Posted 16 July 2021 - 09:00 PM
The previous guys have covered the body shell rust issues. Another common rust problem on StarQuests is the beefy metal beam inside the bumpers. The front bumper is especially vulnerable thanks to the fog lamp openings. Water gets past these openings - especially when water is blasted at them from a garden hose while washing the car - and flows past the hard foam bumper filler piece. This foam though absorbs some water... and then holds it against the face of the metal beam making it rust away. If you crawl under the front bumper and look at it from behind & below, you will see some triangular slots in it to drain the water. The foam blocks much of these drains unfortunately.
There are also long and flat metal bars that hold the chin spoiler assembly to the bumper cover. There are two bars on each side of the car: one inside the bumper and one on the spoiler piece; they basically clamp the spoiler to the bumper. The piece inside the bumper sits in whatever water soaks the foam so those bars are often disintegrated. A member of this website offered stainless steel replacement pieces; I don't know if they are still available or not.
You can't really see or check for this rust when examining the car unless the painted bumper cover part is removed. It's something to be aware of however. On my car I trimmed the back/bottom edge of the foam away - chamfering it - to make a larger space for water to reach those drains. And I don't blast the fog lamp openings with water when washing the car!
Other things I would look at:
1: look at the half-shafts and their CV joints. These are the shafts going from the differential to the rear wheels. Are the boots around the u-joints intact or are they split/torn? If damaged, the CV joints will likely be bad as road grit/grime gets through the cracks and grinds away at the joints. There should grease inside these boots as well; when the boots are damaged this grease is lost which also kills the CV joints. This problem can happen on pretty much any car with independent suspension on the driven wheels: rear wheel or front wheel drive cars. The half-shafts and CV joints can be rebuilt... or aftermarket assemblies may still be available for the 87s; the different (and larger) ones on 88-later cars are pretty much NLA. Finding a local shop that will rebuild your halfshaft/CV assemblies is pretty much the only option for 88-later shops.
2: Look at the differential itself. You'll notice a long piece extending forwards: this is the torque tube. It has a big bearing inside it. If the outer casing is damaged, or if seals are bad, the bearing may have been subjected to road crud. It can be replaced - a lot of labor but not an expensive part. Where the torque tube attaches to the face of the differential is a spline coupler. When the lubrication is lost, or damaged by road grime, this coupler assembly wears. The coupler parts are no longer available (NLA). To test: put the parking brake ON if possible, otherwise hold both rear wheels FIRMLY in position, put the transmission into neutral, and rotate the main drive shaft by hand back and forth. It should rotate only a little bit before you feel it trying to drive the rear wheels. if it can be rotated 1/4 turn or more, the torque tube coupler, differential guts, and/or CV joints need serious attention. Next, look at the mounts for the differential and torque tube. You will see the differential is supported by two large rubber blocks. It is common for one, or both, to fail and be split. When this happens, the engine torque tries to rotate the differential; the block with the split will open up - it will not hold the differential in position - so the differential will rotate a little and lift up until it smacks into the trunk floor. I don't think these blocks are available any longer either. The torque tube has a few long bolts at the front end - where the drive shaft connects to it - that pass through rubber pads. These rarely have problems. It's the big rubber blocks that fail.
3: spin the steering wheel back and forth. How much freeplay is there around the straight-ahead spot? if a lot, then:
- steering coupler is bad. This is a u-joint like thing that connects the steering shaft to the steering gearbox. It's visible just below the brake master cylinder. If brake fluid ever dripped onto it, the brake fluid likely ate through the rubber parts of the coupler, destroying it. The steering wheel will move somewhere around 1/4 turn each way before actually steering the front wheels! Yikes! These couplers are also NLA I believe; other posts on this website talk about alternatives, ways to repair them, etc.
- steering gearbox is worn. These can be rebuilt. Many rebuilt units sold by parts stores and online stores are THE WRONG ONES! StarQuest steering boxes have a longer input shaft compared to many other Mitsu built cars using a similar gearbox... and many rebuilders don't seem to care about this. Send the gearbox from your car to a good local rebuilding shop instead.
Hacked wiring... rust in the gas tank.. body rust... rotted interiors... those are the most common issues with "barn find" StarQuests.