Generator Slow Start

[Charles27909]

Hello everyone....I would appreciate some advice/opinions about the generator on my Dad's Newmar. My father and I have traveled on many trips with his motor home and the starter on the generator has always spun slow but started. Now the starter is not spinning it engine fast enough to start. Outside of replacing the starter, I wonder if anyone else has had the issue and what remedies may resolve it. I am not reluctant to change the starter, just want to try most cost effective ways first....THANKS FOR YOUR ANSWERS.

[shaman52]

It would help if you could please post year and model of your Dad's Newmar. Generator size and make would also assist. Lots of help available with a little more information.

[Karl0525]

I would check battery voltage to the starter first (cheap). If the volts are low this would cause a slow to no starting. Check the battery's.

[jacwjames]

I have a 7.5 kw Onan. The power lugs are mounted on the bottom rear of the generator, check to make both are clean and tight. Check the voltage here to make sure you are getting power from the batteries, if not trace the wires back to where they start from.

[Charles27909]

Originally Posted by shaman52

It would help if you could please post year and model of your Dad's Newmar. Generator size and make would also assist. Lots of help available with a little more information.

The motor home is a 2003 Newmar Dutch Star, 40 ft with 3 slides. 8.3 ISB Cummins and 6-speed Allison. The generator is an ONAN 10.5 KW unit.

[twinboat]

I don't know this for sure, in this case, but some generators were equipped with independent start batteries.

If it has an independent battery, it could be bad.

[shaman52]

From Onan Trouble shooting manual:

Cranks Slowly
1. Low battery: Check battery fluid level.
2. Bad battery connection: Clean & tighten all battery & cable connections.
3. Incorrect oil viscosity: Replace with recommended viscosity oil.

You should be able to measure the starting voltage. Lower than 10.5 volts shows a problem. Should read at least 11.5 on a good system.

[TQ60]

If cranking slow it is LOW VOLTAGE.

Why is the puzzle.

Ours has starting and cabin batteries at the back and the genny and leveler pump is at the front.

A battery is at the front for them as it is far cheaper than the correct size wire.

Many gas class a have batteries in front and genny someplace near back and use a long cable to genny.

This cable is usually not quite large enough for proper operation.

Do the following.

Get a voltmeter and measure voltage on your starting and cabin batteries.

Next check voltage at generator.

Now have a helper hit the start button for the generator while measuring the voltage at the generator.

Next do same while measuring voltage on other batteries to determine which one it is connected to.

If you have a battery near your generator check it.

So as an example say the voltage on the cabin battery drops from 12.6 to 12 volts and the voltage at the generator is 12.6 and drops to 10 then the wire size is too small or there is a bad connection.

Check all connections and if all good then you may need to add a generator starting assist.

Try jumping the battery connection at the generator to confirm it works correctly.

You can get a 12 volt 22 amp hour VRLA battery on Amazon for about 41 bucks, we just got one for one of those portable jump start boxes.

The battery is about 7 X 6 X 3 ish.

You can place this battery near the generator and connect it with number 2 wires and if the wires are routed through any holes fuse at 100 amps on both ends of the wire.

[Mr_D]

Originally Posted by Charles27909

The motor home is a 2003 Newmar Dutch Star, 40 ft with 3 slides. 8.3 ISB Cummins and 6-speed Allison. The generator is an ONAN 10.5 KW unit.

The generator shown in the factory brochure is a 7.5Kw Generac
Here is what the '03 option list shows for generators:

ELECTRICAL FEATURES
7.5 Onan Diesel Quiet Series Generator In Lieu Of Standard Generator 230# 3L681

8.0 Power Tech Diesel Quiet Series Generator In Lieu Of Standard 195# 3L440

In our '02 DSDP 4090 we ordered the PowerTec 8.0Kw option and the 7.5 Generac was standard.
Might want to check to be sure what unit it actually has.
Also the engine is an ISC 350, not ISB if on the Spartan chassis, if on a Freightliner it's a CAT 3126 330 HP.

[DDDonkey]

Originally Posted by TQ60

If cranking slow it is LOW VOLTAGE.

Why is the puzzle.

Ours has starting and cabin batteries at the back and the genny and leveler pump is at the front.

A battery is at the front for them as it is far cheaper than the correct size wire.

Many gas class a have batteries in front and genny someplace near back and use a long cable to genny.

This cable is usually not quite large enough for proper operation.

Do the following.

Get a voltmeter and measure voltage on your starting and cabin batteries.

Next check voltage at generator.

