Chris Edwards

Hey guys bear with me as I'm new to VQ's but not new to motors. Before I put a motor in this thing I'm trying to figure out if anyone has any input for me. A little back story: 2 weeks ago I purchase a caged 2004.5 track car with 26k miles. The guy I bought it from had it few 4 years and took it to the track muliple times. The previous (first) owner is the one that did all the work. When I test drove the car I could smell faint smells of burning oil, but he cold started it and there wasn't any smoke out of the tailpipes, and I assumed it could just be from weeping seals having been a track car its whole life. The motor sounded very sound and healthy. Fast forward a week later and I decide to take the car to the dyno to make sure it's healthy, and also to E85 tune it. Before I do so I decide to go over the entire car, change the plugs, air filter, oil, etc. When I remove the coil packs, I find that 5 out of 6 spark plug holes are literally FULL of oil, as in when I pull the coil out of the hole, oil pours out of the whole all over the valve covers and down the side of the motor. The 6th cylinder (furthest back on the driver side) was bone dry. So I shop vac as much oil from the spark plug holes as I can, and replace the plugs with some oil dripping down into the cylinders but not a ton... When I start the car up after the new new plugs, the car is billowing smoke out of the tailpipes (burning oil). I'm not too concerned as I understand that some oil from the tubes has made its way into the combustion chambers and will take a few minutes to burn off. However, after letting the car idle for 20 mins the smoke is just as bad as it ever was and there is clearly a problem. I do a little research and find that this is a seemingly common problem with VQ's and even though the car only has 26k miles, it probably has heat cycled enough where the spark plug tube seals are brittle or worn out. I source OEM valve covers from the Infiniti dealer and OEM gaskets to the tune of $650. I install them properly, and start the car back up, and it is STILL billowing smoke heavily out of the tailpipes. At this point my expertise has run out (I am new to VQ motors) so I hop on Google and I discover the first owner of the car was having PCV issues of some kind. That thread can be found here:

https://my350z.com/forum/engine-and-...-start-up.html

I have not yet done a compression check but TBH it will only confirm what I already suspect... that the ring seal is compromised and there is excessive blowby in the crankcase that is pushing oil past the rings causing it to smoke heavily on startup. The strange thing is, the car does not do it all the time though. On cold starts, the car has only a light haze and other times it billows heavily. All the while the motor sounds awesome, revs freely, and drives normally. But the smoke billowing MUST be resolved and I do not think it's the spark plug tube seals any longer as it would have burned off by now. I have also since pulled several coil packs after putting a few miles on the car and they are all bone dry.

Anyone have any ideas before I source a motor for this thing?

icer5160

iTrader: (4)

Another common failure point on VQs are the valve stem seals. Since this vehicle was tracked, I'm not surprised things are toast. VQs run hot, you need an external oil cooler if the vehicle is being tracked. Otherwise you risk overheating the block and potentially destroying the rings (among other things). I wonder if the seller had some kind of additive in the oil to prevent the major oil burning. This issue got real bad after you changed the oil right? No way this just started happening out of the blue. I'm sure the car already had issues and the seller did their best to hide them.
-Icer

icer5160

iTrader: (4)

Also, double check the PCV system, does it even have the stock PCV system?
-Icer

Chris Edwards

Thanks for the replies! Yes the car has a fully functioning stock PCV system. I think your post summarizes things very nicely... even though the car is full of high end parts (nothing but the best including the cage, radiator, APS oil pan, etc he somehow forgot to install an oil cooler on the car, which probably would have prevented this entire disaster but I always purchase old race cars under the impression that they need a motor and I pay accordingly. This morning I ordered a 65k mile motor from a 2004 350Z off LKQ with a 6 month warranty. Before I send back this motor as a core I'll pull off my expensive valve covers and keep them as spares. And of course, an oil cooler will go on the car very first thing.

icer5160

iTrader: (4)

The APS oil pan definitely helps, but that by itself won't prevent an overheat scenario on the track. Aside from a large external oil cooler for the sump, I highly recommend installing a baffled oil catch can. These VQs are pretty notorious for sucking in oil through the PCV system (yes, even NA Zs) when under wide open throttle conditions for extended periods of time (such as track use). Lots of aftermarket options out there for both. After you get that squared away, and depending on how serious you are about tracking this car hard, I would look into some brake ducts, 2-piece rotors, or maybe even a bigger brake system. The stock Brembos are excellent, but even those can suffer from heat soak. I would reach out to dkmura, he's has a lot more experience with tracking a 350Z and can give you some solid guidance on must haves vs. nice to haves.
-Icer

iideadeyeii

iTrader: (6)

You purchased a motor before doing a compression test, why?

Chris Edwards

Show me a junkyard where you can take a compression tester kit with you into the yard, and a battery, and climb up on to cars either stacked on top of each other, or motors already removed from vehicles strapped to pallets, and undertake a compression test... OR the alternative is driving all over hell's half acre to craigslist and marketplace sellers and spend an hour + in some ghetto with a compression tester while they breathe down your neck. That's not possible. The best solution is to buy a motor from a reputable outfit like LKQ who asks for the VIN of the recipient vehicle and they will warranty not only the motor but also the labor and misc parts that go into a swap should there be an issue with it. They are also trustworthy and the motors are legally tied to the VIN's they came out of so the mileage's are accurate. So I chose the lowest mile VQ motor in the country, with a warranty. I'd say I made an educated guess and if for some reason my guess was incorrect, they will pay the labor on book rate so I don't have a lot to lose here.

iideadeyeii

iTrader: (6)

Dude, on your car. Not the junkyard motor

Chris Edwards

A compression test would take me at least an hour to do, that's an hour of my life I'll never get back... once I fixed the valve covers and replaced all PCV components with OEM, there's nothing else left that it could be besides valve stem seals or piston rings, both of which I would resolve with a new motor.

iideadeyeii

iTrader: (6)

I also value my time at $2500 an hour, but "time is money" would of been an acceptable response because that's what I was thinking in the first place

Chris Edwards

Yes time is money. Tbh I was depressed for 2 days after I replaced the valve covers since that took me several hours. Total wasted time. What I should have done is a compression test before changing the valve covers.

iideadeyeii

iTrader: (6)

I recommend everyone who has valve cover leaks on the tubes to use permatex 1 minute gasket. Clean the area real good /brake clean and spread with your finger on the seal between the head and the valve cover. There are also aftermarket cheaper alternatives that have worked well for people if you did some searching on the forums.

icer5160

iTrader: (4)

CZP has an aluminum valve cover set now ($200), with serviceable spark plug tube seals. When my OEM plastic covers fail, that's what I plan to get. It's still a fairly new product offering, so only time will tell. A few complaints about paint quality, but I'm more concerned about the seal quality. You can always repaint them and still save money over buying OEM.
-Icer