Tacoma Engine Knocking

Hey guys! I'd like to hear all your opnions if your Tacomas are affected by this. I have a 2003 Tacoma 4cyclinder 4X4 with 170,000. I bought my truck new and at 27,000 miles they engine started knocking when it was started cold. I took it to dealer and they replaced the bottom half of the engine under warrenty. I ran it another 20,000 or so and the knocking started again. It has continued to knock ever since. The dealer called it "piston slap". I was told a TSB was put out on it but was not a serious enough issue to implement a recall. Ive never had any engine issues except for that. Its slowly getting worse. It will knock about every time I start it when engine is cold. During the summer it will knock like 15 seconds. That time triples in the winter. The colder it is the longer and harder the knock becomes. I always leave it in idle til engine warms up which is when it stops knocking. It has never knocked when the engine is warm which I was told as long as it doesn't do that the engine will be fine. Its just really embarrassing when it happens. I guess the problem is the oil isn't getting to the block quick enough. Ive tried different type of special oils. Nothing has made a difference at all. Ive been told Toyota has finally fixed this problem on new trucks. I sure hope so! I heard this happens the most on the 4cyc also. Does anyone else have this issue? What is the root of the problem? What can I use to quiet the knocking as I want to sell my truck to get a new Tacoma so I can sell it without it knocking like crazy? Appreciate your help!

 

Mine does the same thing from a cold start.
Especially in the winter time.
I use prolong every other oil change and it seems to quiet it down some

 

Piston slap means that your piston rings are shot and are not creating a seal in the cylinder which means the pistons are rattling around. It goes away when your engine heats up because the metal expands with heat and then it takes up the excess room.

Changing your oil or using additives is not going to fix this.

You most likely need new rings. Piston slap isn't a death sentence though, just be easy on it and make sure to let it heat up. I've seen a few engines live a long time with slap.

 

Piston slap is the sound of the piston skirt hitting the cylinder wall. The piston will rock/tilt along the thrust plane. It will get louder as the piston wears. This condition is a characteristic of certain engines. Generally it has to do with the piston to cylinder fit. The pistons need a certain amount of space to expand as they warm up. The piston can move more until it fills open the extra space. A different constructed piston could help Ike forged vs cast. They expand at different rates and requires a different fitment. This condition usually does not mean that the engine is worn-out, but if it starts to stay noise after warm up, or at higher ram's then it might be time for a rebuild. But just chains the Rings out will not help this if it is really piston slap. An easy way to diagnose piston slap is to revup the engine, the noise should go away at higher rpm's.

 

Short piston skirts exacerbate the problem which is why some engines seem to have more issues with slap then others.