HI guys, I'm fairly new to this board, but I really need all the help from expert Nissan owners/mechanics with my problem. I originally posted the topic in the Murano forum but there are not much Engine experts to help me out.

My wife's 2003 Murano recently started to make this clanking/rattling sound under load at about 1200 rpm - 1400 rpm. Others suggested it was the fuel injection dampers(regulators) but that was not it. The sound is a louder clanking. Also, it is not the CVT as I can pinpoint that the sound is coming from the front valve cover. Besides this clanking, the car is mechanically sound....no oil consumption, no smoky exhaust, no nothing...except this clunking under load. The Murano even accellerates smoothly when I nail it from a stop. It runs on 92 octane, new plugs, new filters and Royal Purple Synthetic oil. It only makes this clunking sound under light load at 1200rpm - 1400rpm.

This is how I started to troubleshoot. Had the wife start the car with the Parking Brake engaged. Then in Park, with the left foot on the brake pedal had her slowly depress the Gas pedal with her right foot until the revs were at 1500rpm. In Park, with no load on the engine the VQ35 V6 revved beautifully, no clanking, no rattling, just a smooth roar. Next, I had the wife engage the transmission into Drive. While in Drive, I had her slowly raise the revs to 1500rpm. In gear and under load, the VQ35 V6 started to clank at 1200rpm and got louder as the revs went up to 1500rpm. I listened to where the clanking was coming from and it eminated from inside the front valve cover. The cover closest to the radiator. Has anyone who worked on these V6 engines know what's going on???? What's happening under load in gear??? Please Help???? Nissan mechanics????

My mind started racing to find a cure!!! Is the valvetrain lash adjustable??? Could a rocker or valve be loose??? Could the chain tensioner or guide be broken??? Did a lifter collapse??? Did the overhead cam flatten a lobe???

Has anyone run into this issue??? Please help??? If you have a diagram of the cylinder head and valvetrain please post the pics.

This weekend I will remove the front valve cover, hoping not to find any carnage.....I'm soooo sad.....

No one had this problem with a VQ35 ???? They came installed on Altimas, Maximas, G35's, 350z's....etc, this can't be a first ????? Or could it ???

Update.....

I went to see my friend, who is a Mechanic at Honda and we hooked a scanner to my Murano. Apparently, the noise is pinging or spark knock. In Park, while revving, the timing advanced smoothly from 17'degrees and up. In Drive, while revving, the timing was eratic and flashed up real quick to 43'degrees. This was too much advance too fast, creating the pinging or spark knock. My friend suggested to check on the Nov 17, 2003 recall that replaced the cam and crank sensor and the variable timing control sensor. Also he suggessted that I have the ECU reflashed.

I have an appointment next week at the Nissan Dealer to take care of these issues. Hopefully they will not give me any hassles.

Sorry we weren't able to offer helpful input before you went to your mechanic. Thanks for posting up your findings, though. Hopefully they'll help out someone else in your position in the future.

Finally got the wife's Murano back from the dealer and paid $300 for nothing. The dealer had the "engine mechanic" diagnose the Murano. He verified the engine pinging noise. He checked for intake leaks-none. He attempted to"relearn" the idle but failed. So he reprogrammed the ECM with new software and then "relearned" the idle. Engine pinging still there. Nissan mechanic found a dent in the oil pan. He said the ping was from lack of oil because the pan was dented......BULL. If it's not the pan, he suggested a new replacement engine. Why????? So I took the Murano home and replaced the pan. Engine oil pickup was not bent or crushed. With the pan off, I looked at the crank, rods, and bearings....it was spotless, no sludge, no oil burning or oil stains. The bottom of the oil pan was also clean...no sludge, no shavings....just spotless. Called the dealer today and left a message for the mechanic on what he advises to do next. In the meantime.........anyone have any ideas??? No codes or warning lightsNo pinging in Park or NeutralNo pinging at high speed or nailing it from a dead stopPings only at part-throttle load approx 2000rpm 92 Octane Chevron unleadedRoyal Purple synthetic oil 10w-40wNo oil consumption issuesNo blue smoke out of the exhaustWIX oil filterNGK platinum plugsMAF cleanedThrottle body cleanedFRAM air filter

