Old engines need their main bearings replaced.
When your engine's main bearings are worn, it will leave very specific clues to their failure. These symptoms include noisy or clunky operation, low oil pressure indications, and metal shavings in your oil. Obviously, noisy bearings can be heard upon startup and while driving, and a low oil pressure light will usually come on your instrument cluster when it isn't adequate. If you see these two indicators, then you should check your oil. The first thing you should do is open the hood and pull out the oil dipstick. Now wipe it clean, drop it in, and then pull it out again to check the level. If it's low, give it a top-off. Now run your engine for about 3-5 minutes and turn it off. Check the dipstick again, and if you see tiny glittering metal shavings in your oil then your main bearings are worn down or cracked. Not only does this contaminate your oil, but it will inhibit the crankshaft from dispensing oil through the crankcase. This leads to lubrication problems, engine seizing, and ultimate failure. Clearly, this is a potentially large problem that should not be overlooked.
Where are the main bearings, and what do they do?
Crankshaft main bearings are found at either end of the crankshaft and between each connecting rod journal. They provide a smooth surface around which the shaft can rotate, and will prevent it from wearing out the inner surface of the main bore. Almost all main bearings are split into halves, and will have an oil hole so that the engine oil scooped up by the crankshaft can be distributed through the rods and the rest of the crankcase. Main bearings are composed of a multi-metal compound called Babbitt, and can be a mixture of iron, copper, steel, zinc, aluminum, etc. They will usually ; however other lubrication related problems can take their toll on the crankshaft and bearings.
A fun project... if you have the time.
If you are wondering how to replace main bearings in your engine, we can tell you. It is a complicated job, and without the proper tools and experience it might be wise to take your car to a mechanic. Keep in mind, every engine is different. But here's how it's most commonly done:
- First, you will have to remove the engine from your vehicle. This involves draining all fluids (coolant, oil, brake/hydraulic fluid), disconnecting all wire harnesses, cooling hoses, brake parts, vacuum lines, and finally unbolting the driveline components.
- Once the engine is out of the compartment, it needs to be mounted to an engine stand and turned upside down. This will allow you to remove the oil pan.
- Next, take your time to remove the connect rod bearing caps one at a time. Make good notes of their locations and positions for re-installation later.
- Now you can remove the main bearing caps to expose the bearings. Just like the rod bearing caps, you should number the caps from front to back so you know where they will be re-installed.
- You can now replace the damaged or worn main bearings with new ones. The half bearings will install on each side of the crankshaft journal, so you will have to lift the crankshaft out of the crankcase to access all the bearings.
- Finally, you can now rebuild the engine that you just took apart. Remember to follow all the steps in reverse, and torque everything to the manufacturer's specifications.
Use only the best internals for your engine re-build.
The amount of labor going into installing a set of new replacement main bearings is considerable, but that doesn't mean the bearings themselves need to be expensive. At Car Parts Discount, we carry only the highest quality engine main bearings from top manufacturers and original equipment suppliers. Plus, we are ready to ship your order right away. That means you get a great part in as little time as possible. Why go anywhere else?