Diesel turns over slow, then fast ?
 

ive had this ongoing problem in the colder months with the 1772. the issue... the starter will turn over slow then, fast then back to slow then fast and then it will start. all this takes place in about 5-10 seconds. i have two interstate SP-40 batters which put out 425 CA and 340 CCA each. so with the two combined i have 850 CA and 680 CCA. i think that should be plenty of power for the starter. i also have a quality battery tender hooked up all the time so i know the batteries are topped off. all the battery cables are new and tight. starter is 1.5 years old. this problem only happens when its cold(45 and below). once its warm it turns over fast and fires right up. could the voltage regulator be going out?? im at a loss. any ideas??

have you put an amp meter on it to see what the draw is while cranking?

Are the glow plugs working? Gear reduction or regular starter? What do you have in it for oil? How long do you run the glow plugs? VR would only affect it charging not starting. I like to heat diesels some before starting them in cold weather, ask Andy2182.

all the glow plugs are working. i usually give it 15-20 seconds. i have a regular starter. using 10w-30 oil. i put a magnetic heater on the oil pan if it gets below 30. i feel like its got to be electrical related. when i say cranks slow i mean its sounds like the battery is dead. then like magic its starts cranking fast and might fire up or go back to slow crank.

Have you done the glow plug upgrade - adding the solenoid? Mine was behaving in a similar way, and after the upgrade no more problems. Glow plugs get power while cranking, and best way to explain the problem is resistance in the harness. Adding that solenoid pulls all that draw off the main harness. Mine starts fine now with only 1 battery. At least this was my experience. Also double check your grounds.

i did read up on the glow plug mod. it seems that the early diesels only got 7 or so volts to the glow plugs. i checked voltage on my GPs and im getting 9. it would be nice to get 12.

My experience with slow and then fast starting is that there is a lot of resistance when the ignition is first turned on but as the amperage builds the resistance begins to drop. I would look for some bad terminals or corrosion.:beerchug:

How old is the starter?

starter is not even two years old.

Being that it goes from fast to slow and back during a crank cycle, I'd be leaning toward a wiring issue. Find out if the slow crank corresponds to the glow plugs. In other words, when it's slow are they on, when it's fast are they off. If nothing there, I'd be looking at the starter.

Ken, what is your voltage at the starter when its cranking? Can you use a jumper cable to go directly to it and bypass any resistence? I think my 882 ignition switch is acting up but not doing what yours is but it was doing some wierd stuff.

Weak ignition switch wouldn't cause it. The ign just activates a mechanical switch (solenoid) which has a large contact in it. It either makes contact, or it doesn't. If the voltage going to the solenoid is weak, it would just kick the starter out. It wouldn't cause a slow crank. :beerchug:

Now, bad contacts in the solenoid could.... but not likely. The solenoid would get really hot and most likely just burn up.

heres a video of the cold start and it doing its fast slow thing...

https://www.youtube.com/watch?v=KobD6cOybrc

Ken

On the 1782 I had, I would heat it till the light went off then turn the key to the off position and repeat the heating two more times then turn it to start. In your vid I noticed you only heated it one time. I also put a heater blowing under the engine for a couple hours before I tried to start it. On my BX the glow plugs heat as long as you hold it to the heat position. On the BX I heat for about 15 seconds in cold weather, about 8 in warm weather. You also said you have 2 batteries, maybe one of them is not so good? :bigthink: The slow down may be the hydro pump starting to make pressure with cold oil. :bigthink:

Ken,
I'd do an amp draw on that starter. If you don't have the tools to do that, then:

Check all connections at the battery and the starter. (You may have done this already.) Check the points for "hot spots" just after starting. Feel the starter to see if it gets warm. Hook a meter up the battery terminal on the starter. Watch to see what it does while cranking. A analog meter will be better for this, or even a battery load tester with an analog meter will work. (Don't load it, just use it as a meter.) Also, if you have a battery load tester, you can use it in place of the starter to check for bad connection/amp issues. Just pull the battery cable off the starter and hook the load tester to that wire and load check it. Only bad thing is with that test is most load testers are only 50A, and a starter pulls a lot more than that...... but it's a fair test. I think you have a failing starter.

