92 240sx - Knocking comes and goes - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

DaywickelL · 07-16-2008, 02:56 PM

As far as cars go, I'm alright with performing maintenance. I still have my timing chain guides on the engine (KA24DE) so I know for sure that the knocking sound is not that.

The problem I am encountering is a slight knocking sound around 700 to 2000 rpm when the car is warmed up. The sound can be heard clearly from where the header and cat connect. Sometimes I can hear it and sometimes it goes away. I did a compression test on all four cylinders and got 179 psi on all four. The car still runs fine just like it did before the knocking sound started happening. The ecu is throwing a code 55 which means everything is okay.

I plan to partially diagnose the problem by checking the exhaust system to make sure there are no leaks or loose bolts that can clank. I'm also going to take off the valve cover and oil pan. I'm going to take off the valve cover and sprocket cover to take off both timing chain guides and check the tensioner. Then I'm going to drop the oil pan to look for any shavings or other stuff in the pan. This will eliminate the timing chain rattle for good and I will be able to hear the other knocking sound easier. For the oil pan, I will be able to see if there are any metal shavings.

A lot of people told me to just take my car to a mechanic to diagnose the problem but I want to learn on my own. This is going to be my first time taking off a valve cover, sprocket cover and oil pan. What worn out parts should I look for when I have the valve cover off? Will there be anything I can see from taking off the oil pan besides shavings in the pan?

I've also searched about rod knock and it seems like you can use a heavier weight motor oil to make the knocking less loud. Does that actually work? Does it help with actually preventing knock?

Any other suggestions on what I can do to diagnose the problem?

07-16-2008, 02:56 PM	#1
DaywickelL Join Date: Jun 2008 Location: 4 Posts: 32 Trader Rating: (1) Feedback Score: 1 reviews	92 240sx - Knocking comes and goes As far as cars go, I'm alright with performing maintenance. I still have my timing chain guides on the engine (KA24DE) so I know for sure that the knocking sound is not that. The problem I am encountering is a slight knocking sound around 700 to 2000 rpm when the car is warmed up. The sound can be heard clearly from where the header and cat connect. Sometimes I can hear it and sometimes it goes away. I did a compression test on all four cylinders and got 179 psi on all four. The car still runs fine just like it did before the knocking sound started happening. The ecu is throwing a code 55 which means everything is okay. I plan to partially diagnose the problem by checking the exhaust system to make sure there are no leaks or loose bolts that can clank. I'm also going to take off the valve cover and oil pan. I'm going to take off the valve cover and sprocket cover to take off both timing chain guides and check the tensioner. Then I'm going to drop the oil pan to look for any shavings or other stuff in the pan. This will eliminate the timing chain rattle for good and I will be able to hear the other knocking sound easier. For the oil pan, I will be able to see if there are any metal shavings. A lot of people told me to just take my car to a mechanic to diagnose the problem but I want to learn on my own. This is going to be my first time taking off a valve cover, sprocket cover and oil pan. What worn out parts should I look for when I have the valve cover off? Will there be anything I can see from taking off the oil pan besides shavings in the pan? I've also searched about rod knock and it seems like you can use a heavier weight motor oil to make the knocking less loud. Does that actually work? Does it help with actually preventing knock? Any other suggestions on what I can do to diagnose the problem? Last edited by DaywickelL; 07-17-2008 at 03:00 AM..