Hello. Your issue has grasped my attention. My first question is, Are you sure the noise is not emitting from the front cover area more specifically at the top or around the IVT Solenoid. When looking at the front of the front valve cover it should be just to the left. I believe it has a green male connector with a green or grey female connector on the other end. First verify that the noise is not originating around that area. Recommend using a stethoscope or ear to pry-bar/screw driver to verify resonance. If the noise is definatly not coming from there than I would be inclined to view your cam angles at idle and 15k. rpm. If you actually use premium fuel than pinging should not be too much of an issue. Though I did have one customer who swore up and down they used premium and had a fuel injection servous performed and I still had to adjust the timing to compensate for noise. I wasn't happy with it but I am forced to make adjustments outside of factory specs as long as the customer is completely aware. My name is Mike Lucas and I would be happy to be of any further assistance. Thank you...

Thank you mikeblucas!!!!

I haven't touched the car since but, this weekend will pull all the pulgs to "read" them.Out of curiosity, how would I view my cam angles at idle and 15k rpm.

Hello, I was initially curious wether or not you would be able to see them but two preliminary checks I would like for you to perform are:1: Ensure coolent mixture is not over concetrated. The recommended mixture is 50/50 but you could drain the coolent and replace with a 30percent coolent 70 water as a intuitive check. REASON: Block temps tend to exceed head temps when over concentrated. Thus, allowing cylinder walls to become just hot enough to pre-ignite the air/fuel mixture. I would recommend this check if your incident happens mostly after warm up.2: Check to seeif the alternator/a/c compressor belt idler pulley tensioner bracket is not cracked or broken. This will be noticed by the top of the tensioner adjustment nut being very close to the auxillary coolent outlet hose next to the lower coolent hose.This is just some checks I would perform if I did not have the appopriote tools. Thank you...

mikeblucas wrote:Hello, I was initially curious wether or not you would be able to see them but two preliminary checks I would like for you to perform are:1: Ensure coolent mixture is not over concetrated. The recommended mixture is 50/50 but you could drain the coolent and replace with a 30percent coolent 70 water as a intuitive check. REASON: Block temps tend to exceed head temps when over concentrated. Thus, allowing cylinder walls to become just hot enough to pre-ignite the air/fuel mixture. I would recommend this check if your incident happens mostly after warm up.2: Check to seeif the alternator/a/c compressor belt idler pulley tensioner bracket is not cracked or broken. This will be noticed by the top of the tensioner adjustment nut being very close to the auxillary coolent outlet hose next to the lower coolent hose.This is just some checks I would perform if I did not have the appopriote tools. Thank you...

Mikeblucas1. Last week I dumped the coolant and replaced with premixed 50/50 long life coolant. I also put in a bottle of "Redline Water Wetter". I also contemplated on changing the thermostat but it doesn't overheat so I left it alone. Also contemplated on changing the water temp sensor but the ohms checked out ok.

2.Already checked the alternator a/c compressor belt idler pulley tensioner brakcet and it is not broken.

I already bought the intake plenum collector gaskets so that I can change the spark plugs. I have also removed the wipers and cowl to get better access for plenum removal.

keep me posted after you see what the plugs look like. My guess is that they will look normal. I would like to know wether the coolent mixture was able to help. It did fix several other Murano's in the past.

Done...Fixed!!!!A special thanks goes out to my local "stealership" who said nothing was wrong because there was no codes......awesome troubleshooting Nissan!!! I guess that's why their called "technicians" and not "mechanics".

