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Marty, European Car Expert
Category: UK Car
Satisfied Customers: 404
Experience:  ASE & Bosch Certified Master Tech. Over 30 years experience.
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Greg, worked on many Nissan nivara d25 engines?
, urm,

Customer Question

Customer: Hi greg, worked on many Nissan nivara d25 engines?
JA: Thanks. Can you give me any more details about your issue?
Customer: urm, over heating engine, and slightly white smokey exhaust gas when under load, and im trying to rule out the obvious I would like to confirm that the timing chains are not stretched by matching crank markings with cams, looking for info on interent
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Submitted: 1 year ago.
Category: UK Car
Customer: replied 1 year ago.
When the yd25 is put under load, eg hills the vehicle soon over heats, but normal driving will go many miles without an issue. tonight I have started stripping it down to try and diagnose the issue. the reason I am going to such lengths of diagnosis is that the customer says that when some one is following the vehicle and it is under load that their is a thick white smoke from the exhaust.What I have done,
pressure test on coolent system when running climbs to 17psi then sits steady
block test fluid for combustion gas which reads zero (tested fluid at exhaust ends to confirm fluid turns yellow)
removed water pump, doesn't appear any issues,
no water in oil, no oil in water.
I was hoping to check timing to confirm that the crank / fuel pump / cams are inline as I know that the Toyota pick ups have issues with the keyway wearing on the crank and when this happens they produce a lot of white the process of doing, and might have by the time you come back with an answer,
check that water runs through the radiator quickly (eg not internally blocked)
check that the thermostat is opening at about 80dec C,
check that all pipes are clear of blockages.some points that put a spanner in the works,
fan belt isn't loose but also isn't as tight as I would like??? I personally would have thought you would hear it slipping when the viscous fan kicks in
radiator isn't as clear as I would like to see it. farm vehicle filled with dust and debri???I am very aware that this does point towards either a head gasket fail / crack in head. that the combustion gasses only driven though at high loads.the questions I would like answered. do the coolant systems generally run at a higher pressure to most other diesel vehicles. 17psi rather then 12psi?is their any visual timing marks on the yd25 like on most vehicles with a mark on the flywheel / crank pulley, and either on the cam shafts or cam sprockets.also have you ever known a crack in the head / head gasket to only allow combustion gasses to fail under high load, eg very difficult to test when in workshop.their are a lot of little improvements I could make that might solve the over heating problem, but In my mind I would like to resolve the white smoke they describe.kind regards
Robert Jeffery
Agricultural Mobile mechanic
Expert:  Greg replied 1 year ago.

Block tester turned yellow is Co2 so you have a bad head gasket or a crack in the head .

But what is typical with this engine is many have this problem and when you get to a certain temp and put it under load it will start to burn coolant and push out a heavy white cloud of smoke .

I will get back to you with the other question tomorrow when i get back into work .

But as said very typical issue you have ,and believe in what you feel , as you said you are aware that this could be a headgasket .

and you will find it is , or you have a cracked head ??

Robert will get back to you in 12 hrs as its late at night here time 19:16

Rgds Greg

Customer: replied 1 year ago.
Sorry Greg, cant have made that clear, the combust leak fluid test shows a pass, the fluid stays blue. this is only at a high idle and testing for 10 mins. I will purchase some new fluid as this set is over 12 months old.
Expert:  Greg replied 1 year ago.

Okay with this type of problem you need to do the test when the engine starts to smoke .

See if you can get to smell the exhaust smoke when turns white should be sweet if you have coolant in the system and not just water .