MEP002a - Exhaust Shutter

[originalboxcar]

Happy 2010!

Over the holiday, I wanted to test a cold weather start-up of my MEP002a. I went thru the typical startup SOP and after chugging a bit longer in the start position ( roughly 7 - 10 secs) the genset started and ran smooth @ 7 degree farenheit.

It was my understanding that the shutter box near the exhaust is supposed to open to allow warm exhaust air in the intake for cold weather. I let it run for about ten minutes but the shutter never opened on its own. I have the air filter set in cold weather position and the shutter does open by hand without any apparent binding but then it closes if I let go.

FYI - the unit does have the ASK kit installed.

After referencing TM5....-12, I did find that there is a "thermo power unit" that appears to actuate the shutter.

Any enlightenment is appreciated. Thx!

t~

 

[Speddmon]

The shutters are operated by a "Thermo Power Unit" It's the same basic principal as a thermostat in a car....when the antifreeze in your car gets hot enough it melts some wax encased inside your thermostat, which in turn pushes a plunger to open the valve of the thermostat to allow fluid to pass the thermostat.

The "Thermo Power Unit" works very similarly, but rather than the plunger opening a water valve it's hooked to a likage that open the shutters. The shutters will not open if the engine block/heads do not get warm enough....These shutters are to allow cooling air flow around the heads in warmer weather operation, they DO NOT open automatically anytime the set is running...only when it get's hot enough inside the shutter box to need them opened.

TM 5-6115-585-12, page 3-10. The bottom right of the page, section 3-14 "Shutter Box Assembly" spells out the operation and testing procedure of your shutters. However if they opened when you ran the set during the summer months, then your shutter box is working just fine.

 

[originalboxcar]

Hah... I just updated my original post while you were replying Speddmon

I'm a little confused. I would assume that the EXHAUST shutter would NOT open up in the summer as, correct me if I'm wrong, it would open only to allow WARM exhaust air into the intake if it was COLD outside temp and then stay closed while WARM/HOT outside temp.

I don't recall it opening when I ran it in the summer.

Are you sure you're not referring to the air INTAKE shutter?

 

[Speddmon]

The air intake shutter is the black knob located on the air cleaner housing...that is manually operated only.

The exhaust shutters (Shutter Box Assembly) are on the box surrounding the mufflers and has the exhaust pipes exiting through the box.

These units are air cooled, using the fan at the back of the engine...when the shutters are closed the air circulates inside the shutter box and around the housings and exits where it can. When the unit get's warm enough, the shutters open allowing the cool air that is drawn in by the fan to blow directly across the cylinder heads when they get warm and exit through the open shutters to help to cool them. If the shutters didn't open when it starts to get warm, you're soon going to be tripping out the high temp shutdown switch located inside that box which is between the heads. Also, lord forbid, if that switch fails and does not open then you will seize your engine from the heat generated...the shutters have to open when the space inside the box get's warm.

After the first minute of running, even in the coldest temps, the cylinders will be plenty warm enough that that air intake line coming from the shutter box will not be necessary any longer. The air only comes from that box to aid in starting and running until the engine comes up to temperature...once at temp, the hot cylinders will ensure combustion of the fuel, and warm air is no longer needed.

I hope this clears it up some for you...any other questions feel free to ask.

 

[doghead]

I don't think I have ever seen my shutters open on their own. I have never run it in really hot weather either.

 

[Speddmon]

I made a point to watch mine this summer while I was doing it's monthly run, I wanted to verify everything worked on the unit as it should. If you watch them closely, they open to different degrees depending on the temp inside the box. when it starts to get colder outside, mine barely move. The other week when I had to run it for about 3 hours because of a power outage, they had only opened slightly because it was chilly outside (about 40 to 45) and that was with running for 3 hours straight.

 

[originalboxcar]

Thx Speddmon....yes your explanation is clear. I was thrown by the idea of opening the shutter box in close proximity to the warm/hot exhaust for warm up in cold weather as opposed to looking at it opening for cooler air in the summer.

What are other MEP002/003 owner experiences in dead cold starting? How long is anyone cranking in single digit temps before they release the start knob and its running on its own?


t~

 

[glcaines]

I have an MEP-003A GenSet, trailer mounted. The coldest I have started it was at 17 deg F. I heated it for about 30 seconds and held the starter for about 15 seconds. It started as easily as in warm weather although there was a lot of white smoke for the first 30 seconds or so of running.

 

[Speddmon]

I always have to hold min in the "start" position for 7 to 10 seconds, it just takes that long for it to build enough oil pressure. Sometimes I even have to let off and hit it wtice...I could let it go longer to get the oil pressure, but I'm too uptight about burning up the VR, so I ALWAYS let off after 10 seconds.

