Re: Hard start!! Reply #20 – February 25, 2020, 10:17:26 am TRy using jumper cables to add to the ground cabling. Maybe run the cables from the battery pos also to the starter. When in doubt ,add ground cables. Quote Selected
Re: Hard start!! Reply #21 – February 25, 2020, 10:26:57 am ALL diesels are high compression. With the proper starter in good condition, the engine should turn over rapidly even if cold.b You should NEVER have to use the boost switch unless you have a problem somewhere in the starting system.We have owned our coach for eleven years and never used the boost switch with the exception of the time I melted the start battery terminal because of poor maintenance right after we purchased it.Our turbo 7.3 Ford/IH and our 300SD have higher compression ratios than your Cummins and never have to utilize a boost switch. The need for the use of a boost switch indicates a problem somewhere in your main starting system.Cummins has a CCA requirement specification for all their engines. If your battery system meets or exceeds these specifications and you have the proper starter plus the manufacture installed the correct gauge cables for the length of the run when the coach was built, you won't have any problem starting W/O boost. Ours spins like a top from the instant I hit the starter button. I know Craneman replaced his starter and has no trouble starting his engine.Pierce Quote Selected
Re: Hard start!! Reply #22 – February 25, 2020, 10:35:49 am Quote from: muskyman475 – February 25, 2020, 09:23:29 amI have a 1999 40ft U320 M11 initial 1st and/or 2nd crank turns slow then pops around faster on 3rd rotation and fires up.After reading FarrarkC description I can't help but wonder is this a common issue with the 99/2000 U320...Have others experienced this same starting issue on similar coaches?If the mechanics that checked out your starting system are correct, then the cables should be OK.You don't say what size and number of starting batteries on your coach. What do you have?What is the total (combined) CCA rating of your start battery bank? Chart below (copied from M11 Service Manual) says you need a minimum of 1800 CCA at zero degrees (F). Does your battery bank satisfy this requirement? A little extra capacity never hurts.If your batteries are up to snuff, and the cables are clean and tight, then that leaves a "weak starter" as the prime suspect.Roger (Reply #3 above) has a similar size engine. He says a new gear reduction starter made a positive difference on his coach.Craneman (Reply #16 above) also recommends the gear reduction starter. Something you might consider? Quote Selected
Re: Hard start!! Reply #23 – February 25, 2020, 10:49:56 am "Diagnosing" cables is easy. Voltmeter-- one probe at battery, the other at starter or for the negative on chassis ground.Have someone engage the starter. See how many volts (or hopefully fractions of a volt) drop there is across the cables. Quote Selected
Re: Hard start!! Reply #24 – February 25, 2020, 11:00:06 am Quote from: wolfe10 – February 25, 2020, 10:49:56 am"Diagnosing" cables is easy. Voltmeter-- one probe at battery, the other at starter or for the negative on chassis ground.Have someone engage the starter. See how many volts (or hopefully fractions of a volt) drop there is across the cables.Wouldn't a dragging starter show the same excessive voltage drop? Quote Selected
Re: Hard start!! Reply #25 – February 25, 2020, 12:43:29 pm I seem to remember that a m11 engines fuel system won't send fuel until the oil pressure comes up somewhat. That or it's driven by oil pressure. Something like that. So it takes a few turns to start. I replaced everything and put a geared starter motor and it starts the same. Valves adjusted. I will look at the shop manual again and see if I can find the section that talked about this Quote Selected
Re: Hard start!! Reply #26 – February 25, 2020, 03:03:26 pm Quote from: craneman – February 25, 2020, 11:00:06 amWouldn't a dragging starter show the same excessive voltage drop?Only to a small degree. Excessive starter draw would bring down the battery as well. Yes, a little more voltage loss through the cable, but excessive starter draw would show as low voltage at the battery. Yes, hard to separate bad batteries from excessive draw without doing a load test on the batteries. Quote Selected
Re: Hard start!! Reply #27 – February 25, 2020, 03:06:58 pm Quote from: craneman – February 25, 2020, 11:00:06 amWouldn't a dragging starter show the same excessive voltage drop?Yes, it might be a LITTLE more voltage drop in the cable.But excessive starter draw would also lower voltage at the battery-- far more than the drop between cable ends. Yes, more difficult to diagnose excessive starter draw from bad batteries, as both will show low voltage at the batteries. That is where load testing them becomes a good diagnostic tool, as is checking SG if wet cell batteries. Quote Selected
Re: Hard start!! Reply #28 – February 25, 2020, 04:12:29 pm On my M11 there is a short ground cable from the starter negative to the engine. Cleaning it improved starting quite a bit. It is in a particularly dirty place and not readily seen. Quote Selected
