If you’ve ever noticed that your wrist pins or bearings seem to be making noise, it’s likely a spun bearing. A spun bearing is a blockage in the oil feed to the bearing, causing the crank journal and main bearing to run without lubrication. This results in a loud knocking noise and short engine run times. While it’s easy to spot this noise, a spun bearing is a sign that it’s time to replace it.
Identifying a spun bearing
If you’ve heard of a spun bearing and wondered if it could be yours, you’re not alone. Spindle bearings are a common problem for cars, but many people don’t realize what they are. These small components stack on top of each other to create pressure on the piston. Consequently, the piston isn’t producing the required power to make your car run, so the engine will begin to buzz and make noise. A car that has a spun bearing will often make a buzzing noise and will likely make a loud grinding noise when you turn it on or off.
A spun bearing may make a knocking noise when the engine cranks, and it’s usually on the bottom end. Depending on where you hear the noise, it could be coming from the wrist pin, which will knock slightly but not quite as loudly as a spun bearing. A good way to check for this issue is to advance or retard the timing of your engine. If you notice the noise progressively getting quieter as you crank, your car may be having a rod bearing problem.
If you hear a knocking noise, you likely have a spun bearing. Spun bearings are the source of a loud knocking noise, and they occur every time you start the engine or move the vehicle. Drivers and passengers alike can hear it in the middle of the night. Spun bearings are caused by a damaged component inside the engine, which can wear out and cause a noisy engine.
Identifying a wrist pin
There are several ways to identify a worn out wrist pin. You can hear the knocking sound when the bearing is spinning, and this is most likely the bottom end. The crankshaft may have a small amount of metal shavings in the oil, but you can’t hear the wrist pin. The small end will be bluish and may not indicate a failing bearing. Press-fit wrist pins are often the culprit for this, as they expand the bore. Full-floating pin designs may also cause this problem.
Checking for crush fit
If you’ve ever installed a spun bearing in your vehicle, you know that a proper crush fit will keep it from spinning while you’re working. The crush is a slight interference fit between the bearing shell and housing, which keeps the bearing from spinning while you’re tightening the cap. Crush fits are often difficult to measure because the bearings have built-in spreads and can be tricky to determine with a feeler gauge.
The reason why your spinning bearing occurred is due to a series of unfortunate events. High operating loads, insufficient lubrication, and journal spin are all factors that contribute to a spun bearing. A good crush fit prevents this problem by promoting better heat transfer between the bearing and housing. If you’re experiencing the problem, it’s important to fix it as quickly as possible. In the meantime, here are a few easy steps to take to make sure your spun bearing isn’t spinning.
When examining a spinning bearing, remember that the crush fit of each half is different from each other. To figure out the crush fit, measure the difference in height between the parting faces on the bearing’s cap and the journal. Then, multiply the total crush by 6.28. Lastly, compare the diameter of the installed bearing to the bore diameter and make sure the clearance is equal to the required size.