NAST4WD

Hey everyone. I would like to ask a question about my toyota. When i start my truck from a cold start it knocks for 2 seconds when the rpms get high and slows itself back down while still idling off the choke to warm up. It only does it once the engine has sat for about 2 hours and it has gone cold. once warm it does not do it on start up. I think its a piston slap moving the valves and rocker arms because it does the same when i hit the gas and approximately 3000+ rpms. I let the chief on the fire dept. with me listen to it and he is a mechanic and he says its a play in the rod bearing. please help me answer thhis question. Thanks!

xxxtreme22r

Could be rod bearing, but can also be timing chain as well. Assuming here when you said choke it's a carbureted 22r engine.

Here is my symptoms of a bad rod bearing. (not completely gone just "going")

Knock on startup when cold. Knock @ Higher RPMS and on throttle. Knock when shifting gears while the clutch is in. Smaller knock when throttle is removed if idling and engine rpm is on the higher side.

xxxtreme22r

if you have a 22r taking the valve cover off is extremely easy. Once you do, on the front of the engine you can see the timing chain and guides. The drivers side chain guide likes to break since it's plastic versus metal. And the chain especially if stretch due to high mileage wins and beats the guide into submission and sends plastic pieces into the oil pan.

In the below photos you can see the timing chain in front and in the right of the photo the chain guide and a corresponding mark on the timing chain cover from the chain rubbing on it instead of the guide. And also what it looks like with the shards of plastic in the oil pan after the guide looses to the chain.

NAST4WD

na its a 22re fuel injected. im not sure how to say it but when you start it its like an electronic choke that warms the engine up. then itll slow down. but i know its not a timing chain i got someone to check that and the timing chain is great. Im thinking a piston slap because a rod bearing would knock all the time not just for a couple seconds am i right?

NAST4WD

also any information on when my truck has just started and i pull it from park to drive even after it has warmed up it seems like the tranny doesnt just slide the gears into place. its like it puts them into place and my truck will lurch forward. is that maybe a torque converter problem? any advice would help. i hate having an automatic on my 4cyl.

xxxtreme22r

my rod bearing didn't knock full time till the entire bearing spun out.

James Woods

iTrader: (1)

One trick to check for rod knock is to remove one spark plug wire at a time and if the noise goes away then it is that cylinders rod bearing. You can also try using some thicker oil additive like the stuff from Lucas to see if the noise goes away, it could be piston slap as these motors did have a problem with it but typically from my experience with piston slap is that it will last for a little longer than the first 2 seconds usually untill the motor warms up.

xxxtreme22r

Thx james, I hesitated to say the plug wire trick thinking it would also mask a wrist pin and piston slap. I do agree however the piston slap would last a little longer and be louder when engine is cold.

James Woods

iTrader: (1)

Well it will help in knowing what cylinder it is in, and if the wrist pin is bad it should make a double knock noise as it reaches top stroke and then bottom stroke. To me it really does sound like a rod bearing the way it is described though, the only way to make sure is just drop the pan and check.