So what can be done to minimize your chances of getting a cracked sump, and even worse, a seized engine?
When choosing a car to buy
Check below the car from the front and rear ends to determine which are the lowermost points, and how close they are to the ground. If you cannot identify any component, and think it is closer to the ground than the thickness of 2 bricks placed one over the other, get someone knowledgeable to check and determine what it is. Look for the presence of a engine protection plate, made of steel, that prevents the sump from being punctured or cracked.
The underside of the sump is the most vulnerable, and so is the gearbox and differential. Drain nuts on the sump/gearbox/differential are especially vulnerable if they are positioned at the lowermost point and are unprotected. Certain components of the suspension can be pretty tough and survive heavy knocks, even if they hit a stone on the road while driving.
While driving
- Don't follow too close behind a high-GC vehicle, like a truck. It can go over a rock, which can damage your low-GC car when you run over it without warning. Leaving a safe distance will allow you space to brake or dodge around that obstacle.
- Negotiate large speed breakers with care. Read about how to do it on this thread.
Once the damage is done
STOP THE CAR!
Once you hear that sickening *CRUNCH*, *THUD* or *BANG* from under the car, pull in by the side of the road immediately (with heavy oil loss, your engine will suffer expensive damage in 30 seconds or less). Do not accelerate. Try to shift to neutral as quickly as possible, turn off the engine (but do not pull out the ignition key), and coast to a stop. Get under the car and assess the extent of damage. If there is any oil leak, do not attempt to start the engine again until the leak is fixed and the lost oil topped up.
Temporary repairs to get you back on the road
Extensive damage to the sump cannot be temporarily repaired, and the only option you have is to have the car towed to a nearby garage or ASC.
Small cracks or holes on the sump can be plugged temporarily using one of the following:
- Epoxy resin putty (e.g. M-Seal, QuikSteel, Loctite)
- A mix of carbolic soap (e.g. Lifebuoy) and sugar crystals
- Chewing gum (not very effective)
Top up with ANY engine oil available at the nearest petrol pump or automobile spares shop - there is no need to be finicky. Even if it is a monograde mineral oil and not your favourite multigrade synthetic oil, it will still lubricate your engine well enough to let you drive to the next service station without your engine self-destructing.
Finally settling the issue...
Most ASCs will advise you to replace the sump. If it is a steel sump and the damage is minimal, removing the sump, hammering out the dent and welding the hole is going to work as well as replacing the whole unit. OTOH, aluminium sumps are more difficult to repair, and brass brazing in expert hands usually produces good results - if in doubt, change the sump. Also check for impact marks on other components such as the suspension arms, and rectify as required.
In the unfortunate event that the engine suffers extensive damage, the likelihood of your ASC or the insurance company footing the bill is pretty bleak. The best you can expect is perhaps 50% reimbursement - it would be your lucky day if you do manage to get the whole bill reimbursed. The standard excuses include:
- Consequential damage to engine, not directly as a result of the accident. Insurance company agrees to pay for sump replacement only;
- User damage, not covered under warranty;
- Insurance company claims that not having an engine protection plate is a manufacturing defect, and manufacturer is liable to pay for damage.
Rebuilding a burnt engine is always cheaper if done at an FNG, but then obviously not many are keen to trust an FNG instead of the authorized service centre.
FINAL WARNING: Rocks on the road can substantially lighten your pocket.