something odd happening on start up

Joined
Oct 5, 2009
Messages
6
Location
Halifax, Yorkshire, England
Hello All,

just wondering if anyone can shed any light on a whats happening to my 80.

on start up the dash warning lights stay on, and the voltage meter reads low, after about 3 - 4 mins the voltage level starts to climb until the dash lights go out, then its all fine.

i have noticed thats the colder the motor is, the longer it takes for the voltage to climb.

Its an 1994 80 with the 4.2 24v motor, i have replaced the alternator recently. and it still does the same thing. its also go new batteries


hope you can help.


Awesome forum by the way ;)



Martin.
 
Joined
Apr 8, 2010
Messages
265
Location
Oregon
Autocraft--I've heard diesel guys say this is due to the continued glow plug activity for a few minutes until the engine warms a bit more--helps it run better after initial start--pulls juice from the system during that time...
My 86 HJ does that a bit as well for about a minute or 2..
LCDiesel60
 
Joined
Nov 3, 2008
Messages
1,146
Location
Winnipeg, Manitoba, Canada
Mine does the following on a cold morning start (-30°C):
  1. Key on
  2. No 1 glowplug relay clicks on
  3. Glowplug light on for about 5 seconds
  4. No 1 glowplug relay clicks off after about 15 seconds
  5. Voltmeter jumps up slightly
  6. Start engine
  7. No 2 glowplug relay clicks off after 2 minutes
  8. Voltmeter jumps up to normal position

What you're describing does not sound normal. The glowplugs should run only for a maximum of 120 seconds. Also, the dash lights will cycle as normal during the glow cycle - they will not stay on longer than a couple of seconds unless there is a real problem.

Even though you've recently replaced the alternator and batteries, I would get your alternator output measured during the glow cycle and after to ensure it is working properly. Are the battery terminals all clean and tight? Grounds intact? Is the connector plug on the back of your alternator loose? This is the cause of the flickering/steady dash light problem most have run into.
 
Joined
Oct 5, 2009
Messages
6
Location
Halifax, Yorkshire, England
I'll give that a go, im sure its not right, as ive had the truck for over 7 years now and i dont remember it doing it before.

thanks for the advice. I'll let you know how i get on.



regards

Martin
 
Joined
Jul 13, 2008
Messages
1,380
Location
Coldest N. America
Is it a turbo engine with a glow-screen or a NA engine with glow-plugs. On a turbo glow-screen engine what you describe in post #1 is perfectly normal.
 
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Abby
Is it a turbo engine with a glow-screen or a NA engine with glow-plugs. On a turbo glow-screen engine what you describe in post #1 is perfectly normal.

It is the same on my NA Nissan diesel with glow plugs. In cold weather, the preglow is only a short step in the glow process. My second glow relay keeps the glow going until the temp sensor shuts off the relay - usually about 2 minutes or so. Likewise, this is visible on the voltmeter.
 
Joined
Nov 3, 2008
Messages
1,146
Location
Winnipeg, Manitoba, Canada
Is it a turbo engine with a glow-screen or a NA engine with glow-plugs. On a turbo glow-screen engine what you describe in post #1 is perfectly normal.
The OP mentioned that all his dash indicators are staying on and the voltmeter reads low for 3 to 4 minutes. That's 2 non-normal things. My dash indicators turn off right away, and my glowplugs only run for a mzximum of 2 minutes. There is definitely something odd happening.
 
Joined
Dec 29, 2006
Messages
9,165
Location
Abby
The OP mentioned that all his dash indicators are staying on and the voltmeter reads low for 3 to 4 minutes. That's 2 non-normal things. My dash indicators turn off right away, and my glowplugs only run for a mzximum of 2 minutes. There is definitely something odd happening.

He may have an issue with his alternator. He should check the output on cold start-up.
 
Joined
Oct 5, 2009
Messages
6
Location
Halifax, Yorkshire, England
Just an update,

It turned out that the rectifyer in the alternator was giving up, well it fianly died last week.

I bought an induction amp meeter, you can just lay it on the cable and it tells you the direction of the current and how much is flowing.

as soon as i fitted a new rectifyer (borrowed from my race car) the alternator started working again. But the dash lights were still staying on.

I started following the current flow with the amp meeter, the alternator was putting out 100 amp and getting hot. it would seem there is a 100 amp draw on the system.

this massive draw is making the alternator work past its designed limits so the voltage just isn't getting up to 14.4 v to put out the charge light out on the dash.

I started disconnecting large items such as the air pre-heater act. still no joy.

i followed the current flow and it looks like the second Battery is drawing all the current. so todays job is to get the battery load tested to see if its that.


thanks for help and advice, i let you know how i get on.


Martin
 

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