Glow plug timer relay - 300tdi

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ChrisG

Guest
Anybody know what voltage the glow plug timer relay puts out. I'm
talking about PRC6913 on a '96 300tdi,

Although the input is 12v the relay output starts at 9.5 and climbs to
10.5 (measured at the relays spade) before the timer cuts out about 8
seconds later. This heats the plugs but not enough to glow which only
seems to happen if I strap the plugs directly acoss the battery.

I've tried a new relay and get the same result...and also tried
earthing the relay straight to the battery - I assume the temperature
sensor is within the relay body itself. Perhaps the warning light or
timer mechanism is 'stealing' the extra voltage ?

I'm looking for the cause of the big blue cloud that follows me around
for the first 5 minutes on colder mornings


ChrisG
'96 Defender - corrosion, squeaks and leaks
'53 Series One - Dust, bodges and leaks


 
In message <[email protected]>, ChrisG
<[email protected]> writes
>I'm looking for the cause of the big blue cloud that follows me around
>for the first 5 minutes on colder mornings
>


If the cloud really lasts for five mins then it will be nothing to do
with the heater plugs!

I would be looking at valve stem oil seals or turbo.

--
Marc Draper
 
> Although the input is 12v the relay output starts at 9.5 and climbs to
> 10.5 (measured at the relays spade) before the timer cuts out about 8
> seconds later. This heats the plugs but not enough to glow which only
> seems to happen if I strap the plugs directly acoss the battery.


Is that 10.5 open circuit or with the plugs in line? With plugs in I'd
expect a voltage drop which may account for that but otherwise 10.5 seems
low. I could on;y suspect a connection problem in the latter case, maybe
engine to earth strap?

TonyB


 
>
> If the cloud really lasts for five mins then it will be nothing to do
> with the heater plugs!
>
> I would be looking at valve stem oil seals or turbo.
>
> --

........And if it's just on start up only it's normal!!
TonyB


 
TonyB wrote:
>>Although the input is 12v the relay output starts at 9.5 and climbs to
>>10.5 (measured at the relays spade) before the timer cuts out about 8
>>seconds later. This heats the plugs but not enough to glow which only
>>seems to happen if I strap the plugs directly acoss the battery.

>
>
> Is that 10.5 open circuit or with the plugs in line? With plugs in I'd
> expect a voltage drop which may account for that but otherwise 10.5 seems
> low. I could on;y suspect a connection problem in the latter case, maybe
> engine to earth strap?


In general terms (no 300tdi experience) it sounds fine - there's plenty
of engines out there using glow plugs rated as low as 9 volts. If
nobody else come sup with an actual voltage take a glow plug out and
read what voltage is marked on it.


--
EMB
 

> Anybody know what voltage the glow plug timer relay puts out. I'm
> talking about PRC6913 on a '96 300tdi,
>
> Although the input is 12v the relay output starts at 9.5 and climbs to
> 10.5 (measured at the relays spade) before the timer cuts out about 8
> seconds later. This heats the plugs but not enough to glow which only
> seems to happen if I strap the plugs directly acoss the battery.
>

Have you measured the relay input voltage when the glow plugs are on?
It may be showing 12V with the plugs off, but it will probably drop when the
plugs are energised, due to voltage loss in the cables. If you realy are
loosing 2 volts or so across the relay contacts then the relay is duff.

> I'm looking for the cause of the big blue cloud that follows me around
> for the first 5 minutes on colder mornings
>

Nothing to do with glow plugs that mate!
If it only does it for 5 minutes, and does not smoke the rest of the time,
then you have no problem, pretty normal for a diesel engine.


 

"TonyB" <[email protected]> wrote in message
news:[email protected]...
> >
> > If the cloud really lasts for five mins then it will be nothing to

do
> > with the heater plugs!
> >
> > I would be looking at valve stem oil seals or turbo.
> >
> > --

> .......And if it's just on start up only it's normal!!
> TonyB
>
>

It is only on startup, and the longer it sits the worse it is - but
only ever a problem if the temp has dropped to 5 degrees overnight.
I agree , valve seals are a strong possibility. At first theres enough
smoke to cover a house, after about 1/2 mile its considerably better,
after 5 mins its clean .

ChrisG


 
In message <[email protected]>, SimonJ
<[email protected]> writes

>Nothing to do with glow plugs that mate!
>If it only does it for 5 minutes, and does not smoke the rest of the time,
>then you have no problem, pretty normal for a diesel engine.


Blue smoke for five mins is not normal at all for a 300 tdi.

--
Marc
 
Directly earthing the relay makes no difference surely as teh earth comes from the cylinder head. engine earth strap maybe? test voltage from battery to first earth strap, then second down behind radiator.
 
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