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4HE1 problem

bibabo

Active Member
Joined
Feb 19, 2025
Messages
44
Location
France
Thank you very much for your help! When I tested the pump pressure, I used the engine oil compression gauge that I had. Its needle is not stabilized by liquid, which made it hard to read. With the engine running, diesel was still coming out of the orifice a lot without the screw, and there was almost no visible difference in flow when using only the starter.
 

bibabo

Active Member
Joined
Feb 19, 2025
Messages
44
Location
France
Hello, no, I don’t know what to do anymore, but I’m going to test my injection pump differently.

When I took the injectors to the diesel specialist, before doing so, I had removed, cleaned, and tested them outside the engine using the starter. This sprayed diesel everywhere, making it difficult to visually assess the test. However, from what I remember, the output on cylinder 2 didn’t seem to work consistently.

I swapped it with other injectors, and the issue remained the same. I had the impression that there was an anomaly, but I couldn’t confirm it. Since you seem to suspect a pump problem, I will redo this test. It’s less cold now, and there’s more light, so maybe I’ll be able to confirm whether there’s indeed an issue with pressure or its distribution to the injectors.

I’ll keep you updated.
 

bibabo

Active Member
Joined
Feb 19, 2025
Messages
44
Location
France

Hello,

Attached is a video showing the fuel injection pump outputs to the injectors. I don’t have a comparison, but it seems to me that the pressure is sufficient, especially since this is only with the starter. After a while, the fuel doesn't shoot as high because the batteries are running down. What do you think?

A more important clue: I am still connected to a diesel canister, and when the engine is running, I consume 5 liters in 1 minute!
So for me, it's not a compression, combustion, or timing issue—it's because too much diesel is getting into the combustion chamber! Right?


Could it be that my pump is delivering too much diesel? Or are my injectors leaking and staying open? (They were checked, but maybe the technician made a mistake in the tests?)

In your opinion, is this a pump issue or a problem with all four injectors?

Thanks!
 
Last edited:

bibabo

Active Member
Joined
Feb 19, 2025
Messages
44
Location
France
I can't see the video Youtube says its private. Is the return line from the pump also connected to the canister?
It's fixed. Oh no, that's why, I hadn't thought of it... false joy... Attached is a video with the injectors, I tested them all on all the outings, everything looks good. back to square one...
 

bibabo

Active Member
Joined
Feb 19, 2025
Messages
44
Location
France
Are you certain the air intake is not obstructed?
Yes, I am sure, even after completely removing the intake, so with all four ports open and the valves visible, it's the same. My breakdown is supernatural! Incomprehensible!
 

bibabo

Active Member
Joined
Feb 19, 2025
Messages
44
Location
France
I had already tried when the engine was bare. There was no change. But it was very cold, -5 to 5°C, which may have skewed the result.

If I have to try again now, it's so difficult to access that I have to disassemble a lot of things, so I might as well take out the engine. But I don’t have the courage or the space.

And I don’t understand how there could be an ignition timing issue when everything was reassembled as it was originally. How could it have gone out of adjustment?

The only thing that might explain my combustion problem is my "KLAC" noise. But where did that noise come from?

  • A gear tooth that shifted? That’s impossible, right?
  • And if something was out of alignment, wouldn’t I be unable to correctly set my timing marks? No?
  • And wouldn’t the engine struggle to start instantly? No?
Did I break or bend the camshaft, lifters, or rocker assembly when tightening the bolts with the wrong timing? Since I transferred them to my new cylinder head and still have the issue, could one of them be the culprit?

Yet, the engine starts fine, and when I check my valve clearance, everything seems consistent. Could that still be the cause?

With all my tests, everything suggests a timing issue—first with the injection pump, then the crankshaft, or camshaft.

Besides the timing marks, is there a position sensor on any of them? I can’t find anything!

What else could I do (without removing the engine) to confirm this timing issue?

Thanks!
 

mekanik

Senior Member
Joined
Aug 20, 2015
Messages
1,250
Location
Canada's Northwest
If you damaged anything installing the camshaft you would know.
I can't imaging there could be a problem with the gear train.
There is no position sensor.

Are the timing marks are all lined up? All three of them?
Can you verify the timing marks again? Take the valve cover and off take the timing plug out of the pump roll the engine over until the timing mark on the pump is lined up with the pointer then another 6 or 8 degrees to TDC on the crank shaft damper. Is the timing mark on the cam gear lined up with the top surface of the cylinder head on the right side?
 

bibabo

Active Member
Joined
Feb 19, 2025
Messages
44
Location
France
Thanks again for helping me.
If I set my crankshaft to TDC, my camshaft is perfectly aligned with the "B" mark horizontally on the cylinder head. As for the injection pump, I can see the marks, but nothing is aligned, which is normal. If I set my crankshaft to 13° or 8° BTDC (as per the workshop manual), the marks do not align with those on the injection pump. To align them, I need to set the crankshaft to 11° or 6° BTDC (is this normal for the European model, or could this be causing the timing issue?). If I complete a full rotation of the crankshaft to return to TDC, I no longer see the injection pump marks (they are on the opposite side), and if I try to move the camshaft, it is impossible to correctly align the "B" mark.
 

