can anyone give me a run down of what work is usually done in an engine rebuild? any price ranges? and if it is better to pay to have an engine rebuilt or buy a rebuilt engine and swap? these may seem like dumb questions but i am young and fresh in the mechanic scene.

 

Depends greatly on the engine, and reasons for the rebuild.

An older engine being 'freshened up' might simply have all the seals and gaskets replaced. An engine that's been over heated, might simply get a head gasket (or two), have the heads machined flat and reassembled. A 'complete' engine rebuild may go as far as replacing all the bearings, piston rings and/or pistons, machine the cylinder walls, head work, all the gasets and seals, etc. etc.

It all begins with the question of 'why' the engine needs to be 'rebuilt'. Here's three examples from my life...

I popped the motor in my street car, a 1988 Audi 90 quattro. At the time it was simply a 'go to work and back' vehicle, nothing special. A rebuilt motor in the case was as simple as pulling the engine out of a parts car and popping it in...I think changed the oil, that was it.

I recently swapped the motor in my rally car from a 10 valve engine to a more powerful 20 valve motor. In this case I have three engines on the go. The first engine was a simple swap, untouched before install. I took it from a running car, simply to ensure that all my wiring and changes allowed the engine to run. Much easier to diagnose using an engine and sensors that are known runners then chasing down problems. Engine number two is a 'simple' rebuild. I'm replacing all the seals and gaskets, as well as the rod bearings as some were scored when inspected. All components have been measured to ensure they are within 'factory' specs. When finished, this engine will be a 'factory fresh' rebuild, no better (or worse) then the same engine from the factory.

My third engine is a performance rebuild. Here I'm doing everything engine #2 is getting, but I'm going further with the 'in spec' components. I'm porting and polishing the head, to take better advantage of some custom cams that are going in. The pistons are custom, better and lighter rods, heavier valve springs, etc. etc. No expense is being spared, and everything is being measured and remeasured, test fit, and refit. When finished, this rebuilt engine will have far more power and safely rev far past the factory rev-limit.

Why do you want to rebuild, and what are your goals after doing so? Those are the important questions.

-Dave

 

Depending on what needs to be done, it may be cheaper, and certainly quicker, to just get a rebuilt longblock. Most come with a nice warranty too.