Slow starting

Topic: Slow starting (Read 947 times) previous topic - next topic

Slow starting

July 26, 2020, 05:38:06 pm

We today I tackled another issue my coach has had since we purchased it. We always had to use boost switch to get her spinning over good. I removed all the battery cables, cleaned rerouted multiple cables, REMOVED THE STUPID FRAME ground stud which I think was the main issue. And presto the engine spins over like it never has before. Just a very poor system on setting up start battery cables. Weak grounds, weak connections are the biggest killers of computers, ECM, etc. I had also replaced all the start batteries last year while on a trip. And was considering a new 39MT starter if the cabling repairs did not correct the issue.

Re: Slow starting

Reply #1 – July 26, 2020, 06:19:13 pm

Our m11 requires oil pressure to build up before the engines computer turns on the fuel.....

Re: Slow starting

Reply #2 – July 26, 2020, 06:38:18 pm

If the engine turns over faster when using the boost switch and the engine batteries are in good shape, complete cleaning of all terminals until they are bright and shiny is needed as well as the battery lugs. I installed a second ground strap to the frame. Installing a frame to engine block/parts is always a good idea. It always spins like a top hot or freezing on engine batteries alone.

The faster it spins, the less time the compressed air has to loose it's heat and the less time for any pressure to go past the compression rings.

Most diesels don't fail but just get harder and harder to start due to low cranking compression. I bought a 115 body/200D with a tired engine in Germany in winter. Had to start it every two hours or park it on a hill. Took a couple of blocks fairly steep road to start in 2nd or 3rd gear. Once running, tired diesels get just as good fuel mileage.

Pierce

Re: Slow starting

Reply #3 – July 26, 2020, 09:27:13 pm

Mine was a weak starter that had all the symptoms

Re: Slow starting

Reply #4 – July 26, 2020, 09:45:52 pm

We had slow starter issues since we bought our 03 in 2011, boost switch helped but never turned over like it should . About 3 years ago the starter died, as luck would have it in the driveway at home, with the cars blocked in. The new starter spins the engine much faster. A bad connection at any point can also cause the same issue, had issues with that also.

Re: Slow starting

Reply #5 – July 26, 2020, 09:57:58 pm

Starters don't start out spinning slowly. Poor connections from the battery to the starter and ground start to make them spin slower. Slower means taking longer to start, means the starter getting hotter, means overheating and aging the components. Those are not ball bearing but bushings at either end. Sort of like the athlete in their 20's taking up smoking in their 40's. Slowly going downhill when their friends start letting them down.

Pierce

Re: Slow starting

Reply #6 – July 26, 2020, 10:03:19 pm

Pierce. Great analogy of life for sure.
Johnh

Re: Slow starting

Reply #7 – January 23, 2021, 03:11:53 pm

So I too am having issues with slow spinning to start after overnight or longer. I have replaced the start batteries and I've been going through the terminals and particularly the ground wires. I have not found any alarming corrosion or loose connections. I would think it may Be a poor preforming starter but if I jump it, use the boost and give it lots of amperage it spins fast and starts. So if the starter where failing or not working like new would it spin up the engine under perfect conditions and if its not full voltage/amperage it wont do the job? Should I just go ahead and replace the 20 year+ old starter? Any suggestions would be appreciated.
Thanks Phil 305-992-5974

Re: Slow starting

Reply #8 – January 23, 2021, 03:47:26 pm

If you decide to install a new starter, the Delco Remy gear reduction unit gets good reviews from Forum members.

M11 gear reduction starter

Re: Slow starting

Reply #9 – January 23, 2021, 04:40:28 pm

The gear reduction starters have an extra set of gears in them so that the starter motor doesn't have to work so hard to turn over the big motor. If the starter motor on a gear reduction starter turns the same speed at the motor on a direct drive starter the big motor turns over slower. With the help of the reduction gear the starter motor in the gear reduction starters needs less battery power.

My gear reduction starter weighed much less than the original starter. I like mine.

Re: Slow starting

Reply #10 – January 23, 2021, 06:06:23 pm

So with the gear reduction i guess the engine spins a little slower? Assuming that is the case. The slower turn over speed is not a negative consequence? Still fast enough for a good startup?
I am thinking I will go ahead and replace it even though it spins fast if I get enough juice to it? Guess if its tired it may require more power to get the engine spinning fast enough?

Re: Slow starting

Reply #11 – January 23, 2021, 06:45:59 pm

Quote from: philtravel – January 23, 2021, 06:06:23 pm

So with the gear reduction i guess the engine spins a little slower? Assuming that is the case. The slower turn over speed is not a negative consequence? Still fast enough for a good startup?
I am thinking I will go ahead and replace it even though it spins fast if I get enough juice to it? Guess if its tired it may require more power to get the engine spinning fast enough?

Our mechanical turbo 7.3 Int/Ford had it's starter replaced with a geared Denso model. It had a smaller but faster motor and spun the diesel much faster, especially in the cold.

There are several starters available for the M11. Denso makes a R5 geared starter and Mitsubishi also makes high quality starters for the M11 as well as other manufactures. They replace the OEM Delco. I would expect these after market starters to spin the engine faster not slower than the OEM. Rather than buying a pig in a poke, call around to see which starter the diesel shops like the best. Usually, the best starters cost a little more.

