I need help diagnosing my clicking problem.

I just bought the car and i never trust anyone when they say they changed the oil last so I put in some oil cleaners ran it for 400 miles then changed the filter and oil. put in a synthetic blend and new mobile 1 filter. now after my car warms up i notice oil pressure drops to half of what it is cold and my low oil pressure light is on constantly. I am getting oil up to the top so I'm guessing that my sensor is finally failing. also now i have this dull click after warmup. it is reminiscent of placing a car in park while moving. I can also feel the clicking in my shifter.
with it being a dull low pitched click i thought maybe cam bearings but on a quick misfire check there is no discernible difference any help is appreciated.

also just wondering but what MPG is anyone getting on the highway i seem to be running just under 20mpg right now

 

Welcome to ZDriver!

What type of "oil cleaner" did you run? Hopefully it didn't kill the lubrication capabilities of the old oil... because 400 miles is quite far. If I need to change really dirty oil, I run a quart of ATF in the oil and drive it around town for a few miles, then dump it.

On to your clicking noise... if you can feel it in the shifter, it would probably be in the trans no? If the noise is coming from the top of the motor, check the rocker clearances (explanation in the FSM / Hanyes, and here: https://www.zdriver.com/forums/240z-280zxt-s30-s130-tech-tips-275/aftermarket-cams-cam-removal-installation-pics-19939/)

 

For the highway?

Yes, that is a wee bit low.

 

Clicking or Knocking?

If you have low pressure you may have a light knocking. Check/replace the pressure sensor, if it's good check/replace your oil pump. If both are good maybe it's time to pull the oil pan and make sure everything is good there... and I hope you don't kerplode your engine.

My engine slightly low oil pressure and had a quiet knock, that turned into a pronounced knock into a full blown symphony of rattles, knocks, clunks and other cool noises in less then two weeks. Turned a lot of heads on the drive home, luckly these engines are strong enough to drive 5 miles turning 4000RMP on what I assume was 4 or 5 cylinders without tossing it's guts all over the freeway

 

I put about 7oz of "Sea Foam" in the oil to clean it I've had great luck with it before. It's not the trans. while i can feel it through the trans it doesn't matter which gear I'm in or if the clutch is in or out. Today the resonance seemed to get get lower pitch but louder. which has lead me to believe that it is a rod end. i could barely hear it from over the engine while inside the car it was much louder but the sound is getting louder which means its getting worse. All this in about 50 miles so its going quick. I did just hear about a shop in the area that has specialized in Datsuns for 25 years and if he can figure it out in the parking lot its no charge. So I think I'm going to take it there tomorrow morning.

 

Thanks for the welcome and I hope I don't kerplode my engine either. was meant to be a weekend/ possible project car but after 280k miles my alero decided that it had enough and I've been victim of the economy colapse.

 

Yikes! When did this happen?

 

What grade oil did you put in?? Try dumping the oil again and running 15w40 oil It will fill up the bigger gaps in the bearings and the knocking should go away. This would give you time to source a parts engine to build while you drive

 

I had thought about dropping a little 80-90w that I have from working on helicopters. Used to hold together an old truck engine for a while (extra 50k) but getting it out is a bit difficult. have to overheat the engine a bit and then drain and flush it also it helps to remove the filter.

 

Right towards the end of may... I knew the engine wasn't going to make it too far into the year. I had a bad misfire last year. Finally got it sorted out only to find that the misfire was covering the knock... oh well. Working on sourcing a replacement, then I tear into the bottom end and see if it's worth salvaging and rebuilding



Good luck Etherealwolf with the diagnosis...

 

Well the problem is the crakshaft pulley bolt came loose and the key has worn a slight extra 1/4 inch into the keyway

 

So anyone have a 79 crank pulley with powesteering

 

Bad idea. Use the recomended 10W30. Screwing around with other things is what caused the problem from the start....

 

Well what caused the problem was the fact that who ever screwed with the engine didn't properly tighten down one of the most important bolts in the engine. Though 80-90 would have quieted it down the problem would have just gotten worse. How I didn't notice the pulley wobbling is beyond me.