Anyway, I removed my upper and lower pelnum collectors so that I could change all my spark plugs. Not just three, all six of them. I'm a thorough mechanic and took tons of pictures if you want to see the procedure. I was careful not to remove or unplug the throttle body so that I would not have to "relearn" anything on the ECU...same goes for the battery. What I found was that the rear cylinder closest to the brake master cylinder was not firing. The coil had white powder deposits on the valve cover from arcing and was doused in oil. When I pulled the coil out it was soaked in oil. The spark plug was also sitting in a "lake" of oil. What appeared to have happeded was that the valve cover did not have a good seal around the spark plug port which caused oil inside the valve cover to overflow and fill the spark plug port. When I pulled this plug it was blackish-brown, as if it was trying to fire and soaked in oil. The five other plugs were perfect and burning beautiful, but I replaced all six to be sure. As for the valve cover, I got a new rubber gasket and put a thin layer of silicone around the spark plug port so that oil would not seep into the port/coil again.

I also tested the resistence(ohms) on the oil soaked coil and it was good, but on the next oil change I will replace it. Per the 2003 Murano Field Service Manual, it explains how to check the coil wiring from the ECUwithout a Consult2. So, I checked this also and the wiring was perfect. Since I was deep into the Murano and I have the FSM, I tested every single sensor that dealt with ignition timing and camshaft/crankshaft timing. All was perfect. I also changed the PCV valve because it was "sticky" and only made of cheap plastic.

I also flushed the coolant and refilled with premixed 50/50 long life coolant and a bottle of Redline "Water Wetter"and tested the temp sensor. Perfect.

With the plenum collectors off I could see directly in the cylinder head and the backside of the intake valves. They were clean as a whistle!!! No deposits, no oil, no nothing....super squeaky clean. I took pictures if you want to see. A week before this tear down, I went through two bottles of "Redline SI-1 Fuel System Cleaner". I did this because the Nissan technician said I have a lot ot deposits......whatever Nissan technician.

All is running well now and the wife is happy. The next project is to install a custom sound system and a build a hidden fiberglass subwoofer enclosure. I'll take pictures again. So far on the wife's car, I've installed color matched 4-sensor reverse sensors, Yellow ion fog lamps, and added an alarm "shock sensor" to her factory "horn alarm". I have pictures of all of these installs if you folks want a "write-up", please let me know.

I'm a hardcore, backyard, shadetree mechanic and enjoy modifying/racing cars. I could take the Nissan technician to "school" as I have built and raced everything from 2-stroke motorcycles to BMW M50 engines. I'm from the old school and can mechanically find my way around any engine. If my wife decides to keep her Murano I will eventually purchase a "Consult2" and screw the Nissan technician.

See my current toy.....http://www.cardomain.com/ride/1864005

love......tubbedz

Hello. I am glad you were able to figure your issue out. Its is very difficult to diagnose over the phone or the internet for that matter. Any how, congradulations on your findings and repair. Enjoy your Murano and drive safe. Mike Lucas...

Yes its real easy to tear those gaskets around those coilsyou have to be gentle

NutriaforBreakfast wrote:Yes its real easy to tear those gaskets around those coilsyou have to be gentle

The gasket around the coil has no tear or rip. As I stated, it is the clearance between the metal, spark plug port and the valve cover spark plug opening. The clearance is very minimal but enough to sprout an oil leak. This is where I smeared a little silicone on the metal port to fill the clearance and stop the leak. I also swapped the coil onto another cylinder and that cylinder does not leak...so the coil ikn question has no rip or tear in it's gasket.

Hello, Once and a while I will add some nissan gasket maker between the sparkplug tube and the valve cover opening to help supplement the gasket that is within the valve cover. It won't hurt anything and is not often a bad idea to allow for additional sealing. Those individual gaskets will eventually dry-rott from the continuous heat exposure. The coils will not be the problem. Keep me updated on your findings.Thank You, Mike Lucas....

good evening, I have the same problems as you had. Before I remove the intake manifold etc., I would like to know the following:
1 was the knocking sound at + / - 1400 rpm at low power, with warm engine?
2 And maybe you have the pictures still as mentioned.

Thank you in advance for your comment

Sorry to revive an old thread but I have a 2007 G35s and am having the same exact issue as you. First we thought it was the VTC gears making noise from low oil pressure. I switched to motul 5W-40 oil and a new filter. The noise has gotten quieter but is still there. I am going to look into the valve cover gasket as being a possibility now.