Checking the condition and selecting the liners of the main and connecting rod bearings of the crankshaft (Honda Accord 6)

Checking the status

Although crankshaft bearings must be replaced during a major engine overhaul, old liners should be kept for careful examination of their condition, the results of which can provide a lot of useful information about the general condition of the engine. The illustration shows examples of typical bearing liners defects. Bearing failure can occur due to insufficient lubrication, dirt particles, engine overloads, and corrosion. Regardless of the nature of the defects, the cause of damage to the liners must be eliminated during the engine overhaul to prevent recurrence.

For inspection, remove the bearing shells from their beds in the engine block/lower connecting rod heads and main/connecting rod caps and lay them out in the order of installation on a clean work surface. The organized placement of the shells will allow you to link the nature of the detected defects to the condition of the corresponding shaft journals.

Dirt and foreign particles enter the engine in various ways. They can be left inside the block during assembly of the unit, or penetrate through filters or the crankcase ventilation system. All particles that get into the engine oil eventually end up in the bearings. Often, metal filings formed during the normal operation of internal engine components are embedded in the soft material of the liners. There is a high probability of the presence of traces of abrasive in the bearings, especially when due attention was not paid to cleaning the block after the completion of the engine overhaul. Regardless of the method by which foreign particles get into the engine, they are highly likely to end up embedded in the soft surface of the crankshaft bearing liners and are easily detected during a visual inspection of the latter. Large particles are usually not retained in the liners, but leave noticeable traces on their surface and the surface of the shaft journals in the form of scratches, cavities and scuffs. The best guarantee against such troubles is a responsible attitude to cleaning components after the completion of a major engine overhaul and careful observance of cleanliness during assembly. Frequent regular changes of engine oil also allow you to significantly extend the service life of bearings.



Oil starvation can be a consequence of several different, but often interrelated phenomena. Thus, engine overheating leads to dilution of the engine oil and its displacement from the working clearances of the bearings. Insufficient lubrication of the bearings can be explained by excessive size of the working clearances, as well as by common leaks (internal or external). A common cause of oil displacement from the bearing clearances is constant overspeeding of the engine. Violation of the oil flow (usually associated with improper alignment of holes during installation of components) also leads to a reduction in the supply of lubricant to the bearings. A typical result of oil starvation is complete or local wiping/pitting of the surface layer of the liners from the metal substrate. In this case, the operating temperature can rise to such a level that the substrate acquires a bluish tint as a result of overheating.

The driving style of the car owner also has a significant impact on the service life of bearings. Driving at low speed in high gear leads to significant overloads of the bearings, accompanied by the displacement of the oil film from their working gaps. Such overloads lead to increased plasticity of the liners and the occurrence of cracks in the surface layer (fatigue deformation). In this case, the surface material begins to crumble and separate from the steel substrate. Operation of the car in the urban cycle (frequent short-distance trips) leads to the development of bearing corrosion due to the fact that insufficient engine heating entails condensation and the release of chemically aggressive gases. These products accumulate in the engine oil, forming slags and acids. When such oil gets into the bearings, aggressive substances contribute to the development of corrosion of the liners.



Incorrect installation of liners during engine assembly can also cause their rapid destruction. Too tight a fit does not provide the required working clearance of the bearings, which leads to their oil starvation. The result of foreign particles getting under the liners (during their installation) is the formation of elevations, the surface layer of which is quickly wiped off.

Selection of inserts

In case of wear or damage to the main bearing shells, and also when it is not possible to achieve the correct value of the working clearance (see Section Installing the crankshaft and checking the main bearing clearances or Installation of connecting rod and piston assemblies and checking the size of working clearances in the connecting rod bearings of the crankshaft), the situation can be corrected in the manner described below, by selecting and installing new liners. If the crankshaft has been machined, it must be equipped with liners of the corresponding repair (with reduction) dimensions (in this case, the procedure described below should not be performed). Usually, the selection of liners is carried out by specialists who performed the machining of the shaft journals. Regardless of the method for determining the required liners size, the working clearances of the bearings must then be checked using the Plastigage measuring kit (see below).

Note: If the working clearances cannot be adjusted properly by selecting liners, the shaft must be replaced.

Main bearings

1. When selecting new STANDARD size inserts, select the one that has the same color marking as the old one.





2. If the color marking of the old bearing is lost, find the marking stamped on the block in the area of the corresponding bearing cap. 3. Also check the marking of the class of main bearings on the shaft itself.




4. When selecting new bearings, use the appropriate bearing color identification card.

Connecting rod bearings

1. When selecting new STANDARD size liners, refer to the color markings of the components removed from the vehicle.

2. If the color code on the old liners is lost, find the marking on the lower heads of the connecting rods. The mark in the form of a number characterizes the size class of the connecting rod bearing (do not confuse it with the cylinder number).

3. Also check the letter marks on the shaft itself, which determine the size of the corresponding crankpins (see accompanying illustration).

Identification chart for selecting crankshaft main bearing shells for 4-cylinder engines - use the markings applied to the engine block and crankshaft assembly, for example: marking C3 means the need to install yellow and green liners (where they should be different colors), and either of them can be installed in both the bearing cap and its bed in the block

Identification chart for selecting crankshaft main bearing shells for V6 engines

Note. On 4-cylinder engines, the letter-and-digital marking of the bearing journal class is applied to the cheek of the first crank or stamped next to each journal separately. 4. When selecting new liners, use the appropriate identification card of the bearing color marking.

Identification chart for selecting crankshaft connecting rod bearing shells for 4-cylinder engines - use the markings applied to the crank webs and the corresponding connecting rods, for example: marking D4 implies the need to install blue liners



Identification card for selecting crankshaft connecting rod bearing shells for V6 engines - use the markings applied to the crank webs and the corresponding connecting rods, for example: marking D4 implies the need for brown bearing shells (please note that in some cases a combination of two different bearing colors is required)

All bearings

Remember that the final parameter determining the correct selection of liners is the result of measuring the working clearances in the bearings. Feel free to contact representatives of Honda branded service centers with any questions.