# rod knock?



## slideways240sx (Feb 19, 2005)

Ok so today we ran a compression test to see if i bent any valves adn the cylinders came in between 160-155 so that means that none of the valves are bent and the timing chain didnt jump.. correct? i guess the only possible thing thats left is its a rod knock? It only knocks at idle then when u put it under load it stops which is basically the oppisite of what ive heard of the normal rod knock. Any info/input/suggestions what to check now is greatly apperciated

Thanks guys


----------



## 240sxs1377 (Jan 9, 2005)

so your defintaly sure its not your valves that are knocking.


----------



## slideways240sx (Feb 19, 2005)

im nto definitly sure about anythign at this time i still think that the timing jumped but was todl that it would lose compression since valves would be open at the wrong time... guess im going to pull the cams to amke sure none the the valve springs are broke or anything but ive heard that its a huge job pulling the timing chain+gears and all that what sould i look for?


----------



## rogoman (Dec 16, 2004)

slideways240sx said:


> Ok so today we ran a compression test to see if i bent any valves adn the cylinders came in between 160-155 so that means that none of the valves are bent and the timing chain didnt jump.. correct? i guess the only possible thing thats left is its a rod knock? It only knocks at idle then when u put it under load it stops which is basically the oppisite of what ive heard of the normal rod knock.


What does the noise sound like; a ticking or a dull metallic knocking or a chain rattling? If it's a dull metallic sound, then it's the rod or main bearing(s); rod/main bearing knocks are heard through out the RPM range.


----------



## slideways240sx (Feb 19, 2005)

its liek a ticking with a slight knock, the thing it its not heard throught the rpm range thats what ive heard is that rod knocks get lound when the motors underload with this when its under load it dosent make any sound


----------



## Chris90FB240sx (Feb 25, 2005)

Sounds like what happend with mine. From what Ive heard its like a pin on the rod and Piston or something. Im not totally sure, but mine would do the same thing. It would knock and click at only certian RPM then go away.


----------



## rogoman (Dec 16, 2004)

slideways240sx said:


> its liek a ticking with a slight knock, the thing it its not heard throught the rpm range thats what ive heard is that rod knocks get lound when the motors underload with this when its under load it dosent make any sound


Might be from the valve lifters having too much clearance or maybe timing chain guide noise. You might want to check the oil pressure with a temporary pressure gauge; if the pressure is low, the chain tensioner may not work properly.


----------



## Bror Jace (Apr 26, 2003)

Valve noises are generally light "ticking" sounds while the classic "rod knock" is a much deeper, almost hollow noise.

Something which sounds a LOT like a rod knock is "piston slap" which is a piston with a short or worn piston skirt. When it's cold, the piston is shrunken in the cylinder and there is a lot of play allowing the piston to rock (or "slap") back and forth.

This is very loud at start-up but generally goes away as the engine warms up and the parts expand.

Engine oils with a great deal of molybdenum tend to minimize this sound in some engines. I'm not sure why, but this was evident when I switched from Mobil 1 to Red Line Oil in my '95 Honda Civic. The Red Line Oil (which is LOADED with moly) made the car much quieter during winter start-ups.


----------

