Chain rattle on startup - Toyota 4Runner Forum

gaber6 · 06-12-2024, 01:45 AM

240,000 2005 v6.
Just recently on about 3 of 5 cold starts I get a chain rattle for a split second. Once started once, it is fine.
Almost as if the timing tensioner stopped catching the ratchet to keep full tension and it relies on the oil pressure on startup.

Any ideas?

Bigcee · 06-12-2024, 05:02 PM

Hmmm, anyway to inspect the tensioner? I'm not familiar with the process.

waypoint · 06-14-2024, 03:33 AM

There are three chain tensioners, one on each chain. You'd need to use a stethoscope in order to find the noisemaker. The main chain tensioner uses a ratchet as you mentioned, but the #2 chain tensioners do not.

I've had oil filters with (suspected) defective anti-drainback valves cause noisy cold starts. Likely the #2 tensioner(s) but I didn't dig in to locate the source, just changed the oil filter and added oil to top off. Noise gone.

So...what oil filter and oil are you running?

gaber6 · 06-14-2024, 12:02 PM

Probably does need an oil change but I usually just add a quart as it needs it.
Of course the past 3 starts it has been quiet.

The chain guides are all new from my head gasket rebuild but I kept the old chain and tensioner.. it does seem like maybe the ratchet could have stuck. I'll consider the oil filter, too. I think I have a mobile 1 filter on there

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