Td42 cold start misfire and blowing heaps of blue/grey smoke

[Badger]

A good day to everyone. I was hoping for some help with a problem thats driving me crazy with my 02 gu cab chassis td42
( 330000 ks ). When its cold upon start up it blows a ridiculous amount of blue/grey smoke and misfires badly but i only have to drive 100 metres down the road and it pretty much clears itself and runs properly. If i stop and let it idle before it is at normal operating temp. it will still blow a bit of smoke but once properly warm no dramas. I have spent alot of money and time trying to overcome this problem and neither myself, a couple of mechanics and no less than 3 auto sparkies can not find the cause. I am thinking that i cant be the only person that has had this problem so i am hoping someone in this forum can point me in the right direction for a solution. Thanks in advance for any replies of help given . Badger

[Ben-e-boy]

What has actually been done in attemp to rectify this? So we know where thing are at in regards to the fault finding process.

Why 3 auto sparkies? A td42 has 8 or so wires. All they are going to do is check that the glow plugs are working.

[Winnie]

Mine used to do this, the longer the car sat the worse it got.
Turned out to be tiny air leaks in the fuel system. I have just about got it 100% sorted out now, lots of old hoses and hose clamps and they have now all been replaced.

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[Badger]

Hi thanks for the replies, i will try to recall everything i have done to rectify the problem. First i thought it must have been glow plugs so i bought a new set and put those in but it didnt do anything then i took it to an auto electrician who tested the glow circuit and he told me that he hadnt done a great deal of work on diesels but as far as he could see it was all working as it should be. I wasnt overly confident that he was on top of it so the next thing i did was to borrow a glow timer unit off a mate and swapped it over with mine and still no different when i started it the next morning. Someone else suggested it may not be electrical that it could possibly be that the fuel pump was the problem and that it could need rebuilding, i thought this could be the case but before going to the expense of rebuilding pump i borrowed one from another guy i know who has a couple he wasnt using and i swapped that out with mine ( bugger of a job) and again it was exactly the same when i started it with the borrowed pump in it, frustrating to say the least. Then i read somewhere but i cant for the life of me remember where exactly that if i undid the wiring connector that is on the dropping resistor which screws into the inlet manifold and put a bit of wire into the female part of the plug and loop the circuit that it would fix the problem so i did that and bugger me it worked! With the circuit looped when i started it cold it would give the slightest hiccup for a fraction of a second and then run absolutely perfect . Awesome i thought so i left it like that for maybe 2 or 3 months and had no more problems at all with the cold starts. Now i was really confused because the dropping resistor had been completely bypassed yet it was starting and running great. A few months later i was servicing the ute when another mechanic neighbor come by to say hello, he spotted the way i had the circuit looped and he suggested i tape up the bare wiring that was showing as a precaution so it wouldnt touch and short out. So i did that and when i finished the service i started it up and was alarmed to see smoke pouring out from under the bonnet, for some reason the wiring block and the wires from the female part of the dropping resistor connector had melted which i have no clue about why it did. So off to another sparkie who repaired the wiring and tested the glow circuit and tested the glow plugs individually and again he couldnt tell me what was causing the cold start issues. I have also put a new dropping resistor on it for no improvement either. What am i missing here?

[Cuppa]

I think Winnie has probably nailed it. Air leaks in the fuel system results in air bubbles in the fuel one, which results in misfiring, which results in unburned fuel causing large amounts of blue white smoke. May also require longer turning over of the motor before it starts. You could confirm this by extending the fuel line with clear hose so I you can observe for bubbles whilst the motor is running.

[Badger]

Thanks Winnie, Cuppa i will do that tomorrow afternoon and get back to u. Yes it definitely takes longer cranking it over before it starts. Where do i extend the fuel line from, should i do it between the fuel filter and the pump with the clear hose. Thanks again much appreciated i hope its the answer i am looking for but it still wont explain why it didnt do it when glow circuit was looped. Also something i left out in earlier post i renewed all rubber fuel lines from the pump
back, and another thing when i put a jumper cable from the positive battery terminal to the number one glow plug it starts fine but begins acting up when i remove the jumper cable. I just thought to mention that as i forgot about it earlier .

[Cuppa]

If you have renewed the rubber fuel lines on the motor side of the pump, then yes try clear fuel line between filter & pump. There may be very little in the way of bubbles & you may have limited time to see them before the engine is warmed up & running ok. However before doing this it is worth doing a couple of things which may be easier (?) first. Ensure fuel filter is nice & tight....... actually I suggest changing the fuel filter. There were some faulty ones going around a while back, I had two friends with TD42 engined buses both had the hard starting problem, which was resolved by changing the filter! They had seen no leakage. Second nip up any of the hose clamps on the fuel lines from tank to motor. Then ensure all fuel lines, pump & filter housing are clean & dry & then lightly sprinkle them with talcum powder. Run the motor for a while & look carefully for a damp spot. This may or may not reveal a tiny fuel leak otherwise unnoticeable, but if it does you are in luck. Sometimes though air can be sucked in without fuel leaking out.

I went through all of this on my bus, even found & removed a one way valve a previous owner had fitted presumably to deal with a fuel leaking back to tank issue. Turned out the one way valve was restricting fuel flow at higher revs, & taking it out gave me another 10kph - but that's another story.

