Author Topic: DES 8/1 Propane Conversion project  (Read 104072 times)

BruceM

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Re: DES 8/1 Propane Conversion project
« Reply #210 on: July 14, 2016, 06:11:00 PM »
One field coil on my neighbor's ST-3 head failed- open circuit.  Much to my disappointment, Tom at CGG does not have spare field coils.  I wondered if anyone had failed unit with a field coil or two they could sell?  I temporarily loaned the whole rotor from my own spare ST-3 head, but I need that back eventually.

There's a few hundred more hours on the  DES propane conversion set and the KN regulator for home construction work.  It continues to perform very well.  We did have to tighten the valve closing spring tension screw on the KN regulator as sometimes we were getting  noticable raw gas leakage out of the carburator inlet during starting and running.   That solved the problem.




« Last Edit: July 14, 2016, 06:34:18 PM by BruceM »

Tom

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Re: DES 8/1 Propane Conversion project
« Reply #211 on: July 14, 2016, 09:08:33 PM »
Have you checked the connections between the coils. My st5 had a cold solder joint on one of them that opened up after a couple of hundred hours. A little solder in the right place and now 2k hours later all's good.
Tom
2004 Ashwamegh 6/1 #217 - ST5 just over 3k hours.

BruceM

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Re: DES 8/1 Propane Conversion project
« Reply #212 on: July 14, 2016, 09:34:16 PM »
Yes, I removed the open coil from the rotor and checked it separately.  It has a plastic rectangular bobbin and would be very easy to replace if only we could find a replacement.  I'm not interested in rewinding on a volunteer project, though I would if it was mine.

All the other coils checked out fine.  It was easy to find this problem, just measured the resistance between the two slip rings after inspecting the slip rings and brushes, then checked each coil to find the open one, confirmed it after cutting it loose.






rosebud

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Re: DES 8/1 Propane Conversion project
« Reply #213 on: July 18, 2016, 10:48:48 PM »
Appreciate the comments on the forum..

Looks like I have a cold solder on a 3kw st head also... It has about 40 hours total time on it....
It was not powering up intermittently...then not at all.
Using Utterpower guidelines... I started looking... Saw a small ohm value across the slip rings.
Moving along, noticed a lack of continuity across one field coil.
After lightly cleaning a small section of coil wires upstream of the small copper connection cap... looks like the solder is highly suspect.

The trouble shooting idea, came from this thread... thanks

steve

ps.. removing the doghouse per UP's mods
Listeroid 6/1
SL1...4.25hp
ST 3kw
1.6kw PV

BruceM

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Re: DES 8/1 Propane Conversion project
« Reply #214 on: October 24, 2016, 07:11:53 PM »
Bizarre new problem. The DES propane conversion engine is still starting and running fine but has recently developed the serious fore/aft movement of a seriously overbalanced engine.  I checked it over carefully- no lost balance weights, nothing cracked, big end of the con rod looks fine, no slop or play anywhere. For a temporary fix it took 8 oz of lead on each wheel opposite the counterbalance to correct this.

I just can't imagine how it can suddenly be 16 oz out of balance?!

Jeff says the problem has been increasing over the last week, with no other symptoms, sounds or issues.

I'm suggesting that he pull the head and inspect the piston/upper conrod just to be safe.  He has to drain it anyway to put the thermostat for winter morning operation.

Does anyone have any other ideas?



dieselgman

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Re: DES 8/1 Propane Conversion project
« Reply #215 on: October 24, 2016, 07:16:49 PM »
Take a good inspection look inside for parts broken or abnormal conditions. Be sure to slowly roll the engine through its full cycle during internal inspection.

dieselgman
ALL Things Lister/Petter - Americas
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BruceM

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Re: DES 8/1 Propane Conversion project
« Reply #216 on: October 24, 2016, 07:41:18 PM »
Thanks, Gary. I did check the crank and conrod big end for a full revolution.  Nothing loose, no problems.  Better safe than sorry, I just called Jeff and he's going to pull the cylinder and head for a full inspection.  I'd like to see valves and piston rings after 400 hrs of run time, too. 

The current oil has 230 hrs on it.  It looks clean as new.  What kind of oil service interval do you recommend for this engine on Propane, Gary?  His typical load averages about 1500 watts so it is not heavily loaded.


gusbratz

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Re: DES 8/1 Propane Conversion project
« Reply #217 on: October 24, 2016, 08:20:53 PM »
wonder if a flywheel key could be moving? crank bent? your oil is going to stay a lot cleaner with gas but you may find carbon deposits in the oil and building up on the head, i had one with so much carbon on the head that a big chunk fell off when we were baring the engine around an locked it up. pulled the heads and it was like a pancake in there.  carbon pockets can also hold heat and cause pre-iginition or  detonation. that could be mistaken for balance as it can sound like guns going off in the engine. I would think a light load would be easy on the engine. put a vacuum gauge on the engine and load it up. tune your mixing valve until you have the best strongest vacuum. that is your sweet spot. richen it up just a bit for best performance and elimination of preignition and detonation. or lean it out for best emmissons.  if memory serves i would boroscope the cyl on a 10,000 hour Pm for carbon build up when i worked for the gas company.