Now have a helper hit the start button for the generator while measuring the voltage at the generator.

Next do same while measuring voltage on other batteries to determine which one it is connected to.

If you have a battery near your generator check it.

So as an example say the voltage on the cabin battery drops from 12.6 to 12 volts and the voltage at the generator is 12.6 and drops to 10 then the wire size is too small or there is a bad connection.

Check all connections and if all good then you may need to add a generator starting assist.

Try jumping the battery connection at the generator to confirm it works correctly.

You can get a 12 volt 22 amp hour VRLA battery on Amazon for about 41 bucks, we just got one for one of those portable jump start boxes.

The battery is about 7 X 6 X 3 ish.

You can place this battery near the generator and connect it with number 2 wires and if the wires are routed through any holes fuse at 100 amps on both ends of the wire.

I think that this is right on, basically your preforming a voltage drop on the starter, it should be .5 volts of less for the circuit (testing both pos and neg wires). It could be a bad wire, loose connection or a bad starter. The only way to test the stater is to preform an amp draw on it after the voltage drop. Let us know what your find, and good luck!

[Charles27909]

Originally Posted by Mr_D

The generator shown in the factory brochure is a 7.5Kw Generac
Here is what the '03 option list shows for generators:
In our '02 DSDP 4090 we ordered the PowerTec 8.0Kw option and the 7.5 Generac was standard.
Might want to check to be sure what unit it actually has.
Also the engine is an ISC 350, not ISB if on the Spartan chassis, if on a Freightliner it's a CAT 3126 330 HP.

I stand corrected about the engine being an ISC. Being from the trucking world, I am used to ISX, anything else is just a small block...lol. But I am quite sure the generator is what I said....but not 100%. The next time I am over there, this week, I will double check. I appreciate all the answers and advice.

[mel s]

Originally Posted by Karl0525

I would check battery voltage to the starter first (cheap). If the volts are low this would cause a slow to no starting. Check the battery's.

Karl0525

In my experience slow generator cranking, (or no cranking), is most often caused by:
1.) Insufficiently charged batteries...(or bad batteries)...f
2.) Poor cable connections.
3.) Bad batteries.
Mel
'96 Safari

[KEH]

My 02 National Tradewinds has a Cummins 350 ISC and 7.5 kw Generac. I have exactly the same starting situation that your dad has experienced...over the past year the starter would turn slow before the generator would start...now it's too slow to start. I've checked voltage at the generator and it shows 13.5 v; which is what the house batteries are at while charging. I think it's the starter that 's the problem so I've started removing the generator panels to gain access to the starter. I hope to get more into it tomorrow and will let you know if I determine the cause. I can see that there's one, possibly two, solenoids in there that I haven't got to yet to check voltage.

[LETMGROW]

Originally Posted by Charles27909

Hello everyone....I would appreciate some advice/opinions about the generator on my Dad's Newmar. My father and I have traveled on many trips with his motor home and the starter on the generator has always spun slow but started. Now the starter is not spinning it engine fast enough to start. Outside of replacing the starter, I wonder if anyone else has had the issue and what remedies may resolve it. I am not reluctant to change the starter, just want to try most cost effective ways first....THANKS FOR YOUR ANSWERS.

If you run all the tests suggested including a battery load test and all appears well you may not have to replace the starter. There are businesses which will disassemble and repair or rebuild starters much cheaper than replacement units will cost. Sometimes just a thorough cleaning, a new set of brushes and lubing the bearings will return the starter to like new condition. The rebuilder will test the fields and armature and clean the commutater surface. Get an estimate of repairs and compare it to the price of new before giving an OK to repairs or rebuild. It's your call.
Also don't forget to check any and all ground wires for corrosion and tightness. Does the gen set have a ground wire hooked between it and the MH chassis? Remove it and clean all contact points. Use a silicone Di-Electric grease on all terminal ends both positive and negative.
Be sure there is no corrosion buildup between the starter and the engine where the starter is mounted. Clean all surfaces well before reinstalling the starter.
Electrical circuits can be explained simply if you vision them as a circle from positive to negative. The power has to flow from the source (battery) through the starter back to the battery with a minimum of resistance to operate efficiently. This is true with any electrical device including lamps.
There is no such thing as a pretty good connection. They must be surgically clean IMO.
I mentioned the battery load test because it is the only accurate way to test batteries which are sealed. If you have multiple batteries disconnect all cables and test each battery individually. If you find one bad replace them all at the same time. The batteries will expire one by one.
Lynn