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March 2024

Toyota Corolla Start-up rattle fix

My Toyota Corolla 2010 started to make a strange rattle sound at cold start. It's a common problem and on youtube you can find many Toyota Corolla owners describing this problem. Toyota itself claims that this might be due to a problem with the VVT (variable valve timing) cam-gear and the fix would be to replace this part. I am not really sure that this true or that there is just a single cause for this start-up rattle. My theory is that the fault on my car was due to the chain hitting the case and rattling for a second at startup. In any case I don't know the exact mechanical cause but I know the symptoms and I know that it was possible to fix this at a cost of 10$ without visiting a Toyota garage.

corolla vvt gear with chain and camshaft
a view of the corolla vvt gear with chain and camshaft. I never opened my engine. This is a picture from another car and you can see that there is a chain driving the camshaft.


The symptoms of the start-up rattle:

In other words my problem was maybe related to the viscosity of the oil and/or sludge and gum deposits on the chain or the chain tensioner. I fixed it by adding a bottle of "Rislone Engine Treatment" (part number 34102) to the oil. This might have improved the oil flow and disolved some deposits. I added it after a fresh engine oil change and at that point the oil level was already at max. So adding one bottle of this Engine Treatment liquid resulted in slightly too much oil volume. The rattle disappeared after I had driven about 30km over 3 days (the last rattle was on the 3rd day after adding Rislone and it has not come back since). I added the "Rislone Engine Treatment" during the winter months when I would normally observe this start-up rattle problem very frequently. I have now driven for more than a month without ever hearing the start-up rattle and I am faily confident that the problem is resloved.

corolla: add Rislone Engine Treatment
corolla: add Rislone Engine Treatment to fix start-up rattle problem
Rislone Engine Treatment bottle front and back
Rislone Engine Treatment bottle front and back, part number: 34102


I will leave the Rislone Engine Treatment in the engine for few more weeks and then I will do an oil change around mid March (at that point I will have driven about 350km with Rislone Engine Treatment in the oil). After the oil change I will not add anything back because I believe that this Rislone Engine Treatment has actually disolved some deposits somewhere and it should be a permanent fix to the problem. If it does not work out as planed and the rattle comes ever back then I would update this article and let you know.

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