GU 1998 TD42T rough idle and smoke

Hi to All,
I am 65 years, electrical/electronics profession. Always had my nose under my bonnets.
I have been a patrolman for 25 yrs. At present I drive a TD42T done 240000km so far. I have owned it for some 3 months.
Getting it ready for a trip towing a 24' van.
Hope someone out there in 4x4 land can assist with an issue I have with my TD42T.
Here is the problem. After having the engine off for 24hrs, starting the engine when cold, for the initial 10 odd seconds, the engine runs rough as if running on 4 cylinders and at the same time emits white smoke from the exhaust.
I have changed the 2 oil filters and air filter initially. Recently though, I also changed the fuel filter.
When I removed the fuel filter, I found it only half full of diesel fuel. I can only assume it may flow back into the fuel tank.
When I replaced the fuel filter, I pre-filled it with diesel before I fitted it and then pumped the hand-pump on the filter-top.
When I started the engine cold after the fuel filter replacement, I thought I had fixed my problem, but alas, not so as on the next start 24 odd hours later, rough idle and the white smoke was back but I think it was not as severe as before.
After leaving the car for 48 hrs and trying another start, I hand-pumped the fuel filter pump before I started the engine and the engine ran rough only for a matter of say 3 seconds before it settled to a even idle.
Well, what more can I say. Oh, had suggested to me to check the glow plugs and found the G-plugs to draw total of 46.2Amps. Further glow plug tests revealed all plugs draw the same amount of current, hence glow plugs in my view are ok.
Have not removed the main fuel tank. Patrol seems to run well once warmed up.
My question, can fuel drain back to the main tank from the filter ?
I don't believe the fuel can drain the other way, i.e. from filter through the injector pump.
Can see no obvious fuel leaks from front to rear.
Your input would be most appreciated. Thank you in advance.

The WOLF 12/7/2015

Thank you to NISSANPATROL.com for the opportunity to post.

There is a mod the TD blokes do to bypass a sensor.. maybe the cold start sensor? They unplug it and bridge the terminals and sorts it out.

Welcome to the forum mate.

welcome mate

Thank you re the welcome messages DYSONEST and DHUCK. Feel at home already.

Hi Softy, appreciate your response. Will give the COLD START SENSOR a go if I can find it. Do you know what type of sensor it is and where I can find it ?
I have a "Howsyagoin" manual on a disc, so will try to find the sensor there.
As I'm new to this site, took me a while to pickup my thread. But I did find it as you can tell.
Thanks to all who responded to my post.

Sounds like fuel is leaking back...

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loosing fuel :
they are prone (the lift pump) to leaking back to the tank
I'm not sure if they are a repairable item or a replacement item, as I have not as yet had a problem......

with your glow plugs
did you take them out and clean them - or just test them in-situ............?

with the 4cyl running & white smoke
almost all TD42's have a problem with their oil getting to the top on initial startup - thats the rattles
if it is loosing fuel pressure (you have to prime the lift pump) not all the cyls will be getting fuel at the right pressure on startup -
depends on how many Kms on the clock as well - maybe Injectors are nearing their end.......??
the white smoke is only condensation - hence why only on cold start up
black smoke (usually under power) is un burnt diesel
grey smoke under power could be either oil is too thin (oil change needed) or Valve stem seals
grey smoke constantly - rings are shot

hopefully some of this may help you

cheers

BTW - welcome to the forum

Thank you Mudski and Bigcol for making the effort to reply.
Bigcol, I take it you mean the fuel pump in the injector pump assy when you talk of lift pump. I thought the fuel draing back to the tank would only go from the filter back to the tank. You are suggesting it may leak back via the injector pump, is that right?
My Patrol has done some 245000km, so I think the injectors are a possible cause of the smoke problem. Did some more checking today and found that with the Patrol stationary, and reving the engine by hand at the injector pump assy to around 1200rpm, I can detect an occasional miss, reving to 2000 and above the engine runs fine. Suspect injectors again, would you agree? Checked the glow plugs only electrically. Have not removed them, in fact did not know they could be cleaned. I'm not too savvy with the Diesels yet, always keen to learn.
Thanks so much to all of you who have replied. 14/7/2015

Quote:

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Originally Posted by Roland the Wolf

Thank you Mudski and Bigcol for making the effort to reply.
Bigcol, I take it you mean the fuel pump in the injector pump assy when you talk of lift pump. I thought the fuel draing back to the tank would only go from the filter back to the tank. You are suggesting it may leak back via the injector pump, is that right?
the lift pump - is that thing on top of the filter that you had to "pump" to get fuel pressure up, old landcruisers had their lift pump on the side of the injector pumps, but not Nissans
so yes, it is draining back from the filter (lift pump) back to the tank......... NOT from the Injector pump

My Patrol has done some 245000km, so I think the injectors are a possible cause of the smoke problem.
the smoke - is it only when you first start up...... or after you have been driving, you can see it?????
the injectors face is like a flat surface, with a pin sticking out the middle - when the fuel goes through it - it sprays in a fine mist
when the injectors are old or have been baddly treated (eco fuel blends) that flat surface ends up having a "hollow" around the pin - the fuel then dribbles out, instead of misting
hopfully you understand what I am saying
Attachment 59805
Did some more checking today and found that with the Patrol stationary, and reving the engine by hand at the injector pump assy to around 1200rpm, I can detect an occasional miss,
fuel starvation - not enough fuel pressure from the pump to the injector pump - thats why when you rev higher, it is ok.......
reving to 2000 and above the engine runs fine. Suspect injectors again, would you agree?
Checked the glow plugs only electrically. Have not removed them, in fact did not know they could be cleaned.not sure on which type of Glow Plug you have in there (there is 2 or 3 types for the TD42 from memory)but I think you can take them out, and using 2000 or finer wet and dry, give them a very light clean, as they get covered with soot, this may help them. - I have only done this on Landcruisers (2H engine) so not even sure it can be done on Patrols
I'm not too savvy with the Diesels yet, always keen to learn.
Thanks so much to all of you who have replied. 14/7/2015

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hopefully you understand my ramblings

On top of the fuel filter mate is the lift pump. If this is shot, fuel could leak back toward the tank. As you have previously said, you had primed the filter and it started fine. This tells me the issue is there. Or there somewhere.

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