Cylinder case breather box sealing - ZR-1 Net Registry Forums

AndrewL · 10-07-2022

Hi guys

I'm in the middle of dissassembling and cleaning the intake valley on my 91. Upon removing the cylinder case breather box cover, I noticed a small amount of sealant had been used on the box side of the gasket.

My service manual doesn't mention using anything aside from the gasket.

I'll be using a fresh gasket from Jerry's, any advice as to whether there is a reason to add a small amount of rtv to one side of the gasket?

A26B · 10-07-2022

Andrew,
I believe the true cause of seepage from the Cylinder Case Vent Box (and including most other gasket sealed components), is caused by the bolts loosening over time, not gasket failure or lack of sealant. The machine work on the LT5 is incredibly good, so the gasket mating surfaces of the components are excellent.

Before reassembly, I suggest you use a spray can solvent like brake cleaner with the spray nozzle plastic pipe attached, to clean out the 13 tapped holes for the cover bolts and also the bolts themselves. Blow the tapped holes and the bolts dry and clean of residue. Likewise, clean the mating surfaces of residue, spray & wipe down to remove any oil. Then, apply Loctite 242 or 243 to the bolt threads before installing.

Use a cross tightening procedure in all four stages, tightening the bolts to final torque: (1) all bolts screwed down completely but no torque, (2) tighten to 50% of final torque, (3)tighten to full torque, and (4) re-check final torque.

Takes 5 minutes to do it right and sealant not required.

AndrewL · 10-08-2022

Thanks Jerry. I appreciate your detailed answer. I'll follow your procedure, it makes good sense.

10-07-2022	#1
AndrewL Join Date: Dec 2020 Location: Sydney, Australia Posts: 76	Cylinder case breather box sealing Hi guys I'm in the middle of dissassembling and cleaning the intake valley on my 91. Upon removing the cylinder case breather box cover, I noticed a small amount of sealant had been used on the box side of the gasket. My service manual doesn't mention using anything aside from the gasket. I'll be using a fresh gasket from Jerry's, any advice as to whether there is a reason to add a small amount of rtv to one side of the gasket?

10-07-2022	#2
A26B Join Date: Dec 2003 Location: Arcadia,OK Posts: 3,376	Re: Cylinder case breather box sealing Andrew, I believe the true cause of seepage from the Cylinder Case Vent Box (and including most other gasket sealed components), is caused by the bolts loosening over time, not gasket failure or lack of sealant. The machine work on the LT5 is incredibly good, so the gasket mating surfaces of the components are excellent. Before reassembly, I suggest you use a spray can solvent like brake cleaner with the spray nozzle plastic pipe attached, to clean out the 13 tapped holes for the cover bolts and also the bolts themselves. Blow the tapped holes and the bolts dry and clean of residue. Likewise, clean the mating surfaces of residue, spray & wipe down to remove any oil. Then, apply Loctite 242 or 243 to the bolt threads before installing. Use a cross tightening procedure in all four stages, tightening the bolts to final torque: (1) all bolts screwed down completely but no torque, (2) tighten to 50% of final torque, (3)tighten to full torque, and (4) re-check final torque. Takes 5 minutes to do it right and sealant not required. __________________ Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 *ZR-1, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed. Last edited by A26B; 10-07-2022 at 01:35 PM.*

10-08-2022	#3
AndrewL Join Date: Dec 2020 Location: Sydney, Australia Posts: 76	Re: Cylinder case breather box sealing Thanks Jerry. I appreciate your detailed answer. I'll follow your procedure, it makes good sense.