Author Topic: SL1 stalling warm  (Read 940 times)

mikenash

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Re: SL1 stalling warm
« Reply #15 on: October 01, 2020, 02:59:47 AM »
Are you sure it is cooling properly?  Some of those older diesels - if they overheat they just kinda lose power and wond down to a stop but are OK once cool again. Cheers

ajaffa1

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Re: SL1 stalling warm
« Reply #16 on: October 01, 2020, 10:05:28 AM »
Hi Guys, very puzzling. I very much doubt that the timing would be out enough to stall your engine, if it was I don`t think it would start from cold. You do say that you have replaced the injector pump, these are timed by adding or removing shims between the injector pump and the crankcase, you should have checked the spill timing when replacing that unit. While you are at it ensure that the rack on the injector is moving freely and not binding.

Mike is possibly right about overheating. These have an air cooled cast iron cylinder with a lot of cooling vanes on them, cooling air is ducted through these vanes from the flywheel which has a fan cast into it`s face. The ST1 engine I have been working on had all of the cooling vanes filled with oil, dust, mouse sh1t and etc. It is a pretty simple job to remove the cylinder head and then the ducting shrouds around the cylinder, a little work with a screwdriver and an airline should clean out the cooling fins.

While you have the head off, check the condition and seating of the valves and clean the valve stems, diesel engines that have little or no load tend build up a lot of carbon on the exhaust valve stem, this can lead to stalling as the exhaust valve does not close properly and you loose compression.

Another possibility that occurs to me is operator error, When starting these engines there is a lever attached, through the crankcase. to the fuel injector rack. When starting, that lever needs to be in the vertical position, this over fuels the engine making it easy to start. When running, the lever needs to be in the horizontal position. To stop  the engine push it as far down as it will go. An over fueled engine might quickly overheat or clog with carbon.

Bob

Passenger

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Re: SL1 stalling warm
« Reply #17 on: October 04, 2020, 09:38:09 AM »
Hi guys,

And sorry for radio silence.

A lot of good ideas here, thank you!

I took a little videoclip friday, and got it uploaded today. Here is the link: https://m.youtube.com/watch?v=Vi6qInlm5FA this is after about 17mins of idling. Cylinder surface temperature was 112 celsius at this time.

Passenger

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Re: SL1 stalling warm
« Reply #18 on: October 04, 2020, 09:46:28 AM »
Here is another link: https://youtu.be/PASkI28uiDM

This is after 1 min from startup. Less smoke, and easier running. Is there a way to adjust fulp pump feed?


cobbadog

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Re: SL1 stalling warm
« Reply #19 on: October 04, 2020, 11:21:58 AM »
Sounds like it is seizing up and I am guessing it is from excessive heat. So as suggested take off the covers and inspect and clean if required all the cooling fins and check the fins on the flywheel as well. I believe the head has to come off so check the valves and touch up the seats while you have easy access. Once you have seen the condition of the cooling fins let us know what you found.
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hwew

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Re: SL1 stalling warm
« Reply #20 on: October 04, 2020, 03:42:09 PM »
This has been puzzling, did you have a load on the generator when running it? After listening to the clip, the engine sounds like it is loading up to the verge of stalling. I decided to get my headphones and listen to the clip more. The engine clearly sounds and looks like it loading up and 112 centigrade is not hot for cylinder temperature. But after listening to it many times  Iíve heard a faint noise like an electric motor loading up. Could it be gear noise when the engine is on the verge of stalling? Or is it the generator head itself? And could the faint noise be coming from the stator and rotor? What might be happening is the generator head could have a short or being shorted by something.

Another possibility could be the bearing on the generator end. Check for noise and heat. The bearing could be bad.

 Another way to check the engine is just separate the generator head from the engine and run the engine to see if it runs ok.

