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Technical The saga of a difficult to start Multijet continues

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Technical The saga of a difficult to start Multijet continues

DiamondDave

DiamondDave

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I bought a Multijet 120 '06 a few weeks ago. Still have tax on the Marea so wasn't in a rush to put it on the road.
When cold, it never started easily and turned over a lot before it eventually kicked to life.
First thought was glow plugs, so had a look but someone had already put in 4 new NGK Y534J plugs. They all showed a resistance of 0.6Ohms. Then checked the plugs relay and this looked to be working in that it closed the relay and gave power to the plugs. Also checked the fuse and made sure that it had a good contact.
After looking around at plugs, it appeared that there were two options for the Multijet, one being longer than the other. See attached image.
So, I wondered if the NGK were shorter ones and whether a longer glow plug would solve the problem. Picked up some longer Bosch plugs (0 250 202 132) at half price on Mister-Auto.ie. Put them in this morning and the car started far better than it ever did, although not perfectly! The relay looks like it is acting up now. :mad:
Verdict:- if your Multijet is difficult to start and everything else looks OK, then the plugs fitted could be too short, as in the image attached.
What do you all think, could this be something?
 

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I have had my 120 for a few months now, and love it, but I found it very difficult to start, so strange but true, my girlfriend suggested waiting for the glowplug light to go off, on the dash, which I've never done before.....being typically impatient...
This makes a huge difference!!.now I wait 2 seconds, and it starts every time, maybe as its a multijet, it does things differently, like injecting some extra fuel at startup....
If thats just too simplistic, and as a long shot, could it be blocked DPF?
 
I've always waited for the coil light to go out, even a couple of seconds after, and still it was difficult (almost impossible when very cold) to start.
Putting in the longer glow plugs did help a lot, but it's not like it should be.
When I was resetting the oil degradation index after changing the oil, I checked the DPF values and it showed a 40% blockage, which apparently is low and nothing to worry about. A re-gen will take care of it.
Will finish the T-Belt, pump and thermostat in the next few days, so then I'll look into it further.
 
Maybe have your compressions checked as well as having your belt timings AND valve clearances checked. Remember that a diesel works on the principle that if you compress air it becomes super hot. As such compression needs to be 100% within your bore. Compression can leak past piston rings AND through sticky valves.

In a diesel the piston compresses the air, it becomes super hot and then at a crucial point (2mm Before Top Dead Centre) The injector squirts diesel into this super hot air and of course it combusts. The point at which the fuel is injected in is critical, too early (advanced) the air is not hot enough and any combustion that does occur actually works against the motion of the pistons. Too late (retarded) and again heat energy is lost due to conduction and expansion AND the piston is already running away and so any combustion has negligible effect. A dodgy crankshaft and or camshaft position sensor won't help matters either.

ALL systems must be working in harmony to have an easy starting and good running car (this goes for diesel or petrol)
 
OK, you sound like you know a bit about these noisy lumps, in my case I did think a weak battery maybe, and I was considering a leakage test on the injectors, but I always try the simple things 1st, another option is trying to contact the previous owner to get an idea on the history...
My car starts a lot better now, maybe usage?, fully charged battery?, maybe try diesel redex, flush out sticky valves etc...
Just read previous post, yes cambelt check is obvious one too...
 
Last edited:
Although not a mechanic myself my dad was one and so I grew up covered in grease and sifting through bits of cars and motorcycles. Suffice to say I have never nor will I ever send a car to a garage.

You are right in starting with the simple things. However easier starting with a fully charged battery (whilst it may seem obvious) also may indicate a compression issue. The faster the engine cranks the quicker the air is compressed and the less time compression has to find a blowpass. Of course a fully charged battery also means the glow plugs glow hotter assisting in the desired result.

I can tell you are a man with a Petrol history (redex lubricating upper cylinders) Alas this has no effect on a diesel. NO fluid whatsoever (apart from water vapor that results from combustion) ever touches the valves. On a diesel it is fresh charge air in / spent charge exhaust out. The fuel is injected directly into the upper bore which is why diesel systems are under such enormous pressure. They have to overcome the high pressure that already exists in the bore to get the fuel in, atomised and evenly combusted.

You don't say what mileage the car has done. Does it use oil and do you see any signs of white smoke when starting ? Also have you noticed the coolant level dropping ?

A leak down test will give you a good indication. It is a device that screws into your glowplug sockets. Compressed air is then pumped in and monitored on a gauge. The amount of time it takes for the gauge to lose pressure indicates how healthy the seal on the bore is.

Now you could also establish if your glow relay is working correctly. Take another set of 4 glow plugs. Your old ones will do. Remove that stupid plastic cover from the top of your engine. Disconnect your glow plug leads from your in-situ plugs and plug them into the lose plugs earth the body of each plug against a good earth on the car within reach of the plug cables e.g. the intake plenum. Make sure the connection is solid so you don't get arching. Cable tie them down if need be BUT ensuring the tip of the glow plugs are free to the air. Get someone to turn on the car (NOT start just on) whilst you watch the plugs. They should ALL glow a very nice ORANGE. If any are not doing this double check the EARTH. If one is not glowing change it with one that is. If the the problem still exists on that one plug then the relay is at fault.