mekanik

Senior Member
Joined
Aug 20, 2015
Messages
1,250
Location
Canada's Northwest
It sounds like its timed correctly. There is not much left that could be causing the problem you are having. The only thing left that I can see is a problem with the fuel pump not advancing the timing.
 

bibabo

Active Member
Joined
Feb 19, 2025
Messages
44
Location
France
It's probably that. But I don't understand how it could have shifted. It's impossible, it's a mystery! I'm trying to find another engine, but mine isn't available, only newer ones. Or it's in Asia, but with shipping and customs fees, it costs as much as the truck... I'm looking for a mechanic who could repair it, but I can't find anyone willing to try. If I get any updates, I'll let you know. Thanks again.
 

bibabo

Active Member
Joined
Feb 19, 2025
Messages
44
Location
France
double engrenage.jpgplan.jpg

Hello, I'm coming back without any news but with some questions:
Is it possible that the small gear has shifted in relation to the large one?
Is it a single molded piece, or are they each press-fitted together?
Because after my 10,000th check, it seems like my camshaft alignment might not be perfect.
Since there are several gears, each with some play, I’m realizing that there’s a certain tolerance that sometimes makes the alignment look perfect, and other times slightly off—especially depending on the viewing angle.
So I get the impression that it might be offset in the same way as my injection pump (2 degrees in the same direction).
And if that’s correct, the only explanation would be a shift in the double gear.
And that misalignment—I'm the one who caused it during the incorrect installation of the camshaft and that “klac” sound.


What do you think?
 
Last edited:

bibabo

Active Member
Joined
Feb 19, 2025
Messages
44
Location
France
So it's possible. Either the key broke, or there isn't one. If that's it, it's really weird because I didn't force it, for me it was the resistance of the compression. I'm going to try to lock the camshaft and make myself a tool to turn the crankshaft, because turning it the other way unscrews the pulley bolts.
 

Roffe Jingle

New Member
Joined
Apr 12, 2025
Messages
3
Location
Illinois
Bonjour. Je suis en Chicago avec La meme probleme . Et c’est tout Le Francais je sais!

Anyway, I have a 2003 Isuzu NPR HD 4HE1with exact issues: billowing white smoke. I changed the Intake Air Sensor after testing the resistance and getting OL or Open Loop. Changed it and It did not smoke and thought that was the fix, then took it for a drive and it smoked very badly. Will be performing same tests as you, compression, timing, etc. I did drain the oil today and noticed water in bottom of drain pan after I emptied the oil into containers. Mine could be an injector issue, but I thought too much fuel would be black, not white. White usually means coolant. Are you getting a lot of blow-by?
 

bibabo

Active Member
Joined
Feb 19, 2025
Messages
44
Location
France
Hello, I tried to reproduce my initial error ("klac") by aligning my camshaft with the wrong mark. First off, I was really unlucky because it causes valve 2 to drop just enough to smash into cylinder 1 without me realizing it, since the rocker arms screw down fully without any resistance. If it had been one tooth off in either direction, the tightening wouldn’t have gone all the way and I would’ve noticed the issue. Really unlucky.

Plus, when the valve crashes into the piston, the piston just moves down — it doesn't get stuck! To lock it up, I have to move the crankshaft by a tenth of a millimeter and gently tighten the rocker arms so everything finally jams. I had to try like 10 times. REALLY UNLUCKY!

Once it was locked up (just like the first time), I tried turning the crankshaft the other way but, as expected, it just unscrews the pulley bolts and doesn’t reproduce the “klac.” The force applied was already greater than what I used when the “klac” happened.

I kept at it and made a tool to get a bit more leverage. Same result — nothing moves, no “klac.”

So, I haven’t been able to confirm this double gear misalignment issue. I could try turning the crankshaft in the same direction as during the first “klac,” but if it works, I’m afraid I won’t be able to move the truck back home. Still, I’m pretty sure that’s the issue — it all makes sense, even if I’d have better odds winning the lottery than this actually happening!

I might have found someone to help me take out the engine and fix it. I’ll keep you posted.
 

bibabo

Active Member
Joined
Feb 19, 2025
Messages
44
Location
France
Bonjour. Je suis en Chicago avec La meme probleme . Et c’est tout Le Francais je sais!

Anyway, I have a 2003 Isuzu NPR HD 4HE1with exact issues: billowing white smoke. I changed the Intake Air Sensor after testing the resistance and getting OL or Open Loop. Changed it and It did not smoke and thought that was the fix, then took it for a drive and it smoked very badly. Will be performing same tests as you, compression, timing, etc. I did drain the oil today and noticed water in bottom of drain pan after I emptied the oil into containers. Mine could be an injector issue, but I thought too much fuel would be black, not white. White usually means coolant. Are you getting a lot of blow-by?

Hello, it’s possible that you have a worn head gasket, and that a bit of coolant is leaking into the oil passages (coolant in your oil) and also into the combustion chamber (white smoke). But yes, I can confirm — white smoke can also be diesel.
 
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