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Discussion Starter #1
One of the ProMaster based class "B"s (campervans) I'm looking at uses an alternator to power the 120 volt subsystem of the van as opposed to a separate Onan generator. What I wonder about, would there be any ill effects in idling the van for long periods of time? A diesel is one thing (especially with the DPF), but I'm looking at the gasoline engine, and I've not found anything good/bad/ugly about idling the gas model for long periods of time, other than to change the oil and air filter more frequently to offset the use.

I hope this isn't something asked often, but curious about this.
 

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MMXVI - L2H2 in IN
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All idling does is add to the wear and tear of the engine and the components driven by the engine.
 

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2014 136” HR
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There have been, IIRC, two ~140,000 engine failures reported here by expediters. Excessive idling was a common factor, but not a proven cause.
 

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MMXVI - L2H2 in IN
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I believe Ray Magliozzi is unbiased.

It won’t hurt the engine any more than driving will, but it does waste fuel and pollute the air.
By Ray Magliozzi

I think your problem will be the generator belt slicing your radiator hose.
 

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I think I would go by the manufacturers recomendations rather than what's left of the Tappet Bros (and I gave no problem breaking all the rules, as a rule)!
 

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MMXVI - L2H2 in IN
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If someone knows what RAM recommendations are please enlighten me.

I used Ray as a reference because he an educated common sense car guy and I enjoyed the program.

And just to drone on.

From the gas owners manual.

City Driving
When stopped for short periods, shift the transmission
into NEUTRAL and increase engine idle speed.

Severe Duty All Models
Change Engine Oil at 4,000 miles (6,500 km) if the vehicle
is operated in a dusty and off road environment or is
operated predominately at idle or only very low engine
RPM’s. This type of vehicle use is considered Severe
Duty

NOTE: Under no circumstances should oil change intervals
exceed 10,000 miles (16,000 km), twelve months or
350 hours of engine run time, whichever comes first. The
350 hours of engine run or idle time is generally only a
concern for fleet customers.

My take from the owners manual is that RAM acknowledges that this engine might be idled for long periods.
 

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You have your answer then! Good luck and don't forget you were warned in advance.
 

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MMXVI - L2H2 in IN
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Anyway I was just providing an opinion to OP idle and generator questions.

The generator/alternator answer, I recalled reading about it, quick search, page 3 of Winston's build, provided by Dave's not home.
 

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"I think your problem will be the generator belt slicing your radiator hose."

Winston, here is your cue.
The 'belt slicing radiator hose' is a real problem, but it's related to a particular implementation of 'adding a second alternator' and, in any event, is a problem which, presumably, can be solved. There's the bigger question whether idling a gas engine for long periods is problematic.

We were strongly leaning toward a diesel when we learned that modern diesels, with all their 'dpf' filtering and regeneration cycles, were less-than-friendly to long idling scenarios. Fortunately RD is on the road and apparently unable to play his contrarian role on this topic . . . but he's been a thorn in our side . . . arguing, as you noted MsN, that there have been reports of premature gas engine failures due to extended idling. But idling our 2nd alternator is part of our design to replace the generator with a second, high current alternator and high capacity sine-wave inverter. So far, with our high capacity lithium house battery system (500AH), we've only used the idling engine/second alternator system for limited periods when we're drawing large currents, e.g. while operating our dual burner induction cooktop along with other electric appliances. Thus, it may be a MsNomer to say that we're going to idle the engine for "long durations" (note that we don't have air-conditioning which might induce others to operate their 2nd alternator systems for longer periods).

So, delay your decision for, say, 5 years and we'll report back on how many engines our generator replacement consumed.
 

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And radiator hoses. Can you repair a radiator hose with a Leatherman, I wonder. ;)
 

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I believe Ray Magliozzi is unbiased.

It won’t hurt the engine any more than driving will, but it does waste fuel and pollute the air.
By Ray Magliozzi

I think your problem will be the generator belt slicing your radiator hose.

Waste fuel and pollute the air more versus what? That should be the question in my opinion.

Yeah, maybe against solar it waste fuel and pollutes more; but if comparing idling a V6 against running an Onan at 3,600 RPM, then it depends on usage.


I expect the OP may be looking at Hymer or Roadtrek, which use a high-capacity alternator in lieu of an Onan. If that's the case and usage is mostly to power small devices like fans, lights, charge phone, etc., then running the engine at fast idle for a short time to charge lithium batteries is going to use less gas and pollute less than running an Onan for hours at very low load, but still at 3,600 RPMs.

If Onan was used to charge batteries by powering a converter, to then use batteries for devices, that's another scenario to evaluate.

Bottom line is Onan generators use a lot of fuel for their size/capacity, and pollute a lot more than PM engine per gallon of fuel used, so I don't think Magliozzi is correct with such a broad statement.

We also have to consider the Onan adds more weight to van, so will add some fuel consumption when driving whether on or off.


I also agree trying to operate an A/C is a game changer, which depends greatly whether the A/C is used while driving (doubtful) versus while parked (more likely). Running A/C for very long periods on a regular basis is the only scenario I can come close to justifying a permanent Onan.


In my opinion the future (in a few years) will be a second alternator at 48-Volts putting out at least 200-Amps. With 10-kW of charging the van engine won't have to run very long. Lithium battery cost also needs to drop below $300 per kW-hour at retail.
 

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MMXVI - L2H2 in IN
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Chance,

context, in the article Ray was responding to a general question about idling and engine wear, not about generators/alternators/solar or the environment.

