Home » Public Forums » GMCnet » Little used engine consideration (Broken out of unused engine thread)
| Little used engine consideration [message #336297] |
Wed, 22 August 2018 19:43  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Cesar Carrasco wrote on Wed, 22 August 2018 13:10This brings up a good question. I have been starting my gmc's at least once a month for about 10 minutes. I live in southern California, weather is mainly dry and hot. Is this enough?
Cesar,
At least you are thinking, that goes a long ways.
The problem is not the once a month, it is the 10 minutes that they probably idle in place.
Nothing good happens to an engine that is idling. Remember that line and it is hard on flat cam followers. (What most of us have.)
There are two big enemies of conventional little engines. (Remember, I am a ship's engineer.)
Those are:
1 - Thermal Cycles
2 - Corrosion
These two work in close concert to cause damage.
Thermal cycles are every time you start a cold engine. When you do a cold start, parts have to get heated up. Pistons heat up before anything else, and exhaust valves right behind. Then, the head comes along and finally the cylinder block.
The pistons are designed to get hotter than the bores, this is why they are not round and not ever cylindrical. They can take it - more or less.
The exhaust valve problem is the stems, but if the seals are lubricating them right, they will survive. They really only have to deal with the heat for about 20% of the cycle.
But the block and head have a different game. The cylinder block is full of cold coolant and the head is up against the fire ball that you just touched off. On engines with less than effective cylinder head retention, I recorded heads sliding 0.015" along the deck surface with each cold start. This was in a gasket lab, we would cool the engine off, light it and go to WOT. This is what you do not want to do.
Corrosion, on the other hand is a quiet killer. When you burn fuel, you make water - DUH! But because there are other things than just carbon and hydrogen in the fuel, you also make some other things that are acids. These are carried in the combustion by products into the lube oil system. This is the real reason you have to change off lubricating oil so often.
If an engine is run, but the lubricating oil is not heated to a temperature to make the water component evaporate, it and the acids stay behind. While they sit there, they can munch on expensive parts without interruption.
But there is another "Gotcha" coming. Those combustion by-products also get to collect on the internal surfaces like bores and valve faces and rings. Then there is the real big one for us. The entire exhaust system. There is that big long cold pipe to the back bumper. All that corrosive stuff collects there if it is given even half a chance.
I know all about this (Duh - again) but I got a nice warning in Omaha a couple of years back when the sound changed. That last bend at the bumper literally fell off. This was replaced at a local muffler shop and has continued to serve, but it was also a clear warning that the big long pipe under the coach was probably in similar condition. It was. Winter before last, I took it out without needing any tools. The largest piece fit in my trash can.
Now, back to Cesar's case. That ten minutes, unless you fire up and go out to the highway for a nine minute run is doing more harm than it is good. If you have engines that you do not use a lot, better than running them too little is to fog them and then defuel (for carburetor engines).
Fogging is something that every northern boat owner knows well(we put them away when the water gets hard), it is simple. With the engine hot, spray oil into the air intake so all the internal get a coating. That is just that simple. Defueling can be more complex and with our main engines, it is not all that simple. In actual fact, I have never done this to a passcar Rochester. But, if I ever have to, I will pinch off the fuel line before the pump and loosen the steel line at the filter, then run the engine until it starts to falter, then start the fog. When things get quiet, put everything back. The engine can now wait patiently for a year or more and when restarted, it will smoke for a moment, but otherwise be back to its good old self.
Let's carry this one step farther...
On all the RV sites I read that I should run the Onan (or what ever) for an hour a month. They say that this has to be done to keep the windings dry. This is a plan left over from before WWII. We now have better varnishes that are not hydroscopic at all, so that is one excuse that is done, but I do believe that the story is still pushed by the people that sell parts.
Want an Onan to last forever? When it will be ignored for a long time, get it hot (the engine end) and have a can of fogging oil ready. Pull the lead off the fuel pump and give it a minute to jam the governor at WOT. When that happens, start the fog. When it stops, put the lead back on the fuel pump. Now the engine is fogged and the carburetor is about as dry as it can be easily.
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Little used engine consideration [message #336319 is a reply to message #336297] |
Thu, 23 August 2018 12:59  |
Richard Denney
Messages: 920
Registered: April 2010
Karma: 9
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Senior Member |
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Better is to drive the coach to the store or the neighboring town once a
month. It’s still a thermal cycle, but real exercise is better than cold
storage, if it’s an option. Vehicles in regular use seem to last a long
time.
