I need the point of view of experts. I did some research on old posts, without success.

 

Maybe it's a normal behavior, but it seems strange to me.

 

FYI, my oil sending unit is completely new, I drilled a bigger hole in it (about 1.2mm), without damaging it of course ! It means I can see the oil pressure fluctuations more quickly.

 

When starting from cold, the oil pressure rises up to 7kg/cm2, no problem.

Then, I start to drive the car, the oil pressure stands between 4 and 6 and as soon as the rev goes above 3000 (let's say about 3000), the oil pressure drops to 0 (a true 0 !) and as soon as the rev goes down below 3000, it's between 4 and 6 again.

This phenomen occurs during, let's say, 1 minute only, not more.

 

When warm or pretty warm, I get 4 or more when driving and 2 at idle, no problem and no oil pressure drop when warm.

 

Another question, is there an oil restrictor (or whatever) in the return line coming from the front oil cooler and going to the pan ???

Some people tell yes, some no and it seems to depend on the 300zx version, european or not.

As for me, I didn't find this restrictor when I rebuilt the engine but I added one (about a hole of 4mm) thinking the oil will stay a bit more in the cooler for a better efficiency but is there any drawback to do that ?

One of the guys on here found a restrictor in one of the oil lines leading to the oil cooler , not sure if it was a feed or return pipe , he removed it thinking it was restricting too much but i don,t think it made any difference to the pressure readings :headvswal

BTW it was a jap tt .

HTH

................FYI, my oil sending unit is completely new, I drilled a bigger hole in it (about 1.2mm), without damaging it of course !

 

How do you know you haven't damaged it by drilling the hole in it?

 

I'd say therein lies the problem ;)

 

Fit a new one without the extra hole and see what your readings are - failing that, if you want more accuracy or detailed readings then fit an aftermarket guage & sender.

 

Richard :smw:

Because I checked the depth before by using a small pin and inserting it carefully.