bbusbee |
02-08-2007 01:54 PM |
Here is what I did to fix this problem, I copiedmy post from another forum.
<DIV>Update to my original problem. This last week I did all the work to replace the lash adjusters as well as the timing belt and drive belts, etc. When I attempted to disassemble the rocker arms from the rocker arm shafts I noticed that a few of the rocker arms were jammed or stuck in place. I could still move them but it took some force, compared to the other rocker arms that moved freely like they should. A stuck rocker arm must have been causing the tap, tap, tap noise that I had been hearing because the noise was a deeper solid metallic noise as opposed to the noise I assume that the lash adjusters would make. Also for the few rocker arms that were stuck, the oil lubricating holes in the shafts were totally clogged with gunk, as you guys have indicated would be the problem. The lack of oil caused grooves to be formed on the journals where the rocker arms ride so I used some 400 & 600 grit wet sandpaper to smooth out the grooves in an effort to salvage the shafts since I didn't order entire replacement assemblies. I only smoothed them out, I didn't remove the grooves completely because I didn't want to interfere with the tolerances too much.
The instructions from Isuzu for prepping the lash adjusters said to submerge in oil and then push in the small ball in the top of the adjuster while pushing up on the piston from the bottom to bleed out any old fluid and then prime with new oil by pumping a few times until no more air bubbles are seen exiting from the adjuster. After the adjuster is filled with new oil the piston should be pretty much impossible to push in by hand unless the adjuster has an internal leak.When I started I pushed too hard on the ball until it went all the way down into the adjuster resting on the top of the piston, in essence collapsing the internal springs on the first 5 or 6 adjusters. I didn't realize that I didn't need to push that hard until I got to about the 6 or 7 adjuster. However, after I finished priming them all with new oil I went through them again testing them to make sure that they would hold their oil by pushing hard on the piston to see if it would move. For the majority of the adjusters the piston was solid and would not move any, but for a handful the piston would only move a fraction, enough for me to feel the movement. Anyway I put everything back together. I used camshaft lube on the camshaft and rocker arm bearing surfaces and where the cam shaft lobes and rocker arms made contact. I installed a new timing belt, tensioner, and water pump and all news hoses and drive belts. Filled up the engine block with coolant before installing the thermostat housing with a new thermostat (made a hugh difference) and then filled the radiator. </DIV>
<DIV>Changed out the oil with synthetic and she has been running quietly ever since. Because of the design of the rocker arm assembly I fully expect the noise to come back but I don't think it will happen for several years at the earliest. </DIV>
<DIV>The temporary solutions offered by other posters on this forum only mask the real problem which is damaged/gouged rocker arm journals on the rocker arm shafts. Contrary to some beliefs it is doing real damage, don't be fooled. The only true fix is to replace the assemblies and again, because of this design, that will only give you smooth operation for 100k miles or so. The key to longevity is regular oil changes. </DIV>
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<DIV>Good luck.
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