I haven't had to start it in below freezing temps yet...although I do need to go out and run them for them monthly workout...I guess now in these frigid temps would be as good a time as any.

 

[atankersdad]

This weekend I started all 4 of my 003a's when it was 13 degrees. I was skeptical about cold weather starts.The three with new batteries fired right off with less than 3, 10 second cranks. Lots of white smoke and then back to running like it was 70 outside. Now onto my oldest unit with a set of 2 year old batteries. After 3 10 second cranks it did not fire.It sounded kind of limp cranking over. I broke out the slave cables and she fired off on the first crank. I let all four run for 30 minutes. These are great units and easy to work on thanks to all of the technical help in these threads and on smokestak.com .

 

[glcaines]

I always have to hold min in the "start" position for 7 to 10 seconds, it just takes that long for it to build enough oil pressure. Sometimes I even have to let off and hit it wtice...I could let it go longer to get the oil pressure, but I'm too uptight about burning up the VR, so I ALWAYS let off after 10 seconds.

Speddmon,
I have drifted off-topic, but I am going to show my ignorance and ask how the VR could be damaged by holding the start position longer than 10 seconds. Not that I doubt you - you are the resident expert on the MEP-003A GenSets and have been very helpful. I thought that holding the start button in the start position after firing simply bypassed the cutoff from low oil pressure? It sounds like I've been holding it in the start position longer in the mistaken belief that I was saving the starter from extra wear and tear.
Gary

 

[Speddmon]

Gary,

The TM says not to hold it longer then 15 seconds...I stop at 10, I'm not in that much of a hurry to get it running that I can not wait 20 to 30 seconds and try it again. Here is an explanation I posted for someone else...he was dealing with a burned up rectifier board. Both holding the generator in the start position too long and Idling the motor can cause the problems he experienced. The main result of these action would be just burning up the rectifier board...If you're lucky, but that board feeds directly into the VR and there is a chance it could cause problems with that as well...a chance I'm not willing to take

When the start switch is engaged terminal 27 of S1 has 24 volts on it; which in turn, through the wiring, feeds the exciter field to start the generation process. The resistor provides a means of voltage drop for that 24 volts so you do not over excite the field in the initial stages of start-up (by holding the start switch too long you are putting more power across that resistor than it can handle and it burns up). Once the set is running and you release the start switch then terminal 27 is no longer powered and CR2 effectively prevents the power from the voltage regulator from going anywhere but to the exciter field.

But, this member was idling his generator for 3 to 4 minutes as a "warm-up" period before bumping it up to full speed. Both actions (holding the start switch and idling the set) can cause the same end result, but in a little different way. Here is a brief reason you do not want to idle your engine, but rather start it up and get it to full speed quickly. Again, he was dealing with a burned up rectifier board.

When you first start the set up, by moving the main switch to the start position you "flash" the generator field. This allows the generator to start producing power, from there out it is self excited, meaning it rectifies it's own power (through the rectifier board) to feed the DC to the field. The voltage regulator "regulates" for a lack of a better term, the DC voltage to maintain the output voltage. I don't remember right off hand what the supplied voltage is exactly, but I think you are supplying 12 volts to the field to maintain the proper output voltage. By allowing the set to run at idle, you are not able to generate a high enough voltage to be rectified properly, meaning the voltage regulator has to draw harder on the bridge board to get the power it needs. You will be very lucky if you do not damage the voltage regulator as well.

I think your chances of damaging the VR are more likely when running the engine at idle, but again, I don't want to take a chance with either scenario. I hope this helps out some.

 

[glcaines]

Speddmon,
Thanks for the information. You are indeed a wealth of information on these GenSets. I'm also guilty of idling my MEP-003A for a couple of minutes prior to taking it to operational RPMS. I'll definitely stop letting it idle and start bringing it up to speed immediately. I have had zero problems with the GenSet, so I have gained no practical experience with maintenance. yet I plan to replace the fuel filters soon. I'm still running the unit with the diesel fuel that was in the full tank when I picked it up. It appeared to be clean and relatively fresh. I wish everything I have ran as well as the MEP-003A. The only thing I had to do was replace the original batteries.
Gary

 

[Speddmon]

Gary,

Don't feel bad about idling the engine...that is something that has been ingrained into us about engines from a very early age..."let it warm up a bit...it's bad for the engine, especially on a cold start"

However, these engines and generator set's in general are designed to start and go directly to running speed, via the governor, much like most lawn mowers and various other small engines.

The difference with these sets being, you have a manual over-ride for the governor (the veneer cable), and can force it to slow down or speed up. When I have mine running and providing the necessary frequency or 60Hz (1800 RPM) I don't touch the speed adjuster again, I just shut it down when done, and when it starts again, it ramps right up to speed on it's own.

