Old Car Engine Repair and Restore

Just because your classic car is old doesn't mean the engine needs a rebuild. Minor symptoms by themselves may be repairable without pulling out the motor and doing a complete overhaul.

old car engine repair

To determine what is the best course of action, consider the following engine conditions and symptoms.



Excessive Mileage

One of the more common reasons for an engine overhaul is excessive mileage. Today's modern car engines can run for 200k + miles, but on a 1970s or older model, anything over 100k is considered high mileage.

Poor fuel mileage is another reason. It might be hard to tell on a large V8, but anything below 10 mpg on the highway is probably a good indicator the engine is old and tired.

Excessive Oil Consumption

Years ago, I had a 1971 Camaro that burned a quart of oil every 250 miles. Turns out a piston ring was broken, but it still ran OK. Anything more than a quart every 500 miles tells you something is wrong.

Sometimes you don't have a clear indicator of whether or not an engine needs a rebuild, but if you have several minor issues (for instance, bad mileage and oil consumption), it may a good idea to rebuild the entire engine.

Poor Engine Compression

Readings of 30-35 psi lower than specs indicates worn rings or valves (or both). If one or more cylinders read considerably lower than the highest one, those cylinders are most worn. It's always best to do a compression check when the engine is warm, but it can still be performed if the engine doesn't run. It just needs to be able to crank at normal speed.



Engine Testing Tools

For checking engine compression, you need a compression gauge.

tools needed to work on engines
Hand-held engine compression tester with quick-release.

Compression Tester

The two common varieties of compression gauge will have either a rubber tip (that you need to hold down) or a thread-in fitting that goes into the spark plug hole.

tools needed to work on engines

Shop: Engine Compression Gauge


Can I Rebuild An Engine Myself?

If you decide that a complete engine rebuild is necessary, you may find yourself asking, "Can I rebuild an engine myself?"

Here are some points to consider.

Work Space - You will need a clean place to work in, preferably a well-lit and secure You'll be leaving various engine parts around, so try to keep people out as best you can without offending them!

Mechanical Ability - Some people are naturally mechanically inclined. My guess is that if you're reading this article, you are.



Tools Needed To Rebuild Engine

Aside from basic hand tools, you'll be needing a piston ring installer, a torque wrench, dial caliper, feeler gauge, harmonic balancer remover and installer, and possibly others.

piston ring installation tool

Read: Tools Needed For An Engine Build

There's a few outside sources needed while restoring your engine, which include a parts supplier, a tool supplier, and a machine shop.

Shop Manual - When restoring an old engine back to new condition, a factory shop manual for your make and model car is invaluable.

Machine Shop - Without expensive, dedicated equipment and a lot of experience, you'll need to farm out steps such as block boring, crank and rod balancing, and cylinder head rebuilding.

Parts Supplier - It seems like good auto parts stores and good parts guys are becoming a thing of the past. That's where the internet helps the old car hobbyist.

If you're removing the engine, you'll need to rent or buy an engine hoist.

engine repair and restore

Shop: Heavy-Duty Engine Stand

spray painting engine

Rebuilding an old engine requires patience. There are many small steps in engine rebuilding, each as important as the others. It could become long and complex, particularly if parts are hard to find. You need common sense and you need patience.



Never Take Anything For Granted

Rebuilding your old car engine requires measuring and re-measuring, assembly, disassembly, and reassembly. Make sure everything is right before continuing to the next step.


Crate Engines (Short Block vs Long Block)

If you don't want to rebuild your old motor, there are numerous crate engines on the market. A short-block will include a pre-assembled block with connecting rods, pistons and crankshaft.

crate engine swap

A long-block gives you all a short-block does, plus cylinder heads, valvetrain, and engine tin, which usually includes a timing chain cover, valve cover(s), and oil pan.

engine swap basics

Most crate motors do not include manifolds, accessories, and wiring harnesses.


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Engine Swap Basics