If your able, try to get a Megger test done on the generator head. It generally provides information about the leakage current and whether insulation areas have moisture as well as the amount of moisture, deterioration and winding faults.
« Last Edit: October 04, 2020, 06:23:17 PM by hwew »

mobile_bob

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Re: SL1 stalling warm
« Reply #21 on: October 04, 2020, 07:16:14 PM »
i am suspicious of the generator head, possibly a short in the stator windings?
after reading the topic thread i didn't see anything about whether the head is connected to a load or not?

check the leads in the junction box, make sure nothing is has rubbed through or is rubbing on the case.

from what i gather, the engine stalls out after running until hot,
from the clips it appears that the engine begins to slow down, and there is a noticeable increase in exhaust smoke
the smoke looks dark, not white
the owner reports that the engine still turns over freely after it stalls, that tells me it isn't seizing up.
if a diesel seizes, it generally damages the piston/rings and/or the cylinder walls, losing compression, making it harder
to start if not impossible to start.

if the timing was the issue, i would not expect this problem
if the fuel was overheating, not sure that is even possible without serious engine damage happening first
if there was a pump problem, i would expect difficulty restarting after shutdown, loss of prime issues and,
if that were the case i would expect to see the exhaust smoke clear up as the engine starts to die out, same thing
if the fuel was vaporizing

also if the exhaust valve is too tight, not enough clearance, generally there is a huffing sound coming from the exhaust
and clearly audible when the engine stalls and coasts to a stop.

intake valve being too tight, that can be heard barking back up the air cleaner, easy to hear with the air cleaner removed

so in recap

don't believe it is seizing ,  easy to turn over after stall
don't believe it is a fuel issue, or you would have to reprime to start
if you can't hear the exh or intake valves barking or hissing probably not the problem either
(after the engine dies, immediately roll the engine over and see if you hear hissing back passed valves)
exhaust smoke seems to increase as the engine is stalling, indicating a load to me,

something about the generator head is suspicious to me
maybe run the thing to stall and take a temp gun and check for hot spots on the stator, junction box, etc

hard to tell from here, with short youtube clips, a poor audio from my laptop, and not much else to go on.

fwiw
bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

Passenger

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Re: SL1 stalling warm
« Reply #22 on: October 04, 2020, 08:24:01 PM »
Hi!

There is no load, just idling. I have drove it with load, and it only quit a little bit faster with load. The generator is rated at 1.75kw. Load doesnt seem to be problem, whether its big or small.

So short circuit isnt likely here, because electricity is generated.

Bearing on the other hand is possible . Though I would suspect it would lower the power output. Now I tried 1.5kw load with no problem.

To me it feels like its getting too much fuel in ratio to air. Engine doesnt burnout all that fuel, and thats why it smokes. A/F ratio gets worse when engine gets hot. What is the mechanism engine to adjust this ratio? Or is the spill timing only thing that you can adjust?

 Injection timing seems to be correct. I tested it with injector spraying open air. Not sure if this is the way its supposed to be done.

I also cleaned those cylinder fins with break cleaner and brush. There was basically just some black oil /soot that game off  suprisingly easy. I havent measured temperature after cleaning, but I think it wont make a big difference.

Also removed the inlet/exhaust manifold to see that its pettynyt clean.

The smoke is white/Light Grey at the beginning, and gets darker after a while. Not Black anyway


mobile_bob

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Re: SL1 stalling warm
« Reply #23 on: October 05, 2020, 12:39:18 AM »
if the injector is atomizing properly, that is it is spraying a good pattern and not a squirt and dribble

if that is true and the engine is over fueling the rpm will rise in relation to the amount of fuel being injected

i am not familiar with your particular unit, so i ask the following

is the intake unobstructed?  all the way to the intake port?  no rubber parts/couplers collapsing in the intake air cleaner piping
(this might not apply to yours but i have seen rubber elbows collapse and stall an engine)

from what you post, the engine does not stall or exhibit this stalling problem when under a 1500 watt load?  but does with a higher load?

another thing to check would be the output voltage under load, does it stay stable and  even after the problem first starts to show its
ugly head? 

does it slowly taper downward just a bit, but stay relatively stable until the engine shows signs of having trouble running?

or does it run relatively stable, and then show a sharp or sudden reduction in voltage, (doesn't need to be much, but under a fixed load
i would expect perhaps a small and slow droop in voltage under load, but i would not expect a sudden drop of even 5 or 10volts.

without load, i am to understand that the thing will run and not show signs of stalling, run just fine, smoke consistent in quality/color?
and under 1500 watts or less 1.5kva it runs fine, smoke consistent in quality/color?

under a heavier load of say 1.75kva or 1750watts, the problem shows up?

how about this

check the voltage at 1.5kw load, let it run for 20 minutes or so and chart the output voltage

then raise the load and let it run for 20 minutes of so and chart the output voltage


what i am getting at is this, coppers coefficient of expansion is fairly high, and copper windings in the stator core are wound tightly
and packed closely together, it might be that under enough load the copper gets warm enough to expand enough to press against another winding and breakdown the insulation/varnish so that there is a short.

