1998 Chevrolet Monte Carlo

The Monte Carlo is basically the 2 door version of the lumina. Thru the years it had 3 different engines available, the base 3.1 (3100), the earlier twin cam 3.4, and the much preferred 3.8 (3800) 90 degree V-6. The 3.1 is of course the most common, the other 2 offer extra horsepower at the expense of gas mileage. There are also reliability and difficulty of repair/maintenance issues associated with the 3.4 twin cam, (not to be confused with the standard 3.4 used in other GM vehicles such as Malibu).

There are only a few well known, well documented problem areas with this car and they are all engine related and it's not a matter of "if", but a matter of when. The first issue is well known on the 3.1, it is an oil leak at the oil pump shaft block-off. There is a hole cast into the block for access and it has a plug in it. The plug eventually leaks, not really bad, more of an inconvenience, the worst I've personally ever seen is leaking a quart or 2 per month. The repair although simple is time consuming, figure 2 to 2.5 hours labor.

The second issue is also a problem in many other GM engines as it involves the coolant system, more specifically DEXCOOL which has been GM's coolant of choice since 1995. DEXCOOL is advertised as lasting 5 years or 150,000 miles before needing maintenance...Sigh...if only that was true. DEXCOOL eats at internal gaskets, specifically in this particular engine it eats the Lower Intake Manifold (LIM) gasket. Depending on where exactly the damage begins, it will leak either externally (coolant will seep outside and down the block), or in the much worse but more frequently occuring leak, it will be internal, with coolant mixing with the engine oil, most usually discovered at an oil change with a chocolate milkshake type substance on the inside of the oil fill cap. It will get progressively worse, overheating from coolant loss, and the possibility of internal engine damage if enough coolant mixes with the oil preventing the engine from being properly lubricated. The repair is to replace the LIM gaskets and a coolant system flush, figure about 4 hours labor. A more rigorous maintenance schedule such as flushing the DEXCOOL yearly may stave off the problem, but in an older used car it's probably too late. A Google search of DEXCOOL will bring up 1,000's of hits relating to this issue.


The third issue is known as "piston-slap". It is a tapping, clicking, rapping etc. etc. type noise that is only heard on start up, lasting maybe a couple miles or up to 5 minutes. It is also very well documented and there are some class action issues about the 1999 and up model years being addressed (Google it up!!). If buying a car, make sure the motor is absolutely stone cold before starting it up, a warmed up car will mask this problem. I'm not sure if piston-slap is a reliability issue or more of a nuisance, but it can definately affect the value of a car.