I'm not saying that this is the proper way to do it, I'm just saying that's the way I do it. But the TM does say not to idle the engine, but rather get it to operating speed. Attached is a snap-shot from the TM that says both not to hold the start switch longer than 15 seconds and to get the set to operating speed.

 

[glcaines]

You are correct - it is difficult for me to go to operating speed directly with a cold engine! I need to get over it. Thanks again.

 

[Speddmon]

Thx Speddmon....yes your explanation is clear. I was thrown by the idea of opening the shutter box in close proximity to the warm/hot exhaust for warm up in cold weather as opposed to looking at it opening for cooler air in the summer.

What are other MEP002/003 owner experiences in dead cold starting? How long is anyone cranking in single digit temps before they release the start knob and its running on its own?


t~

Well, today I started the generators and ran them both for a full hour. I really wish I could run them with a load on them, but as of yet, I have not rigged up any kind of load bank for them...it's coming though.

When I ran them last month it was still in the mid 40's here so no cold weather starting until today. It was about 24 when I started the first one. I let it pre-heat for a full minute and tried to start it. It cranked slower than I would have liked, but it did good. 10 seconds in, I was getting a good bit of dark smoke, but not firing off yet. So I stopped and gave it another 30 seconds of pre-heat, and tried again for 10 more seconds...it wanted to fire off, but again was cranking kind of slow. Now keep in mind that I have no way to slave it off of another vehicle unless I would have tried to start the deuce and get it close enough to use jumper cables to the generator, so, not wanting to drain the batteries completely, I did NOT pre-heat the third time and tried again....10 more seconds and it still wanted to fire, but wouldn't. So this time when I stopped, since I had not used the pre-heat the last time, I went into the garage and brought back the ether can. I started cranking again, and hit it with a very quick shot of ether and she fired right off. Of course with all of that cranking, I was getting some oil pressure, so as soon as it fired, I had enough pressure to keep it going.

After running that one an hour, since I only have batteries in one set and have to jump the other one anyway, I left the first one running for the extra cranking capacity. I pre-heated the second one for a full minute, and when this one cranked it was doing really well, It started but being that the oil was so cold I didn't have the pressure to keep it going after about 12 seconds of cranking (only 10 PSI). So I stopped and waited about 30 seconds and hit it again...this time it fired right off again, and still took almost the full 10 seconds to get the oil pressure up enough to hold it's own.

I did look at the shutter box on the first one, and even after an hour of running at 24-25 degrees, the shutters did not move. Maybe if the set had been running under a load they might have, but without a load in those temps....they didn't open. I'll check the second one when I go out to shut it down soon, and let ya'll know.

 

[originalboxcar]

As far as getting up to operational speed...doesn't startup SOP include having the throttle out halfway? This is what I do and then I adjust to 60hz.

I'm using amsoil synthetic and pressure wasn't an issue @ 7 far.

t~

 

[Speddmon]

When I went out to shut off the second unit, the shutters were closed on that one too. Apparently 25 degrees and no load does not build enough heat for them to open.

As far as getting up to operational speed...doesn't startup SOP include having the throttle out halfway? This is what I do and then I adjust to 60hz.

I'm using amsoil synthetic and pressure wasn't an issue @ 7 far.

t~

I've read though the TM, and went back through the TM section covering start-up. I cannot find any place that mentions any throttle "preset". It only says to hold the start switch for 15 seconds of until the set come up to operating speed...this leads me to believe that they intend for you to leave the speed control knob in it's normal running position for start-up. I could very well be wrong though, if you saw it in the TM please let me know where it was.

Again, I'm not saying my way is right or that any other way is wrong. I'm only telling you the way I do it, and that it is not a good idea to idle the engine for any extended length of time.

 

[originalboxcar]

I'm not sure if it's in the TM either but I recall in an email conversation with a retired military individual who was selling 002a filters at the time specifically stating that I should adjust the throttle to half when starting cold.

I've tried lower throttle settings but the above rule of thumb actually works best based on my experience.

Speddmon, what is the "normal running position"?

t~

 

[Carl_in_NH]

I keep my throttle setting at the last known 60 Hz setting - just let it spool up quickly, and remove the load and let it run at speed for a few minutes before shutting down. Never do much more than tweak the throttle setting to keep it on 60 Hz.

As a point of reference, I had my 003A running at ~10% load in 50 degree F weather, and the shutters only opened a hair - perhaps 1/16" at the bottom edge.

Given the size of the blower wheel and the amount of engine heat produced, I suspect they are overcooled by design to make them happy in the desert