[Help] Timing chain broke, now I need a new motor
 

All,

I would appreciate your experienced and sage advice. I have a 2007 350z that has about 57K mileage on it. I can work from home alot, which is why the mileage is so low. I have only tracked and autocrossed it once, so the engine isn't abused. While I have installed several mods over the years, the only engine mod was the Stillen supercharger, dampener, and intercooler (installed by Ptuning, Manassas 2016). This past Friday during normal driving, my engine seized and the dash lit up, so I got it towed to Ptuning since I have a great relationship with them. After a few days, they called me back and said that the timing chain broke which is very odd as its a low mileage car. This can happen in Zs, but only in the 100K+ range. Best case scenario, only one piston rammed into the top of the engine block. Because of the time and expense of testing and fixing each and every piston, they recommended to just get a new motor from a reputable source that way they know everythings working. I called up Moore Automotive (Fairfax, Va), and they agreed, saying that the Z engine is an interference engine, and when the timing chain goes the motor goes with it.

While they were able to find a used 350z motor at 54K mileage with a 3 year wtty, the issue is the cost and labor of this entire endeavor will be around $8000. My questions to the community are:

1. What could have been the cause of a timing chain breaking at such low mileage?
2. Could the supercharger have caused it? It was installed 2 years ago and has been working fine every since. I have 400hp on the dyno.
3. While the car is in pieces, what else should they be looking at? What else is liable to break?
4. At $8000, am I just wasting my money? Is something going to break next year and I just flushed it all down the drain? What's stopping me from buying a new car is that this level of performance will cost new $50K+ easy.

Thanks peeps. You all know more than I ever will.


https://cimg5.ibsrv.net/gimg/my350z....8868da7102.jpg

1. Something obstructed the normal operation of the chain and it failed.
2. No, that doesn't put more stress on the chain
3. Just check pistons of damage, replace bent valves and chain; you shouldn't need a new engine.
4. I don't see why you would need a new engine.

1. What could have been the cause of a timing chain breaking at such low mileage?
I'd suspect the chain tensioner or a cam tensioner might have failed. Spring and oil pressure keeps them 'pumped up' during normal engine operation.

Could the supercharger have caused it? It was installed 2 years ago and has been working fine every since. I have 400hp on the dyno.
Possible, but I don't see how.

While the car is in pieces, what else should they be looking at? What else is liable to break?
Other timing components, clean oil galleys

At $8000, am I just wasting my money? Is something going to break next year and I just flushed it all down the drain? What's stopping me from buying a new car is that this level of performance will cost new $50K+ easy.
8K for a replacement engine installed? :confused: Seems astronomically high. You can find import blocks all day long for ~$1500.

Strictly speaking, Ptuning said I didn't need a new engine, it was just more cost-effective to go that route. It was going to cost alot to replace the chain, compression test each piston/value, machine fix any values if needed, assemble the motor back, assemble the super charger back, dyno, start the engine and hope it works. They said I could spend all this money and the engine could still not work, which puts us right back to square 1. Moores, a performance shop competitor, agreed that timing chaining break takes the motor with it.

I'm not saying you are wrong, but in the Northern Va area, there are only so many performance shops and they both say the same thing. What argument would you have me take to them?

I just asked them for a quote, will post here when I get it. I know the engine is more expensive due to the low mileage and the wtty. They said they can get it for around $2-3K

In that case the warranty should be your safety blanket. That nothing will break this year, or next, or the year after that. Because if it does -- the warranty will cover that, right ?

Yep, as long as we take off the supercharger first :icon17:

I'd be pretty surprised if they gave a used motor a 3 year guarantee with FI. If it was one they built, I could see it.

How much should labor be? Bear in mind, they have to take off the super charger and dampener, add it back on later, dyno it back up to 400hp.

For 8k you can buy a turbo z. That's a ridiculous amount.

lol ...how long does it take to remove a stillen supercharger? Assuming it's the vortech-sourced and not the roots?

Don't over think this ... sh!t happens and things break - nature of the beast with anything that has moving parts!!

If I was going to spend $8k on a engine I'd have my (damaged) engine removed and rebuilt with my choice of components. I'd plan on replacing the pistons($1000), rods($800), bearings($200), valves/springs/retainers($300), timing chain kit ($500) add another $1000 for stuff you gotta replace when rebuilding a block. Fair chance the heads and/or block are gouged but you wont know until you tear it down.

and why are you pussy-footing it around at 400hp? You say it like it's a badge of honor? Rebuild the block with quality internals, retune to 12-14psi and push closer to 550-600

$1000-1500 fuel upgrades
$1000 tuning platform
$500 dyno tune
$1000 uninstall/reinstall
$1000 engine builder

what else am I missing?

Do you know of a shop in the DC metro area that can do all of what you just said at that price?

I'm in Colorado ... those were all off the cuff

ask around, search, talk to your shop, and see who has a good reputation for building engines.

call to setup a 30min appointment to review your engine. Ask them for a rough/not set in stone prices to disassemble, clean, assess the damage, help you order parts (start a build thread and get input from trusted members on this forum) and then reassemble everything ... you'll probably over-run the $1k in that bucket but it'll be money well spent.

A good place to start might be a rebuild kit from Z1 performance - they have good packages for cases like this.

ask your shop for a quote to remove the engine, drain all the fluids, and arrange to get the engine over to the machine shop (unless you can do it yourself). and then get a price to reinstall the rebuilt block.

Let the machine shop disassemble the engine - they'll be more organized about it and it'll be like CSI for them to figure out what went wrong.