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.

[Volvoist]

Originally Posted by v8volvo

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......

What exactly can happen? I am wondering if this led to my destroyed GP's and motor in my 84. I was running 100% biodiesel, already processed from a local biofuels company. I don't want to trash another motor if this was the reason. I am also running it in my wifes Jeep Liberty CRD (though not at 100% usually) and around 40% in my home furnace...

[Jason]

What kind of GPs? Anything other than Bosch is probably junk, and even some Bosch plugs haven't lasted me very long. Seems kind of hit and miss. I replaced some of the plugs in my old engine a couple times within a couple years, while the set i have now in the new engine has been in for over a year and they are all fine.

jason

[Volvoist]

I have/had Bosch 80010's. They are the only plugs I have ever used in a D24/D24T and have never ever had any issues in the past...