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The mkiv Supra Owners Club

Saxo diesel cold starting issues


Tyson

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got myself a multimeter and checked the voltages;

 

battery 12V

Glow plug relay 12V

Glow plugs 11.5V

Coolant temp sensor 9V

 

Ran a direct current to the fan and that is working fine.

 

This is with the engine off.

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OK well if you are getting 11.5 volts at the glowpulgs then assuming all glow plugs work and the engine is getting fuel, it should start at the temps we are having this time of year.

 

Are all the plugs connected together with a strip of metal and a small nut at the top of each plug? If so carefully loosen each nut and move the strip of metal away from the plugs. Using your meter on ohms each plug should have a very low resistance reading between the top of the glow plug (the nut) and ground (the engine). If you have one with a reading higher than a few ohms it is probably faulty, most read between .3 ohm and 2 ohms, but I believe some are as high as 5 ohms but have to say all the ones I have come across have been much lower than that. At least then you have rulled out the glow plugs and associated circuitry like the relay etc. Let me know how you get on.

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OK well if you are getting 11.5 volts at the glowpulgs then assuming all glow plugs work and the engine is getting fuel, it should start at the temps we are having this time of year.

 

Are all the plugs connected together with a strip of metal and a small nut at the top of each plug? If so carefully loosen each nut and move the strip of metal away from the plugs. Using your meter on ohms each plug should have a very low resistance reading between the top of the glow plug (the nut) and ground (the engine). If you have one with a reading higher than a few ohms it is probably faulty, most read between .3 ohm and 2 ohms, but I believe some are as high as 5 ohms but have to say all the ones I have come across have been much lower than that. At least then you have rulled out the glow plugs and associated circuitry like the relay etc. Let me know how you get on.

 

all have between 1.3 and 1.5 ohms.

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all have between 1.3 and 1.5 ohms.

OK well thats good, so if you have 11.5V for a short period on them glowplugs, that side of things should be OK and certainly in this temperature be enough to start it, and as it's not then its something else. So, next step, crack the pipe union nut undone on the top of each injector and get someone to spin it over a few times while watching. You should see diesel being forced out around each nut proving you have fuel and under pressure up to the injectors. If not, there's your problem, if so, then you have to get the feelergauges out and look at them valve clearances, especially the exhaust.

 

with the fuel thermostatic valve I am going to try new o rings and see if that stops it from leaking.

Well if it's leaking then yeah it has to be done, but cant see its causing the problems you describe re the cold start. If it was the middle of winter, then maybe but we are in double figures now and most diesels even if worn should start very easy from cold.

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OK well thats good, so if you have 11.5V for a short period on them glowplugs, that side of things should be OK and certainly in this temperature be enough to start it, and as it's not then its something else. So, next step, crack the pipe union nut undone on the top of each injector and get someone to spin it over a few times while watching. You should see diesel being forced out around each nut proving you have fuel and under pressure up to the injectors. If not, there's your problem, if so, then you have to get the feelergauges out and look at them valve clearances, especially the exhaust.

 

 

Well if it's leaking then yeah it has to be done, but cant see its causing the problems you describe re the cold start. If it was the middle of winter, then maybe but we are in double figures now and most diesels even if worn should start very easy from cold.

 

Ok will do and let you know how I get on.

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Just had some dinner and went out to the car to check the injectors. Guess what as soon as I turned the key it fired up and there is no smoke !!! So it was the fuel leak and cost me 30p for an o ring.

 

Thank you everyone for your help !!! I never got any replies from the numpties on the saxo owners club. They only know about petrol models .... Going out for a spin :)

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Will test it again in the morning but pretty sure all is well. There was quite a bad leak and there was a lot of air in the fuel lines. Just glad its all sorted now. Bought the car as spares for 150 with cold start problems, cost me 30p to sort RESULT !!

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Wohoo its all sorted fired it up this morning and it roared into life straight away with no smoke at all !!!

 

Well done, glad you got it sorted. This generation of diesel engnes are great. I see you say its got a bosch pump, they are very resilient and have a great survival reputation when running veg oil. Makes for even cheaper motoring.

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Well done, glad you got it sorted. This generation of diesel engnes are great. I see you say its got a bosch pump, they are very resilient and have a great survival reputation when running veg oil. Makes for even cheaper motoring.

 

I know its a great little car, I am going to run it on a 50-50 mix of oil and diesel. I bet if I told the previous owner how much it cost me to fix he would kick himself !!

 

I love working on cars even if I don't know much, I gave it a full service and did everything myself. It so much more satisfying doing it yourself as you get a sense of accomplishment and the knowledge that it has been done properly.

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