dieselgman

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Re: DES 8/1 Propane Conversion project
« Reply #218 on: October 24, 2016, 08:23:55 PM »
A normal 250 hour oil service interval is recommended for diesels... but that is primarily because of soot buildup from the diesel combustion. If your oil remains clear, then I would tend to just monitor it closely and change when it starts to change color. One of the nice things about Propane... a very clean burn. One of the major combustion byproducts of propane is water vapor, which also tends to keep the innards quite clean. No need for water injection!  :laugh:

The out-of-balance and sudden-change report sounds like a weird one. Something MUST have moved or changed to allow that to happen!

dieselgman
ALL Things Lister/Petter - Americas
Lyons Kansas warehousing and rebuild operations

BruceM

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Re: DES 8/1 Propane Conversion project
« Reply #219 on: October 25, 2016, 02:55:18 AM »
I helped finish the tear down of cylinder and get her inspected and put back together.  Everything looks clean and tight and nothing amiss. Very strange, as the fore aft movement was obvious and I would never have put it in service like that.  So I have no idea why this imbalance shows up after 400 hrs.  A mystery.

Valves look perfect.  So stock valve with hardended seats seems to work.


BruceM

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Re: DES 8/1 Propane Conversion project
« Reply #220 on: November 29, 2016, 05:43:17 PM »

Since changing to the KN/Garretson type regulator, Jeff says he has noticeably better fuel economy and no running issues.  Unfortunately he has had some very noticeable raw propane smell in the engine room.  A problem for someone disabled with severe chemical sensitivity.  The first obvious offender by stiffing while running was leakage at the carb inlet.  We fixed that by adding 3" tube to an auto air cleaner housing mounted on the wall. Next we found there was a leak at the KN regulator. Internally, there's a sewing type straight pin through the rubber faced disk which seals the gas inlet. The pin head was not sealed. Gas was slowly leaking through and then out of the diaphram chamber. A simple dot of gray silicone gasket maker over the pin head stopped that leak; no more leaking with engine off but gas on. I suspect that parts or material changes over the years may have caused this problem with the KN regulators.

After this we still had a very minor leak with engine running, barely noticeable near the KN regulator.  We traced this to the lack of a gas tight seal on the diaphram to actuating pin attachment; gas was leaking through the diaphram to the vented side of the die cast KN regulator housing.  Fortunately, the vented side of the diaphram has two 1/8 NPT threaded holes. We plugged one, and connected the other to a 1/2" ID hose which we routed into the air cleaner housing.  This eliminated that last of our leaks.  I felt that venting the leak to the air cleaner was preferred over having to modify the diaphram assembly with new sealant and rivets, a fussy job that would have be redone with every new diaphram.

So while I think the KN/Garretson regulator is the way to go for the gulping Lister CS type engine, with gulping intake compatible CA110 gas carburetor, it does need these fixes to not leak gas into the engine room. 







dieselgman

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Re: DES 8/1 Propane Conversion project
« Reply #221 on: November 29, 2016, 06:09:27 PM »
Wow Bruce, You sure are persistent and patient! Sounds like a considerable number of small quirks to get worked out. Glad you are managing it so well!  ;)

Keep up the good work and thanks for letting us know the problems and solutions!

dieselgman
ALL Things Lister/Petter - Americas
Lyons Kansas warehousing and rebuild operations

Tom

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Re: DES 8/1 Propane Conversion project
« Reply #222 on: November 29, 2016, 08:49:04 PM »
+1 for what DGM has to say. It would be interesting to know if the intake valve timing is to spec. Perhaps opening the lash a bit would help the root cause of the back flow of LP out of the intake.
Tom
2004 Ashwamegh 6/1 #217 - ST5 just over 3k hours.

BruceM

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Re: DES 8/1 Propane Conversion project
« Reply #223 on: November 30, 2016, 07:23:33 AM »
Thanks Gary and Tom.   I hope this thread might save someone else doing a low speed (gulping intake) engine conversion some time and trouble, someday.

We did open up intake and exhaust valve lash greatly to avoid overlap and any ezhaust backpressure to the carb many months ago.  This did reduce the gas leakage at the carb intake noticeably and did not affect performance.  Our next step is to take the timing back to stock and see if we are now OK with that using our free MB300D air cleaner.  We have the flywheel marked with the stock intake open and exhaust closed timing events, per 38ac's (brilliant, I think) method, so it's easy to play with the intake and exhaust overlap timing.  On propane at least, the timing makes no noticeable difference in power or running, but our pneumatic valve lifter will have a lot more clearance once we tighten up the exhaust valve lash.

Through all of our regulator work the engine has remained in service and Jeff's off grid house exterior has been completed. All compressed air and electrical power via the DES 8/1 propane conversion engine.  Absolutely no audible noise and no exhaust fumes regardless of wind direction are a big plus for him and his also disabled gal. 



Tom

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Re: DES 8/1 Propane Conversion project
« Reply #224 on: November 30, 2016, 06:02:26 PM »
Before you reduce the lash, consider that as it's operating now, there is an explosive mixture in the intake.

I had bought a LP Onan RV generator for backup power at our previous home. It was the good old days when LP was $.61 per gal. In firing it up the second time, I guess the LARGE muffler was filled with the perfect LP/O2 mixture and it went off with a thunderous boom. My 8 year old son about soiled is shorts.

I'd hate to see this happen to an air cleaner full of LP because it will probably be blown to bits.
Tom
2004 Ashwamegh 6/1 #217 - ST5 just over 3k hours.