I want to add to this:

Something I've found that helps is, crank the engine first until you see fuel smoke. Then stop and cycle the glow plugs. That way, they are heating up raw fuel, and warming the air. When you start cranking again after the GP cycle, it usually starts immediately. I only do this if it's cold, not in the warmer weather.

I agree J. What if his battery voltage is droping off? If it is not, then its time for a GR starter. I can't hear his video so I'm not sure what it sounds like. You are correct my switch will only pass about 5 volts until the tractor is warm and then I get 12 volts at the solenoid coil. At 5vdc the solenoid will only click.:bash2:

If the meter drops it could be bad connection or weak starter. A starter pulling too many amps will draw the battery down. That's why I suggested checking connections first. If all connections are good, batteries test good, and still pulls down, it's a bad starter. It's a poor test, the best way is amp draw, but you have to have an amp clamp. That's the best test I could come up with.....

Sam.

i checked the voltage at the glow plugs while they were on (9-10 volts). then i waited till the light went off, i did not see any drop in voltage. so i assumed the GPs are still on. that's why i hold the key for the desired time. i thought the light was just a timer and not actually a timer on the GPs. am i wrong??

J.

both battery's are the same age as the starter less then 2 years old. i hope ones not shot already. i do have a load tester, ill give your idea a shot. today i cleaned up all the grounds and added another ground wire from the engine/battery ground to the frame.

don't assume the batteries are good. I've had batteries last for years and I've had batteries that didn't make it a year. you could always have them load tested. sounds to me like its a bad connection, cable or starter. jumper cables straight to the starter would narrow things down.

i play the video to a friend who has built engines and he says it might be a fuel problem. fuel may not be getting to the cylinders at first while it turns over fast then (no smoke from the exhaust) when the fuel does get to the cylinders the compression slows the starter. (smoke starts to appear) then as the fuel starts to burn the rpms increase and it starts. it makes sense, but im not sure im sold on the idea.

so under that theory it would just turn over slow from the state of cranking if the fuel system where corrected? so I still see a problem there. why don't you start getting some of the things that have been suggested tested and start to narrow it down from there.

Fuel is going into it shortly after you start cranking. Just takes it a couple revolutions to show up in the exhaust.

I'm with Don. Start checking over the other stuff. Do the test, then report back.

Not everyone who has "built a few motors" knows what they are doing. You should see some of the stuff I've worked on from guys who were supposed to be "in the know".

This may or may not help but on my 1782 I found it started much faster by setting the throttle half way, then heating for 1 cycle. As soon as it fired up I immediately moved the throttle to idle and haven't had any problems doing it this way. Mine doesn't like to start cold at min throttle. Your problem sounds like a intermittent high resistance problem in the starter or solenoid.

today i tried some of the mentioned spots to check and techniques for cold starts. i ran the glow plugs for two cycles. although the glow plug light only came on for the first cycle. ?? then i put the throttle to full. cranked it over till i saw smoke, then dropped the throttle to half (while still cranking) and it fired up. the starter didn't drop rpm this time. so i let it run for 30 seconds, shut it down in tried a restart. two cranks of the starter and it fired. i went ahead and pulled the wires off everything starting related. looked for anything abnormal. all was fine. i load tested both battery's. both good. i used the load tester wile running the starter, the volts never dropped below 11. everything seemed to check out.

Did it ever do the slow crank during this test?

Sounds like you did a thorough check of the machine. Perhaps even fixing the problem before the tests. If it does it again, put the load tester on and see what the voltage does. I still think the starter is the culprit. But it could have been a poor connection too. :beerchug:

j

i never got a slow crank during any of the testing. ill have to agree with you on the starter too. being that's its an intermittent problem, the starter is the only thing i can think of that would do that. ill keep the load tester on it for the next couple cold starts and see if i get any slow cranks with it hooked up.

My 882 will crank fast if the oil is very warm... I have found the fast cranking will give it a better chance to start. I have never had luck on starting cold in the winter months. I also had a advantage as I having a deep cell battery to mounted off the back hitch side..... which also more weight for traction.
I went out about a hour ago @ 0 degrees after a hour on the heater with throttle half way up and the third crank it fired right up (new injectors). I think each individual may be misdiagnose some times..... by its individual characteristics and temperament. The Kubota components are very good and have good longevity on the wear. Just my personal thoughts here..... I like hearing other points of view as well.