Rod Knock

[kewlcoconut]

I have a quick question on rod knocks. I did some reading about this, and I have only found cases where people had this problem with low oil levels. Is it possible to get a rod knock with the oil levels being fine??

I just checked my oil yesterday, and its fine. And tonight when I got home, I noticed my engine was idling kind of noisy. I looked under the hood, and I'm scared to say it, but sounds like a knock. But yet my oil level is ok, unless it is possible to develop a knock with normal levels. And if so, how does it happen?

[Bullz_EyE]

Sounds like you've done some research and I concur. I can't speak from experience, but from what I've gathered it occurs usually when oil levels drop low. So, in your case, I don't know what it could be. Just run it and keep checking the oil. If worse comes to worse (knock on wood), you really don't have choice but to do something about it, as there is really nothing to prevent it. Best of luck, hopefully there's more input.

[ddmcse]

one time my main pully was loose . you couldn't tell it was loose by looking but you could tell by twisting it a little , damn if that didn't sound like an engine knock

[suprra_girl]

it could be that the previous owner had run it low on oil and it was just a matter of time

are you able to take any video of it?

[mrnickleye]

I too have seen a loose crank pulley sound like a rod knock, on a couple of cars.
Rod knock develops due to the bearing(s) on the rod that attach it to the crankshaft, getting too much clearance (gap, play).

It can happen when the oil LEVEL gets too low, and you go around a corner and the pump doesn't pick up oil for a moment. Lack of oil at the bearing is the cause.

Oil quality plays a role. If the oil level NEVER got low, but has not been changed for too long, it won't lubricate very well.

Repeated high RPMs stress the bearings.

I change my oil every 2k, just to be safe. Oil is still cheap enough, and cheaper than engine work.

[kewlcoconut]

Yea, I always keep an eye on my oil and get it changed a lot. I'm scheduled for a tune up as well. I never let the oil get low, I'm always paranoid about it. I always have bottles of oil on hand in case I need to top up.

I will check my crank pulley and see if it is loose. This morning when I started up my car, it was still there, I drove it to work and came out 5hrs later, and I couldn't really hear it. Odd...

As for the previous owner, it was my uncle, and he babied this thing. So I think that rules out lack of care on his part haha.

[mrnickleye]

Go ahead and put a 19mm socket on that crank bolt to see if its loose.

[Bullz_EyE]

Originally Posted by mrnickleye

I change my oil every 2k, just to be safe. Oil is still cheap enough, and cheaper than engine work.

WoWzerz! Drive your car much? Just a note (not to you, just being general), the recommended interval for oil changes is every 3000 miles or 3 months, which ever comes 1st. It's been studied before that changing every 3000 may be a bit excessive, although I religiously change it at that interval.

[rnoswal]

If you start it up in the mornings and it rattles pretty good then quietens down a lot when the oil light goes out then it is in irrepairable rod bearing. There can be loose torque converter bolts and bad harmonic balancers and very loose valve settings but anyone that has heard the rod knock before know what it is almost immediately and sighs because it means pulling the engine.


All it takes is one time for the oil level to get to low to be picked up and the damage has been done, from slight to major. Putting thick oil in will help, like STP or others like these, but..........

Let us know.

Russ

[mrnickleye]

If it is a very light knock, you can prolong a rebuild by using 20-50w oil with one bottle of STP. It will be a little thicker and fill in the clearances more.