If the engine is cold, weak detonation noises from the engine compartment should not necessarily be a cause for concern. If the engine is warm, then the appearance of metallic hard detonation and rumbling noises, on the contrary, almost always indicate the presence of serious defects. Most often, such defects occur in connecting rod bearings, less often they can appear in the main bearings of the crankshaft. Defects in bearings always mean a complete overhaul of the engine. If you have sensitive hearing, then, fortunately, bearing defects can be detected at their initial stage. If so, then sometimes it is enough to replace the plain bearing shell of the corresponding connecting rod or main bearing - a specialist, of course, will advise you to carry out significant repairs (grinding, nitriding, new installation of the crankshaft, etc.) of the engine units.
How to recognize bearing defects
Accelerate the engine to medium speeds while not moving and then release the gas abruptly. If you then hear a slight detonation noise (nack-nack-nack) and notice this noise also during abrupt acceleration, you can immediately send the engine to a specialized workshop. Such noises are a typical sign of a defect in the connecting rod bearings.
If you initially ignored the noise (nack-nack-nack), then after a few kilometers you may hear a hard "click-click-click": the bearing defect has worsened, the bearing shell has melted and most likely the crankshaft is already damaged. You can forget about cheap repairs - you will have to put up with a completely replaced engine or some of its components. If a uniform rumbling noise is heard from the crank mechanism, increasing synchronously with the engine speed, trouble has happened with the main bearings. Stop the engine immediately, and then diagnose the damage in a workshop.
If you wait a little longer, a new danger will arise - you will have to scrap the entire engine block: the bearing shells "rotate" in the bearing locations and instantly turn the block into unusable scrap iron. All this will require repair costs in the amount when your dealer will no longer be able to offer the old cylinder block as a replacement.
| PRACTICAL ADVICE | |
|