1997 4 cylinder motor noise

[buttercup]

My '97 4 cylinder (man. trans., 140K) has a loud, hollow, metallic knocking sound on cold startup. It dissapears in a minute or two, doesn't happen in summer and gets worse as temps drop in winter. Anyone know what it is?

Thanks

 

[Stick Figure]

tried making any changes in oil weight or brand? With out being able to hear it, it is tough, what makes it even harder is i have no idea on the style of components used in the 3rz. I'm going to assume that it is a solid puck lifter design like every other current toyota which means there are no hydraulic lash adjuster to bleed out. The only other thing that comes to mind is if the timing chain has a hydraulic tensioner that is on its way out. Not sure how easy it is to check the slack in the chain on that engine, but might be a good start.

 

[buttercup]

Thanks, Stick Figure. I'll look into those things, and try 20W-50 on my next oil change.

 

[riverrat44]

The timing chain tensioner is a good guess- cold start rattle is a classic symptom of timing chain problems on the older Toyota 22RE motors with the plastic timing chain guides that would wear out or break. This design flaw was fixed on the newer 3RZ motor but it is still possible to have issues.

I'm not a mechanic, but I don't think it is a very good idea to put 20-50 oil in an engine that takes 5-30 or 10-30 in hot weather, especially at this time of year.

You might try registering on TTORA and ask the same question, there are tons of Tacoma owners with the 2.7L 3RZ motor over there...

 

[shawnstcyr]

I am a mechanic, I would definitely NOT run 20w50. That is way too thick for colder climates.

 

[shootmymime]

i am a mechanic also. and i 2nd that, but i cant quite figureout what the sound could be

 

[loner]

Back in the day when I had a 4-cylinder Tacoma (same 2.7L engine as the 1997 4R above), this was a relatively common problem and was widely attributed to "piston slap".

 

[pat161]

Agreed with the above poster, I ran a 2.7 in 2 Tacomas and an 00 Runner and once cold weather came they all made that noise on cold start up. It would never last more than a few seconds and is not a problem at all. I ran 2 of those 2.7's over 100k and never had any issues at all, and they both did it their very first winter with only a few grand on the odometer.

 

[buttercup]

Thanks again for all the info! I checked out the Tacoma site and they agree it is piston slap and not a problem. Evidently Mobil 1 synth and an oil filter with an anti-drain valve will help, as the noise is annoying to me.

 

[Charlee78]

If it's actually a piston flap, no matter what oil you put in it, the noise will still be there IMO.

Usually this sound is caused by the difference of temperature between the cylinder and the piston itself. They don't expand at the same speed so the clearance is greater than the specs, resulting in a wobbling piston.