I really need help with this. We have several cars parked in our yard, 3 pick ups, 2 vans, a sedan and a ford bronco 2. Some (the trucks and ford) have been sitting in the same place for going on 12 Years! Empty gas tanks, no starting the engines, no movement. One of us (not me) wants to keep them, because they may be collectible and worth something. Accept they’re all wrecked or broken in someway. “I just need to fix one thing and we can sell it,” he says, for years now. How can I convince him mechanically that they need to go? I just want a clear driveway! None of our kids have ever known what it’s like to park close to the house! to clarify, I would most appreciate a list of all the things that will go wrong to a vehicle parked for so long. I’ve seen the posts here concerning cars parked for several months, but for a decade? Please help!
You won't convince him on a mechanical level, because he'll just lie to you about the state of the car, and you won't have enough knowledge to call him out on it.
Instead, turn it back on him.
“I just need to fix one thing and we can sell it,”
OK. Fix that one thing, and sell it by the end of the week/month.
"But I don't have time to do that"
Sell it as-is, and let the new owner fix 'that one thing'
"But we won't get as much for the car"
But we won't be paying for parts to fix it.
Don't accept the argument of 'they might be collectable'. The only collection going on is rust. Cars - especially common ones - don't become collectable when they're sitting in the open.
Of course, if you name is on the title with a 'OR' modifier, you can sell them without his agreement anyway...
I'm reasonably certain that taking a photo on your cellphone and then visiting the local car dealership or even wreckers yard with a "give me your best cash price for these; why is your offer so low" will produce an even longer list of excuses and barter-downs than I can think of here (especially as he will know the toll your climate has on vehicles) but a car that is parked up exposed to the elements for a long time will likely need the following considering to be restored to service:
new battery - they self discharge at varying rates and once 5ey drop below around 70 percent charge they're well on the way to being goosed
full change of all fluids and consumables that would be done in a service (paper filters degrade, oils degrade especially if they've been in service prior and acquired moisture and acidity from combustion by products, waters stagnate and block with algae if the appropriate chemicals aren't added)
air con systems usually get ruined by lack of use as regular pumping of the refrigerant is vital to keeping seals in good condition
rubber becomes harder and brittle with oil contamination and sunlight exposure; gaiters, pipes, new set of tyres especially if any have gone flat and perished the side walls. Rubbers and plastics especially in the cab exposed to day heat, lose their plasticisers and become brittle
mold takes over every surface regularly touched by humans; radio knobs, indicators etc become sticky and slimy especially for cars parked in the shade
wires corrode where different metals (eg aluminium connectors on copper wires) are in contact - this is electrolytic and independent of climate, but also repeated cycles of condensation and other climate effects have a corrosive nature.
full check over for the effects gnawing animals have on pipes and wires
check and replace moving parts and safety parts, particularly on the underside, that will have become encrusted with road salt or mud during service and subject to hidden corrosion thanks to acidity or alkalinity - no one power washes all the dirt off the brake lines before they park their car up for 12 years
Parts of cars that are regularly driven get warm and the residual heat can combat a lot of the environmental effects, meaning that regularly used cars last longer in practice than those left to fester. In realistic terms anyone who knows their salt will understand they're potentially buying a huge can of worms - a car parked up because it has a broken driveshaft and left for 10 years will need more than just a new driveshaft and it should be priced accordingly; I'd be looking to bid scrap value because if it did turn out to be a write off I could maybe recover my outlay by selling usable parts
If you want a real life appraisal of worth put one on eBay with a very high reserve (so you don't have to part with it come auction end) and honestly List every fault and circumstance relevant to the car. Maybe don't set a reserve actually, just sell one and note the difference between what you think it's worth and what the market actually pays - it will likely be quite a stark difference