engine knock

A&Q about 350Z
Q:



When starting in cold weather(below freezing) experienced a knocking noise. Dealer saiad it is normal in cold weather if you havent driven in a few days. Sounds wrong. Antone else experience this?


A:



koz,

I haven't started my Z up in really cold weather, but through mid-November, I really have not had any issues. The Z is in its winter slumber mode in my garage now.

I have the same VQ engine in my 2003 Infiniti FX35, and I have never had such an issue.

Zed Head
2005 350Z Enthusiast in Silverstone
AZA Z-2 18x8.5 & 18x9.5
Yokohama ES100 245/40-18 & 275/35-18

2003 Infiniti FX35
Bone Stock


A:



"When starting in cold weather(below freezing) experienced a knocking noise. Dealer saiad it is normal in cold weather if you havent driven in a few days. Sounds wrong. Antone else experience this?"

koz:
What they said is true. What happens in cold weather is the oil gets cold and thicker and sits at the bottom. When the engine fires up, it takes a few moments to get the oil moved up to the upper engine and heads due to the thickness, and the lack of lubricaion is whats making the noise.

This happens in my 300ZX and my moms G35 every once in awhile as well. Using a filter with a check valve may help somewhat, but the Nissan one is crap and I recommend not using it. Here's a you can check out about the Nissan filters.

Just let the car idle for about thirty seconds and make sure you have a good oil presure reading from the gauge before driving. Also, keep the RPMs under 3,500 for the first 2 minutes of driving or so during cold weather. 90% of engine wear comes from startup and the first few minutes of driving after letting the car sit.

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1985 300ZX n/a


Post Edited (Dec 12, 8:38pm)


A:



What he said.

Currently parting out 1990 300zx TT.


A:



I have the same issue (started to occur most cold mornings here in NJ almost one month ago). Upon turning the ignition before pulling out of the garage, the engine makes a knocking noise. It seems to occur when temperature is below 40 degrees. Also, my driver side window does not adjust itself upon opening and closing the door in frigid conditions. I guess the car wasn't meant to be driven in colder climates. Thanks for the insight phxZ31.


A:



i agree with phx

oil does have a tendacy to get thicker when it gets below freezing outside

93 z32 convertible=pearl white, 5 speed
jwt pop-charger, hks hypers, asp underdrive pulley


86 z31 na=super white, 5 speed




A:



I use a half quart of Marvel's Mystery Oil in my crankcase in the winter for both my Z and Pathfinder that has the VQ Motor. If I don't the car will tap-click ever so lightly until the temp gauge starts to move. That's about a half mile. So, I when I sat in the drive for a minute the clicking would go away before MM Oil. After a week of this, I put MM oil in the Pathfinder and I have not had a single problem since. This was over three years ago. The Z got the same treatment and it also doesn't click at all at start up now. Only a half a quart is needed.

So, every October the car get a half quart of MM Oil. I change my oil ~Feb of every year and don't add the MM Oil for spring/summer driving.

What's happening here is the lifters are not getting light enough oil to pump up in the cold weather so valve lash is loose (clicking). If you were to go to 0-30 oil it would improve this as well. NISSAN doesn't recommend 0-30 so..... MM Oil seems to be a great solution I think. MM Oil also help lifters not to stick and motor to be cleaner. I also use 5-30 Mobil 1 oil and stock NISSAN filter.

My .02

"Racing is life. Anything that happens before or after is just waiting"
Quote - Steve McQueen


'04 350Z Silverstone 6spd
Previous owner of 240, 280, and 300 Z's


A:



mecinoid:
hmm, interesting. I have always wondered if that Marvel Mystery oil worked... perhaps i'll have to try it. Last oil change I tried a half quart of Lucas Stabilizerbut it didn't help the cold oil clicking. I'll give the MM Oil a try next oil change.

You really should read that link I posted above and consider not using the stock Nissan oil filter though. There are plenty of cheaper, higher quality oil filters that also have the check valve to prevent oil drain besides the Nissan crap filter.

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1985 300ZX n/a



A:



^^^^^agreed again

93 z32 convertible=pearl white, 5 speed
jwt pop-charger, hks hypers, asp underdrive pulley


86 z31 na=super white, 5 speed




A:



according to some very knowledgable folks on the 90-96 forums, the oem filter for the 300zx do have a check valves, and using that with mobil1 oil seems to solve most of the ticking problems that many have had on their 300zx,

i can't say if the oem filter is the same for the 300zx and 350z...

could someone cut a 300zx filter and check??

1993 Red TT


A:



The knock could be the dual mass flywheel. If yours is a manual the flywheel has a center section that can move back and forth and that really makes noise when cold. The G35 and Corvette use the same design to preclude breaking bearings in the transmission. It softens the blow of the engine when shifting but it rattles like hell.


A:



"The knock could be the dual mass flywheel. If yours is a manual the flywheel has a center section that can move back and forth and that really makes noise when cold. The G35 and Corvette use the same design to preclude breaking bearings in the transmission. It softens the blow of the engine when shifting but it rattles like hell."

what?

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1985 300ZX n/a



A:



Good to hear PhxZ31. Give it a day or two and you might feel a little power gain across the curve from the loosening of carbon up around those lifters.

Check you oil in a couple of weeks. If it is black change the oil. That means that the motor had some carbon build up and you just cleaned it out. Most likely not if it just started to click a bit.

Then refill with fresh oil see if it still clicks when cold. If it does, add a little MM Oil and check the oil after two weeks. If the oil is clean at that point your in the clear.

Sometimes on really old motors you might have to do this again.

My guess is on your motor just the one time will be enough. ;)

I had heard for years how good this stuff was but never needed to try this until my Firebird started loading up at 40K. My Pathfinder started to do the same thing about the same time so I gave it the treatment. Then when the Z started. I tried it again. Good stuff. With all the stop and go driving we do those valves and lifters get gunked up pretty fast. :(

"Racing is life. Anything that happens before or after is just waiting"
Quote - Steve McQueen


'04 350Z Silverstone 6spd
Previous owner of 240, 280, and 300 Z's


A:



Yeah I was surprised how effective that stuff is. I think I will change the oil in week and do the treatment over again just to be safe. I keep my engine in pretty good shape, but its getting way up there in mileage now (133,000) and since it worked so well with only 6oz, I'm thinking next oil change I'll put in a half quart and then change it again in mid Jan.

This has made me wonder if this stuff might be effective at relieving some of the bearing "whirring" in my tranny. Have you ever heard of anybody adding this to their gear oil at all? I noticed its quite thin, so I would guess it wouldn't help much with gear oil, but its got me wondering now... I change my tranny/diff gear oil once a year, but my tranny is definitely making noise in certain gears.

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1985 300ZX n/a



A:



phxZ: I wouldn't put anything in my gearbox but the proper gear oil.

I learned about MM oil forty years ago, when I worked in a garage on Long Island. My boss--who would pass for one of the Click and Clack brothers, BTW--swore by the stuff and had us use it on cars that were in for long interval maintenance. At the time, I thought Tony was totally nuts or that he had stock in the company. Imagine my surprise when, decades later, a trained Isuzu technician recommended it to me to help with lifter noise in my aged '92 Trooper. Did it work? Dambetcha. To this day, I have no idea why--maybe that's what the "Mystery" is all about.

Sorry to run on, but you've pinged a geezer's memory, and that's the risk you take.

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