Does propane eat glow plugs?

[paramax55]

As much as I hate this car, I'm glad I bought this 240D. I'm using it as a learning platform so I have this all figured out when I buy a "real" truck. I've made mistakes and this car will recover from them inexpensively.

One of my recent mistakes involves glow plugs. I've started experimenting with propane. Mysetup is as complex as one of those little camp-stove tanks hooked to a 1/4 turn ball valve with a hose going into the air cleaner. I get a LOT more power when I turn it on (the car only has 65 hp when everything is going well). From what I've read, it looks like I'm getting about 15 more HP when I'm sucking vapor and considerably more when I'm sucking liquid.

The car has been hard to start and the other day, I pulled out the glow plugs. The end of them was eaten off down to the core. I replaced them with a set I had pulled out of the boneyard and the car started normally again. Two days later, I pulled them again to clean out the prechambers and the new ones were eaten just like the old ones. Now, since cleaning the prechambers, I can make it into traffic again without fear of life so I probably won't be running the propane any more. But has anyone had experience with it? Can that be what ate the glow plugs? BTW, I've also added 5* of timing, but I more suspect the propane. The car has never had issues with the glow plugs until a few weeks ago.

 

[Blownoiler]

I have had glow plugs erode away very quickly in the past, the tips had melted. No propane was used, only extra injection timing and fuel. My guess was much higher peak temps and pressure had done the damage. After going through a few sets in a matter of weeks I detuned the engine a bit and then got a few months out of each set.

 

[paramax55]

Maybe I'll try sticking in one new glow plug and see what happens to it without propane. I hate to detune. This thing is so happy right now, it's the least I've hated the car. If it still eats a glow plug, I'll know it's the timing.

 

[JPhauler87]

Interesting. I wonder if timing and/or rug caused the issues with my glow plugs. I was thinking it seemed to timely to be a coincidence.

 

[paramax55]

I'm not suspecting the RUG. I was running it for a long time before my glow plugs went out. But it seems that everyone having trouble is also running advanced timing. I have 8 more glow plugs coming. I'll do some "experiments." They're only $3.00 each.

 

[FarmerFrank]

I'm not suspecting the RUG. I was running it for a long time before my glow plugs went out. But it seems that everyone having trouble is also running advanced timing. I have 8 more glow plugs coming. I'll do some "experiments." They're only $3.00 each.

$3 a hole for glow plugs?? Who, what and for what?? Normally I end up paying 3x that

 

[paramax55]

That's off eBay for a Mercedes 240D. It's a generic Champion glow plug, though, and it was listed for a wide range of vehicles.

 

[AcIdBuRn02ZTS]

You using a pyro?

If you are melting glow plugs... what about valves, pistons, injectors... they are seeing the same heat if not more.

 

[bbjordan]

My understanding is that propane causes the "burn" to happen faster, essentially raising the cetane rating of the fuel. Higher cetane fuel requires less advanced timing, not more. Eaten glow plugs are a sign of having the timing too far advanced.

 

[paramax55]

I'm not using a pyro and I'm aware that I could be hurting things. I'm hoping that it's the propane, but I'm aware that it might be the timing. I advanced the timing because of coking and overheating while running WMO. This car's purpose is for me to experiment and learn everything before I do this stuff to a "real" truck. If this thing explodes, I'll hate finding a ride home more than I'll hate not having this car.

I'm waiting for my new glow plugs to get here. First, I'll put one in and try running without any propane and see if it burns up. If so, I'll try backing out a couple degrees of timing and try another plug... When I had backed out timing before, I lost all kinds of power (this thing has none to spare) and was overheating. But the prechambers were coked up pretty bad. I've taken care of that and I'm trying to find a good balance. Right now, the car runs better than it ever has before.

 

[JPhauler87]

Why is advanced timing eating glow plugs? Doesn't make sense to me. Also, doesn't advance timing typically lower egt's?

 

[paramax55]

It definitely lowers the operating temps...

 

[Josh Carmack]

Advanced timing increases cup chamber burn temps the fuel burns closer to the injector hence reduced coking, and is known to burn GPs, but the Champions are most likely fully pr partially at fault. Buy some Berus, or OEM's champions, autolites and several other are window licking useless for anything more than a few days to a few weeks.

 

[Josh Carmack]

Easiest way to look at it is timing changes where the fuels burns with the most heat expenditure. Late timing, the fuel is still burning while it is being exhausted, hence the high EGTs several factors come into play that take lots of research, but an easy way to coarsely determine where the heat will be felt is the later the timing, the farther from the injector the fuel burns. there are other factors that come into play including piston shape, prechamber shape valve locations and the list goes on.

 

[paramax55]

Thanks for the note on the GPs. I'll keep that in mind. At least they were dirt cheap. Champion or not, they will last more than a day if the timing is not at fault. Honestly, it was just a little less than 24 hours - and less than 10 miles - before the last ones burned up. I'm not sure what brand they were, nor what brand the first ones were, but I do know that something with my engine burned them up. I had run both sets for some time, switching back and forth, before this suddenly happened.

I know about the timing. I think I might start a totally separate thread with what I've discovered about WMO and timing and my fuel mixtures. I'm waiting on a couple of more formulas I want to go back to just to see if some of the issues creep back up. That way I'll know what the limits are. This car is very happy with an extra 5* of timing on oil. It rattles and smokes on D2 but, switch to oil and give it about 3 seconds and it purrs like a kitten.