AGG Knocking Noise - Video Inside

Discussion in '8-valve' started by bmouthboyo, Sep 16, 2018.

  1. bmouthboyo Forum Member

    Mar 1, 2011
    Likes Received:
    OK so I recently converted the engine in my VW T25 camper to a donor AGG engine. Seemed to be running nicely for a few weeks and so I decided to take it on a good blast on the motorway up to 80. No issues, drove home and parked her up. Today I go out and when I start it up it is running with a rough knocking noise:

    I got it up to temp, checked VCDS for errors and it had a lambda fuel mix error so cleared it. All hall readings in VCDS spot on so decided to do a compression test for the first time. Engine warm, all spark plugs out, 10 cranks each. Then same again with 2 tbsp oil in cylinders.

    Upon removal noticed spark plugs 3 and 4 were oily on the tips:

    Compression test results:

    Dry - 113 / 140 / 190 / 180
    Wet - 131 / 185 / 222 / 201

    Cylinder 1 is low but not sure how to interpret the dry and wet readings. Given No1 didn't increase by much with oil in the cylinder does it point to head / valve issues? Also what would cause Cylinder 3 / 4 to read high and the plugs be oily?

    What should I look into next?

    I popped back out to double check oil pressure and that is good (3 bar at idle once warm) but did notice a Hall sender error which is strange as the crank sensor is a brand new Meile one. I can't seem to get this error again however despite still having the knocking as the engine warms up.


    Thanks for any pointers everyone.
    Last edited: Sep 16, 2018
  2. rubjonny

    rubjonny Administrator Admin

    Oct 31, 2003
    Likes Received:
    hall sensor error is down to the distributor, not the crank sensor. since its not come back after clearing its probably an old code and you dont need to worry.

    did you do the compression check with throttle wide open?

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