D24TIC Poor Cold Starting

[DLM48]

MY 945 24tic is having a few problems cold starting.............starts in about 20/30 seconds after some cranking - usually two goes on the key. The problems seems to be that the glow plugs are not activating at least the light on the dash is not coming on.

So are the glow plugs activated on every cold start? Are they temperature dependent i.e. are they only activated if the air temp is below xx deg? OR what?

cold start device is working fine as i have a VERY fast idle until it warms up - but the the idle is very fast normally i suspect the fuel mixture has been played with for extra performance.

thanks in anticipation

[craig8661]

the cold start can stick hence fast idel when runing just try nudging it with your hand and if it drops just look at the meck may be dry as for cold start look in the pipes for air if thats ruled out look for your heater relay im not sure where its located will look in mine soon if your heaters are working right you should hear a audible click from under the bonet after about 20 secs or other test you can do is vault meter on the plugs and earthed to battery and get some one to turn the ign on if you get 12 volts the electronics are fine then suspect the glow plugs i have 2 down on my engine and both behind the pump

[craig8661]

found the heater controle module thats just abouve the battery see photo

cheak this lever on your pump

[jor]

As per Craig's post the usual culprit is the glow plug. I changed mine a year ago buying the cheapest type (non branded) and guess what - they have just needed replacing again. TFB suggests checking the resistance between the connector part and earth, having removed the copper strip that connects them. I could not get consistent values (above 4ohm is bad) and wasn't certain I was doing it right, so I took out the 4 easily accessible ones and connected them to a battery, one at a time. Working ones definitely will light so watch out for the carpet. None of them did so they have been replaced with 4 Bosch ones. I'm sure the other 2 are also kaput, but it starts well enough so will do the others 'sometime'.
The engine will start on compression alone when the temp is somewhere around 35C.
I know engines will start on 3 functional plugs - as the first time I did mine I forgot to connect the copper strip to the inner 3 plugs, so if you find that the ones you test are working then the trouble lies elsewhere. The fact that the light is not coming on is a bit suspicious of an electrical rather than a plug problem. There is a diagram of the glow plug circuit on Ross Winberg's volvoturbodiesel.blogspot.com, however I can report that I know nothing about electricity so to me it's meaningless. However if the plugs work and you can get hold of a working relay and the thing still won't start then by exclusion it's got to be the switch that's faulty. The one part of the relay that's easy to look at is the fuse visible at the bottom after you undo two nuts and the connectors.
My guess is that the switch is bust.


john

[DLM48]

Originally Posted by jor

As per Craig's post the usual culprit is the glow plug. I changed mine a year ago buying the cheapest type (non branded) and guess what - they have just needed replacing again. TFB suggests checking the resistance between the connector part and earth, having removed the copper strip that connects them. I could not get consistent values (above 4ohm is bad) and wasn't certain I was doing it right, so I took out the 4 easily accessible ones and connected them to a battery, one at a time. Working ones definitely will light so watch out for the carpet. None of them did so they have been replaced with 4 Bosch ones. I'm sure the other 2 are also kaput, but it starts well enough so will do the others 'sometime'.
The engine will start on compression alone when the temp is somewhere around 35C.
I know engines will start on 3 functional plugs - as the first time I did mine I forgot to connect the copper strip to the inner 3 plugs, so if you find that the ones you test are working then the trouble lies elsewhere. The fact that the light is not coming on is a bit suspicious of an electrical rather than a plug problem. There is a diagram of the glow plug circuit on Ross Winberg's volvoturbodiesel.blogspot.com, however I can report that I know nothing about electricity so to me it's meaningless. However if the plugs work and you can get hold of a working relay and the thing still won't start then by exclusion it's got to be the switch that's faulty. The one part of the relay that's easy to look at is the fuse visible at the bottom after you undo two nuts and the connectors.
My guess is that the switch is bust.


john

thanks i thought that it cant be a plug issue as i would expect the light to still come one even were the plugs duff
thanks

http://photos1.blogger.com/blogger/2...5/1600/g11.jpg

RELAY 130 is clicking

BUT no 12V at glow plug buss rail

so it would seem that i have a problem with the relay or one of the two sensors the temp sensor (199) or the fuel valve one (195) on the injector pump

fuses 8,9&10 are OK

need to double check the glow plug bulb is good - it is

the cold start lever on the pump moves a little 1/4"/3/8" when you pull forward on the top slot where the ball that contact the throttle lever is

there is a micro switch on the pump at the back of the throttle lever but the actuator is no longer there - is this the fuel valve sensor?

Fed the glow plug buss rail with 12V and cars starts fine so this IS a glow plug actuation issue.

[tfb]

The glow plug funtion is activated by a coolant temp sensor that's hidden on the engine block around the back of the IP.
The manual suggests the following glow plug times for coolant temp
9 seconds for -20C
6 seconds for 0C
4 seconds for 20c
3.5 secionds for 40C
0 seconds for 50C

The dash light is controlled by the Glow plug relay, but it doesn't exactly mirror what the glow plugs are doing. The glow plugs can still be heating when the dash light is off, but if the light is on then the glow plugs are on.
I would suggest that you use a multimeter to measure the voltage to the plugs to confirm the function of the relay (but it does sound like it is working to a degree).

