GT-Four Buyers Guide
From gt4dc_wiki
Contents |
Chassis - Visual Inspection
- Check front of car, ensure there are no additional weld points any part of the chassis. If any are found, this is usually an indication of frontal impact. A dead giveaway are imprints on the radiator.
- Jack up car and check swaybar mounts. In some situations, i.e. the car going into/over a ditch, etc. the mounting points will be compressed, indicating damage to the undercarriage/steering assembly. They can be pulled out, but usually will show some crumpling.
- Above the viscous diff., check for marks that the swaybar is touching/hitting/rubbing the body of the car (the curve that goes over the diff and propeller shaft. This is also an indication that the undercarriage may have suffered damage.
- Check steering rack and pinion mounting points. In a frontal impact, these have a tendency to crack, and will later break, requiring re-welding.
- Check rear of car, pull up carpeting and look for additional welding.
Chassis - Drive test
- Find a nice stretch of empty road (make sure!!), take the car to 35 km/h and jam the brakes hard. If the chassis has been damaged, it is unlikely that it may be repaired perfectly. The car will usually throw to the right or left. If the car is equipped with ABS, you should feel it kick in as a regular series of pulses against your foot. If not, and the wheels jam, then the ABS is not working.
- Listen for any knocking or creaking sounds coming from under the car. This will be an indication that the bushings need changing.
Engine
- Start engine with bonnet up. Listen for initial knocking sound on start-up. This is an indication of worn crankshaft, or con-rod bushings/bearings. As the engine runs, and oil gets to these parts, the noise will dissapear, or get very much softer. Easy to miss if engine is hot.
- Check engine for leaks, excessive oil etc.
- Locate the diagnostic port (left side of the engine compartment, close to the windshield). Jump points TE1 and E1. Start engine, and check for codes. The check engine light should flash at a steady 4 pulses per second. Should codes be present, then discharge ECU by pulling out EFI fuse, count to 10, and reinstall it. Repeat procedure again.
- Ensure that no smoke, no matter how light comes out of the exhaust. This must be done when the engine is hot. White smoke is a possible indication of turbo trouble. But if it's a damp day, don't mistake water vapour for smoke. Take the car for a spin, boost up the turbo and hold for 10 - 15 seconds at max boost. Then check again for excessive smoke.
- Engine should run steadily at 800 to 1000 rpm, without missing. Let car idle for 15 minutes, and check for excessive smoke from exhaust. This is an indication of valve seal/guide condition. If seals or guides are worn, then when the car is hot, oil will drip down into the cylinder and burn up with combustion.
- Take the car for a spin, boost up the turbo. Try and hold boost aggressively. This will force a rise in pressure under the cam cover, forcing oil through worn valve seals and guides. Symptoms are that the ignition will begin to miss, as the plugs foul, and you may have a little smoke from the exhaust. When you stop the car, one whiff of the exhaust gasses should already tell you if oil is burning. (But don't over-do it.....ha ha).
- Turbo should spool up smoothly to end of the stock boost gauge from 3rd gear onwards. At lower gears, the stock ECU limit boost below max.
Drivetrain
- From stationary, accelerate suddenly (preferably forward), and see if you can feel a thud, or hear a clunk from the rear. If you feel a thud, this indicates that the LSD mounting may be worn, or that there is freeplay in the LSD itself, or that the rear drive shafts may require rebuild. An audible clunk is usually a dead giveaway.
- Take the car up to a steady 80 - 100 km/h. Listen if the LSD begins to hum. Also an indication that the LSD may require rebuild. If you feel a steady vibration through your seat, this is an indication that the propeller shaft bearings/mounts may be worn.
- Do a couple of tight figure eights, and see if you hear any noise from the drive shafts.
- The gear shift in a GT4 has a tendency to be a little sloppy. But should shift into each gear smoothly without any grinding, or stiffness. This is an indication of the condition of the gearbox synchros. Accelerate hard again and hold rpm above 5000 for 2 kms or more. Then stop the car and see if you can smell the clutch burning.
Another point to check is the timing belt which should be changed every 60,000 miles.
