Cylinder head cover torque?

[tech_dog]

I've searched my hard copy FSM and the soft copy online, and I can't seem to find the torque specification for the 13 bolts that secure the cylinder head cover to the head.

Can someone point me to where this is documented? I've checked all the diagrams and summary torque spec lists, and it's missing from everywhere I'd expect it.

ChatGPT says it's 10nm, but ChatGPT is gullible and I don't trust it.

 

[tech_dog]

This seems to be the closest thing to a fully qualified answer, 9 ft*lbs by CDan, but it seems odd that it takes conjecture: Info Valve Cover bolts......? - https://forum.ih8mud.com/threads/info-valve-cover-bolts.949273/post-11716439.

My bolts have 4 hash marks, so they're 8T not 7T, but I don't think that matters. The rubber gasket and aluminum head threads are the limiting factor.

I see some people using the class 8 bolt class to choose a higher default torque, but this is class 8 going into aluminum, and I see people reporting stripping the threads in the head by going this high. Typically, for M6 bolts in aluminum the safe torque is often around 7 Nm (5 ft-lbs).

I'll probably go with 8 ft*lbs and see what happens. I can always tighten more if I get leaks. I'll have to break out the torque wrench normally reserved for my bikes.

Any other opinions?

 

[NeverFinis]

It appears to be 9 ft*lbs

 

[Malleus]

All bolt torque into the head is 15-lb·ft. Except those

 

[tech_dog]

It appears to be 9 ft*lbs
View attachment 3835237

I wish my FSM had that line. Which FSM is that?

Thanks!

 

[NeverFinis]

I wish my FSM had that line. Which FSM is that?

Thanks!

1996 LX450. I can't find the same torque specification in the 1996 FZJ80.

 

[Malleus]

It's in the 1996 LX450 service manual:

and the 1997 LX450 service manual:

None of the 1993-1997 Land Cruiser service manuals specify a torque, for either the (13) bolts that secure the camshaft cover nor the the (4) that secure the spark plug wire covers.

 

[tech_dog]

I'll consider this fully proven at 9 ft*lbs. Thanks team!

T.

 

[robnicko]

I'll consider this fully proven at 9 ft*lbs. Thanks team!

T.

& tighten in the same sequence you would do the head bolts to ensure no leaks, IE from middle to either end

 

[tech_dog]

To summarize this, I think:

In 1993 and probably before, there was no specific torque spec. You got the correct torque using the 9 ft*lbs default for a 6mm 7T.

My 1994 came with 4 hash mark 8T bolts, so it appears they changed the bolt but didn't update the Toyota FSM. There's no default value for a 6mm 8T, and there's still nothing specific for the head cover. It's easy to see how people assume the 8T bolt needs to be tight and end up doing damage.

It appears that Lexus picked up the missing spec when they created the LX450 FSM in 1995, but Toyota never did.

 

[Malleus]

From what I've seen, comparing the service manuals between Toyota and Lexus, Toyota leaves a lot to a mechanic's general knowledge, unless their design mandates some critical procedure. Lexus specifies everything, as far as I have seen, except for the procedures they intentially omit, becasue they want to sell assemblies and not have the dealership mechanics rebuild them.