Keep glowplugs on for longer?

[ian2000t]

I'm running Veg now (usually 50-60% mixed with diesel or misfuel). Car always starts, but sometimes on a lumpy 4/5 cylinders if the temps are a bit low. I actually have no Cold Start at the moment because it seized and Volvo want £65.00 for a replacement wax stat, so the timing 0.96mm is probably a bit too retarded for cold starts.

As a cheap temporary fix until I find a good secondhand cold start, is there any way I can make the glowplugs stay on for the first 10 seconds of engine running, rather than just pre-heating them and starting when they switch off? I think this would help get the remaining cylinders going before I drive off.

I know I could take the relay out, put a standard 100A relay and 80A fuse in linked to a rocker switch in the car, but just wondered if anything can be done with the standard glowplug relay? Or maybe there is some reason the glowplugs should not be "lit" during the engine running?


Engine has been well serviced already - monark nozzles at 163bar, glowplugs, valve gaps done, oil changes, etc.

[michaelovitch]

There is a post heating system in this relay.
If the sender is still good and plugged it should post heat alone.
the viscosity of your mix is faulty i think.
have you got hydraulic lifters ?

[v8volvo]

Does it start easily on diesel? If it does, then you don't have a problem with your motor; your issue is with your fuel mix, and the poor starting is a major warning sign that you need to re-think your fuel blend before things get much worse very quickly.

The D24T relay does have an after-glow provision; it is only about 2-5 seconds after the key is released rather than 10, but in a healthy engine running on good fuel, it is plenty. If you find yourself needing more than that, then you have an engine compression, timing, or injector problem (and I it sounds like you have pretty well made sure your unit does not have any of those issues), or again, you need to reduce your veg oil usage.

Let me be clear -- running veg in your mix without a heated fuel system, at a high enough percentage to affect starting, is asking for trouble. Running small enough quantities that it does not affect engine operation -- small enough quantities that you really think of the veg as an additive, not a significant component of your fuel) you can get away with OK, though you will go through fuel filters at 3 or 4 times the rate you normally would, especially in colder weather when there is some precipitate drop-out from the unheated veg, which cuts into your savings a bit. However, running 50-60% without a heated fuel system is a sure recipe for engine and fuel system destruction, landing you with a dead motor and a big bill, at which point the idea of savings from running cheap fuel starts to sound a little silly......

[ian2000t]

Yes, it starts fine on pure diesel (on a cold morning needs 2 heats of the glowplugs and does chug a little). Bear in mind I have no cold start device at the moment. With the cold start lever manually activated it starts fine with veg oil in a 50/50 mix with diesel. However, I can't find a good cold start device and the waxstat replacement is £60+VAT from Volvo.

Also, bear in mind that I'm using SVO currently - i.e. Straight Veg Oil from the supermarket. No fats etc to drop out as temp falls. I have so far changed fuel filters twice (in 8,000 miles I've had the car) but this was precaution - neither needed changing, but at £5 a time I thought it was worthwhile as Veg oil can clean any diesel deposits from the fuel system/tank.

I will be using WVO soon - waste veg oil. However, I am processing it very carefully. Pour just good liquid oil through a bedsheet into a Burco Tea Earn. Heat it to 90-100C first for an hour or 2. Some water evaporates, some falls to the bottom (below the tap). Leave it to cool till the following day. Any fats and water fall to the bottom below the tap. Drain good oil off through filter socks (50mic, 25mic, 1mic) at the coldest possible time. This ensures all possible fats are caught in the filter socks. So, if I filtered tonight when it's 5C, unless it dropped to -5C (which it won't this week). I then will be pre-mixing it with 10% petrol (in bottles, before it goes in the tank) and adding a couple of caps of veggi-boost, which is a cetane enhancer. So I'm not just dumping old oil through a tea towell into the car and expecting it to start! 10% petrol should roughly halve the viscosity of the veg oil.


Re: Glowplug relay - my glowplug light lights up (only if engine cool) and stays on for probably 5 secs... then I start the car. The light never stays on after I've started the car. Has anyone got a wiring diagram for the glowplug relay?

[michaelovitch]

I don't want to be annoying or bitching but :
first : how want you start correctly without cold start device ? mmhh?
Your first step is this device: think it's a vw engine : this device is avaible at a vw dealer and others brands using the ve pump !
the golf 2 3 etc...the vw lt peugeot too etc....at the junk yard .

then you do not have to cycle 2 times the glow plugs if the system work properly.

my sister's car have 250 000 kms and the engine cranck even if it's very cold on the first time.

remember the vo is thicker and is less well sprayed by your injectors even once hot.

thicker means slower and you have to set the pump with a bit more advance.