Re: Hard start!! Reply #29 – February 25, 2020, 06:24:49 pm M11 should be an instant start. Faulty oil pressure sensor should only keep the engine from going above idle but not effecting starting time. ECU will trigger auto shutdown after 30 seconds. Delayed starting is usually because of loss of pressure in the system. See these videos. Terry takes his time getting to the point but good information: https://www.youtube.com/watch?v=oCxojfhkYBkhttps://www.youtube.com/watch?v=HkUj8-2wZwsPierce Quote Selected
Re: Hard start!! Reply #30 – February 25, 2020, 09:10:22 pm Starter would be my first choice Quote Selected
Re: Hard start!! Reply #31 – February 25, 2020, 09:50:59 pm Quote from: dans96u295ft – February 25, 2020, 09:10:22 pmStarter would be my first choiceMay be, but diagnosing by "parts replacement" can get really expensive. Much less expensive to diagnose the root cause. Quote Selected
Re: Hard start!! Reply #32 – February 25, 2020, 10:40:45 pm Thank you everyone for taking the time to chime in. Being I had the problem from day one and due to the age of the coach, I have taken Roger's suggestion and have ordered the new Delco 39MT 8200308 starter. I will keep everyone posted! Quote Selected
Re: Hard start!! Reply #33 – February 25, 2020, 11:01:09 pm Again how long were you cranking when you found your hot cable. Heat is a direct indication of excessive load/resistance. Put your volt meter in parallel to your cable. Should read zero. Crank engine, should still read zero. If it shows voltage you have corrosion, undersized cables, excessive load, internal resistance. Costs nothing to do. Clean cables. Check voltage across all connections. Should be zero. Cable size should be correct. Verify battery state of charge is above 12.8 volts. If voltage drops excess battery's could be weak. Weak battery will reduce engine start rotation speed. If cranking slow will draw lots of power without reaching starting speed. All good? suspect excessive starter load, change starter. Great batteries will hide failing starter. Oh yes air if fuel will not reach higher needed fuel pressures and will start poorly or not at all. Cables may get hot if start cranking time is exceeded. Will also damage starters. Follow recommendations for starter crank limits and cool down times. Hope I don't sound too matter of fact, it's just what I would do to troubleshoot issue. If your cranking and cranking stop and resolve your problem. I've always preferred the gear reduction replacement starters. Less power draw and I believe faster rotational speed. IMOScott Quote Selected
Re: Hard start!! Reply #34 – February 26, 2020, 12:06:56 am When I first got my coach I phone Cummins and asked why the M11 turned over a few times before it started not like my old8.3 which started immediately. They told me that the computer had to read the RPMs before the computer would give the engineany fuel. I believe he said that the computer wanted to see the engine turning over at a certain RPM Quote Selected
Re: Hard start!! Reply #35 – February 26, 2020, 09:25:29 am QuoteWhen I first got my coach I phone Cummins and asked why the M11 turned over a few times before it started not like my old8.3 which started immediately. That's interesting. I've had two M11s both of which did exactly that. My current coach has the 8.3 which, like yours, starts immediately.jor Quote Selected
Re: Hard start!! Reply #36 – February 26, 2020, 12:42:25 pm The geared Delco turns over my m11 at roughly the same speed as the original starter. Meaning my original was not bad I would think. Only way to know is to switch it out it seems after checking cabling and batteries of course. Quote Selected
Re: Hard start!! Reply #37 – February 26, 2020, 03:55:44 pm My geared starter always starts with no boost now, but with the gear reduction I can't compare the speed as the sound isn't the same as the old starter. Same batteries and cabling so my old starter was the problem. Quote Selected
Re: Hard start!! Reply #38 – March 07, 2020, 07:36:05 pm No one warned me about what a pain in the rear it would be to take out the starter!!! Here are a few pictures. I obviously have have/had a power draw at the starter. Should I now replace the entire power cable or can I replace the eyelet? Trying to trace everything is a total pain!!I did not have the extension, with me, I needed to remove the 3rd bolt today so I hope to have the old starter out tomorrow. I do believe this is the original starter and I believe the installer used an impact and cross threaded one of the bolts!! I had to use a cheater bar to get the thing out!!Any tips are greatly appreciated! Quote Selected
Re: Hard start!! Reply #39 – March 07, 2020, 07:42:59 pm When working with recalcitrant bolts it doesn't hurt anything to try and work some penetrating oil into the threads as you go along.You can replace the cable ends if you want to spend the money on the crimping tool for that size cable. Quote Selected
Topic: Hard start!!