Starters will have the KW listed on the specs. The R5 Denso is rated at 5KW. http://alternatorstarter.com/Portals/0/pdf/DENSO%20Brochures/DENSO%20R5%20Offset%20Gear%20Reduction%20Starters.pdf

The starter on my 8V-71 Detroit was starting to spin slower, especially when warm so I just had a small electrical shop overhaul it. Problem solved as it started on the first revolution after that.

For cold weather starts, you need a starter that cranks the engine faster for fast starts. The more compression strokes the engine makes in a given time means the less time the heat has to escape and less time for the air to bypass the compression rings on the pistons.

Pierce

Re: Slow starting

Reply #12 – January 23, 2021, 09:01:12 pm

so is the Delco Remy 39mt Starter 8200308 CW 12v starter the correct gear reduction starter for my 1998 U320 M11?
If so....are they difficult to install?
I use the boost often to start my coach even after the cables etc have been cleaned. AND the batteries are in excellent shape

Re: Slow starting

Reply #13 – January 23, 2021, 09:16:42 pm

Quote from: dicksop – January 23, 2021, 09:01:12 pm

so is the Delco Remy 39mt Starter 8200308 CW 12v starter the correct gear reduction starter for my 1998 U320 M11?
If so....are they difficult to install?
I use the boost often to start my coach even after the cables etc have been cleaned. AND the batteries are in excellent shape

I have never use the boost to start our 9 liter engine in all the years we have owned it except for one time at altitude and temps in the teens. We have three start batteries and if all your start batteries and cables are in good shape, using the boost switch should make zero difference in how fast it turns over. There is no effect using it on ours.

R&R the starter is easy on ours except it's heavy. Perhaps you should have an electrical shop look at yours. If you have the Cummins recommended CCA batteries, good cables, it has to spin over quickly. If not, you have a fault somewhere in the starting system. Perhaps an engine to chassis ground or high resistance at the starter connection.

Pierce

Re: Slow starting

Reply #14 – January 23, 2021, 10:03:15 pm

Quote from: dicksop – January 23, 2021, 09:01:12 pm

If so....are they difficult to install?

See this thread for some enlightenment:

Changing starter on M11 engine

Re: Slow starting

Reply #15 – January 24, 2021, 12:00:10 am

The top bolt is the hardest. Impacts usually don't work as the extension do too much flexing. I find use the shortest extension and
the longest ratchet or flex bar you can find. I have them 2 feet long and if that isn't enough and pipe. Another trick if you can use
piece of 3/4 round stock and hit the end of the bolt with a 4 lb. hammer.

Re: Slow starting

Reply #16 – January 24, 2021, 12:21:49 am

8200308 39MT 12v 11T CW is what the label on mine said.
Getting the old one out is tough. Installing the new one is easier, it is much lighter. While you are in there make sure your cables ore in good shape and all connections are clean. For the level of effort and cost new cables, even 4/0 cables won't be too much $.

I had a nearby diesel mechanic do mine, he charged me 1-1/4 hrs. It would have taken me that much time to get ready.

I think the starter motor turns faster and with the gear reduction the big motor might turn over about as fast as with the old one. It sounds different so it is hard to tell. Starts every time, seems easier but maybe cranks a couple seconds longer.

Re: Slow starting

Reply #17 – January 24, 2021, 08:58:23 am

Quote from: oldguy – January 24, 2021, 12:00:10 am

The top bolt is the hardest. Impacts usually don't work as the extension do too much flexing. I

If there is room around the bolt head, a 3/4" drive socket, extension and breaker bar make a big difference. You're no longer wasting effort winding up a spring.

FWIW Lynn asked "What was that big bang I heard?" Answer "That was your 3/8" breaker bar exiting this world."

Do as I say, not as I do.

Re: Slow starting

Reply #18 – January 24, 2021, 10:17:16 am

Quote from: oldguy – January 24, 2021, 12:00:10 am

Another trick if you can use
piece of 3/4 round stock and hit the end of the bolt with a 4 lb. hammer.

This is a long used advantage known by few. Striking the end of a bolt or stud almost wakes it up. Harder the rod the better. There is also a huge difference in hammers. I loaned out a 32oz Snap on dead blow hammer to a friend that had all but given up. They actually transmit more energy. Came back calling it a magic hammer 🔨 Same thing with extensions. Good Impact extensions flex less and transmit more energy. Truly you get what you pay for.
Scott

Re: Slow starting

Reply #19 – January 24, 2021, 11:13:33 am

HF has an excellent single jack at $10. https://www.harborfreight.com/4-lb-drilling-hammer-98258.html

P

Re: Slow starting

Reply #20 – January 24, 2021, 12:15:25 pm

As I already had to coach up and blocked so I climb under and a 3/4 drive extension would be too thick. I/2 in drive would be fine.
When I looked at the starter it doesn't look that big.

Re: Slow starting

Reply #21 – January 24, 2021, 01:18:40 pm

If it is original it is heavy, but doable I've seen posts about someone above lowering it with a small rope. I was able to lift it without that aid and the new one was much lighter and easier to install. The 12 pt 5/8" socket and 1/2" extension worked with my air impact.

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