When I fitted the clear hose the bubbles were quite large & very obvious & coincided with a temporary loss of power & huge clouds of white smoke from the exhaust. A mobile smoke screen! And would then pick up again until the next bubble. However in my case the cause turned out to be a sticking valve allowing the a piston to push air back into the fuel line! From what you have described I don't for a minute think that that is your problem, but your description does sound consistent with what is probably a small air leak. I could be wrong, but at least if I am, if you've checked it out methodically it will be one less variable in the mystery mix.

Of course you instead of all this mucking around you could just replace the full fuel line & filter (& check mounting surface on filter housing) but I'm not sure if it is possible for the fuel pump itself to suck air in without obvious fuel leaks, & I'm not sure how easy it is to replace the fuel all the way back to the tank.

This is my 'non-expert thinking' ...... if anyone thinks I'm leading Badger down an unnecessary path - speak up.

Hope you get it sorted mate - be sure to report back.

[MB]

Awesome advice all round, quite simple beasts, nuffy confused myself quickly reading of your glow plug elecy stuff mentioned but try feeling the pressure on your OEM primer pump. Should stay rock solid for many months if your system aint weeping at rest like Cuppa kindly mentions.


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[Badger]

Thanks for the reply MB. I have been given so much poor advice from too many "experts" and havent found a solution, thats the main reason i put the post up on this forum asking for help. I appreciate the replies and advice / suggestions.

[Badger]

I am not getting far in the way of solving this problem despite the knowledgeable and detailed troubleshooting advice from those who replied, which by the way is greatly appreciated. I put a piece of clear hose between the filter and pump and there was no evidence of air bubbles as it sat idling, but curiously if i pressed on the primer on top of filter housing, (it was quite hard to press but it did slowly go down) then some bubbles would appear and it would take a few revs before they would clear themselves out of the line. So i bypassed the filter completely by putting a joiner between the inlet and outlet hoses on the filter. But next morning it was exactly the same no improvement at all. So i reconnected the filter and the next morning i tried something i mentioned in my first post on the subject and that was to disconnect the dropping resistor connection plug and i looped the 2 terminals in the female part of the dropping resistor plug connector with a split pin and again it started and idled beautifully. Can anybody explain to me why it does this when what i would have thought is an essential part of the glow circuit is completely disconnected. Thanks

[Cuppa]

Sorry can't help with the resistor other than to suggest replacing it with a known good one, but I expect you have already thought of that.
What is the purpose of the dropping resistor in this situation? Is it to do with the glow plug timer or???? Do you have info re the expected in & out voltages so you can check them?

EDIT: This thread on another forum may help? https://www.patrol4x4.com/threads/large-glow-plug-thing-in-td42-intake-manifold.199506/

Also from Patrolapart (Who have new ones for sale at $192)

Genuine Nissan Glow Resistor

Suit GU & GQ Patrol's Fitted with this Resistor from Factory.

This Resistor is fitted into the intake manifold of Some TD42 Models
Some cars don't have one at all, some have it but it doesnt plug into anything, and some have it and Use it.
The purpose of the Unit, is to allow the engine to continue to cycle the Glow plugs in very cold conditions.

These are Mainly used in Overseas model Cars, However if the car is fitted with it, and it is not working properly
Then it can up-set the glow system and cause it not to work Properly.

Seems that bypassing it is a reasonable strategy in our warmer climate.

[the evil twin]

Wot Cuppa said and quoted ^^^^

In the hotter climates like Aus (using standard glow plugs) you should be able to turf that resistor and eliminate any problems it is causing without any adverse effects.

[BillsGU]

Did you check your glow plug voltage when it is cranking? You may have crappy contacts on your glow plug relay which is causing a voltage drop under load.

[Badger]

Sorry for late reply Billsgu, auto electricians checked and tested everything that could be checked and tested electrically regarding the glow circuit including relays, timer and glow plugs individually, as well as when engine is turned off with the ignition on, when cranking and when engine is running. We even went as far as getting a mates ute that has the same glow circuit setup ie with the dropping resistor in the inlet manifold and it tested almost identically on all the above mentioned tests, differing by .1 of a volt in one instance. Again i have absolutely no answer as to how or why undoing the dropping resistor connector plug and looping the two terminals on the female part of that connecting plug fixes the symptoms of very rough idle and clouds of white/grey smoke on cold start ups but it 100% definitely does and not knowing how or why it does frustrates the hell out of me, but i have used a small length of heavy gauge wire put a terminal on each end and looped the connector plug as i described and it starts beautifully. A complete mystery to me! I spoke with a farmer from the area around where i live who told me that he had a 2003 gu td42t ute that had the same issue not long after being bought new ( it wasnt even 2 years old ) and despite 4 or 5 trips to the nissan dealership from where it was purchased as well as being taken to other mechanics, auto electricians and diesel fuel injection specialists, he could not get the issue resolved and in the end out of frustration sold it for less than it was actually worth at the time because in his words, "it annoyed the s..t out of me and i couldnt put up with it every morning". There has to be an explanation as to what causes this and how it can be fixed without resorting to looping electrical circuits that for some reason solves the cold start issues mentioned above. Any suggestions or known fixes for this would be hugely appreciated if passed on.

[Mickhead]

Hi Badger. If your playing with the glow plug circuit and getting positive results what do you think the problem might be?
Get hold of a DC current clamp, put it on the main wire feeding the glow plugs. If your mate is turning the ignition engine cold and you are seeing less than 20 amps on the meter keep looking at glow plug shyt.