From your description I would guess that one or more plugs have failed. No 5 and 6 are a bugger to get to withour removing the injectors or pump. I would try removing and testing the resistance of No1 to 4 and replacing if required. If this makes starting tolerable then leave No5 and 6 untill you have a good amount of free time and something to go and kick to take out your frustrations!

Regards
TFB

[DLM48]

Originally Posted by jor

As per Craig's post the usual culprit is the glow plug. I changed mine a year ago buying the cheapest type (non branded) and guess what - they have just needed replacing again. TFB suggests checking the resistance between the connector part and earth, having removed the copper strip that connects them. I could not get consistent values (above 4ohm is bad) and wasn't certain I was doing it right, so I took out the 4 easily accessible ones and connected them to a battery, one at a time. Working ones definitely will light so watch out for the carpet. None of them did so they have been replaced with 4 Bosch ones. I'm sure the other 2 are also kaput, but it starts well enough so will do the others 'sometime'.
The engine will start on compression alone when the temp is somewhere around 35C.
I know engines will start on 3 functional plugs - as the first time I did mine I forgot to connect the copper strip to the inner 3 plugs, so if you find that the ones you test are working then the trouble lies elsewhere. The fact that the light is not coming on is a bit suspicious of an electrical rather than a plug problem. There is a diagram of the glow plug circuit on Ross Winberg's volvoturbodiesel.blogspot.com, however I can report that I know nothing about electricity so to me it's meaningless. However if the plugs work and you can get hold of a working relay and the thing still won't start then by exclusion it's got to be the switch that's faulty. The one part of the relay that's easy to look at is the fuse visible at the bottom after you undo two nuts and the connectors.
My guess is that the switch is bust.


john

when i replace mine i will use the hotter Bosch ones that elsberg use i think the Part number is on the VEG OIL thread

[Steve V]

Just had similar problems with my 850.
Check the plugs are working by measuring if there is any resistance from the terminal to earth. If they are open circuit they are US.
Another way is to connect a wire to the live side of the battery and touch this on the end of the plug and look for a small spark. If you get one the plug is good. Be careful though not to touch earth anywhere i.e. the engine block or pipes...
Every one of my plugs was gone but at 117K I shouldn't moan.
Starts first touch now. Mint

[DLM48]

Originally Posted by Steve V

Just had similar problems with my 850.
Check the plugs are working by measuring if there is any resistance from the terminal to earth. If they are open circuit they are US.
Another way is to connect a wire to the live side of the battery and touch this on the end of the plug and look for a small spark. If you get one the plug is good. Be careful though not to touch earth anywhere i.e. the engine block or pipes...
Every one of my plugs was gone but at 117K I shouldn't moan.
Starts first touch now. Mint

thanks but i have already proved that the glow plugs are functioning by feeding the buss bar straight from the battery and also when the light on the dash comes on the car starts on almost the first turn - this is i am sure a relay problem

[DLM48]

Well i got seriously fed up with the bad starting when cold and today had a good long look at the problem. I found two wiring diagrams online in fact found a whole 940 wiring diagram thing online and took a copy of that. It is a PDF so if you want a copy PM me please. Anyhow using both diagrams and getting my head into 'electronic' mode i sat down and worked things out. The first diagram has all the bits identified but does not explain the inside of the glow plug relay 'properly' using both i understood the circuit quickly.

Here is what i know now.

The relay box is 'intelligent' it is not just a relay - the glow plugs are well just dumb provide them with 12V and assuming they are good they will glow - at the back end of the engine is the 'critical' 199 sensor. This 199 sensor 'appears to be a temperature sensitive resistance. When the engine is 'COLD' like freezing and below it has a very high resistance which reduces as the sensor heats up to Bonnie Scotland temperatures 2/3 deg above freezing.

With the engine COLD and i mean winter type cold this sensor has infinite resistance (this has still to be measured - when i get a new sensor in my hand) - infinite resistance tells the electronics in the relay box to activate the glow plugs for the maximum 'set time' (i think 40 secs) as the sensor heats up (the car being parked in a less cold area - or the engine has been running recently) or get less cold the resistance changes and therefore the time the glow plugs are actuated is reduced.

So what we have controlling the glow plugs is a variable timing circuit within the relay box with the timing set by a variable (temperature sensitive) resistor sensor 199. Simple yes.
The Relay box also has another trick in that when you move the ign key from pos 2 (ignition on) to pos 3 (engine start) the glow heat circuit is disabled until the ignition switch is cycled back through pos 1 (ignition off).

SO if you are having glow plug activation problems it is really easy to determine which component is faulty.

1. Remove the wire from sensor 199 (this is difficult to locate - at first) switch ignition to pos 2 glow plug lamp should light on the dash if the relay is good.

2. Remove wire and measure resistance on sensor 199 (i got 50ohms - DUFF Sensor) cold it should have a very high resistance

3. With the wire off sensor 199 and tucked away somewhere safe and insulated you are providing the relay box with an infinite resistance on this circuit so the relay thinks it is in a sub zero temperature and will run the glow plugs for 40 seconds. Assuming your not in a sub zero temperature situation with this wire off sensor 199 you have manual control of the glow plugs ign switch pos 2/3 - simply by trying to start the engine you will switch off the glow plugs so you can time the glow circuit to suit your needs 5/10/15 seconds dependent on how cold the car is 'UNTIL' you can replace sensor 199.


i hope all of that is understandable and will help someone else.

regards