timing chain rattle

[vjharpe]

I have a rattlie in my 90 240sx sohc that I think may be the timing chain. I have the valve cover off- the passenger (tensioner) side is tight, but the driver side (guide side) seems real loose. The guide appears to be intact (looking from the top) but I'm surprised how loose the chain seems. How loose should it be?

[drjohn]

The timing chain will have a little play even when new because the tensioner puts pressure on the chain when the oil pressure is up. The chain may have about a qrt. of an inch but this becomes more with higher mileage. If your car has high miles it is likely do for a timing chain and if it is rattling it needs replacement. Make sure you get the updated guide rail for the drives side when you do the job. Also if high mileage replace the oil pump, this controls the tensioner.