Obsolete qlow plugs for generators

[hurst01]

OK, I will concede that. I also understand what you are saying about it being a hunk of junk. But it would still be an expensive glow plug even though it might be necessary at some point. You are much more experienced with these generators that I am. It looks as though there may come a time when the heads might have to be modified to accept another glow plug, hopefully that won't be anytime too soon, but who knows?
I have considered modifying the generator to accept another glow plug. I am a Journeyman Machinist and I have a few skills in this area. I have read a lot of concerns about an imbalance of the batteries with hooking up 12V circuit to just one battery. This would be more of a concern to me if it was a constant drain on that one battery. The glow plugs I have are for the civilian version of the Onan which operates on 12V. And yes, they are obsolete also but I have a bunch of them so that is the way I was thinking about going because they are a direct fit in the mechanical aspect.
The drain on the battery would be 15-20 seconds at start-up only because the glow plugs are rated for 11V, they heat very quickly on 12-13V. That small of a drain on one battery for such a short time would be miniscule at best. The thread size on the CH42 is 7/16-20 TPI. The thread size on the CH41 is also 7/16-20 TPI. I haven't done any research to see what other 24V glow plugs are on thread size. If there was one available with that thread size it would make it easier to adapt depending on the type of seat was in the head for the glow plug, whether conical seat or flat-bottom.
I believe these Gensets are far from being a 1000 pound clunk of junk as long as people put their minds together through discussion and ideas. There is too much knowledge on this forum to believe otherwise. I found a 24V-12V 20A reducer that could be put inline with no modifications to the existing wiring, is vibration resistant with heat sink for $25, but the added cost of $25 is prohibitive to some people. This would allow the use of a 12V glow plug and still be totally reversible should the CH42s ever be produced again.
I sold 68 CH42 glow plugs in the classifieds in 3 weeks so I know there is a need for the glow plugs, and I didn't try to screw everyone's eyes out on the price. I kept enough for my own Gensets and sold the rest. I bought a sizable quantity of what was supposed to be CH42s but turned out to be CH41s that fit the 12V version of Onan. I am just trying to figure out how others might use them since the CH42 are not so readily available. Glow plugs should last a long, long time on the correct voltage.
I started out with these Gensets, buying them and doing repairs for Disabled Vets that needed them for power outages. I repaired about 12 of them. Mine is the only one that the glow plug blew out on, flat burned the the complete spade connector off the end.

 

[dependable]

Don't forget to let the folks on Smokstak know you have the 12v ones available.

 

[BradBMI]

finally got thru the pile. The box looks the same but it appears to be a spark plug

Let me know if anyone needs these they are free

 

[DieselAddict]

If a 12v plug is available the best long term solution is to install a current controller to reduce the amps to the 12v plugs. To generate the same heat energy the 12v plug will need to pass twice the amps. Drawing less amps is OK but will lengthen the preheat times before getting a good start. If you want to use 12v plugs and keep the same preheat times you will need to evaluate the wiring harness and make sure it will take 9 amps @ 12v where now its doing 4.5 amps @ 24v.

Has anyone looked at using a DC motor controller? They operate on 24v and can be used as a (fancy) current limiter to the 12v plugs.

 

[Keith_J]

I decided to experiment to see when my 002a needs pre-glow..this morning with 50 F temps, it started fine with NO pre-glow. I'm going to stop using any pre-glow to save the life of the glow plugs.

 

[CDR]

I decided to experiment to see when my 002a needs pre-glow..this morning with 50 F temps, it started fine with NO pre-glow. I'm going to stop using any pre-glow to save the life of the glow plugs.

Did you know that when u turn to start the glow plugs light?

 

[storeman]

Did you know that when u turn to start the glow plugs light?

True but the short cranking time has little effect on fuel ignition attributable to the glow plugs. IMO
Jerry

 

[DieselAddict]

Hi Everyone, I am new here but I think I have something valuable to contribute to this problem. Just so you know a bit about me, I'm an electrical engineer with 30 years of field experience. I'm also a diesel enthusiast which would be immediately evident if you saw the number of diesel powered vehicles in my driveway. I do all of my own work on my vehicles.

Lets look at the problem - 24v glowplugs are in short supply but mechanically compatible 12v glowplugs are available. Running the 12v plugs off a single battery is an option but not ideal due to the battery imbalance situation it creates. Also using a 12v plug with the factory wiring harness/GP relay isn't ideal due to the higher current demands of a 12v plug.

The ideal solution would be to run the 12v plugs off the 24v system. This creates a problem because most 12v plugs are around 1.5 ohms. At 24v this will be much more current than the wiring harness and relay of the generator should have to contend with. It also rapidly damages the plugs from overheating. Using resisters to ballast the circuit is an option but with that solution you are creating a second set of glow plugs that are doing nothing but heating the air and wasting energy. If you do choose that option you need to use one resister for each GP and not one resister for all 4 (or at least do them in pairs). Otherwise as correctly stated in another post any single GP failure throws the entire circuit out of balance and your heating from the GPs will be negatively affected.

