300ZX.CO.UK's  Z-BUYING GUIDE


ENGINE / MECHANICAL

• Try to avoid very early Z's '89/jan-feb '90, due to possible cylinder-head and valve problems. TT's with engine-numbers below 619550 or NA's with numbers below 777599 may be subject to this problem. If unsure check with Nissan.
  

• Try to get a full service history (if car has been serviced by Nissan, they should 
  be able to get you a list with EVERYTHING that has been done to the car in the past)

• Have a compression-test done
  
  
  Preferably go see the car in the morning, when the engine is still cold from standing overnight or arrange a time when you can view the car from cold.
  Also arrange to go for a long test-drive (60 minutes)
  If the seller doesn't want to cooperate with you on this matter, walk away and go find another car
  

• listen for weird sounds during test-drive. (whining or rattling noises from the engine bay is not a good sign)

• Watch the boost-gauge (TT's only) during idle.
  The needle should be to the far left (around the -14)..this shows that the engine
  is in good shape:
  
  If the needle is closer to the middle of the gauge during idle, it might indicate the engine has compression problems or there are vacuum leaks in the system.
  (usually comes together with rough idle):
  

• Once warmed up, the engine should idle as smooth as silk...no vibrations at all.
  A rough idle may indicate there's something wrong

• oil pressure should be between 30 and 60 psi during normal driving 
  
  During idle the oil-pressure should be around 10-15psi

• Timing belt should have been replaced every 60k miles..make sure this has been done !

• check for play in the rear Axel - try to get them to jack up each side and check for excessive lateral movement in the wheels. Also check for vibrations thru the seat upto and over 80mph / Motorway speeds.

• Cooling system - TT's are a lot more prone to overheating problems than NA's Take the care for a long test drive - check the gauges in car and look in the near side wheel well for signs of coolant expulsion
  
  weak points:

• Fuel smell (especially when the engine is cold)
  This is usually caused by hoses that have become brittle/dry.
  

TURBO'S

• drive the car hard during the test-drive (with engine fully warmed up) and 
  take a good look at the boost-gauge

• maximum boost-level on a stock 300Z should be around around 9psi, 0.6bar:
  (..bare in mind that the stock boost-gauge might not be very accurate.)
  
  If it doesn't go past the first positive line (7psi) it's in safety-boost and something is probably wrong:
  
  Note: It's very hard for someone that has never driven a Z before to tell the difference between normal boost and safety boost, so if you're unsure take it to Nissan or
  ask someone that owns a 300ZXTT to come along with you
  
  If the needle wanders off the scale, the boost has been increased...this might give you a nice push in the back, but without the right chip this is NOT good:
  
  If the needle doesn't get past 0, there might be something seriously wrong with the turbos or there's a wastegate sticking:
   
  

• If the boost-meter doesn't work at all, then the seller is probably trying to hide something. (run away)

• listen carefully for whining or whistling sounds as soon as the boost starts to build.
  you shouldn't be able to hear the stock turbos (unless you have the windows wide open and drive through a tunnel)

• Check for smoke during heavy acceleration (rearview mirror)

• After the test-drive let the car idle and open the hood and see if smoke or a burning smell is coming from the area around turbos or on the bottom of the car
• Let the car idle for at least 5 minutes and see if blue smoke is coming from the exhaust, which indicates that the turbo-seals are probably on their way out.
  
  weak points:
• Z's with over 60 - 70K miles is in danger of failed turbos/seals - if they have been well looked after with regular servicing and good quality oil the turbos and seal can last to over 120K. White smoke is usually ok for a while as that is often steam although prolonged white smoke can be a symptom of head gasket / cylinder hear problems.
  

GEARBOX

• try to avoid automatics from '89/'90/early '91, especially higher mileage ones..
  (the early automatic-gearboxes have overheating problems, due to a design-flaw)

• Automatics: check (dipstick) oil-color and smell of gearbox-oil (dipstick is behind the engine). Very dark or black oil and/or burned smell is not a good sign.

• Automatics: Do an automatic-gearbox diagnostic (automatics only) :
  ( http://www.twinturbo.net/ttnettech/autodiag/autodiag.html )

• check for oil leakage from gearbox/differential

• Manuals: check for grinding (ALL gears, up AND downshifting)

• Manuals: make sure the clutch bearings aren't making a lot of noise. They can make a little noise for 30K miles or more. But a lot of noise usually indicates an upcoming clutch replacement
  
  weak points:

• Manuals can have problems with the hydraulic system that operates the clutch 
  (leaks or air in the system, causes slipping clutch or soft pedal)
  

• Check the calipers, see if they look all the same.
• check brake rotors during test-drive (shaking steering wheel while braking) 
  
  weak points:
• The brake master cylinder on '89,'90-'91 cars will begin leaking (at around 40-50K miles).  The new part is redesigned and is supposed to be better. 
• Stock rotors on the '90+ Z's can warp quite easily.
  (Warped rotors will cause the steering wheel to shake while braking)
  
  

• Lift up any rubber seals on the car even around the windows & look for a paint edge.

• Check every wheel well & even see if you can lift up the edge of the liner to see if there is a paint edge.

• Open the hood & hatch. Check the bolts that hold the quarter panel on, they should be covered with factory paint & look like it's never been removed, if it's been removed you will know it because it's near impossible to line it back up & not show where bolt location was previously.

• Check the gaps on both sides of hood, should be small & equal. Check the gaps right under door where fender meets door, make sure same on both sides.

• Check gaps on both sides of bumpers front & back, also the gaps between the doors should be equal on both sides of the car.

• Open doors & look through hinge areas for messed up sheet metal on the pillar.

• Check in back upper hatch seal area for signs of wreck.

• Always look in the spare tire well. (leaks, rust, etc)

• Look for OEM glass & always check for cracked windshield this is easy to miss & not uncommon (windows for the Z are very costly)

• Look up under the bumper at the frame that connects to it, look under hood area at that also, this is what gets straightened from a head on collision.

• Whatever you do NEVER & I mean NEVER buy a car at night! Even if you go where lights are. In the day look down the body for dings & depressions especially since Zs are durasteel.

• Use a small magnet to check the body parts for filler-repairs. 

• Check lights for condensation, though sometimes this is not indicative or wreck, check the seal area & alignment around the lights very hard to get to factory spec.
  
  weak points:

• The spoiler on the TT's is made of some kind of foam that integrates in time
  The paint on the spoiler will start to bubble and crack and allows the foam to act as a sponge...result: hatch will start to rust.

• T-tops are prone to leak

  more body-stuff checking:
  http://www4.bs.monash.edu.au/oz32/Tech/NewZ.htm

   

• Check ECU for error codes ( http://www.ttzd.com/tech/diagnostic/diagnostic.html )
  If everything's ok, the ECU will come up with code 55.
  BTW: a Nissan dealer should be able to perform this check also by using an ECU-consult...this consult will also check for errors in the ECU's for the HICAS, ABS and ECU of the automatic-gearbox (if present)
  
  weak points:

• Alternators on the Z are crap and some last only 50K miles.(so if the owner has installed a big ICE, expect the alternator to go soon) 

• ignition system power unit (PTU) will go sooner or later. (they last around 6 years)

• The electrical connectors become very brittle, due to high temperatures under the hood. Especially the TT's suffer from this and it may lead to all sorts of problems

• Knock or detonation-sensor (or actually the wires to the sensor) is prone to failure. This sensor is very costly to replace.
  A broken knock-sensor will cause the car to run in safety-boost and have a big impact on the performance of the car (NA's also ! )