Voltage draw after engine start

two sailors · 01-31-2008, 09:32 AM

After starting the cold engine I get a heavy voltage draw for about 1 second, three or four times about 30 seconds apart. I can hear the engine noise change as it puts a load on the alternator. Any ideas what or why??
Brad

two sailors · 01-31-2008, 09:32 AM

After starting the cold engine I get a heavy voltage draw for about 1 second, three or four times about 30 seconds apart. I can hear the engine noise change as it puts a load on the alternator. Any ideas what or why??
Brad

**Route 66** · 01-31-2008, 09:39 AM

If you have a Cummins, it's the air intake grid heater cycling to warm the incoming air for a starting aid when it's cold.

Ecker · 01-31-2008, 10:18 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by two sailors:
After starting the cold engine I get a heavy voltage draw for about 1 second, three or four times about 30 seconds apart. I can hear the engine noise change as it puts a load on the alternator. Any ideas what or why??
Brad </div></BLOCKQUOTE>

Dirk has it right - I'd just add you may be able to hear the heater cycling even before you start engine as you wait on WAIT dash light to extingish for same reason i.e. the heater is cycling on and off to preheat air in intake.

two sailors · 01-31-2008, 10:34 AM

That's a relief!! Thank you very much. It is sure nice to have access to so much experience.

Brad

heavyequiptmentmover · 01-31-2008, 03:30 PM

Observed the same thing afew days ago for the first time when I was starting up the coach in preparation to takeing it out for a winter run.

Thanks for the information as to why the voltage varies during start-up.

Pusherman · 01-31-2008, 04:08 PM

My prior coach w/ Cummins ISB did the same thing. Would cycle 2-4X after starting. You could watch the voltmeter moving during this process.

Dirk has it nailed (as usual).

**Route 66** · 01-31-2008, 04:42 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Dirk has it nailed (as usual). </div></BLOCKQUOTE>

Only because it happened to me last year, and I had to ask.

SargeW · 01-31-2008, 05:57 PM

Hey Dirk, I have a related question. I have a internal 120 volt engine block heater to use in cold weather. Would that prevent the heater grids from cycling if I preheated with the 120 volt system first?

Oh, and does the light go off in the refridgerator when I close the door?

Sarge

Ray,IN · 01-31-2008, 07:21 PM

Sarge, no it does not. My old 1996 Dodge CTD would cycle the intake heater just the same. Reason? The incoming air must be warm enough to support, then sustain, auto-ignition.
FWIW- never use starting fluid with a grid heater equipped engine!

**Route 66** · 02-01-2008, 02:23 AM

I've never been anywhere cold enough to use the block heater, and don't intend to!

However, I agree with Ray's post.

SargeW · 02-01-2008, 06:07 AM

Yeah, me too. I have had the rig almost 2 years and haven't turned on the heater switch yet....

I have had something diesel for about 10 years so I was well aware of the no starting fluid rule. I had a 97 Dodge diesel that could wake the neighborhood on a cold morning.

Ecker · 02-01-2008, 06:21 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Route 66:
I've never been anywhere cold enough to use the block heater, and don't intend to!

</div></BLOCKQUOTE>

It an urban legend that a block heater doesn't need to be used in warmer climates. The use of the block heater to prevent "cold" start and subsequent possible piston scuffing is desirable. In fact, emergency standby generators often are setup to have block heater on 100% of time and it's non-operation ranks around #6 on top 10 reasons for failures of emergency gensets. #10 is run out of fuel.