I have to get better about that myself.
Rick “rust never sleeps” Denney
On Wed, Aug 22, 2018 at 9:12 PM Matt Colie wrote:
> Cesar Carrasco wrote on Wed, 22 August 2018 13:10
>> This brings up a good question. I have been starting my gmc's at least
> once a month for about 10 minutes. I live in southern California, weather
>> is mainly dry and hot. Is this enough?
>
> Cesar,
>
> At least you are thinking, that goes a long ways.
>
> The problem is not the once a month, it is the 10 minutes that they
> probably idle in place.
> Nothing good happens to an engine that is idling. Remember that line and
> it is hard on flat cam followers. (What most of us have.)
>
> There are two big enemies of conventional little engines. (Remember, I am
> a ship's engineer.)
> Those are:
> 1 - Thermal Cycles
> 2 - Corrosion
> These two work in close concert to cause damage.
>
> Thermal cycles are every time you start a cold engine. When you do a cold
> start, parts have to get heated up. Pistons heat up before anything else,
> and exhaust valves right behind. Then, the head comes along and finally
> the cylinder block.
> The pistons are designed to get hotter than the bores, this is why they
> are not round and not ever cylindrical. They can take it - more or less.
> The exhaust valve problem is the stems, but if the seals are lubricating
> them right, they will survive. They really only have to deal with the heat
> for about 20% of the cycle.
> But the block and head have a different game. The cylinder block is full
> of cold coolant and the head is up against the fire ball that you just
> touched off. On engines with less than effective cylinder head retention,
> I recorded heads sliding 0.015" along the deck surface with each cold
> start. This was in a gasket lab, we would cool the engine off, light it
> and go to WOT. This is what you do not want to do.
>
> Corrosion, on the other hand is a quiet killer. When you burn fuel, you
> make water - DUH! But because there are other things than just carbon and
> hydrogen in the fuel, you also make some other things that are acids.
> These are carried in the combustion by products into the lube oil system.
> This
> is the real reason you have to change off lubricating oil so often.
>
> If an engine is run, but the lubricating oil is not heated to a
> temperature to make the water component evaporate, it and the acids stay
> behind.
> While they sit there, they can munch on expensive parts without
> interruption.
>
> But there is another "Gotcha" coming. Those combustion by-products also
> get to collect on the internal surfaces like bores and valve faces and
> rings.
> Then there is the real big one for us. The entire exhaust system. There
> is that big long cold pipe to the back bumper. All that corrosive stuff
> collects there if it is given even half a chance.
>
> I know all about this (Duh - again) but I got a nice warning in Omaha a
> couple of years back when the sound changed. That last bend at the bumper
> literally fell off. This was replaced at a local muffler shop and has
> continued to serve, but it was also a clear warning that the big long pipe
> under the coach was probably in similar condition. It was. Winter before
> last, I took it out without needing any tools. The largest piece fit in my
> trash can.
>
> Now, back to Cesar's case. That ten minutes, unless you fire up and go
> out to the highway for a nine minute run is doing more harm than it is
> good.
> If you have engines that you do not use a lot, better than running them
> too little is to fog them and then defuel (for carburetor engines).
>
> Fogging is something that every northern boat owner knows well(we put them
> away when the water gets hard), it is simple. With the engine hot, spray
> oil into the air intake so all the internal get a coating. That is just
> that simple. Defueling can be more complex and with our main engines, it is
> not all that simple. In actual fact, I have never done this to a passcar
> Rochester. But, if I ever have to, I will pinch off the fuel line before
> the pump and loosen the steel line at the filter, then run the engine
> until it starts to falter, then start the fog. When things get quiet, put
> everything back. The engine can now wait patiently for a year or more and
> when restarted, it will smoke for a moment, but otherwise be back to its
> good old self.
>
> Let's carry this one step farther...
> On all the RV sites I read that I should run the Onan (or what ever) for
> an hour a month. They say that this has to be done to keep the windings
> dry.
> This is a plan left over from before WWII. We now have better varnishes
> that are not hydroscopic at all, so that is one excuse that is done, but I
> do believe that the story is still pushed by the people that sell parts.
