Nissan VQ35 valvetrain clunking under load

[tubbedz]

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 & VQ35 Engine forum but I need more 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 and does not make the clunk sound in Park.

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 or left bank. 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 lash cap(lifter) worn out??? Could a rocker or valve be loose??? Could a chain tensioner be broken??? Did the overhead cam flatten a lobe??? Could the camshaft hold downs be cracked???

Has anyone run into this issue??? Please help???

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

[jwerty1]

These motors don't sound good low on oil, are you sure of the oil level?I've seen belt tensioner brackets crack on the alternator belt on the muranos, and make a horrid noise like you're describing, check that

[tubbedz]

These motors don't sound good low on oil, are you sure of the oil level?I've seen belt tensioner brackets crack on the alternator belt on the muranos, and make a horrid noise like you're describing, check that

Jwerty1Thank you so much for the suggestion. I guess no one else knows the mechanical workings of the VQ35.

I double checked the oil when it was cold and it was topped off. I will check the belt tensioner bracket this weekend. Cross your fingers!!

[OldmanPurdy]

The transverse VQ in my altima makes the same noise and I recall someone on this forum saying it was timing chain related most likely the tensioner. I've had the noise for a good 20,000 km/s and it hasn't gotten any worse if that takes any of your worries away.

[tubbedz]

Thank you OldmanPurdy for the reassurance. I'm hoping it's something minor. I'll open her up this weekend and check the chain tensioner also.

What confuses me is that it revs so nice, silent, and smooth in Park, but in gear it makes the clunking sound.....Anyone???

[jetroy240]

I would check first if there's any trouble codes, if the oil level & condition is good & clean. Check these items:

- drive belt idler bracket probably cracked(for buzzing/rattle noise)- exhaust tube gusset bracket cracked (for buzzing/rattle noise on acceleration)- bank 1 catalytic converter heat shield( for buzzing/rattle noise)- if AWD, check transfer case for any crack housing- intake timing control solenoid valves faulty(for loud clunking/rattle noise)- faulty VTC sprockets(for loud clunking/rattle noise)- timing chain guides broken or worn

I f you have access for a scan tool or Consult 2, go to data monitor & check what's the reading on intake timing control valve solenoids in degrees , should be plus or minus 1 deg at idle.

[tubbedz]

I would check first if there's any trouble codes, if the oil level & condition is good & clean. Check these items:

- drive belt idler bracket probably cracked(for buzzing/rattle noise)- exhaust tube gusset bracket cracked (for buzzing/rattle noise on acceleration)- bank 1 catalytic converter heat shield( for buzzing/rattle noise)- if AWD, check transfer case for any crack housing- intake timing control solenoid valves faulty(for loud clunking/rattle noise)- faulty VTC sprockets(for loud clunking/rattle noise)- timing chain guides broken or worn

I f you have access for a scan tool or Consult 2, go to data monitor & check what's the reading on intake timing control valve solenoids in degrees , should be plus or minus 1 deg at idle.

Thanks jetroy240

-oil is level clean Royal Purple, no trouble codes whatsoever=perfect-drivebelt idler bracket= perfect-exhaust tube gusset bracket=perfect-bank 1 cat converter heat shield=perfect-AWD transfer case no cracks=perfect*intake timing contol solenoid= will check*faulty VTC sprockets= will check*timing chain guides worn or broken=will check, although noise is eminating from the rear of left valve cover, not in the front where the chain and sprockets are

Once again...thank you for the suggestions.

[OldmanPurdy]

Thank you OldmanPurdy for the reassurance. I'm hoping it's something minor. I'll open her up this weekend and check the chain tensioner also.

What confuses me is that it revs so nice, silent, and smooth in Park, but in gear it makes the clunking sound.....Anyone???

Yeah I only really get the sound under heavy load too mostly going up a hill in too high of a gear or things like that, I could rev the engine all day long in N and not hear a thing. It reminds me of the noise my S13 used to make before I did all the tensioner/guide repairs on it so I'm leaning towards that direction.

[tubbedz]

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.

[tubbedz]

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

[tubbedz]

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

[OldmanPurdy]

When I replaced the pcv on my altima I also found oil in the back cylinder bank (passenger side for you longitude mounted guys) spark plug sockets, I read that the valve covers on the 2005 and up VQ's are supposed to remedy this issue. Thank you for posting your results I really though i had a chain slapping issues but I guess its time to pop off that pleneum again.

[SteveTheTech]

I would check first if there's any trouble codes, if the oil level & condition is good & clean. Check these items:

- drive belt idler bracket probably cracked(for buzzing/rattle noise)- exhaust tube gusset bracket cracked (for buzzing/rattle noise on acceleration)- bank 1 catalytic converter heat shield( for buzzing/rattle noise)- if AWD, check transfer case for any crack housing- intake timing control solenoid valves faulty(for loud clunking/rattle noise)- faulty VTC sprockets(for loud clunking/rattle noise)- timing chain guides broken or worn

I f you have access for a scan tool or Consult 2, go to data monitor & check what's the reading on intake timing control valve solenoids in degrees , should be plus or minus 1 deg at idle.

Great advise, we need someone with some 240 experience around here.

~tubbedz Great write up there, sorry for your frustration a power balance test would have shown #3 cyl drop to be a little off, but only under load. Unfortunately this is not uncommon on some of the earlier VQ35s. The best way to resolve this once and for all is to replace the valve covers. The small gaskets are not available separately. With 90% of pinging under load conditions are caused by inferior fuel, or increased combustion temperature due to poor heat transfer in either the oil or cooling circuit. Many of these things will through a hard fault DTC (ie INT/V solenoids or TB) when they are out of range. I am surprised though that despite the frequency that this occurs that no codes are ever thrown in these cases. Despite effected both Air/Fuel ratios on the effected bank and the ckp and knock sensor should detect this type of malfunction. I do not get the logic behind this driveability concern but let me tell you this is indeed a frustrating one, the first on I have was on an I35 and it had me chasing my tail for a while, until I decided to tear into the valve covers just like you.

[OldmanPurdy]

The 2005 VQ valve covers fixed this didn't they? are they a direct bolt on for older VQ's ?

[SteveTheTech]

They superseded the part number several times since the inception of the VQ35. Usually superseded parts make their way into production when model year changes, or in half year increments depending on the number of changes needed.

05 sounds right though.

[OldmanPurdy]

Thank you i'll be sure to get this fixed up this spring.