Black Smoke


Torque Junkie
Rexton 270xdi 2005
Hey guys it's been a while , My question is this . Is there any way an Engine head can cause black smoke ??

The car is a 2005 Ssangyong Rexton 270Xdi diesel , common rail no DPF and the EGR system has been disabled and blocked ..

The issue started after fitting a used engine head , ever since then the car has been smoking alot out the exhaust , I've already repaired and then replaced the injectors , followed by diesel filter , I have also tried running the car without an air filter , even bypass the intercooler ... The car produces visible black smoke even while idling ..
No fumes out the engine oil cap , Knock sensor readings start off perfect but as the engine warms up the knock readings on the rear sensor grow to be 4 times higher than the front sensor which means something isn't right with the rear part of the engine ... I'd like to point out that the engine block and its contents supposedly have less than 5000 miles on them ...

I have tried fuel additives , tried dropping the fuel tank to check for contaminants but to no avail as the additives had no effect and the tank was clean ..

We have suspected bad timing on the engine but the way the car drives just throws that possibility out the window since there was no lack of power or violent shaking ..

Fuel efficiency was also unaffected somehow even with all the smoke which should've indicated extensive fuel burn ...

Also the engine overheated for the first time ever after I pushed it to it's top speed for over a minute .. something it never did before no matter how hard and how hot it was ..

I also suspect that the engine is consuming oil faster than it should but I have no way to guarantee it since I can't drive the car like this without a cop pulling me over and labeling the car illegal to drive

I fear I might have to replace the engine just cuz I can't think of a logical solution to this matter ...

All I can tell you is that something isn't right with this engine head but I've asked multiple mechanics and they all tell me that there's nothing in an engine head that can cause black smoke ..

Can anyone please guide me cuz I have given in to despair ?
It sounds like worn piston rings to me. Get a compression test done on each cylinder which should show up where the problem or issue is.

The soot from burning oil will also cause the o2 sensors to clog up and won't be doing the catalyst any good.
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Catalyst is removed on my car , just silencers ... im not sure it even has O2 sensors since its a EURO 3 spec ..

Based on the knock sensor readings the bad cylinders should be at the rear of the engine .. either 4th or 5th ..

sadly no one seems to have the tools to measure compression on a diesel through the glowplugs .. only places that can do compression tests in my area are the ones that do these major checkups before buying cars or so ... in other words the test alone is going to cost 250$ ... is it worth it or can i just remove the engine head and find enough leads that reveal the mystery ?
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