the reason i am on this track and wanting you to eliminate the possibility is based on the following

sometime back in '07 i having built a changfa s195 into what i referred to as a trigenerator, it drove a pair of prestolite/leece neville 110-555-jho alternators 12volt nominal, i was working with running one of the alternators in 24volt nominal operation (28.8vdc). under one of the tests the 195 exhibited very similar problems to what you are experiencing.

the problem was related to the alternator having been fitted with 30v avalanche diodes and when i ran the system up to 28.8 and as things warmed up the voltage at the alternator bumped 30volts... this in turn basically created a short and made the alternator into a really effective electric brake. 

the 195 would lose rpm, but not quite die, the reason was as the rpm dropped the alternator would drop below the 30volt avalanche threshold and allow the engine to speed up, and of course this cycle is very fast and in effect just dropped the rpm to reach equilibrium and not stall the engine.

so basically the stator was shorted by the avalanche function

now you don't have that problem, but the theory of operation is similar in that "if" you have windings in the stator that are old enough, and have broken down insulation, they might well start to short under load when things warm up, and because the short cannot go away like my alternators did (below 30vdc the avalanche shuts off and so does the short), then it continues the loading until the engine stalls.

i am not suggesting tearing down the genhead, what i am suggesting is removing it as a possible problem by running some voltage tests, and if you have one of those laser temp guns, check the stator core for hot spots, that is if you can get to it fairly easily.

if you don't have a laser temp gun, just feel around the outside of the generator housings to see if anywhere seems warmer to the touch than the rest of the housing, you might feel a hot spot that way?

it just seems really odd to me, that the engine is actually seizing up, i would expect other problems caused by that happening, and none of them are good.  and i don't think that 1.5kva of load would be enough to cause a problem, but if there is a short the actual load would be much higher then 1.5kva or even 1.75 for that matter.

most times it is the simple things that we overlook when it comes to diagnostics, so carefully make a list and check off everything, when it comes to hard to find problems, more info is always a good thing.

fwiw
bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

scott p

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Re: SL1 stalling warm
« Reply #24 on: October 05, 2020, 03:00:39 AM »

Hello all:
While watching the video I was reminded of an issue I had with a AC 2. It smoked just like your SL1 but being a two cylinder it kept running at a lively rate. Any way turned out one of the cylinders had a crack in it. The warmer it got the more it smoked.

scott p

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Re: SL1 stalling warm
« Reply #25 on: October 05, 2020, 03:14:15 AM »
I forgot something.
According to the Ld/SL manual I have here the valve clearance is 0.002 both valves when cold with RPM above 1200. Below 1200 RPM inlet 0.002 exhaust 0.006.

Passenger

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Re: SL1 stalling warm
« Reply #26 on: October 05, 2020, 06:46:10 PM »
I forgot something.
According to the Ld/SL manual I have here the valve clearance is 0.002 both valves when cold with RPM above 1200. Below 1200 RPM inlet 0.002 exhaust 0.006.

Thanks Scott for sharing this..and  thanks for everyone else too!

I think that I'll do a full rebuild and hopefully problem presents itself during process. Thats what I was going to do anyway.
Its an old machine, and deserves to have new organs.

I owe you guys the answer what ever the problem may be. This way we can learn something from this.

I'll get back to you when I have something to share.

-JP

AdeV

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Re: SL1 stalling warm
« Reply #27 on: October 06, 2020, 07:22:04 AM »
Hi JP,

Could you do a massive favour, and document your strip-down and rebuild, with plenty of photos? I've been planning to add a documentation site to LEF for some time, this could be the first "user made manual" to go into it, if you'd be willing.

Cheers,
Ade.
Cheers!
Ade.
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0x Lister JP4 :( - Sold to go in a canal boat.

cobbadog

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Re: SL1 stalling warm
« Reply #28 on: October 06, 2020, 11:38:52 AM »
Could I suggest something before you strip the engine down?
There has been some very good points put forward pointing towards the problem being in the generator. If it was me I would separate the engine from the gen set and try the engine again and see what happens.
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mobile_bob

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Re: SL1 stalling warm
« Reply #29 on: October 06, 2020, 11:06:36 PM »
+1 for cobbadog

it seems to me that "if" one were wanting to tear down the engine for overhaul, you would be removing the generator head anyway
so what harm would be to eliminate the head as a possible cause of the problem?