[ian2000t]

Thanks for your reply. I see where you are coming from. Please note though, that although in the US these engines are more common, they are rare over here. Also, yes similar to a Vw golf, or LT engine, and same type of pump as many other diesels, I believe the cold start is unique to Volvo. I know for certain that the Vw LT35 that this 6 cylinder was also used in had a manual cable operated cold start, not a wax stat like Volvo...their the Vw dealers are no use to me.

This is why I was asking about keeping the glow plugs on - if I can do something like that and it costs me just the wire in my garage and time, then that write be my temporary solution until I find a good cold start.

[michaelovitch]

[ATTACH=CONFIG]278[/ATTACH][IMG][/IMG]

Originally Posted by ian2000t

Thanks for your reply. I see where you are coming from. Please note though, that although in the US these engines are more common, they are rare over here. Also, yes similar to a Vw golf, or LT engine, and same type of pump as many other diesels, I believe the cold start is unique to Volvo. I know for certain that the Vw LT35 that this 6 cylinder was also used in had a manual cable operated cold start, not a wax stat like Volvo...their the Vw dealers are no use to me.

This is why I was asking about keeping the glow plugs on - if I can do something like that and it costs me just the wire in my garage and time, then that write be my temporary solution until I find a good cold start.

you're right about the LT it's a cable with a red square attachment on the pump ! i forgot it i've bought one two months ago

I f you are in the UK you have this cold start device on the citroen xm and others brands it's not a volvo specific system i'm sure of that.

a rapid search on google will help you to see this system is not specific. "cold start device ve pump"
The d24 is not "rare" here in France i'm lucky for that.


you really need this cold start device it will help a lot.
you will can find it at the others dealers for sure

remember the thickness doesn't help too

if you plan on a glow plug homemade button use a relay 80 amps or 2 40 amps like you said from golf or VAG cars to power the glowplugs.

don't run a straight wire to the glowplugs in your car or it could be dangerous.


FROM A CITROEN XM

http://i75.servimg.com/u/f75/11/85/90/82/demarr10.jpg


FORD TRANSIT

http://www.forum-auto.com/pole-techn...ujet482899.htm

here there is the preheating system diagram :

http://www.scribd.com/doc/59773021/volvo-D24-Preheating

you can have others useful things on my account !

the cold strat device PAGE 41 here : http://www.scribd.com/doc/19099617/Bosch-Ve-Pumps

[ian2000t]

V8Volvo:

I tried to PM you but your box is full. I was hoping you could give me some more explanation as to what problems the hunting on startup is likely to cause if you don't mind? Not that I don't believe it's a bad thing, I just like to understand why it is.

Message I tried to send:

Hi mate, hope you don't mind me contacting you. As you might remember I run Veg oil on my motor and was experiencing some hunting on startup, which you warned was bad and to re-think the % of veg usage.

I have currently increased the petrol % to 15% and use a cetane enhancer which has helped a lot, and I will be adding a fuel heater very soon (although this will not affect cold starting I understand). If I manually hold the cold start open it starts with barely any hunting but I am still really struggling with the CSV unit.

The reason I am contacting you is for further explanation of what you said before "before things get much worse very quickly". I understand hunting on startup isn't good for a diesel, but I've not found anything that says what problems it causes. The only thing I can think of is unburnt veg making it's way through the pre-chamber and into the combustion chamber, and then collecting in the rings and drying hard... leading to sticking rings. Is this what you were referring to?

[ngoma]

Originally Posted by ian2000t

The only thing I can think of is unburnt veg making it's way through the pre-chamber and into the combustion chamber, and then collecting in the rings and drying hard... leading to sticking rings. Is this what you were referring to?

Likely also passing the rings and making its way into the oil sump. Over time, the veg tends to polymerize into lumpy sludge which will get distributed thru the engine. This lumpy sludge does not lubricate well...

But ring coking itself is bad enough. The most important thing a diesel engine needs is good compression.

[ian2000t]

Right, good points. IDI diesels are far less susceptible to veg oil making it into/past the rings than DI diesels, but obviously they are not completely void from the issue.

I change oil every 5,000 miles (maybe sooner) and always use semi-synth. Last time was 10/40, this time 5/30 for the winter months. Before I started using Veg I also ran some BC109 through the oil before change - I will do this again the next time I change the oil.

Understood about ring coking. I think my engine may always have had low compression on one cylinder, as there is always a bit of a "shake" to the idle when warm - has done this since I bought it. I thought new nozzles had resolved it, but no. I am going to add water injection very soon which on the veg forum has been very successful in resolving ring coking, low compression, and crankcase pressure (blow-by) on several cars - mainly the Mercedes OM606 IDI's. I will be using it as a preventative measure, but also wonder if it will stop my "shakey" idle that I've had all along.

I have gone for a very small misting nozzle (1Gph), and a 65psi pump, so it should produce the finest mist (fog), so not for performance increase, just a "steam cleaning". I will give it a few motorway miles with it switched on (when the boost is 5psi+). If it does any good, I will get a boost operated switch and set it to 10psi.