat control after the first few years. As I recall, it was basically a change to how the glows were utilized on warm starts, and the key difference was the water jacket sending unit. Along that line I've got 2 x 4005 senders and one 1047 sender. I assume the latter is from the demil motor, the other 2 from the civi donor motors.

But my question is, what do I want to run in the Sad Sub? Since the demil long block I built from was a 90 model based on internal engine stampings, and the 1047 is the oddball, I assume that's the one I want to use, presumably that will provide the desired later post-heat behavior. Is this correct?

 

[campfire]

I've got another question that I haven't been able to answer with searching (sites or Google).

Some time back I have read that there was a change to the glow plug post-heat control after the first few years. As I recall, it was basically a change to how the glows were utilized on warm starts, and the key difference was the water jacket sending unit. Along that line I've got 2 x 4005 senders and one 1047 sender. I assume the latter is from the demil motor, the other 2 from the civi donor motors.

But my question is, what do I want to run in the Sad Sub? Since the demil long block I built from was a 90 model based on internal engine stampings, and the 1047 is the oddball, I assume that's the one I want to use, presumably that will provide the desired later post-heat behavior. Is this correct?

The biggest factor in play here is not what type of block you have, but what type of glow plugs you're going to run. Early plugs heat quickly and then burn out. Later plug styles heat more slowly and are less prone to failure. If you run an early (short-cycle) controller with late (long-cycle) plugs, they won't be getting very hot. If you do the opposite the plugs will quickly burn out.

Personally, I use a hand button and skip the control system altogether. But if I were using one, I'd track one down from a later 6.5 truck. One long cycle and then several shorter ones as needed to hold temperature.

 

[BadDog]

Thanks.

The only reason I mentioned the apparent date of the block is as a possible origin for the odd-ball 1407 sensor. And I have new Kennedy Quick Heats in it.

Like my little C10, I plan to run both glow systems. When it works correctly, the stock system provides a nice convenience, mainly for the post heat warm up cycles. But, in my C10, I not only have the auto system still functioning, but also have a button to add heat if I choose, or if the automatic system fails. It has the slow slower plugs in it, and on the rare days when we have cold temps, it could prove a little grumpy starting and running until warmed up, which is why I added the parallel control system.

But my main point here was to try to identify the 2 water jacket sensors, and determine which (if either?) is needed to provide the later improved warm start cycles. As I recall from the article I read (and couldn't find when I started this thread), the only difference was in the "sensor". And I seem to recall that the new version wasn't even a sensor at all, but rather just a resistance. I thought it likely I could find an authoritative answer here, but if not, I'll apply more effort to searching out the article I read a year or so ago, or just investigate along the lines of my half-remembered details.

 

[BadDog]

Ok, I managed to find some of my own answers. The biggest problem was not having the right search terms, and the sender unit numbers weren't helping.

The 4005 sender is actually GM 2350-4005 (23504005), which is the new version of the "glow plug inhibit switch" that controls the glow plug circuit for 83-87 (23504006 for 88-91). These are the new numbers that effectively disable the glow-inhibit function. Originally, above a certain temp (nominally 125*F), the switch would open and eliminate the glow cycle. But this caused intermittent hard start problems addressed by Chevrolet Bulletin #88-49, GMC Truck Bulletin 88-T-39 and GM of Canada #88-662-100.

So, that's clearly the one I want for the glow inhibit switch. It can be located either in the front cross over, or at the rear of the passenger head in the crossover cap plate.

More detailed information can be found HERE, or by searching for variations "6.2 glow plug inhibit switch".

 

[BadDog]

I still haven't figured out 1047. After finding out the 4005 was the new-n-improved glow inhibit (dissable shunt) I suspected it might be "Housing Pressure Cold Advance" (HPCA), but that seems to be ACDELCO 10154649. That is always located on the passenger head on the side near the firewall. Looks identical, so maybe 1047 is a mill version specific? I need to look around and see if I have one of 10154649 (should have 4649 molded into face) somewhere.

More information can be found HERE

Side Note: That same Delco number appears to also be used as a cooling fan control among other things.

Also note that installed it looks just like 4005, but if removed you will see it has a copper cylinder about 1/2" long that protrudes into the water jacket.

 

[BadDog]

Aha! Finally found it, and yes, it's the HPCA as described in Post #3 HERE. Pop it back up to read the whole thread for more information.

