1992 240sx - Rod knock and temp gauge question

[DaywickelL]

Edit: I forgot to add that before I went to Kragen, I checked the ECU and it gave me a code 55 which meant that everything was okay.

My car still has the timing chain guides installed and is making the timing chain guide rattle sound. Today I went to Kragen and when I was driving back I noticed a slight knocking/louder marble in a can sound in addition to my marble in a can sound comming from around the head. I checked for where the knocking sound was comming from and it can't really be heard from standing over the engine bay but can be heard when crouching down near the header and cat. The sound disappeared and reappeared a few times while I was driving. When I got home, changed my thermostat, and started the car a few times to flush the radiator, I raced the engine in neutral. The knocking/louder marble in a can sound only happens when the car at idle (700 rpm) - 2000 rpm. The car also slightly bogs when the rpm drops back down after reving. It bogs around 3000 and 2000 rpm. Do the lower and upper timing chain guides make different sounds or do I just have the beginning symptons of rod knock?

Also another problem I am having is my temp gauge. It used to read the temp at random. It would randomly be up at around 2-3 bars then it would drop to dead cold. Today I replaced the thermostat with a new one from Kragen (Stanley 170º F) and the temp gauge problem was still present. I followed the coolant flush procedure from NICO and already noticed a weird problem after the flushing the coolant for the first time. When I refilled my radiator with water, warmed up the car, and raced the engine, the temp gauge read around 2-3 bars but dropped when I applied the gas pedal. I was hoping it was just a problem with the radiator having bubbles in it. I flushed the radiator with water a few more times until the water came out clear. Then I filled up my radiator with coolant, had the heater on full blast, went to a steep hill, took off the radiator cap and bleeder screw, and bleed all the air out. So now the temp gauge does not randomly go up and down. It now reads at idle but drops during acceleration. Does anyone know whats wrong with my temp gauge? Is it a temp gauge sensor problem?

Modified by DaywickelL at 2:06 AM 6/29/2008
Modified by DaywickelL at 2:07 AM 6/29/2008

[MaximA32]

As far as the knocking sound goes, it sounds like you floated a valve. I would take it to someone who knows what they're doing and have them take a look at it.

As far as the temp gauge, do you have an after market radiator in it? Do you have after market fans? Anything that would have changed the factory cooling system?

[DaywickelL]

I checked and cleaned a few sensors and grounds today. The temp gauge is working properly now.

I drove the car a little bit today (my only car) and despite the knocking sound, it seems to drive like how it did before the knocking sound started. Again the knocking sound would come and go.

What are symtpoms of floating a valve?

[rms13Mike]

I checked and cleaned a few sensors and grounds today. The temp gauge is working properly now.

I drove the car a little bit today (my only car) and despite the knocking sound, it seems to drive like how it did before the knocking sound started. Again the knocking sound would come and go.

What are symtpoms of floating a valve?

sorry to bring this thread back up but what sensors and grounds did you clean to fix your temp gauge problem? im having the same problem right now