How to check up on a late model used car

In the old days of car shopping, you’d take a used car for a compression test, pressure test the cooling system before you bought it. Now, my mechanic says if the check engine light isn’t on, there probably isn’t much he’d find wrong with the car. Is he missing the boat? Are there checks that should be done, beyond a eyeball for collision damage In looking at a 2007 Mazda5. Are there mechanical check that should be done. I don’t mind paying for an hour or two of labour when I’m spending at least $10,000 on a possible clunker. Thanks.

There is some valid basis for the mechanic’s assessment. The ECM continues to monitor the engine for emissions, and any problems would set a ‘check engine’ light (CEL). But, the mechanical tests you mentioned are still a good way to determine the mechanical condition of the engine. I’d like to add a hydrocarbon test for the cooling system and a leak-down test of each cylinder to get even more data on the mechanical condition. Even a mechanical gauge on the oil pressure system. This would give a better picture of the wear this engine has experienced and can detect problems before the dreaded CEL is lit.

The vehicle should be put on a lift so the brakes, exhaust, suspension, and fluids can be inspected. Also, with the vehicle on a lift sometimes collision damage is revealed.


An engine can have major problems without having the CEL on so I think your mechanic is off base here.

Ask him to show you the code for lower than normal compression on Cylinder 2 or a code for abnormally low oil pressure.

Sometimes what people say isn’t what they really mean. I think what your mechanic means is that he’s not really interested in looking at the car.

If he truly believes what he said, you need to find a more competent mechanic.

This probably is a case of a mechanic who doesn’t really want to look at the car. Some mechanics would see this as a waste of time they could otherwise be spending doing something that will make them more money. I never really cared too much about such things, but some mechanics do.

There’s another issue as to why some mechanics don’t like performing inspections. There is simply no way on Earth that even the most comprehensive of inspections by the finest mechanic on the planet will guarantee the buyer a problem free car. It may improve the odds quite a bit but that’s all it does.

They may pronounce the car fine and if a problem surfaces a week, month, or even a year later the buyer of that car may be upset with the mechanic who stated the car was good to go.

Save A Little More Money And Then Shop. You’re In That Getting Stuck With A “Possible Clunker” Price Range.

I buy used cars with factory warranty coverage for the very reason you are discussing.

The 15 month old, 2009, 10,000 miles GM certified used car I recently bought has (balance of) factory warranty coverage up the tailpipe, both bumper-to-bumper (car qualified to extend to 48 months / 48,000 miles) and drivetrain (60 months / 100,000 miles).

This car cost very little more than a car with 4 or 5 times the miles and a model-year or two older that wasn’t certified. It took a couple months of digging, but I found it.

Ecellent idea to check for collision damage / repair, as you suggested. I managed a body shop for a couple of years so I’m pretty good at eye-balling and always look underneath, too.

The warranty coverage still won’t assure you that the car is free of defects, but you’ll be getting the same protection as buyers of brand new units.

I can drop 5 or 6 grand on a car with no warranty after I’ve checked it out. However, there’s no way I’m spending 10 to 20 thousand and not getting a decent warranty. I don’t sleep nights doing that.

Keep saving. Start shopping. Get plenty of restful nights.