Valve tap on cold start-up

[rrobe99999]

I have an S14 SR20DET. I've just noticed a tapping noise under the valve cover that occurs during a cold start up. It abruptly goes away after about a minute, and then the engine sounds fine and runs good. I've experienced this before with other old cars, and found that adding marvel mystery oil to the oil will help. But since this is my first turbo car, I am cautious about using any additives. I have used Mobil 1 10W30 oil for years, and it was changed about 500 miles ago. My problem may have started due to the cold weather, or a recent drag race with a peak redline of 7200 RPM. Is this just a noise that I should ignore? Would it be OK to use Marvel Mystery oil or some other additive? Is this something I need to fix? Any DIY advice would be appreciated, because I don't have a local shop that can work on this engine. I am confident with the procedure for removing the valve cover, but what should I look for after that?

[undesiredshoe]

yea i have the same problem with my ka24e. I live in wisconsin where the winters get cold and i get valve tap when i start it up in the morning. It sucks. I would also like to know how to fix it or make it go away.

[Chrischeezer]

marvel mystery oil!!
i would never put anything that says "mystery" in my motor

-pull off your lower oil pan... look for dents and traces of the oil pick up being restricted, you can't tell by just looking at the outside of the pan.. the clearance is very very little..

[kuruptR]

low oilpress could cause noises up in the head, from the timing chain.

How to fix it?
Remove oilpan, make sure its clean of dents.
Check if pickup(sump) is bent or clogged, do so by removing it.
There should be a o ring or gasket between the pickup and the oil pump.
Replace the gasket or o ring get it from nissan. This is basiclly the main cause of low oilpress from old motors that have been sitting around...

hope that helps its a bit of work but youll be happy with the results.

[rrobe99999]

Thanks for the advice. I don't suspect low oil pressure, because, my oil pressure gauge shows high pressure (50-75PSI) at startup. It then goes to normal (15-25PSI) when the car is warm at idle. Is there anything else to look for? Removing the oil pan is a lot of work, so I want to make sure I'm going after the right problem.

[fliprayzin240sx]

It could be the lifters...they could be either going bad or have air in them. Look into the FSM and see how to check for bad lifters. Its a lil time consuming but if youve never lifted your valve cover before, this would be a great time to get to know your engine too.