Curious how much service you've gotten out of these, and have they started puttering again.

 

manifolds dont cause leaks; dying motor mounts cause the motor to shift, and the manifold studs are the next weak link, which break.

those manifolds should be fine.

 

Just had a cheap **** front motor mount from autozone cause my mani studs to break. I thought I was doing a good thing replacing the front mount but not when it's duralast from AZ.

 

Autozone sucks and so does their line of products......Fill them w/poly!!!!

 

Thanks. Regarding the studs. I may have bought the wrong ones, and curious your input on what we are trying to achieve. Do we want extremely hard studs that maintain the clamping force, and have a high tensile strength, or do we want a lower tensile strength and not as brittle a stud.

Here are the values:

Metric Class Yield Strength
8.8 93,000 psi
10.9 136,000 psi
12.9 160,000 psi
A2-70 65,000 psi
A4-80 87,000 psi

I bought the 12.9 studs, but I also have access to the A2-70 stainless steel ones.

 

they *can* cause leaks if the mating surface becomes warped over time due to broken studs. if 2 ports are secured to the head and 1 isn't, the heat could allow that non-secured port to deflect a little bit (probably not even enough to see with the naked eye, but enough to allow leaks)

 

Ya, I couldn't see it either with the naked eye. The 92 VG I just tore down has warped flanges on both LH & RH. Half the studs were snapped on both sides. Warping was 0.007" on both sides. I'm now in my friends workshop trying to remove the annoying studs. Like 5 of them!

 

I hope you have access to a lift... it's no fun removing broken mani studs/nuts laying on your back. I went to my Nissan Dealership for the studs that go into the head. As far as the front pipe I'm using the studs/nuts that came with the OBX headers/front pipe. Good wrenching!!

 

whoops! Sorry if there was some confusion in my post. Yes, if the manifolds get warped, they'll leak, and need to be planed or replaced. I simply meant that the mani doesn't cause the leak, other factors do.

Nissan has a revised part for the OEM studs, much stronger and will withstand the engine movement better.

 

I got the ATP rear (RH) exhaust manifold for my engine rebuild and it was a PITA to install because the heat shield wasn't shaped well to just plug and play. So I spent at least half an hour with a punch and hammer to reshape the shield so I can get it onto the block and had to reshape it again to get the washer and nuts on.

Also it didn't come with the right hardware like the studs and nuts came with the wrong sizes. Luckily I had already ordered those parts from Courtesy, and I suggest you get them too.

 

Why not buy used OEM...I got one on a non leaking 94 VG block. Going into the garbage soon when I start prepping the motor for FWD operation.

 

I don't have a lift, but the engine is torn down so I drilled them out on a work bench. I got all of them out but it took hours. The hardest part is starting the drilling. I used a center punch but it's hard to get it to stand still.

 

Thanks jbbons, this is good to know. I'll try the Dorman one instead.

 

Don't want to risk a pinhole leak that I can't detect from inspecting the flanges. It's disastrous to have to remove the VG30E after completely installing it and turning the car on to test it.