Common problems associated with late model GM engines
Which engines to avoid
I recently published a hub on what to look for when looking at a used car. I thought I would write another one on which engines you should avoid, and which ones are desirable.
I would avoid, at all costs, 2.4L quad four engine. This engine has an internal water pump which when it wears out, will leak antifreeze into the oil sump and wear out the bearings on the bottom end of the engine. Replacing the water pump is a major job due to the lack of room in the engine compartment also. Replacement parts are also something of a problem, due to the fact that the supply of good used parts have somewhat dried up in the 11 or 12 years since this engine has been out of production. New parts are obtainable, but they are also expensive.
The 2.2L ecotech engine is another, in my opinion, which should be avoided. This engine can be identified by the coil pack on the very top of the engine that says "2.2 Ecotec". It is a dual overhead cam design, unlike the old 2.2 which was a single cam design. These engines are known for oil filter issues if the AC fliter is not used. Aftermarket filters such as Fram or Purolater are a fraction too tall and this will cause the filter to collapse onto itself and oil starvation will result. These engines are also known for jumping time. If the timing gets off to any large extent, the valvetrain will not be in sync with either the compression stroke or the exhaust stroke, and major damage will result.
In 3.4L engines made in the last 10 years, a common problem is intake and head gasket issues, at around 140000 to 160000 miles. The Dexcool antifreeze that was recommended along with a poor gasket design make gasket issues a nearly unavoidable problem. The good news is that the replacement gaskets are much thicker then the factory gaskets and, if the work is performed by a good mechanic, no further problems should be encountered. The design itself is a very good one, so once the gasket issues are addressed, you should get good service from it.
I would also avoid Northstar V8 engines found in Cadillacs, especially those from the early to mid 1990s. The head gasket design combined with a very poor thread design in the engine block is a recipe for disaster. The threads will strip when you loosen the head bolts to remove the cylinder head. I have been told that there is an aftermarket kit available online that fixes the thread problem, but as I have had no experience with it, I can't say how good it is. A replacement engine block will cost anywhere from $6,000 to $7,000 dollars, so my advice would be to just avoid this design.
As always, be sure to have a mechanic or someone well versed in auto mechanics look over an automobile before buying it. Spend some time researching potential problems online. There are many good sources of information on the internet, or call an auto shop and ask them what sort of problems are associated with a given design. There are a lot of unscrupulous sellers out there, so let the buyer beware.
Good luck and happy motoring.