I installed my 5/16" MD spacer last weekend and I love it; however, every day I check the center six center bolts and they don't stay torqued. According to the MD directions, these 6 bolts are to be torqued to 60 in/lbs whereas the other 12 bolts are at 100 in/lbs (which stay properly torqued, btw). All 6 center bolts loosen equally and need about 1/4 turn to meet the 60 in/lbs spec which equals a mere 5 ft/lbs. I'm certain the reason they loosen is because the internal plastic spacers give too much and don't allow proper torquing after the motor has heat cycled. Anyone else have this problem?

 

Mine were fine when i checked them 3weeks later.

 

Dave,

I had to retorque 4 out of the 6 bolts to 60 inch-lbs. some 3 weeks ago. That was the 1st time after the initial installation. I just checked the bolts again after reading this. The 2 center bolts, numbers 1 & 2, were approximately 1/2 turns out of torque. I'll recheck all 6 bolts again this weekend. I'll keep you posted.

 

Is it a possibility that your torque wrench is out of specs?? Dunno maybe its not the bolts nor the motor... maybe the tools?? Just an idea??

 

Well, my particular inch-lb. wrench was recalibrated some 6 months ago. Even then, if it was the wrench, the margin of error should remain the same per bolt. Another member, RBull, had the same experience with his 6 center bolts, as well. He had to retorque 4 out of the 6 center bolts, as well. Actually, he was the one whom had made me aware of this.

 

The torque wrench is a brand new 25-250 in/lb Craftsman unit. I put the wrench at 250 in/lbs (~20 ft/lbs) and it matches my 20-110 ft/lb Craftsman torque wrench when set at 20 ft/lbs. The other 12 bolts that surround the lip of the manifold are still holding 100 in/lbs. The problem lies in the plastic internal spacers. Since they're plastic, they give when torqued. Since the manifold requires a minimal amount of torque, there just doesn't seem to be a good way to hold the torque. A little red loctite would fix the problem immediately. I'm going to let the bolts stay for 3 to 4 days and see if they loosen anymore than a 1/4 turn. I don't think this problem is a huge deal because most of the sealing of the manifold is around the lip and those bolts are hold fine.

 

yeah, i heard some other guy on this forum had the same problem with the center bolts loosening up. like what you said, use some red/blue loctite and call it a day.

 

I wonder if the people that aren't experiencing problems have torqued the center bolts to 100 in/lbs?

 

Infiniti Svc manual shows all upper plenum bolts at 9-10 ft-lbs except for the bolt studs (5 ft-lbs) that you wind up replacing with bolts from Tony's kit anyway.
I installed and torqued all of mine to about 100 inch-lbs and haven't had any issues. I do think it's important to tighten the bolts in the numerical order that's shown. Loctite shouldn't be necessary but I guess anything that prevents you from over-tightening and stripping these threads is important. Last advice, tighten these parts when engine is cold as heat seems to be suspect for some of the problems previously reported.

 

just a hypothetical guess but i think the center bolts are loosening up due to the expansion and contraction at those localized areas and of course, the plastic spacers/standoffs...

 

does it affect the car's performance in anyway?

 

Throw a dab of paint on one side of the bolts and onto the plenum like the factory does in some places so that you can see if they are loosening, or if the spacers are compressing. Could be that 60 in lbs isn't enough to keep them from backing out.

Curt

 

It will if the bolts loosen enough to cause a vacuum leak past the bolt head into the plenum.

Curt

 

Quote:
Originally Posted by 05g35mt
does it affect the car's performance in anyway?

It will if the bolts loosen enough to cause a vacuum leak past the bolt head into the plenum.

Curt


Im glad this problem came up. I just ordered my MD/Iso. I will mention this to the installer to prevent problems later.

 

+1 I'll have mine put some locktite on those bolts. In fact, I don't see any reason why he shouldn't loctite all of them during the install.