And yes, it likely to be that it came from a HMMWV.

 

[longbedder]

Everything 6.2...and I mean everything, suggests that you'll be much happier and served more reliably in the long run with a manual control & self-limiting plugs (like AC 60G or Kennedy).

Or I guess if you really want to remain OEM, you certainly can...but the GP setup was a shit system. Why dump money into it when the alternative is so easy and works so well?

 

[BadDog]

I do have the Quick Heat plugs, but also want to keep the automatic glow system for convenience and function, particularly the reglow during warmup. I don't really see a problem with the stock system other than the OEM glows, and correcting the original early model "no glow on warm start" issue, certainly not something I feel that negatively about. But, like my C10, I'll be adding a manual glow override for backup or should I decide it needs a bit extra, but for day to day the automatic system will suit my needs just fine.

 

[campfire]

Hey, i just thought of something i always been meaning to do.
It would have helped diagnose my issue too.
I meant to power the gp "WAIT" light on the dash, from the plug side of the gp solenoid instead of letting the gp card do it.

That way, if there even was a problem with anything causing the gp plugs to be energized at the wrong time, i'd have an indicator light.
Alternately, i suppose you could leave the gp card in and just disconnect the grounding wire it supplies to the gp solenoid.
Then it would simply operate the dash light and you could use that as a guide for how much glow to give.

By the way, you can unplug the gp card and HPCA and fast idle still work just fine.

Hmm.
As a matter of fact, i might just try that.
I will remove the ground wire that the gp card has on the gp solenoid.
Reinstall the gp card.
Use it simply as a WAIT light glow time generator.
Then use my manual button.

I like the yellow glow of the WAIT light.
Sorta puts me in my happy place.
If you are going to have a stinky, loud, slow moving 6.2 diesel.. you might as well be in your happy place.

My offer stands.
If you want this Hillbilly Wizard gp card, you can have it.
Does what you want.
Pm me an address.
I'll ship it to you and you can reimburse me shipping.

That's how the older simpler controllers operated the light. If you manually jumper the solenoid closed the light comes on.

Of course, those systems say: GLOW PLUGS" instead of "WAIT." Might not give you the same warm fuzzy feeling...

 

[BadDog]

Wow, lots of good information, thanks. I'm trying to get this thing buttoned up to achieve a first crank in-frame. I've got a new OEM glow plug controller already on the sub, and haven't had any problems with the one on my C10, so may just go forward with that. When it's finished, I'll have the ability to both disconnect it and override/replace with a momentary button (just like the C10), so should be good on that front. I haven't heard anyone having excessive GP run after startup using the OEM GP controller, and don't recall ever seeing a burn-out issue on the Kennedy Quick Heats, so hopefully not an issue there. But I do really like the idea of a bulb on the plug circuit to show accurately when it's running, assuming this one doesn't already do it that way. I'll have to look at the schematic and see how the current one works.

 

[BadDog]

Good point, and I've made that argument (wouldn't have spent if they weren't sure it was necessary) myself. Certainly can be skinned, but may require more than a simple wire.

 

[longbedder]

I know i am sick for loving the 6.2.
The next time a crankshaft granades, i will do something else.
But I might keep the WAIT light and wire it to a toggle switch..
Hey, at minus 40, i swear i can feel the heat from the embers of a dying fire from that WAIT light.

I've been running my 6.2 for 13 years and my 6.5 for 8 years and many miles now, both with turbo assistance.

I've had no colossal failures of any sort yet.

I think the Information Age helps - back in the day they would fail due to maintenance issues. Now we just Google 6.2/6.5 diesel mods and can apply preventative fixes. I spent $800 on Fluidamprs between those two diesels and I don't worry one bit about bad dampers and their effects on the cranks. I had the pan off the 6.2 and not long ago and there's not a crack to be found on the bottom end.

 

[campfire]

So i am wondering if the resistive loading of the glow plugs pulling 10 amps a piece then suddenly having the solenoid break contact.. i wonder if that would burn the bulb out instantly or prematurely.

I don't think that could burn out the bulb.

For what it's worth, I haven't yet burned out any bulbs, 8 years later.

 

[K5wrench]

I don't think that could burn out the bulb.

For what it's worth, I haven't yet burned out any bulbs, 8 years later.

Well thanks!
I can have my happy light back just by tapping the glow plug side of the gp solenoid.