Hey guys so idk if this thread was made or not but I couldn’t find it, I was installing a Z1 plenum spacer into my 2003 Z 5AT and was I was torquing the 6 bolts that go onto the upper plenum I popped one, I removed the upper plenum to check the damage and there was a little bit of thread sticking out but I couldn’t pull it off with vice grips and so I tried the easy out method and I drilled a hole into the bolt to try to pull it out, unfortunately I just had surgery and it got to hard for me to bend that much so I gave up, I’m taking it to my mechanic and when I put everything back and turned on the car it did a really gross noise and then idled really low, did another noise that sounded like a clunk and as soon as I heard that I turned the engine off, now my question is, since there is an obvious hole in the upper plenum will the car be able to drive? And that clunking noise is it normal(in respect to not having a bolt in place)? Thanks for the help guys.

 

You're not the first..

https://my350z.com/forum/intake-exha...o-replace.html

Your low idle is because there is most likely a minor vacuum leak created by the poor seal that the absence of that bolt has created. As for noises, I don't believe there would be any reason for any like you are describing just because you broke off the head of a bolt.

How far away is your mechanic? The car will be safe to drive, (may feel a little funny due to the vacuum leak), but I wouldn't drive it for very long.

Once the broken portion of the bolt is extracted, you will need a new M6 bolt with a 1mm thread pitch. Just stop by Nissan and ask them for one. Shouldn't run more than a few bucks.

Also, as a word of advice, it is best to allow the car to cool overnight before attempting to work on these manifolds. The bolts are much easier to break when they are warm.

 

I agree, easy mistake as torque setting should be around 48 INCH pounds. (That's 4-5 FOOT pounds ). I'd get a 1" square of the stickiest tape you have to put on that hole and see if the idle improves enough to drive.

 

Look into a Kinetic v+ intake, it doesn't even use those bolts

 

Yeah most 1/2 drive torque wrenches start at 24-25 ft lbs. If you are going to torque those you will want to get a 1/4 drive. At Harbor Freight they are like $20

 

Keep 1/2" of the bolt there and put some silicon and stick it in the hole...done. You don't even need those center bolts.

 

If you do replace the bolt, the torque spec has already been stated, but I would just go by feel, then you can tell if it's about to snap. I had a similar occurrence with the valve cover bolts.

Also, for the replacement bolt, a fastner supply store should have the bolts much cheaper than a dealer, even though it's only a few $, just something to keep in mind if you need any other bolts around the car.

 

M6 bolts aren't common in most supply stores, especially in automotive high strength alloy.

If you're struggling that much that you'd need to save a buck on a bolt, maybe a different vehicle is recommended.

Not being a ****, I'm just saying. It's fine and dandy for bolts you'd use to hold your bumper on, but I wouldn't skip out on anything that holds my engine together.

 

It's an unnecessary bolt. A class 8 bolt from home depot that's 75 cents will work just fine. I wouldn't consider those plenum bolts "High strength" at all

 

If you want replacement OEM hardware let me know - have a few sets sitting in the garage.

 

bolt not required.
leave it.
plug hole in plenum with JB weld. or magic metal rods and a torch.

 

good point … I chopped the 6 bolts out, welded the holes closed and plugged the bottom sides... One & Done!!

 

Honestly bro , i torque one bolt on the manifold gasket haha it was just to the point where it was sticking up a bit but to still hold the gasket in place , and i literally just left it alone and torque the others carefully , haven’t even had a issue at all no idling weird nothing , i did have it idle weird to where i found the stupid *** oil plastic trim was caught in the spacer so i had to legit take everything off and cut it off and bolt and torque everything it was a pain ): but idle got corrected and worked perfectly till this day no issues ! So don’t even worry check where the oil trim is where you pour oil and check if it got caught in the spacer

 

For those recommending to leave the broken bolt installed...what happens if it vibrates out and get sucked into one of the ports? Sounds like a good way to turn a simple problem into a shitstorm.

 

It wouldn't get sucked into the engine as it'd have to slip between the essentially zero gap between the lower plenum and the supporting post in the upper plenum.

but yes - this is how things go from good to bad to worse...

 

I have short bolts locktited on the inside, been like that for years no issue's.