skootin wrote:I believe ENGINES AUSTRALIA in Dalby QLD do them.
I have also fixed this problem by drilling a hole in the case behind the valve so the pressure bleeds back into the sump. This was done with the engine pulled apart. Very hard to explain without pics -to hard now engine is running fine.
digging up an old thread
I notice you suggest drilling a hole to bleed the pressure back, i believe this is what the hole and recessed ring at the top of the piston is for? it lets the pressure bleed through the bypass hole when the piston is closed. (could just be for lubrication though)
with the worn piston there could be too much oil getting past which means the little hole cant keep up, which would explain why my pressure is fine (if a little low) when im at running temperature (thinner oil and plenty time for oil to bleed out)
Perhaps enlarging the hole in the side of the piston, or adding another hole(or two) could perform the same action as drilling a purpose bypass hole in the timing case.
I cant believe toyota would design this without thinking of the hydraulic complications of oil leaking past the piston, so im convinced the hole and "ring" in the piston is for this purpose.
I might also try getting another nut from the wreckers and drilling a hole in it to see just how much leaks past the piston, and this should also confirm it is indeed the pressure buildup behind the piston causing the problem, and not a step in the bore as many people seem to suggest (cannot feel a step in the bore myself).