New 280z owner, trying to fix some of it's problems. Need your knowledge!!

[ambigu0us]

Hey! So I just recently purchased a '78 280z. It, for the most part is in amazing condition, but it has a handful of noises/problems that I want to try to fix. If anyone can help with the following, that would be awesome!

• A metal 'shrill'/metal vibrating noise when car is parked or while accelerating. Wasn't as bad before, but has gotten progressively louder.
  
• Oil pressure gauge dips to near 0 when parked or at a stop, but moves back to the middle of the gauage when driving.
  
• Heat comes out of defroster vents, but not from the regualr vents on the dash.
  
• Water leaks into passenger side when it rains. Seems to be coming from the top left side of the passenger feet area. (Behind the glovebox-ish)
  
• There is a thumping noise when I hit bumps coming from the rear of the vehicle. The car also rocks side to side when I hit a bump at high speeds. I think these two are connected.
  

I know it's an extensive list, but any help would be great!

Thanks!

[esmit208]

AMBIGUoUS

The thumping noise from the rear may be a worn out differential strap or struts that need to be replaced or a combination thereof

Water leak sounds like a heater core that needs to be replaced or a hole that is not visible possibly caused by an unseen rusted out area behind the dashboard or a grommet in the firewall that has rotted out

The heat is the hot water from the radiator that circulates through the heater core that normally provides interior heat and defrost

Oil PSI issue could possibly be a faulty sending unit located about a fingers distance from the oil filter passenger side engine compartment.

Not sure what this is would have to hear it "A metal 'shrill'/metal vibrating noise when car is parked or while accelerating" So there you go.

[grantf]

congratulations on the "new" Z

shrill noise: check belts ect. while in park pop the hood and listen close for the location, do you have AC?

oil pressure: others correct me but I believe this could be normal that the gauge moves upwards as RPM's are increased while driving

heat: are you referring to the side vents? not shure if heat is diverted there at all.

water leak: I had this problem on my 78 280, problem was from shot door weather seals, both the main door seals and the little funky shaped one located on the upper forward area of the door, it looked like it could have come from under or forward of the dash but it was just the weather seals, leak caused a puddle in the foot area of the passenger side.

thump: sounds like worn struts, having the car shift a little after hitting bumps on the road may just be the way these little cars handle

[Dobber]

ambigu0us, Congrats. on your new Z. At least your not asking about hard to relate engine probs. That shrill sound may be coming from your alt., you will have to listen with hood open and reach over and blip the throttle. The water leak could very well be the fresh air intake snorkel. It is located above the glove box. It is welded to the firewall under the cowl and is pron to rust and leak at the base. Royal pita to fix with everything in the car. I hope it is just door rubber. The dash vents are for fresh air only. Oil pres. will vary with engine r.p.m.. Depending on how well maintained and or how many miles are on the car will determine how good that pres. will be. I.E. regular oil changes, etc. The thumping could be loose or worn susp. parts. you will have to get it safely supported and get under with a prise bar and check it out. Hope some of this helps.

Edited January 26, 2011 by Dobber

[Dobber]

Just thinking, your noise may be coming from the water pump. ? ?

[ZCurves]

Welcome to the family...

Here are my 2 cents...

• A metal 'shrill'/metal vibrating noise when car is parked or while accelerating. Wasn't as bad before, but has gotten progressively louder.
  

Does the sound stop when you engage the clutch?

If it is from the front of the engine, check the Belt Tensioner Wheel. The bearings give out and can make that sound.

Check the Water Pump and Alternator for the source.

• Oil pressure gauge dips to near 0 when parked or at a stop, but moves back to the middle of the gauage when driving.
  

Do you have plenty of oil?

Replace Oil Pressure Sender on side of engine.

Consider replacing the Oil Pump as the springs in it may be fatigued (this is not likely though ).

• Water leaks into passenger side when it rains. Seems to be coming from the top left side of the passenger feet area. (Behind the glovebox-ish)
  

You will need to remove the Blower Fan Assy from under the dash and replace the seal that presses against the bottom of the Cowl. You probably should also open up the Cowl and check for rust and debris.

• There is a thumping noise when I hit bumps coming from the rear of the vehicle. The car also rocks side to side when I hit a bump at high speeds. I think these two are connected.
  

The bumping noise can come from two places:

1. Broken Differential Mount.
   
2. Wornout Shock Cartidges
   

From what you describe I am betting on the later. Check all of it anyway.

Now find an FSM (download or email me), take a deep breath and relax. You have plenty of help from all of the fine folks here.

[ambigu0us]

Thank you all for the replies! I am going to look into the car this weekend and will let you know what I find!