>
> Want an Onan to last forever? When it will be ignored for a long time,
> get it hot (the engine end) and have a can of fogging oil ready. Pull the
> lead off the fuel pump and give it a minute to jam the governor at WOT.
> When that happens, start the fog. When it stops, put the lead back on the
> fuel pump. Now the engine is fogged and the carburetor is about as dry as
> it can be easily.
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan
> OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com
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| Re: [GMCnet] Little used engine consideration [message #336321 is a reply to message #336297] |
Thu, 23 August 2018 13:46 |
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Cesar Carrasco
Messages: 30
Registered: September 2017
Location: Riverside, California
Karma: 0
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Member |
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|
Thank you Matt for your very insightful response. I'm saving it for future
reference.
Cesar
1974 Glacier 26' all original
1973 Sequoia 23' Holly carb and headers (and many other things I don't know
what they are yet)
Riverside California
On Wed, Aug 22, 2018 at 6:12 PM Matt Colie wrote:
> Cesar Carrasco wrote on Wed, 22 August 2018 13:10
>> This brings up a good question. I have been starting my gmc's at least
> once a month for about 10 minutes. I live in southern California, weather
>> is mainly dry and hot. Is this enough?
>
> Cesar,
>
> At least you are thinking, that goes a long ways.
>
> The problem is not the once a month, it is the 10 minutes that they
> probably idle in place.
> Nothing good happens to an engine that is idling. Remember that line and
> it is hard on flat cam followers. (What most of us have.)
>
> There are two big enemies of conventional little engines. (Remember, I am
> a ship's engineer.)
> Those are:
> 1 - Thermal Cycles
> 2 - Corrosion
> These two work in close concert to cause damage.
>
> Thermal cycles are every time you start a cold engine. When you do a cold
> start, parts have to get heated up. Pistons heat up before anything else,
> and exhaust valves right behind. Then, the head comes along and finally
> the cylinder block.
> The pistons are designed to get hotter than the bores, this is why they
> are not round and not ever cylindrical. They can take it - more or less.
> The exhaust valve problem is the stems, but if the seals are lubricating
> them right, they will survive. They really only have to deal with the heat
> for about 20% of the cycle.
> But the block and head have a different game. The cylinder block is full
> of cold coolant and the head is up against the fire ball that you just
> touched off. On engines with less than effective cylinder head retention,
> I recorded heads sliding 0.015" along the deck surface with each cold
> start. This was in a gasket lab, we would cool the engine off, light it
> and go to WOT. This is what you do not want to do.
>
> Corrosion, on the other hand is a quiet killer. When you burn fuel, you
> make water - DUH! But because there are other things than just carbon and
> hydrogen in the fuel, you also make some other things that are acids.
> These are carried in the combustion by products into the lube oil system.
> This
> is the real reason you have to change off lubricating oil so often.
>
> If an engine is run, but the lubricating oil is not heated to a
> temperature to make the water component evaporate, it and the acids stay
> behind.
> While they sit there, they can munch on expensive parts without
> interruption.
>
> But there is another "Gotcha" coming. Those combustion by-products also
> get to collect on the internal surfaces like bores and valve faces and
> rings.
> Then there is the real big one for us. The entire exhaust system. There
> is that big long cold pipe to the back bumper. All that corrosive stuff
> collects there if it is given even half a chance.
>
> I know all about this (Duh - again) but I got a nice warning in Omaha a
> couple of years back when the sound changed. That last bend at the bumper
> literally fell off. This was replaced at a local muffler shop and has
> continued to serve, but it was also a clear warning that the big long pipe
> under the coach was probably in similar condition. It was. Winter before
> last, I took it out without needing any tools. The largest piece fit in my
> trash can.
>
> Now, back to Cesar's case. That ten minutes, unless you fire up and go
> out to the highway for a nine minute run is doing more harm than it is
> good.
> If you have engines that you do not use a lot, better than running them
> too little is to fog them and then defuel (for carburetor engines).
>
> Fogging is something that every northern boat owner knows well(we put them
> away when the water gets hard), it is simple. With the engine hot, spray
> oil into the air intake so all the internal get a coating. That is just
> that simple. Defueling can be more complex and with our main engines, it is
> not all that simple. In actual fact, I have never done this to a passcar
> Rochester. But, if I ever have to, I will pinch off the fuel line before
> the pump and loosen the steel line at the filter, then run the engine
> until it starts to falter, then start the fog. When things get quiet, put
> everything back. The engine can now wait patiently for a year or more and
> when restarted, it will smoke for a moment, but otherwise be back to its
> good old self.
