Engine trouble/ Heavy Knocking

[asorensen]

I have developed some rather frightening engine symptoms: Heavy loud knocking (almost a rapping noise) accompanied by lots of blue/gray/ white smoke, with severe power loss on rapid acceleration.

No problems starting, idling, slow acceleration to red line or when the van is cold. The oddest part of this is that the last four days after developing this problem it has continued to work beautifully for the first 5-10 minutes of driving everday but after that time it is back to the awful noise and complete loss of power.

Started acting up after I moved some things around in the engine compartment to make room for a veggie oil system (None of this is connected yet so no reason to suspect this as the problem) I did replace some lines and had to increase the lengths of lines in order to make room for everything. I also realized that some air got into the injection pump (can this cause problems?) as a result of not purging the new lines very well. I also moved the vacuum parts (solenoids?) previously located behind the fuel filter from a vertical position to a horizontal position.

I have considered things like: injectors(newly reconditioned), fuel filter (tried a new filter and housing), air filter (tried with no filter same problem), Timing, (belt looks fine, and a timing light showed it to be in time) etc.

Some things I wondered about were: How timing advance is acommplished (because the timing light didn't seem to show any advance with acceleration). Is there a temp. sensor which affects the injection pump function? Could this explain why the van works fine when it is cold and awful when warm? Does vaccum have any bearing on the running of the engine? Can a mechanical failure only show when the vehicle is warmed (or run for several minutes)?



I am at a complete loss and getting very frusterated, not to mention the blow to my pride, any insight would be greatly appreciated.

Andy

[docsavage]

Andy,

Could you get audio and video of what happens by chance? Might help to hear and see what is going on for those mechanics around here.

Check the oil - is it clean with no milky whiteness in it. If it is milky - you have a problem - big problem. The milky, maybe foamy oil would mean water in the oil. This is usaully the head gasket or head. The water in the cylinders does not compress and causes knocking and rattling. Cost me a lot to fix my old Land Cruiser after the head gasket went. Get it to a doctor soon.

James

[asorensen]

Ok day five of this ridiculous problem and I have finally figured it out!

Now here is where it gets fun for you the reader; I am not going to tell you what the problem was. Only that it was an easy fix and all the info needed to diagnose the problem is in my first post.

If you wish to play my game I will answer any questions you might have and give the occasional hint.

On day five I will reveal the problem and solution (seems fitting because this is how long it tortured me for).

If you think you have the answer before then or are to impatient to wait that long just PM me and I will respond.

Good luck

Andy


P.S. If you get stuck try scouring the MDOCUK forum that's were I finally got my answer.

[BCDelica]

PM sent with my "guess".

Right on, see you Saturday!

Cheers,
Kev

[collector]

I am unfamiliar with diesel motors, but I'm gonna guess that it was air in the fuel lines? (improper/incomplete purging of the system?)

[asorensen]

Ok all you players out there. (well thase that played my little game)

Here is the answer to my little problem:


When I moved things around in the engine compartment (4D56 deisel)
I had moved some vacuum solenoid items. while doing this I unplugged two of the lines and then inadvertently crossed them when I pu them back. Two incorrect vacuum lines is enough to screw up One Van!

Actually it was the line which operates the EGR which was causing the grief. Torchard you were on to something you obviously have some know how.

It was this post on the mdocuk forum which lead me to the answer ironically this is info for the L400 so I guess this can be a problem with them as well. http://www.mdocuk.co.uk/forums/viewtopi ... knock+deli

Thank you all for your responses.

Andy