Cause of a Spun Rod Bearing | Eagle Specialty Products

I spun a rod bearing. What happened?

So you heard a knocking sound in the bottom end. You shut the engine off and tore it down. Your rod looks something like this and you are wondering "what happened?"...It may have even broke, but the big end is discolored like in the picture.The discoloration is a result of excessive heat. Almost without exception, this is caused by a spun rod bearing. Rod bearings spin due to a collapse of the oil film between the crank journal and rod bearing. Why this happens is a topic of great discussion. Mahle/Clevite has a very nice guide on their website to help you diagnose bearing wear patterns and failures. To view their guide, click HERE . When discoloration is visible (even a very small amount) the rod has been heated enough to compromise or ruin the heat treatment in the steel. This can have unpredictable effects on the strength of the rod. It is impossible to be sure if the rod can be used reliably once this has happened. The best course of action is to replace the rod. See our FAQ topic on single rods for information on ordering single rods.

Can a discolored rod be used?

The problem with using a discolored rod is not the coloring, but what caused it. The only way a rod will discolor is if it is exposed to excessive heat. When the rod is heated like this, it has an unpredictable affect on the heat-treatment of the material. It might be fine. It might not. Even if you replace the bolts and resize the big end, there is not much you can do if the heat-treatment of the material has been compromised. The best course of action is to replace that rod.

Can I buy a single rod?

Single rods are available through any of our dealers. If your dealer will not get them for you, they can be purchased through Eagle. You will need to call us directly to order. Our phone number is 662-796-7373. We are open Monday through Friday, 8:00 am to 5:00 pm CST. We accept Visa, Mastercard for orders. The price of single rods is not the set price divided by the number of rods in a set! If you bought your car one piece at a time it would not add up to the price the dealer charges for the entire car! Please call us for pricing.

There is some information you need to have before calling!

Since all sets of Eagle rods are sold in weight-matched sets, we will need to know the weight of one of the rods in your set so we can be sure and send one to you that will keep your set weight-matched. Eagle weighs the big end and small end separately when we put sets together and we would like your rod weights like that also if possible. If you do not have the means to do this, then total weight will just have to do.