>
> Let's carry this one step farther...
> On all the RV sites I read that I should run the Onan (or what ever) for
> an hour a month. They say that this has to be done to keep the windings
> dry.
> This is a plan left over from before WWII. We now have better varnishes
> that are not hydroscopic at all, so that is one excuse that is done, but I
> do believe that the story is still pushed by the people that sell parts.
>
> Want an Onan to last forever? When it will be ignored for a long time,
> get it hot (the engine end) and have a can of fogging oil ready. Pull the
> lead off the fuel pump and give it a minute to jam the governor at WOT.
> When that happens, start the fog. When it stops, put the lead back on the
> fuel pump. Now the engine is fogged and the carburetor is about as dry as
> it can be easily.
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan
> OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
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| Re: [GMCnet] Little used engine consideration [message #336323 is a reply to message #336321] |
Thu, 23 August 2018 15:02 |
Deb
Messages: 349
Registered: October 2016
Location: Logan Lake, BC
Karma: 2
|
Senior Member |
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|
Cesar Carrasco wrote on Thu, 23 August 2018 11:46Thank you Matt for your very insightful response. I'm saving it for future
reference.
Cesar
1974 Glacier 26' all original
1973 Sequoia 23' Holly carb and headers (and many other things I don't know
what they are yet)
Riverside California
On Wed, Aug 22, 2018 at 6:12 PM Matt Colie wrote:
> On all the RV sites I read that I should run the Onan (or what ever) for
> an hour a month. They say that this has to be done to keep the windings
> dry.
> This is a plan left over from before WWII. We now have better varnishes
> that are not hydroscopic at all, so that is one excuse that is done, but I
> do believe that the story is still pushed by the people that sell parts.
>
> Want an Onan to last forever? When it will be ignored for a long time,
> get it hot (the engine end) and have a can of fogging oil ready. Pull the
> lead off the fuel pump and give it a minute to jam the governor at WOT.
> When that happens, start the fog. When it stops, put the lead back on the
> fuel pump. Now the engine is fogged and the carburetor is about as dry as
> it can be easily.
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan
> OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Ditto here! Great advice Matt. Having just just got the Onan running (and very well thank you very much!) I would love to do everything I can to keep her that way. I was planning on running it once a month as you said is suggested in everything you read.
Taking the coach for a run in the winter is not an option for me up here (usually too much snow to even get her out of the driveway). And it is fuel injected, so no carb to muck up. I will be leaving her parked with a full tank of ethanol-free gas this year rather than E10 and fuel stabilizer. But I CAN definitely defuel and fog the Onan.
Doing some reading on fogging an EFI engine (all information are from marine sites BTW).
Some say yes, some say no.
Some talk about mixing some 2-stroke oil with gas, popping off a fuel line and drawing that directly into the system that way.
Some say fogging an EFI will clog the injector tips so you should never do it.
Some say pull the plugs and put a tablespoon down each spark plug hole and manually turn the engine.
Would you advise trying to fog the GMC as well?
Deb McWade
Logan Lake, BC, CAN
GMC Alumnus
It's Bigger on the Inside!
[Updated on: Thu, 23 August 2018 15:14] Report message to a moderator |
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| Re: Little used engine consideration [message #336330 is a reply to message #336297] |
Thu, 23 August 2018 17:37 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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In critical service we ran gensets weekly, with load for an hour. I try to do the Onan monthly at worst, and load it with one of the roof A/cs till it runs about an hour.
For the coach, it goes out every month or two anyway to shows. It's powered at home to keep the natteries up. Otherwise I'll fire it and trun up to the pure gas staion and till it, and then do one exit of freeway and about 6 miles home. Gets it nice and warm and keeps the oil clean.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Little used engine consideration [message #336345 is a reply to message #336323] |
Fri, 24 August 2018 08:05 |
|
Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
|
|
Deb wrote on Thu, 23 August 2018 16:02Ditto here! Great advice Matt. Having just just got the Onan running (and very well thank you very much!) I would love to do everything I can to keep her that way. I was planning on running it once a month as you said is suggested in everything you read.
