Post by
Big-Bird »
https://forums.nicoclub.com/big-bird-u44704.html
Wed Jun 20, 2007 1:37 pm
If you have the V6, the rattle could be caused by the lifters which are hydraulic. The small oil journals inside the lifters do have a history of getting clogged and this doesn't allow the oil pressure to over come the mechanical load of opening the valve so you get valve train noise.
The only known cure for this is to replace the lifters...all of them.....Yeah I know that sucks.
You can try to switch to a 5W30 synthetic oil that may reduce the noise, or you can try to clean the engine with an additive you pour into the crankcase and let it circulate to loosen the blockages. (These additives don't always work either )
If you have a 4 banger then a rocker shaft could at the heart of the noise.
The last issue could be that the oil pump can't maintain high pressure due to scoring inside the pump body....but unless you have a seriously high miler engine and/or have been negligent with your oil change regiment, this is unlikely. ( PS this applies to both engines... )