What Happens When A Car Sits?

We have a 2002 Mazda Protege. It has been sitting outside for many months now. The battery needs a jump, and when I did that, the car started but I found the alternator instantly seized up. We could smell the burning rubber from the belt. Not a car buff, I was surprised it would die just from sitting awhile. So, my questions are:
a) Besides the risk of dry rotting hoses and tires, what else might I expect to go bad just by sitting awhile? (A friend mentioned brake lines. Is that true?)
b) What do car dealers do to protect their vehicles during hard times when their vehicles just sit for quite awhile?
c) Last, is there any tire treatment I could apply to reduce dry rot?

Several things and a lot depends on how long it sits and what condition it was in before it was left to sit.

Obvious things:

  • if there are any leaks, expect fluids to be low or completely drained. That can include: engine oil, transmission fluid, diff fluid, power steering fluid, brake fluid, coolant.
  • tires will lose pressure
  • brake disks will rust and brake pads or calipers may seize
  • battery will die
  • several species of small furry animals may gather in the engine bay to groove together with a pict, build nests and chew through some of your rubber and electric cables
  • brake fluid is hydroscopic so it will eventually absorb moisture from the atmosphere and cause spongy braking, if not complete failure. But probably not in a matter of a few months unless your brake fluid is quite old and already quite bad. If it sits long enough, brake line may begin to rust.
  • UV destroys rubber over time but again, not in a matter of months. You could put on tire dressing with UV protection, but honestly, it should be the least of your concerns
  • fuel will go bad and absorb moisture as well

a) It’s not just the tires and hoses that dry rot. Some gaskets seem to last a lot longer in regular use than when left to dry out for a long time. I partially rejuvenated an old Miata that sat for a while. Among the things that dried out from sitting were the gasket in the fuel cap (which tripped an evaporative emissions code) and the power steering fluid reservoir. Some other gaskets, like the valve cover gaskets, are also prone to drying out over time. I also had a flexible brake line (which is basically a steel belted rubber hose) dry out and leak. The brake fluid will collect moisture from the atmosphere and promote corrosion. Let it sit long enough and a brake caliper might seize. The antifreeze has anticorrosion chemicals that are consumed over time, so some rust in the cooling system and failed water pumps could occur. The parking brake and hood cables can also rust if they don’t get regular exercise. If you don’t regularly use your parking brake, it’s a good idea to set it and release it every month or two.

(b) So far as I know, nothing. They always expect to sell that car tomorrow.

(c) Not that I’m aware of but dry rot in tires is greatly increased by exposure to ozone. Park it in the garage (or use tire covers) and put it up on blocks to prevent flat spotting.

Excellent point. What didn’t used to leak may begin to leak like a sieve.

QuickSilver has some good ones too. He’s right that modern fuels may attract water due to their alcohol content. He didn’t mention that even pure petroleum fuels break down over time. The light parts evaporate leaving heavy varnish behind that can clog fuel lines and carburetors. (And fuel injectors too? It’s never happened to me but I don’t see why it couldn’t).

If it’s somewhere subject to vibration, like from passing traffic, bearings can get something called false brinelling. Bearings are lubricated when they’re turning, but after long idle periods the oil layer breaks down and allows metal to metal contact. This, coupled with vibration, damages the bearings and races. That may be what caused your alternator to seize up.

It’s called false brinelling because when you inspect the bearings there are indentations similar to what you would see after using a brinell hardness test. In industrial applications when you have installed spares of critical equipment good manufacturing practices swap on a monthly basis.

C. Tire rubber is an off-gassing compound. It will get progressively get more brittle as these volatiles evaporate. Sunlight makes it worse. I am not aware of any surface treatment the will prevent this. For long term car storage many people will jack up the car on car stands, this relieves the strain on the suspension mostly, like the shocks, springs, and struts. It will also help prevent the tires from developing flat spots in the part that is in contact with the ground. As far as I know this does not prevent the ageing of the tires.

A. The brake fluid system is not a circulatory system, meaning that new fluid does not get to the moving parts, the brake cylinders, etc. The fluid at the end of these working parts does not get renewed. So these parts tend to get contaminated with water. Brake fluid just loves to suck up water. Unless the brake system has been bled regularly, or completely changed, the part of the fluid that operates the pistons in your brake calipers can cause those parts to rust up, seize up. Be sure to have someone bleed the brakes before you drive the car.

B. They polish and wax it and sell it to the next fool. As far as I know.

The belts on the engine running the alternator will have the same issues as the tires, they deteriorate with age and need to be replaced. Same with any important hoses. Most gasoline has ethanol added now, this also will attract water. After a certain amount of time, the daily cycles of heating up the air in the tank, and cooling back down at night, and heating back up, etc, will condense moisture out of the air in the gas tank. For this reason it can be best to store the car if not driven for awhile with a full take of gas, this reduces the amount of air in the tank for the moisture to condense out of. I would plan on replacing the fuel filter before or shortly after getting the car running. Most cars now have the fuel pump inside the gas tank, so if there is water in your fuel it is sitting at the bottom of the tank in water, there could be a problem with that, but just hope for the best because changing the fuel pump can mean dropping the entire fuel tank.

Well played!