Taking the coach for a run in the winter is not an option for me up here (usually too much snow to even get her out of the driveway). And it is fuel injected, so no carb to muck up. I will be leaving her parked with a full tank of ethanol-free gas this year rather than E10 and fuel stabilizer. But I CAN definitely defuel and fog the Onan.
Doing some reading on fogging an EFI engine (all information are from marine sites BTW).
Some say yes, some say no.
Some talk about mixing some 2-stroke oil with gas, popping off a fuel line and drawing that directly into the system that way.
Some say fogging an EFI will clog the injector tips so you should never do it.
Some say pull the plugs and put a tablespoon down each spark plug hole and manually turn the engine.
Would you advise trying to fog the GMC as well?
Deb,
Yes, you can fog an EFI engine and you don't have to worry about defueling the system, but add a storage fuel treatment to no-alcohol fuel would be the way to go. Get the fogging oil in a spray can and with the engine hot and idling, spray oil in the throttle body for 15~20 seconds or until she starts missing, then turn off the ignition and keep spraying until the engine is still.
The reason you have to defuel the carburetor of the Onan is divided between two problems:
The light ends of the fuel evaporate an leave behind the other stuff that is thinker.
The fuel will oxidize in the carburetor (varnish) and it will have to be cleaned out.
This is not an issue with any EFI type system.
Fortunately, the vast majority of GMC owners are literate and above normal intelligence (if you think this is brag, go read some of the other RV sites) so doing things like this to take care of the whole unit are possible.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
|
|
|
|
| Re: [GMCnet] Little used engine consideration [message #336347 is a reply to message #336345] |
Fri, 24 August 2018 10:42 |
Deb
Messages: 349
Registered: October 2016
Location: Logan Lake, BC
Karma: 2
|
Senior Member |
|
|
Matt Colie wrote on Fri, 24 August 2018 06:05Deb wrote on Thu, 23 August 2018 16:02Ditto here! Great advice Matt. Having just just got the Onan running (and very well thank you very much!) I would love to do everything I can to keep her that way. I was planning on running it once a month as you said is suggested in everything you read.
Taking the coach for a run in the winter is not an option for me up here (usually too much snow to even get her out of the driveway). And it is fuel injected, so no carb to muck up. I will be leaving her parked with a full tank of ethanol-free gas this year rather than E10 and fuel stabilizer. But I CAN definitely defuel and fog the Onan.
Doing some reading on fogging an EFI engine (all information are from marine sites BTW).
Some say yes, some say no.
Some talk about mixing some 2-stroke oil with gas, popping off a fuel line and drawing that directly into the system that way.
Some say fogging an EFI will clog the injector tips so you should never do it.
Some say pull the plugs and put a tablespoon down each spark plug hole and manually turn the engine.
Would you advise trying to fog the GMC as well?
Deb,
Yes, you can fog an EFI engine and you don't have to worry about defueling the system, but add a storage fuel treatment to no-alcohol fuel would be the way to go. Get the fogging oil in a spray can and with the engine hot and idling, spray oil in the throttle body for 15~20 seconds or until she starts missing, then turn off the ignition and keep spraying until the engine is still.
The reason you have to defuel the carburetor of the Onan is divided between two problems:
The light ends of the fuel evaporate an leave behind the other stuff that is thinker.
The fuel will oxidize in the carburetor (varnish) and it will have to be cleaned out.
This is not an issue with any EFI type system.
Fortunately, the vast majority of GMC owners are literate and above normal intelligence (if you think this is brag, go read some of the other RV sites) so doing things like this to take care of the whole unit are possible.
Matt
Thanks Matt. Sounds like I have a plan for this winter. Last year it was fuel stabilizer, winterize the plumbing (I hoped - first time - wasn't sure if i did it right), kept it plugged in and crossed my fingers till May. Didn't worry about the Onan since it wasn't running at that point anyway. This year I will go with fuel stabilizer and EtOH-free, winterize the Onan as you described and do the plumbing. Still think I'll keep it plugged in though.
One last run down to Oregon to my first rally in September and then we'll be pretty much done till spring 
It's been an excellent first season!
Deb McWade
Logan Lake, BC, CAN
GMC Alumnus
It's Bigger on the Inside!
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