How To Fix Timing Chain Noise on Cold Start
How To Fix Timing Chain Noise or Rattle on Cold Start (Maybe)
Worth a try as you got nothing to lose even if it doesn’t help. At the very least you will have a cleaner engine.
How To Fix Timing Chain Noise
Rattle on cold start is sometimes (not always) caused by a bad chain tensioner. Timing chain tensioner utilizes oil pressure to keep timing chain under tension while engine is running.
However, oil pressure will drop when car is parked for hours or overnight. Timing chain tensioner will need to keep pressure to ensure timing chain stays under tension on a cold start. Some designs utilize a mechanical spring but there are some designs which use a check valve to keep oil pressure up inside chain tensioner when engine is not running.
How To Fix Timing Chain Noise or Rattle: Check valve will get dirty with sludge (neglected oil changes) won’t close properly and allow oil pressure to bleed when engine is not running. Bleeding of oil pressure from tensioner check valve will cause timing chain to lose tension. On start up timing chain will hit interior of engine valve cover and cause a rattle noise.
There is something you can try which might work to fix a timing chain rattle on cold start. Since it will only cost an oil change and a liter of ATF, it’s worth a try.
Automatic Transmission Fluid (ATF)
Automatic transmission fluid has high cleaning capabilities and might help clean chain tensioner check valve sludge to make it hold normal oil pressure again.
It does not matter what kind of ATF, go to Canadian Tire or any automotive store in your area and buy cheapest one you can find.
How to do it: Drop 1 liter of automatic transmission fluid in your engine prior to oil change. Leave your car idling for 20 minutes or so, idling only.
Do Not Drive or Rev Engine, Idling Only.
Afterwards, change oil and filter. Check if rattle is still there next morning. If timing chain still rattles, is time for timing chain tensioner replacement or you will lose your engine if tensioner gives up.
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