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MTU trouble
Posted: Wednesday, July 31, 2013 12:42 PM
Joined: 15/07/2012
Posts: 18

Hi All, I have a couple of MTU 16V 4000 M90 circa 2008 that have recently started giving trouble.

As the second turbo kicks in there is a spike in the load, injection goes to 100% and there is a big puff of black smoke. You can really hear and feel the load.

The engines have only done 400hrs.

I have had MTU in several times and they are not sure what the problem is, as all the parameters are normal.

Just thought I would put it out there to see if anyone had some ideas.

I am not an engineer, I just point it in the right direction.

The Norris
Posted: Wednesday, July 31, 2013 11:08 PM
Joined: 05/09/2008
Posts: 6

It sound to me like it could be something to do with the blow over valve not working correctly.  

There is a valve that bypasses air from the after cooler to the 2nd turbo to help it speed up quicker and eliminate the turbo lag that you get with the 2000 series. 

If this valve was not opening, the engine would become over fueled and give out lots of black smoke. 

Does the engine reach higher revs and does the smoke clear when you get past 2000 rpm?

Posted: Wednesday, July 31, 2013 11:30 PM
Joined: 15/07/2012
Posts: 18

Hi, Thanks for your reply.

Yes, the the engine reaches 2075rpm and the smoke clears quite quickly after the second turbo speeds up.

Posted: Saturday, August 3, 2013 4:43 AM
Joined: 09/10/2008
Posts: 134

Try a different MTU dealer or go to MTU direct in Germany. Where are you located?
Posted: Saturday, August 3, 2013 8:23 AM

I had same problem on 12v 4000 series, it was the boost bypass valve bearing tightening up, carbon etc...