Thread: Rodbearings, a couple of questions

1: If these bearings are worn, will the engine performance gradually worsen, or will they just suddenly fail catastrophically?

2: Can they be a cause of erratic idle?

3: If I want to replace them, can I just take 4 of the same grade, for example the smallest size? The reason I ask this is that I can't just pull the engine apart while out on the street. And they only have to last a few 1000 miles (cause I want to hurry the VE).

So should I take grade 0, and thus have a max of 2 grades difference if any, but be sure they aren't too big, and thus remove the chance on friction?

Or get the grade 1's, and have a max grade difference of 1, but risk having too big of a bearing?

or you can just get some ACL's, they are about the same price as the oem's and better quality. Just get the standard grade. Probably not the cause of your erratic idle. When they are bad you will have rod knock. If your not getting any knock then dont worry about the rod bearings. Especially if your just gonna take the motor out soon anyways. Not worth the hastle. You erratic idle is caused by something else, either vac leak, bad iacv, or etc.

Never heard an actual example of rod knock, but what do you hear when there is rod knock?

EDIT: Like these?
http://cgi.ebay.com/ebaymotors/ACL-Rod-Bearings-Nissan-SR20DE-SR20DET-S13-S14-S15-50-_W0QQcmdZViewItemQQhashZitem27b0fe2781QQitemZ170473170817QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

A loud knocking sound that steadily increases consistency with rpm. usually happens under load. You can mistake it. Its usually gets pretty loud quickly once the bearing spins. You can actually verify rod knock by unplugging the injector clips or pull up the spark plug wires one at a time until the noise goes away. When the noise disappears after pulling up one wire then you know which rod number spun the bearing. If its an old original motor they usually spin #3. Common issue.

But again you would hear a loud knocking when the engine is running and under load and reving. If your not getting any loud noises from the motor then your motor is fine as far as bearings go and dont worry about it.

Cheers!