Do You Torque Valve Cover Screws?

[FlyWalt]

Hi Guys,

I am finding some leaks at my valve covers and am about to tighten them up. Do we have to torque these? And if so, what would be the spec. This is a TSIO-360LB.

Thank you in advance,

Walt

[smwash02]

If you have the RealGaskets (silicon) you need to follow their specs closely. Over tightening will cause a leak.

If you don't have them, I suggest them. Reusable and have done well for me.

[PT20J]

5 minutes ago, smwash02 said:

If you have the RealGaskets (silicon) you need to follow their specs closely. Over tightening will cause a leak.

If you don't have them, I suggest them. Reusable and have done well for me.

SL L272A Silicone Rocker Box Cover Gaskets.pdf

[kortopates]

Following the spec ensures they remain leak free, as well as re-usable for many years.

[Fly Boomer]

40 minutes ago, FlyWalt said:

Hi Guys,

I am finding some leaks at my valve covers and am about to tighten them up. Do we have to torque these? And if so, what would be the spec. This is a TSIO-360LB.

Thank you in advance,

Walt

Other similar engines suggest 55-65 inch-pounds.  That is probably not correct for silicone gaskets.

EDIT:  I just read the SL provided by Skip, and I see that the torques are somewhat less than the Continental reference I found, but still illustrate that silicone gaskets require less torque.

[EricJ]

1 minute ago, Fly Boomer said:

Other similar engines suggest 55-65 inch-pounds.  That is probably not correct for silicone gaskets.

The cork gaskets require higher torques.   The Lycoming service letter points out this distinction.

[jetdriven]

Continental has you torque the silicone valve cover gaskets to a lower number, and have you put blue Loctite on the screws when you install them. The last time I torqued a Lycoming valve cover with a torque wrench, three of them fell out off of one valve cover in the span of an hour flight.

[Guest]

8 hours ago, FlyWalt said:

Hi Guys,

I am finding some leaks at my valve covers and am about to tighten them up. Do we have to torque these? And if so, what would be the spec. This is a TSIO-360LB.

Thank you in advance,

Walt

Yes you need to torque these, with a new lock washer as well.  The value listed assuming factory gasket not aftermarket.

[FlyWalt]

Clarence,

A Sincere Thank you to one of the great mechanical minds on MooneySpace. We greatly appreciate it.

Walt

[MisfitSELF]

The Lycoming SSP-1776-5 shows 35 in-lbs for silicon gaskets.  Not sure if this applies to your engine.

Lesson I've personally learned.  If you get the gaskets that are a buck or two cheaper from aircraft spruce (the one that don't say if they are PMA'ed) then the bolt holes will be too big and it will leak oil through the bolt holes.  Make sure you get the ones the seal up against the bolts.  In other words, the gasket bolt hole diameters should be snug against the bolt as you screw them in.  But don't over torque!

Bruce

[carusoam]

17 hours ago, FlyWalt said:

Clarence,

A Sincere Thank you to one of the great mechanical minds on MooneySpace. We greatly appreciate it.

Walt

Great thank you note Walt!

@M20Doc probably came by already…

Go MS!

Best regards,

-a-

[jetdriven]

On 9/10/2022 at 8:17 PM, M20Doc said:

Yes you need to torque these, with a new lock washer as well.  The value listed assuming factory gasket not aftermarket.

I think the on  Lycoming valve cover screws, the lock washer is integral to the screw. 

[Guest]

2 hours ago, jetdriven said:

I think the on  Lycoming valve cover screws, the lock washer is integral to the screw. 

Correct on a Lycoming and they are seldom replaced other than at overhaul.  On a Continental the lock washer so readily replaced.

[Will.iam]

Which is better for low torque values like what is required for silicone gaskets for the rocker covers, lock washers or star washers? I ask as i noticed i have lock washers on all my covers except the one cover that is next to the oil cooler it has a star washer. Shouldn’t they all be the same one way or the other?

[kortopates]

My recollection is split washers.
But the TCM IPC is available online for free.
So I’d encourage anyone with a parts question to look it up online.
M-O and other TCM maintenance manual’s unfortunately aren’t free nor online; except for perhaps an out of date version.


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[Guest]

10 hours ago, Will.iam said:

Which is better for low torque values like what is required for silicone gaskets for the rocker covers, lock washers or star washers? I ask as i noticed i have lock washers on all my covers except the one cover that is next to the oil cooler it has a star washer. Shouldn’t they all be the same one way or the other?

Generally, Lycoming engines use internal star lock washers, MS35333, while Continental engines use split lock washers use MS35338.

[Fly Boomer]

56 minutes ago, M20Doc said:

Continental engines use split lock washers use MS35338.

18-8 or 316?

[Yetti]

I torqued my silicone gaskets to spec.  After carefully cleaning the old ones off.    Then the grumpy IA came up and put a screw driver on them.  So I had to glare at him.    Still have not leaked.   The drain tubes are another thing.

[Guest]

49 minutes ago, Fly Boomer said:

18-8 or 316?

Cadmium plated carbon steel

[MikeOH]

Per the Lycoming parts manual for the IO-360 the valve cover P/N: STD-1925 comes with external star washer: