does it blow smoke? what colour
check/adjust valve clearances

 

Some help maybe!

no idea sounds like fuel if the noise changes or comes on when hot

 

when it does it under load is it constant, like driving up a hill.
or only when u put you foot down?

 

the mechanic may have use the wrong thickness head gasket.

 

It does blow smoke Adoom. Black smoke and plenty of it, even under moderate throttle. The mechanic checked valve clearances at 1000klm, but no change??????

 

It is constant gqnissan. And yes up hills it is more noticable, or towing, but just putting your foot down gets it knocking too. It has to be hot, not over the top hot just full running temp. But the hotter you get it the louder the knock.

As for head gasket, it was the thickest. They said there was no option in that depatment at the time, as it was the only one available for my motor, 94 model.

 

I would start by going to a diesel shop and get a exchange set of injectors or get them to clean and reset
if you get them to do it get them to tune your fuel pump while your there

 

Black smoke is excessive fuel, Heavy Knock is less than normal fuel. Doesn't sound like a fuel issue at all. If the smoke is white, then its a fuel issue. I'm no expert but just my 2 cents.

 

im no expert either sherwan, but when my head gasket went it was white smoke. my understanding is... white smoke = water, blue smoke = oil, black smoke = unburnt diesel. going by this theory could be glow plugs, injectors, or injector pump?? id bet my left nut that white smoke is water though (only my left because i already lost it in a previous bet )

 

you are right in your smoke theroy

and i bet my left nut its the injectors because he did say black smoke
and the knock is called "diesel knock" is because the injectors are injecting before the pressure is high enough to atomize the fuel causing to long of "uncontrolled burn" (diesel knock) and over fueling (black smoke)
sorry if i lost you in there some where... LOL I think it make sense (to me anyway)

 

white smoke can b a number of things i think, like ip timing for one glow plugs, injectors oil in exhaust housing. it wont b glow plugs. and i dont think that it would b injectors. could b a big end. does it miss at all hot or cold. I thought wrong thinkness headgasket because, if the gasket was to thin pistons might b hitting the head. what oil do u use 15-40 20-60 does the knock come from the top of the motor(head) or does it sound like bottom end of motor. oil cold would hide a bigend knock to a degree. black smoke can b ip timing, blocked air cleaner, could b injectors, low compression, incorrect valve adjustment( maybe) banjo bolt on fuel inlet side of ip. blocked fuel filter.

 

white smoke in a diesel doesn't mean water.

Usually improper combustion for one reason or another.

 

white smoke in a diesel doesn't mean water.

Usually improper combustion for one reason or another.

 

i say post a vid with the noise if possible , then we may be able to help a bit better

 

its because of the way the injectors work they are "hydrolic" injectors
the injector pump pumps fuel to then and when that fuel reaches a certain pressure in the fuel line they "crack" (a valve in the injector opens) and inject to the cylinder and stop injecting when fuell pressure drops below a certain pressure. this prevents fuel leaking out of the injector and line into the cylinder when its not on the intake stroke. after time the injectors were and start cracking at a lower pressure.

 

So you drove it for a year with knock??!!i'm no expert but i doubt bad bearings or pistons slapping head would have survived for a year But it's obviously something that your mechanic did wrong,any mechanic that tells you to drive away with bottom end noise should be thumped fairly hard IMO

 

Well thanks for the replies guys. Where do I start!!!

The knock does sound like top end, thats not to hard to misdiagnose. The smoke is black.

I mentioned to mechanic the other day that the knock is ****ting me and that I was thinking of pulling the big end down my self, he made comment that "but what happens if you do all that and it still knocks". Well you could have knocked me over with a feather. Obviously not to confindant with their sub contractors machine work.

The thing that I just realised today, was that when I did cook her, I didnt hear any knocks, and I was on the highway, over taking and giving her a workout, with the temp gauge through the roof. I would have thought that it would have knocked then.

As mentioned earlier, he did stuff up on the first re-assembly, and installed two washers under number 3 injector, which made it knock and miss horribly. Im hoping its the injectors. This was suggested by my mechanic at the time.

But the way its looking I'm going to spend 10K and never know what it was. Or put my near new head on at the end of all this and find out that some spanner screwed up the machining and just cost me a mint.

The donks got 330 000 Klm on it and i've owned it since 170 000 Klm. I have'nt done injectors or pump in the time I've owned it, and doubt it was done before my time with it. I guess this is as good a place to start, but does it make sense that this happened after cooking it?

Keep the comments coming guys, because the experts I've seen about it don't have a clue.

 

The head gasket should'nt be a drama, as I wanted the thickest available due to the Klm's on the clock.

I uae RX super 15-40, and tried moreys oil stabliser to thicken it up a little, but no change.

The mechainc did install the number 3 injector with one to many washers originally so thats a possibilty also. But I did take it back to them for a day, so one would assume they would have checked that.

 

Just another thought. If I get the motor hot, put the foot down and get it knocking, wouldnt a big end knock after I take my foot off? Because how it is now, if I take my foot of the petal at around a1500-1800RPM it stops knocking. Put the foot down again, knocks again. Any thoughts anyone?

 

The noise does go away as soon as I lift my foot. Maybe it is the injectors. I would have thought that big end noise would still be there when coasting at 2000RPM. But as soon as I put the foot back down again, it knocks.

 

Could be a cracked piston , could also be a failed little end bush .

I had to fix one in a Diesel Pajero a couple of months ago . The little end bush was broken in two , the engine would be quiet for a few minutes and then would rattle like mad . The loose pieces would sit in their correct location for a while and then would over lap each other and raise the piston by that amount . The piston would then slap the head and make a racket .

A cracked piston can cause your rattle as well because the crack opens and closes with temperature changes . As soon as you apply the throttle , the piston temp shoots up immediately .

What other work was done to the engine after you cooked it , not just a replaced head I hope ?

 

R & r ur injectors with new washers n c what that does. or try some reco injectors.

 

big end will make a noise at idle to

 

It defiantly doesnt knock at idle, or decel.

 

just had a thought a mate put a set of high flow injectors in his hilux. it knocked and smoke u couldnt c the back of his ute it was that bad. the tip of the injector was the problem. he put his old injectors back in problem fixed. maybe the mechanic droped one. or as u say maybe there is a washer on another injector that u dont know about.

 

Mine knocks when i apply even a mili of the accelerator and goes away when i lift my foot up.. gives white smoke at idle, nothing at constant revs, a little black smoke when accelerating.

I had a rebuild on my TD42 a year ago, and i ran around in circles trying to get rid of the white at idle, nothing worked. The weird thing is, it doesn't burn oil or water.. Goes like stink..

I guess Nissan motors are unpredictable..:toothmis:

Have you tried bringing the fuel down a bit? Black smoke is always a fuel issue.
The knock...well its a TD42... if it doesn't knock at idle, then there is nothing wrong with it.

 

I know they are noisey things, but only started after I done the head.