So, installing the Motordyne Thermal gasket set and plenum spacer, I just broke one of the long bolts that mount the lower plenum to the head. I wasn't overtightening, first off ... maybe it went in strange, but I was on the step where you tighten them to 110 in/lb, and it just CRACKED!

Where can I get a replacement bolt ASAP?! Can anyone tell me what size, or spec to look for?!? I am screwed, as I need this car tomorrow.

 

You can drive the car without one of the bolts. (I know. Some time back I did the same thing when untightening the stock bolt the first time. The aluminum was still quite warm when I did it so it was my fault.)

After reinstalling all but the one bolt I drove around for a couple days and it wasn't a problem. You could probably do the same so you can drive it to sears and get a bolt extraction kit.

PMed.
Tony

 

Actually I don't even need an extractor... I was able to get the entire bolt out, as it just snapped (most of the way) about the center of the threads.

You said it was an M6 bolt, with a 1mm thread pitch. Do you know what length? I'm going to bring it with me, to compare, when I go to the hardware store.

Thanks for the lightning fast response!!
I'll post back here what I come up with...

 

If you can get it from Infiniti or Nissan I recommend thiers. M6 bolts are quite uncommon in hardware stores. And they are much more difficult to find in the automotive grade high strength alloy 10.9.

And although you can use 8.0 or similar, 10.9's are much prefered in that location.
Also, let your engine cool down real good before doing the work. The aluminum is less sticky at lower temps.

Tony

 

Found some bolts that were M6 x 1.00 at a 10.2 strength. Should work OK.

Strangly enough, my engine was bone cold. It had been sitting overnight in the garage, for at least 14 hours.

 

which one was it?

we have them all listed here..

http://performancenissanparts.com/ca...1135_1136_1182

 

Mine broke on the way out. Did yours break going in or out?

 

Tony - Mine broke on the way IN. Since I was turning the tq wrench so slowly, I felt it as soon as it broke, and slowly backed it out.

The bolt was cracked right in the center of the threads, and was almost broken completly off. None of it was left in the lower plenum, thank god!

The replacement bolt I got worked like a charm. Perfect fit, and no more snapped bolts! Everything is back together, and I didn't even have any air leaks!

The spacer is awesome... I definatly feel some more "pep" in the acceleration. After I do a few more mods this month, its going back on the dyno, to compare to my baseline... we'll see!

 

For good pre/post testing it is best to do the install on the dyno of course, but this understandably impractical for most. The next best thing to do is slam the accelerator from 1500 RPM to redline several times shortly before going into the shop. This will put your ECU into performance mode. Then once you get on the dyno do a ECU reset.

This will help keep your ECU from going into granny mode. If you can keep the ECU in the same mode every time when you dyno you will get the best benchmarked results.

Tony

 

I wish there were a better way to reset the ECU. It took me almost 20 mins to get it done ONCE tonight! Someone needs to invent a switch that resets the damn thing!

Thanks again for all your help Tony!

 

Your dyno operator should have a OBD2 scanner that can reset the ECU with the push of a button.

If not, you can simply disconnect the battery negative and turn on the dome lites for a few seconds. That will do it too..

 

I did the same but my bit is left into the lower plenum. I went ahead and put it back together because I need the car. Its the left middle screw. what kind of bit extractor do i need cause it is deep in the bottom of the lower plenum. Is it ok to drive like this for now??

 

You will probably suffer major vacuum loss, and drivabilty as well. Do a google images search on the type of extractor you think you might need, then clic over to the "shopping" tab.

Courtesy Nissan might be of help w replacement bolts.
972.231.2600

 

If I take the lower plenum off am I going to see the bit poking out? Is it poosible to k=just feed it all the way threw the threads?

 

please dont post the same thing multiple times....

https://my350z.com/forum/intake-exha...t-snapped.html

 

VQ35DE Lower Plenum Bolt Nissan Part Number: 081B6-6701A

One of my lower plenum bolts broke too when I opened it up. I replaced it with with a 8.8 strength M6 x 75mm and used extra washers so the threads would tighten down as opposed to getting stopped by the unthreaded portion. Worked fine.

Now with plenum open again, and old OEM bolts being stretched/weak in the middle, I ordered some from a local Nissan dealer at $3.99 a piece, for next-day pickup.

Also found them on CZP for a better price $1.62. Would buy from here if not in a rush. Hope it helps someone!

 

I heard a loud pop when installing the center two (top and bottom) plenum screws. I fear I have overtorqued them, but neither broke off into the plenum, however, they no longer tighten like the other 4 screws. I am sort of scared that I've broken something! I've shut the hood for tonight and left it alone until further help form the community.


Any input is very much appreciated, and Thank-you in advance

 

where did you get your bolts I have the same problem unfortunately