been giving this thing more "thunking" and i recall over the years some really expensive problems relating to similar problems

1. back in the late 80's while working in seattle, we had a used IH 4070B cabover in the shop because of low power and excess smoke
the diagnostics lead the foreman to conclude that it needed a new turbo, so it got a new turbo
when that didn't work, they put in a set of injectors,
when that didn't work they did an inframe overhaul,
when that didn't work, the condemned the transmission, and exchanged it
when that didn't work they removed the front and rear differentials, and of course found nothing

i came to work for the company after all this had been done, and was tasked to find the problem

the first thing i did was ask to talk to the former owner, i asked him how it ran for him

"well, uh it ran fine up to 3 years ago when we parked it!" 

ok... hmmm i wonder

i took down the air cleaner stack and found a huge birds nest clogging the bonnet, and of course it clogged off a huge portion of the air needed to run properly, removed the nest and waalaaa... back to full power!

lesson learned

2. i got a call from one of my customers with a p30 stepvan, with a chevy 350 early throttle body
the truck started fine on a monday morning, ran 30 miles without issue, and up restarting after his first stop
it couldn't make 15 mph, and even at that it took about a 1/4 mile to get to 15mph

i removed the dog house engine cover and started the engine, and notice that when i pushed down on the gas pedal
the intake flex house seemed to move just a bit, i removed the hose from the aircleaner and started up again, this time pushing the pedal to the floor, and that is when i saw the top cover suck down so that the wing nut was about 1/4" loose..hmmm

took a look up into the snout,and saw what appeared to be an extension spring, maybe 3/8" diameter, thinking it was something to do with the thermo door, i grabbed ahold and gave it a yank.... "HoLy Crap!"

out came the biggest rat i ever saw! he apparently crawled up from the flex hose to the air cleaner snout and when the driver started the engine he got sucked up to the thermo door and then made a 30 mile trip which sucked all the juice out of him... but he effectively jambed the door and the intake so there was little air flow available for the engine.

lesson learned?  A. never ever overlook the simplest of possibilities, and B. bring a change of undershorts because you never know what you might have on the other end of whatever you pull on.

the point is this, over 40 plus years of twisting wrenches i have seen a lot of crazy stuff,  and i have seen mucho dollars spent trying to correct a 50 cent problem.

digression

two other examples of what i am talking about

a kenworth boom truck with a 400 big cam cummins,  runs with good power, little to no smoke, not problems, until you come in off the road and shut it down and try to restart in 15 or 20 minutes, then if you do it will turn the whole world blue, smoke everywhere, massive engine knocking,  and oil coming out of the expansion joints of the exhaust manifold... and i mean running out and looking/feeling like engine oil.

cummins shops, they sent it in to two for two different opinions, both quoted near the same for a major overhaul

problem ended up being a 3 dollar fuel tank vent, which plugged and built up pressure, cummins injectors being cam actuated and pressure time type will continue to dribble or nearly spray fuel into the cylinders if there is pressure in the tank...  so fuel continued to be issued to the cylinders and when the engine started of course it is near hydro locked, and fuel that is chared looks just like engine oil.

3 dollar vent and the company was saved a $22k dollar overhaul bill

i found this problem twice in the 90's and cummins sold one engine overhaul and when that didn't fix it they would not stand behind the
problem and try to make it right with the customer.

another example

another boom/crane truck,
the crane when placing roof trusses on the plate line would swing slowly then without warning sweep at a vastly faster rate, knocking off framers, which if they are on a second story get really grouchy.

the company had it in to 3 hydraulic crane/boom shops in the seattle olympia area, spent $55k dollars and still no fix

turned  out to be a pressure gauge that measured lift and sweep pressures and had a double check valve in it do that it could read
for one function or the other, not both.

the gauge was broken, cost was about 200 bucks, so one of the shops at some point connected the two lines together and removed the gauge, "who needs a stinking gauge anyways?"

it took me about 2 weeks of spare time research to determine that "if" you connect both of those 1/4" lines together you connect two pilot valves, one for lift one for sweep together, the result is the pilot for sweep senses the higher pressure from the lift circuit and increases the pressure and flow to the sweep valve and away to the races you go

bottom line, before you tear things all apart, spend all the time needed to eliminate all the cheap and easy possibilities, unless you have a lot of spare time and money to expend.

fwiw
bob g

otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info