Toyota recalled 250000 vehicles, because the pump resin impeller swelling, swelling how terrible? This hidden defect will have to wait several years to be discovered, not only the resin, these places are also prone to failure.
On April 17, Toyota China announced a recall of 250000 vehicles with defective low-pressure fuel pumps. For some vehicles within the recall scope, due to the imperfect resin forming conditions in the manufacturing process of low-pressure fuel pump impeller, the resin density of impeller is insufficient. The impeller may be affected by fuel, resulting in swelling deformation, and interference with the low-pressure fuel pump housing, resulting in poor operation of the low-pressure fuel pump. In extreme cases, the engine may be shut down while the vehicle is driving, and there is a potential safety hazard.
What is swelling deformation?
First of all, what is bentonite? In fact, resin, rubber and other parts absorb the solvent (gasoline, engine oil) and swell. Swelling is the phenomenon of volume expansion of polymer in solvent. It can be understood that organic solid is being dissolved, but it is not completely dissolved in solvent. In this process, the volume of organic solid will become larger, the density will decrease, the strength will decrease, and the organic solid will start to expand. And the limit of swelling is dissolution. Organic solid disappears completely and dissolves in solvent.
Resin impeller resin impeller
In the case of Toyota recall, the impeller of fuel pump is made of resin material, which has swelling in gasoline (solvent). We all know the similar and compatible chemical principles. Resin and gasoline are organic matters. Gasoline has a very strong ability to dissolve organic matters. Natural rubber will have a strong swelling in gasoline, and finally completely dissolve in gasoline. This time, Toyota also said that due to the "imperfect resin forming conditions in the manufacturing process, resulting in insufficient resin density of the impeller", the insufficient density is more likely to cause gasoline to penetrate into the resin, resulting in swelling. Toyota's solution is to replace the low-pressure fuel pump.
Where will swelling happen?
As long as the rubber parts and resin parts contact with gasoline, engine oil and other organic solvents, swelling may occur. And this kind of defect is likely to be ignored by manufacturers, because it will take a very long time for them to have fault performance, and at this time, it often exceeds the vehicle warranty time, so they can only pay for repair.
For example, the M271 engine oil filter base of Mercedes Benz. After driving for many years, the rubber of the filter base and the engine oil have a "dissolution swelling" reaction, which makes the rubber parts lack elasticity or even cracking, resulting in the cooling water flowing into the engine oil cycle, which is manifested in the floating of engine oil on the coolant pot, the increase of engine oil, the emulsification of engine oil, etc. The solution is to replace the oil filter base.
How to avoid swelling?
To the regular gas station, avoid adding too much gasoline additives. In many gasoline additives for cleaning carbon deposits, polyether amine pea, a chemical that dissolves carbon deposits, has very strong detergency and solubility, and various rubber sealing rings and gaskets are prone to swelling. If each tank of gasoline is added, it must be added in a small amount, and the proportion with gasoline shall be controlled within one thousandth, that is to say, 1ml additive can be added to 1L gasoline. Or choose to add deep cleaning additives every 5000 km.
Engine oil additives are produced by large factories. Engine oil additives will break the additive formula of the original engine oil and easily lead to rubber swelling. Therefore, regular engine oil additives must be selected. At the same time, some oil additives can protect the rubber and can be added every 10000 km.
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