My MazdaSpeed 3 engine blew up, so I bought a new one. When I saw my new engine, it was painted in gray color. My previous mechanic said it was brand new and he bought it from a company from eBay. When my new mechanic saw the engine, he said it seems like the engine came from a dismantling shop. He said mechanics have a term for these kind of engines and they call it "Mexican Chrome". What the dismantlers do is they paint their engine gray to cover up the dirt and other damages and sell it off as is. My new mechanic was not sure about it, but I am certain my previous mechanic just ripped me off. I don't really know what to do. The previous mechanic said he bought the engine for $4500.

How can I tell if the engine my old mechanic bought and installed is new?

  • Gah, another "my mechanic ripped me off"... A reman long block is $4000, with shipping, probably close to $4500... edgeautosport.com/…
    – cory
    Commented Oct 17, 2016 at 18:43
  • 3
    @cory - I don't think the question is "should the engine have cost $4,500" – the question is "did I get what I paid for?"
    – dlu
    Commented Oct 18, 2016 at 2:05
  • What year is your car? The specific engine you have may not be available "new" but instead as a remanufactured part. There is nothing specifically bad about that if it is remanufactured by a reputable company. But they should have been upfront about that if that is what they did. As an aside I just ordered a remanufactured alternator for my BMW because I felt like the new one available was a generic knockoff and I prefer the original quality part.
    – Ukko
    Commented Oct 18, 2016 at 16:26

6 Answers 6


Engines have an "engine stamp." Find it, write down the numbers on it and call the Mazda Head Office for your region (delearship can't always help for this). They will tell you which car the engine was previously installed in, if any.

Also, licensed mechanics don't buy parts off eBay, they buy parts from reputable distributors, both for warranty purposes and the possibility of exchanging the part if it proves to be the incorrect one.

Also, brand new engines don't get sold on eBay, they get sold by the manufacturer directly.

  • 1
    Brand new engines are also sold by approved third parties. Usually dealerships or businesses with a direct relationship to the manufacturer.
    – race fever
    Commented Oct 17, 2016 at 15:56
  • 5
    Brand-new engines are sold on eBay when they fell off the back of a truck.
    – Mark
    Commented Oct 17, 2016 at 20:37
  • Brand new aluminium block engines are not painted.
    – John U
    Commented Oct 18, 2016 at 14:22

It definitely sounds like you have been ripped off.

It honestly sounds like the old mechanic is up to no good. You can search the VIN which is stamped on a metal plate on the engine to make sure it is not stolen or money owed on it, which can be verified with Mazda. Another thing you can do is remove something external like the coil pack to see if there is debris or dirt in there. If there is, the engine has likely been used.


A few objective ways to do this:

  • perform a compression test

    This will not help much if the engine was only slightly used but you would be on the lookout for wild discrepancies across the cylinders and compression values that are out of spec

  • inspect the spark plugs for wear/fouling


You can do a quick and rough check by looking at the paint job – if the paint is fresh and the engine really is new the paint will be the factory color and there will be clean demarkation between what's painted and what's not. Some things to look for:

  • There should be no overspray on the wiring harness or belts.
  • Mating surfaces will often be masked and have clean lines between painted and not painted. One place to look is the joint between the engine and transmission.
  • The engine stamp is often in bare metal as well.
  • Accessories (alternator, power steering pump) and the oil filter should also be free of paint or overspray.

Take a look at some other Mazda engines and you should get a good feel for what the factory paint job looks like – and you'll see what the factory paint color is. If the engine looks right, that's not proof that it is new, but if the paint job doesn't look like a factory job odds on it's not a factory new engine.

It's worth being clear about what everybody means by "new" here. As a model ages there will be engines in the supply chain that the official sources want to get rid of – so you could find a NOS (new old stock) engine on E-bay or through a third party dealer. Also, I could see some people referring to a rebuilt or remanufactured engine as "new." Depending on the quality of the job and the integrity of the shop that did it, the engine might well be "as good as new." The engine shop I worked for took as much pride in the paint jobs as they did in building the engines, but not everybody will be like that, and different shops may have different opinions about when to paint in the rebuilding process. We painted after the engine passed dyno and did a lot of masking.


Remember that your previous mechanic might have bought the engine under the impression that it was new, and although he probably should have guessed the difference, he may have shoved it in anyway to save himself hassle and time.

Although this is quite obvious, are there any signs of previous use? Main way I check is to unscrew any caps and check the interior and reverse of the cap as these are the parts can show - does the interior look scratched, worn or well used? If the radiator came as part of the new engine, is there any rust insde the cap? If you are confident about engines, you can also unscrew a bolt or screw and check what the metal looks like underneath these. If a new engine it should show new metal / new paint underneath as per condition of the surface around it. (Although a dismantling shop that is good at this will repaint each part individually, so surfaces under bolts etc won't look any different)

Just because it looks fine, doesn't mean it's new - these things can be covered up. They just may give you an indication.

If nothing like that shows any wear, or previous use, then as before - checking the engine stamp or number with the manufacturer should give you an answer, or an interior check of the engine should show up pretty soon whether or not it's new.


Compression test is the most important thing. If its making good compression, who really cares if its brand new or a rebuild? Good compression is good compression! But like others said, check the stamp, that's the main indicator of the block age. Even still, the engine could have been rebuilt instead of being brand new...so caveat emptor. My thing is always compression rather than trying to read plugs or any other system that is subject to error. The compression test or better, a dyno test, is objective and empirical.

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