So to use 12v plugs in a MEP-002 or MEP-003 you will need to replace the GP wiring and evaluate the GP relay to see if it can handle double the the current. To limit the amount of power going into the 12v plugs I would recommend using a PWM based power supply. These power supplies are common on electric cars and scooters and are very easy to find and CHEAP. I just looked up units in the 24v/40a range (suitable for this application) and they can be sourced for around $20. You will need 40a for 12v GPs. With one of these supplies you can then drive the 12v GP directly from 24v without overheating and damaging the GPs. This solves the battery imbalance issue. The downside of this is it does add one more thing to the system that can break. It means you have to change wiring and likely the GP relay to handle the extra current. It also isn't free. However it will work. It will allow you to use 12v GPs on a 24v system. It is a cheaper solution than being wallet gauged for the last few remaining 24v plugs on the open market.

On the plus side it allows for a very clean install. This is much more energy efficient than using resisters or liner power supplies (voltage regulators). There is room in the control panel to put one of these PWM speed controllers in there. And it keeps you from breaking out your MAP torch to warm up the heads enough to fire off on a blistering cold day.

If anyone is interested in the specific details on how to do this or where to get the parts I would be more than happy to help.

Chris Medico
KC4YLE

 

[Isaac-1]

The problem as I see it it is that the 12V compatible glow plug does not have any better long term availability prognosis, it just has better off the shelf availability at the moment. I too had mentioned a PWM circuit of some type as an option, but did not have a particular source in mind, in one of these discussion threads, since both the MEP-002a and MEP-003a use the same glow plug relay / solenoid and the MEP-003a has 2 additional glow plugs, I suspect there would be no need to upgrade due to amp draw at least on the MEP-002a's. I think our best hope may lie in a threaded insert adapter that may fit some of these new ultra thin 2mm element glow plugs coming onto the market now, unfortunately all of the ones that I have found so far have a 10mm threaded body. I am not sure how practical it might be to rethread a metric glow plug to fit the 7/16x20 holes in our heads as an alternative option.

 

[DieselAddict]

Understood about the 12v direct fits being not available long term. It is likely that any GP able to be modified to work mechanically in the MEPs will be 12v. That just seems to be the nature of the market for the consumer stuff.

I have a MEP-003 for parts that I am planning to look at regarding this situation. The GPs from the VW TDI look very similar. I'm not suggesting these are the right candidates but a simple drill and tap may be a viable solution if a GP with the correct reach is determined. Even with that solution a current controller will be needed since most GPs are rapid heat 12v units in the 1 to 1.5ohm range. For reference the VW GPs are around 1.1 ohm.

 

[cuad4u]

As someone who has several 002A and 003A generators and who maintains a few more for others, I am facing possible 24V GP issues in the future. As late as two weeks ago I was able to purchase 4 each brand new 24V GP's with copper washer for what I consider to be a very reasonable price. I could have bought more than four if I wanted them. I say get them and stock up while they are still available.

Another source is parts generators. Two weeks ago I went to a sale where a number of 002A and 003A generators were being offered. Every one had been cannibalized and was missing various major parts. Before I placed a bid I looked them over very carefully. They all had GP's that looked to be OK and that tested 5 ohms from tab to ground. Never go to a sale without your VOM. They all had voltage / phase selector boxes that looked OK. These cost up to $500 each used and working. I removed the cover and the innards looked OK (always take a 7/16 socket and ratchet with you to sales). The 1 / 3 phase selector switch (reconnection switch) in each one was not locked up and turned easily. Several had all 3 electric fuel pumps ($242.00 each if bought new) and a few had no fuel pumps at all. A few were missing some gauges. Two were missing fuel tanks. All were missing the 3 section fuel filter assembly. Two had the external fuel tank adaptor, hose, and fittings that looked to be never used.

Any way I placed a bid that was basically what I considered to be a scrap metal price. I won all 4 generators that I bid on. I may swap parts to see if I can get one or more running or I may not. At least I have what I consider to be a lifetime supply of spare parts. If I sell just one working voltage / phase selector box I will easily recoup all the money I spent on all 4 generators. Just another way to look at it.

 

[Keith_J]

http://www.championsparkplugs.com/product.aspx?zpid=26137

"Item is on national backorder, contact customer service for estimated lead time..." Now what would happen if they had a sudden order for 3000 of these? That might justify a short production run.

 

[Chrispyny]

Another source is parts generators. Two weeks ago I went to a sale where a number of 002A and 003A generators were being offered.

Any way I placed a bid that was basically what I considered to be a scrap metal price. I won all 4 generators that I bid on.

Jeez, where r u guys finding these things like this ? Where can i find mep's on auction ? Goodness gracious!

 

[dangier]

Right place at the right time..?

 

[cuad4u]

Right place at the right time..?

Exactly right! You may go to many sales before hitting the jackpot. I was actually looking for parts units, which were plentiful at this sale. It seems that most people are interested in "whole" generators. Many times the generators that are "ugly" and that have been cannibalized and butchered are not bid on.

 

[sandrak]

Hi I am looking for four ch41 glow plugs.
Thanks
John

 

[CDR]

Have plenty email me at Davidnykp@aol.com

 

[rustystud]

Hi I am looking for four ch41 glow plugs.
Thanks
John

Why not use the CH42 plugs ? You can buy them for a real good price on Amazon now.