I have a 1988 Pickup SR5 with a 2.4L 22RE with 200k miles. Recently, my engine decided to throw 2 rods. I was traveling at a low rate of speed and all the sudden they broke. The truck seemed to be running fine. It sounded good. It was not running hot. I had just checked the oil. It started and idled fine. There was no indication that this was about to happen. I am not sure about oil, fuel, or any other pressures because I only have idiot lights. I was wondering if anyone know what could have caused this?

I just put a rebuilt engine in the truck, but now I am worried that this might happen again.

 

Well if it broke two Rods Some one slacked off on those two rod bearings.at the least.

Did you build the engine or buy it ??

There was no noise what so ever they just failed??

Really going to see the crank to know just what happened

If they broke I would venture your needing a new block

 

How do exactly do you define "thrown rod"?

In my vocabulary.
A "thrown rod" means the rod snapped into two pieces and they are now sticking out the side of the engine block or laying on the ground, and you have a large hole with the rod sticking out the side.

Is that what you have? (Test with a flash light looking at both sides of the engine block , (edit!) And from below at the oil pan, for rods sticking out or large gaping holes)

Or "piston threw a rod"
The wrist pin has seperated from the piston, you have shattered the piston or writing now the rod and wrist pin are gouging the cylinder walls.

Is that what you have? (Test, pull the spark plugs, rotate the crank shaft with the crank bolt by hand with a breaker bar while looking in the spark plug hole for the piston moving up and down)

Or "throwing a rod bearing"
Bearing has disintigrated and worked its way out of the journal and what is left is laying in the bottom of the oil pan.

Is this what you have? (Test by removing the oil pan and visually confirming there is no longer a bearing under the rod cap)


The answer to "how this happens" for all of the above is metal fatigue creates a weak spot that either failed by meeting a threshold of forces where the fatigue cracks have traveled all the way through the object. There can be compounding by issues that accelerated this like predetionation (know as engine ping), improper cam timing on an "interference style engine" (valve and piston trying to occupy the same space at the same time), a broken spark plug or valve in the above mentioned "interference style engine" (the broken pieces reduced the clearance between the piston and valve or the head surface)

 

The connecting rods broke and punched two huge holes a hole on each side of the block (3rd and 4th pistons). The engine gave no indication this was about to happen. It was running great before they gave out.
i bought a rebuilt block and head.