If you want to clean your injectors (although I do not believe this will help your problem) you can try one of the off the shelf products (Millers is a very good choice).

Personally I use method handed down to me from my dad (NOTE I am NOT making a recommendation merely stating what I do). 100ml's of Acetone(must be at least 99.9% pure) + 100mls of redex (or kerosene) in my tank every 3rd to 4th fill up.
 
glowplug said:
Although not a mechanic myself my dad was one and so I grew up covered in grease and sifting through bits of cars and motorcycles. Suffice to say I have never nor will I ever send a car to a garage.

You are right in starting with the simple things. However easier starting with a fully charged battery (whilst it may seem obvious) also may indicate a compression issue. The faster the engine cranks the quicker the air is compressed and the less time compression has to find a blowpass. Of course a fully charged battery also means the glow plugs glow hotter assisting in the desired result.

I can tell you are a man with a Petrol history (redex lubricating upper cylinders) Alas this has no effect on a diesel. NO fluid whatsoever (apart from water vapor that results from combustion) ever touches the valves. On a diesel it is fresh charge air in / spent charge exhaust out. The fuel is injected directly into the upper bore which is why diesel systems are under such enormous pressure. They have to overcome the high pressure that already exists in the bore to get the fuel in, atomised and evenly combusted.

You don't say what mileage the car has done. Does it use oil and do you see any signs of white smoke when starting ? Also have you noticed the coolant level dropping ?

A leak down test will give you a good indication. It is a device that screws into your glowplug sockets. Compressed air is then pumped in and monitored on a gauge. The amount of time it takes for the gauge to lose pressure indicates how healthy the seal on the bore is.

Now you could also establish if your glow relay is working correctly. Take another set of 4 glow plugs. Your old ones will do. Remove that stupid plastic cover from the top of your engine. Disconnect your glow plug leads from your in-situ plugs and plug them into the lose plugs earth the body of each plug against a good earth on the car within reach of the plug cables e.g. the intake plenum. Make sure the connection is solid so you don't get arching. Cable tie them down if need be BUT ensuring the tip of the glow plugs are free to the air. Get someone to turn on the car (NOT start just on) whilst you watch the plugs. They should ALL glow a very nice ORANGE. If any are not doing this double check the EARTH. If one is not glowing change it with one that is. If the the problem still exists on that one plug then the relay is at fault.

If you want to clean your injectors (although I do not believe this will help your problem) you can try one of the off the shelf products (Millers is a very good choice).

Personally I use method handed down to me from my dad (NOTE I am NOT making a recommendation merely stating what I do). 100ml's of Acetone(must be at least 99.9% pure) + 100mls of redex (or kerosene) in my tank every 3rd to 4th fill up.
Click to expand...
That's a good call about checking the glow plug relay. From what I could see from the relay there is only one contact that switches all the plugs on or off at the same time. Loads of other electronics for other stuff.
I was planning on using an amp-meter to connect each glow plug in turn and check the current. What do you think it should draw, the multi meter is 10A max. When I measured the plugs before installing them they showed 1.2 Ohm but reduced to 0.6 Ohm while measuring. I = V/R, so that's either 10A or 20A depending on which was correct. Don't want to blow the multi meter either!!
If all else fails I'm going to connect all 4 plugs direct, maybe using a cooker switch, and heat for 10 Sec, then crank.
If it still has issues starting, then it is something rather than glow plugs.
What is still annoying me is that it starts perfectly once warm - any bit warm at all!
 
Use my method first. A picture speaks a thousand words. You will see straight away if the relay is working.

Of course the engine will start fine once hot because the engine will now have latent heat. As I described a diesel works by super heating air through compression to combust the fuel. The colder the air AND the colder the engine the less efficient this process is. A super cold engine is simply going to extract any effort a poorly functioning glowplug has tried to put into the compressed air via conduction. Heat transfers from hot to cold, that is why the correct name for a radiator is a heat exchanger. The heat from your home radiators gets transferred to the air via conduction. Hot radiator ------> cold air = warmer air.

In your car heat in air warmed by glowplug ------> cold surrounding metal = car that won't start.

Once the engine is warm less or no heat get's lost and hey presto BANG !!!!

I can warrant that come summer you won't have any issues either as the ambient temp of the air will be naturally higher.

The glowplug relay is not one relay (internally) it is a pair. Each controls a pair of glowplugs, the two outers and the two inner's. On the older Multipla's the relay is mounted in the engine bay, right hand side, to the upper side of the body more or less behind the battery. I assume it would be the same in yours but can't guarantee that.
 
I had a good look when I had it off and it is only one relay contact, which is surprising as that single contact has to switch at least 40A. Could be why they give trouble. I cleaned the contact with an emery board and contact cleaner. If it turns out that the relay is an issue, with the cost of them, installing 4 more reliable individual relays could be on the cards.
 
Hmmmm funny mines got two and is a Delphi unit. In my experience cleaning with emery paper has mixed results unless superfine. The minute scratches it creates cause arcing which inhibits efficiency.

I did ask if you had white smoke? That is generally an indication of a glowplug issue as it is unburnt diesel.

Let us know how you get on.
 
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