Almost. “Real” brinelling happens during normal use and it resembles the brinell test marks. False brinelling occurs during non-use.

They start them frequently and move them to another location on the lot. You should have done the same with your Protege, at least weekly.

Agreed, and make sure the engine gets up to temperature. Just running it for a minute or two can rust out the exhaust from all the condensation and lack of heat.

aircraft tend to sit much longer than owners intend and are a good indicator of what will happen. They get condensation in the crankcase which causes all kinds of problems. to that end owners will add cylinder heaters or crankcase heaters and battery trickle chargers.

I’ve left cars sit for months at a time and brakes will seize in a bad way. Batteries eventually discharge and freeze to failure. Older tires will age faster. It’s best to run the car until it’s brought up to temperature and run it so the tires and brakes are exercised. I’ve never had a belt fail that was replaced on a normal schedule and the same for alternators. I usually get 200,000 miles out of an alternator and 4-5 years out of a battery if they’re maintained.

I have a car I only drive maybe once a month. Is this frequent enough?

Another point about car dealers: customers take the cars for test drives.

I’ve heard this many times. So dumb question: how does water get in the brake line?

If you simply jack up the car on the frame, the wheels and suspension will be hanging at full displacement, and some people claim this is bad on the suspension parts. I think the trick is to jack up the car while maintaining the wheels and suspension at their “normal” vertical positions (or close to it). I’m not really sure how this would be done. I suppose if you’re really hardcore, you would remove the wheels and temporarily install old wheels and tires.

[quote=“Crafter_Man, post:15, topic:953189”]
I think the trick is to jack up the car while maintaining the wheels and suspension at their “normal” vertical positions (or close to it). I’m not really sure how this would be done.[/quote]

The lift points would need to be under the suspension arms, just inboard of the wheels. Possible, but tedious.

My personal experience with leaving a car sit outdoors is when parking it in long-term parking at the airport for a 3+ week vacation, typically in Michigan fall weather (cool, somewhat rainy). When we come back, the brake pads are seized firmly to the rotors, requiring the application of a bit of throttle to crack them loose. Generally the rust on the rotors gets scraped off within a few miles of driving, but the last time we did this, the rusting was so severe that it didn’t go away - it wore the rear pads unevenly, and the rotors never cleaned up, so I had to install new pads/rotors. Granted, the car had about 50K miles on it at this point, so the pads were probably already worn down pretty good.

The tires also develop flat spots when parked for this length of time. Makes for pretty bad vibration on the highway drive home, but they eventually recover; no issues the next time we drive the car.

That’s unusual.

Usually the battery goes dead first. Tires will develop flat spots, but tires that have been sitting for a year or two will usually work out the flat spots and go back to round after a week or two of driving.

Gas goes bad. Six months usually isn’t an issue but a year or longer and you’ll have issues. Most cars will run on crappy gas, they just won’t run as well.

Brakes rust. Usually you can scrape the rust off of the rotors just by driving around for a bit. The brakes may be seized though and you’ll need to get those working before it’s safe to drive the vehicle.

I’ve had to start several cars that have been sitting for some time. My brother-in-law left a small pickup truck sitting for two years. Getting the engine to kick over was a bit of a chore, but all it needed in parts was a new battery. The brakes were rusted in place, so I had to drive it around his neighborhood constantly slamming on the brakes until they finally broke free and started working. The truck had half a tank of 2 year old gas in it and ran like crap. Once I got the brakes working I drove it to the gas station and filled it up with fresh gas, so it had basically half a tank of new gas and half a tank of crap gas. It ran well enough, but I drove the truck to work for a week. There was a lot of vibration from the tires but after a week of driving the flat spots went away, and with a full tank of fresh gas the truck ran perfectly.

The easiest was an old Cadillac that I own. The car sat for seven years. Put a new battery in it, turned the key, and it started like it had been parked yesterday. I guess that’s a Cadillac for you.

That’s probably pushing it. Once every couple of weeks would be better.

Make sure you drive it long enough for the car to fully warm up (usually about 15 minutes or so).

The typical “old lady” driving pattern (once a week to the store and that’s it) is bad for your car. Water vapor in the exhaust will condense into water and will rust out the exhaust system, making your exhaust system die an early death. If you drive the car long enough to fully warm it up, then any water in the exhaust gets flashed into steam and expelled. Any water that condenses into the engine’s oil will also get flashed into steam and expelled.

Gas in the tank will start to go bad after about six months, so you should drive it enough to go through a tank of gas in about that amount of time.

I had this happen to me, but the tires never really recovered. On a deployment to Afghanistan from Oct '05 - June ‘06, I left my truck with a friend (on base, so it was safe), and that good ol’ truck sat for 8 months without moving. She was fired up periodically, but because the tires sat in place for so long, they developed “cupping”* which never worked out. My PCS from Montana to Georgia was made with an incessant, irritating “whup whup whup” during the whole trip, until I had the tires replaced at Costco.

  • That’s what the dealership in Montana called it. I knew the Service manager and trusted him.

Tripler
This was before the days of Bluetooth, so no podcasts to help drown out the noise.

Car dealers also talk of “lot rot.” That is, cars that take a long while to get sold mysteriously develop problems they didn’t have when they arrived. Any minor funkiness in the interior will also edge toward major stinkiness.