GM Century/Lumina/Grand Prix/Intrigue 1997-2000

Buy or Rebuild-

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Now that you have determined that your engine is worn out, you must make some decisions. The question of whether or not an engine is worth rebuilding is largely a subjective matter and one of personal worth. Is the engine a popular one, or is it an obsolete model- Are parts available- Are special tools available. The Dual Over Head Camshaft engines (3.4L VIN X and 3.5L VIN H) covered in this guide require special camshaft holding fixtures for most procedures. If they are not available, you will have great difficulty servicing these engines. Will it get acceptable gas mileage once it is rebuilt- Is the car it's being put into worth keeping- Would it be less expensive to buy a new engine, have your engine rebuilt by a pro, rebuild it yourself or buy a used engine from a salvage yard- Or would it be simpler and less expensive to buy another car- If you have considered all these matters and more, and have still decided to rebuild the engine, then it is time to decide how you will rebuild it.


NOTE
we feel that most engine machining should be performed by a professional machine shop. Don't think of it as wasting money, rather, as an assurance that the job has been done right the first time. There are many expensive and specialized tools required to perform such tasks as boring and honing an engine block or having a valve job done on a cylinder head. Even inspecting the parts requires expensive micrometers and gauges to properly measure wear and clearances. Also, a machine shop can deliver to you clean, and ready to assemble parts, saving you time and aggravation. Your maximum savings will come from performing the removal, disassembly, assembly and installation of the engine and purchasing or renting only the tools required to perform the above tasks. Depending on the particular circumstances, you may save 40 to 60 percent of the cost doing these yourself.

A complete rebuild or overhaul of an engine involves replacing all of the moving parts (pistons, rods, crankshaft, camshaft, etc.) with new ones and machining the non-moving wearing surfaces of the block and heads. Unfortunately, this may not be cost effective. For instance, your crankshaft may have been damaged or worn, but it can be machined undersize for a minimal fee.

So, as you can see, you can replace everything inside the engine, but, it is wiser to replace only those parts which are really needed, and, if possible, repair the more expensive ones.

In the real world, where time and convenience often count more than money, a worn out engine can be simply replaced with one of the following choices:



A good used engine from an automotive dismantler. In some cases, a reputable automotive recycler may even offer a limited warranty on the used engine.
 
A "short block", or "short engine" is a rebuilt engine that includes a reconditioned engine block, crankshaft, connecting rods, pistons, usually the camshaft and maybe the timing set, depending on the engine. This may be an option if the cylinder heads are in good condition and/or may have been recently reconditioned (a "valve job") themselves, but the engine's "bottom end" is damaged. A rebuilt short block from a reputable dealer should have a warranty.
 
A "long block" is a completely assembled, rebuilt engine that includes all the parts in a short block plus reconditioned cylinder heads. Normally you will need to transfer your intake and exhaust manifolds, fuel and ignition systems and other engine accessories. A rebuilt long block from a reputable dealer should have a warranty.
 

Swapping in a rebuilt long block or good used engine is the solution most individuals and even professional shops will use. It is the quickest, and often the least expensive way to return the vehicle to service. On today's front-wheel drive cars, removing and installing an engine can be long, arduous task. Most individuals and certainly all professional shops will only want to do the job once. Installing an engine rebuilt at home, then having to remove it again (perhaps several times) because some component failed, was incorrectly installed, is out of specification or some leak needs to be corrected, can be most discouraging. Professional engine builders deal in such volume that their prices for an assembled, reconditioned engine may be less than the cost of buying parts, having other components reconditioned and then assembling the engine yourself. Dealership parts departments can often order a so-called "crate motor" which is a factory reconditioned or even brand new engine, at surprisingly reasonable prices. You simply open the "crate", transfer a few components from your engine, and you're ready for installation. A new engine (keep the receipt) should have a warranty and may even enhance the resale value of your vehicle.

If you choose to recondition the engine yourself, look into engine rebuild kits. Most popular engines have kits available containing the major components. The crankshaft is generally reconditioned to a standard undersize and matching oversize bearings are included. Pistons and rings, oil pumps, timing chain sets and gasket sets are available. Since the major components in a rebuild kit are reconditioned, or even new, it takes the guesswork out of precision measuring (if you have the proper tools) and evaluating used parts. These kits, purchased from a reliable supplier and carefully installed in your clean and prepared engine block, can produce a successful overhaul.

later in this information, we will break the engine down into its two main components: the cylinder head and the engine block. We will discuss each component, and the recommended parts to replace during a rebuild on each.

 
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