Didn't mean to imply anything else with the quote.
 

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Discussion Starter #14
Waste fuel and pollute the air more versus what? That should be the question in my opinion.

Yeah, maybe against solar it waste fuel and pollutes more; but if comparing idling a V6 against running an Onan at 3,600 RPM, then it depends on usage.


I expect the OP may be looking at Hymer or Roadtrek, which use a high-capacity alternator in lieu of an Onan. If that's the case and usage is mostly to power small devices like fans, lights, charge phone, etc., then running the engine at fast idle for a short time to charge lithium batteries is going to use less gas and pollute less than running an Onan for hours at very low load, but still at 3,600 RPMs.

If Onan was used to charge batteries by powering a converter, to then use batteries for devices, that's another scenario to evaluate.

Bottom line is Onan generators use a lot of fuel for their size/capacity, and pollute a lot more than PM engine per gallon of fuel used, so I don't think Magliozzi is correct with such a broad statement.

We also have to consider the Onan adds more weight to van, so will add some fuel consumption when driving whether on or off.


I also agree trying to operate an A/C is a game changer, which depends greatly whether the A/C is used while driving (doubtful) versus while parked (more likely). Running A/C for very long periods on a regular basis is the only scenario I can come close to justifying a permanent Onan.


In my opinion the future (in a few years) will be a second alternator at 48-Volts putting out at least 200-Amps. With 10-kW of charging the van engine won't have to run very long. Lithium battery cost also needs to drop below $300 per kW-hour at retail.

You hit the nail on the head. I'm looking at a Hymer model, but because the battery life of it is measly (200 ampere-hours), in reality, the engine will be running a lot. Since I live in Texas, running the A/C is a major factor in the summer time, so when RV-ing, I either will be idling the engine for long periods of time or will be looking at a Honda generator. I would rather idle the engine, since the Honda consumes a lot of space in a little van. Hymer/Roadtrek are basing a lot of their technology on running stuff from the vehicle's engine. On diesel, that can be debatable, but on gassers which are relatively simple and well refined, I really have no idea how much it will affect engine life or vehicle life in general.
 

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Read up on some of kip's problems with idling - you will never idle again!
 

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MMXVI - L2H2 in IN
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Unless Kip-on-truckin has changed his opinion, this is from his thread "blew another engine" post 6 , 03-24-2017

Good ideas fellas. It was me who postulated that this problem, which happened to me and to another guy on the board, was caused by excessive idling. I think we can rule that out. This engine, installed 170k ago in Feb of 2016, got idled a little bit at the tail of winter 16, but I didn't idle it at all this winter. Didn't need to, figured out other solutions to keep warm. It was just a wild guess anyway - so far as I've been able to find out there's no connection between idling and carbon, or idling and valve issues. As a pure highway van, I idle FAR less than the average soccer mom idling in the drive thru lane of a Starbucks anyway.

Nope, my guess is that when I get the head off I'll find that the valve seat has fallen out of the head and is loose on it's seat, just like the last engine. My mechanic partially ruled out a lifter or rocker issue because those would have constant symptoms. My misfire comes and goes, and is highly load dependent. And the vacume loss means it has to be intake valve related.

My mechanic did put a horoscope on it and didn't see anything noteworthy except two shiny spots on the top of the piston. This could be normal, or it could mean that it was drinking coolant. But the van wasn't loosing a drop of coolant, nor is it burning a drop of oil. When I have the head off, I can compare it to the other cylinders. It may turn out that the problem is something I haven't thought of, but since it's identical to the previous problem, and the pentastar has a history of valve seat issues (supposedly resolved by 2013) I have no choice but to assume that's the problem.

One remote possibility is the problem is magnified by the internal EGR design. The pentastar, like a CAT Acert, overlaps the valve timing to keep some exhaust gas in the chamber. This is why it doesn't have an EGR valve - it does it internally through cam timing. It's possible that if the cam wears, or the cam phasers get funky, it draws in too much exhaust and that carbons it or otherwise fouls it. Dunno. I'm clutching at straws.
 

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Read up on some of kip's problems with idling - you will never idle again!

Just install a larger alternator so engine won't know it's idling. :)


Seriously, a good size alternator, plus running the A/C, can exceed power requirement of cruising at steady +/- 30 MPH.
 

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You hit the nail on the head. I'm looking at a Hymer model, but because the battery life of it is measly (200 ampere-hours), in reality, the engine will be running a lot. Since I live in Texas, running the A/C is a major factor in the summer time, so when RV-ing, I either will be idling the engine for long periods of time or will be looking at a Honda generator. I would rather idle the engine, since the Honda consumes a lot of space in a little van. Hymer/Roadtrek are basing a lot of their technology on running stuff from the vehicle's engine. On diesel, that can be debatable, but on gassers which are relatively simple and well refined, I really have no idea how much it will affect engine life or vehicle life in general.
We looked at a Zion in Tampa which had 400 Amp-hours of lithium batteries. They said the A/C would run about 3-1/2 hours off batteries, which seemed about right based on specs.

You are correct that if you do the math, once the batteries are discharged the first time, the engine would have to run a lot in order to keep up with power demand of a roof-mounted A/C.
 

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MMXVI - L2H2 in IN
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Nations starter/alternator spec is 198 amps, 15.33v at engine idle. $1800 kit
 

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Just install a larger alternator so engine won't know it's idling. :)
A smaller pulley makes the alt produce more power at idle. They do make them mostly used on plow trucks.
 
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