Kzn130 3Ltr Turbo Diesel

[wotever]

Hi to everyone out there.....having a little trouble with my kzn130 3ltr turbo diesel hilux.....it's a front top end knocking noise which sounds the most loudest right at the fron of the cam, even though i've inspected the cam and it looks fine.........( just like the old ford escort tappet noise but slightly heavier)......as i'm sure most of us remember that noise, and just wanted some advise before total strip down.....I thought it was the timing belt tensioner or pulley, but i've replaced both those with new belts as well.....i have'nt put fresh oil in yet, incase i've got to drop the sump off to check the shells...but as there is no noise from the bottom end, i counted that out straight away....only other thing is when the oil filler caps off....there is a bit of air pressure coming out of the cap hole......If anyone has experienced anything like this and has'nt had to take the head off etc.....i would really appreciate any direction you could send me in......Also if i do have to drop the sump, is there anyway i can remove the pistons from the bottom rather than taking the head off....as i've done this on other vehicles but i can't find any sort of reference to see if this is possible on this model......many thanks for any advise you can give me on this.......markus