CRD 2.8 - Turbo vacuum vane system check

bigluck · **Joined:** Sat Oct 06, 2018 8:54 am **Posts:** 3

Hello. I took the challenge to fix the 2006 CRD 2.8 Diesel of my son (student, no money to get it fixed by experts) and the symptom is very rough idle, black smoke and no power. I am down now at investigating the turbo trying to understand the vacuum operated vane actuation system and found no real help so far on the internet. Mechanically, the actuator works smoothly with the arm up with vacuum directly applied to the actuator which slowly drops down smoothly when the vacuum is removed. I am now at the solenoid and reservoir but have no clue on how all this works together. And just to simply check proper functionality, when I start the engine at idle, should the vacuum be full on which means that the actuation arm is full up and when i increase RPM is increased, the vacuum should drop hence the actuation arm should also drop down. So does any of you have an understanding of how the solenoid & reservoir works and how can I test these components either electrically or with an engine running test. Any help would be greatly appreciated!

flash7210 · **Posted:** Sat Oct 13, 2018 11:15 pm

Your turbo actuator seems to be functioning properly.
The small vacuum solenoid is just a on-off switch.
The big vacuum solenoid modulates the vacuum to control boost.
Most black smoke, low boost problems are due to leaking intercooler hoses or a dirty MAP sensor.

Actuator position is determined by throttle position and MAP signal, not RPM. Turbo boost is entirely controlled by the ECU.
High vacuum = high boost.
At idle, the vanes are set to full boost but there isn’t enough exhaust flow to create more than 1 psi.
It’s hard to know exactly how well the turbo is performing without a boost gauge.
If you can’t install a boost gauge, use a OBD scan tool to read the MAP sensor.
I use the torquepro app for Android and a elm327 OBD Bluetooth adapter.

bigluck · **Joined:** Sat Oct 06, 2018 8:54 am **Posts:** 3

I need to say that since the beginning, there was a C0301 for cylinder 1 misfire hence so I removed the injector, had it flow checked, reinstall and no change. Then it seemed to me to be pointing to valve rocker failure but was still investigating for other probable issues. I read on some post that if the exit air from the turbo which goes through the intercooler to the inlet is like "pulsating", this is an indication of valve rocker issue. Well after some tests today and reading codes, which now I have C0121 (valve relay malfunction?) and trying to roll the truck a couple of minutes, I let it idle, erased the codes and crancked to 2000 RPM, read the codes and etc. and then a mechanical noise was heard and the engine died and could not be restarted again. I think that probably some bent rockets (which since day 1 was the issue letting not enough air into the #1 cylinder) just broke off which terminated more than 28 hours spend investigating the problem.

Hope this post could be helpful to some, I must say that when I first started to investigate the issue, there was 3.5 litres of excess oil in the engine and when I drained the oil, it was black like I have never seen any oil most probably badly contaminated with soot (I could not just wipe off to clean my skin, it was like black dye) which most probably did not help to lubricate adequately these valve rockets which may somewhat be related to their failure. But I must say that the engine has 253 kkm (158 kmiles) and maybe this is not too bad for these engines based on what I read so far.

Best of luck with your CRD's

geordi · **Posted:** Sun Oct 14, 2018 7:53 pm

Misfire codes and then the engine making mechanical noises and stopping abruptly... These are not the things that happen with just bad rockers. The computer has been very good at detecting misfires, and the results are usually related to either an injector malfunction or (more worryingly) a valve problem.

At this point you will need to start the disassembly - I would pull the injectors and see if any of the tips looks damaged - that would indicate bad happenings within the cylinder. Can the engine be turned over by hand? If so, then you could still be looking at just a fuel issue. You will need to take it down to at least the top of the head (removing valve cover) to see the rockers, and if nothing has presented itself by that point, likely continue to remove the head and look directly at the pistons to see what you can find.

WWDiesel · **Posted:** Sun Oct 14, 2018 9:31 pm

If you post your location it may be helpful as there may be some members in your area willing to help....

bigluck · **Joined:** Sat Oct 06, 2018 8:54 am **Posts:** 3

The car still start but now, it idles so roughly that it dies right after it start as before that last event, it did hold idle but was abnormally shaking.

As i initially stated, it is not my car, I have put enough hours on it and the truck will be sold "as-is". Thanks all!

CRD 2.8 - Turbo vacuum vane system check

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