300tdi cylinder head torque

[inchman]

hi all, I changed the cylinder head gasket on my 300tdi 90 at the weekend, i torqued the head as per the manual but im just wondering should i check the bolts again after a few miles hours etc and if so to what torque setting ??

hope this makes sense.

cheers gary

[western]

No, leave well alone, if there was another check after a full engine run to operating temp or to a defined mileage then the LR manual would specify another torque check.

[Big.Mike]

Gives you itchy fever though... Thinking of those little bolts coming undone... Ralph is correct (as always).

The nice thing about torque settings is that, unless there is some oddness, they are generally fit and forget. Think of the scenario once repaired, we don't have to take the car back to the garage to have the bolts checked.

I think they only suggest you do this on wheel nuts because you can...

Cheers,

Mike

[inchman]

thanks for the info .

cheers gary

[Tetsu0san]

I think I am right in saying that as the first part of tightening them is torque and the next 2 settings are rotation degrees, you would have to undo them and redo them to get the correct settings anyway. Unless there is a known torque value for the bolts when they are done up fully?

[Tanuki]

The whole point of "torque-to-yield" bolts [the kind you first do up to a torque-value then add so many degrees] is that rhe bolts stretch in a controlled way.

This stretchiness provides a much more-uniform and repeatable clamping force - which persists through innumerable heat-cycles.

As an analogy: if you keep your underwear in place using a belt whose tightness you set at the beginning of the year, it cannot compensate for the day-to-day changes in your waistline.

Elastic, OTOH, reliably stops your pants falling-down when you breathe out.

I like torque-to-yield fasteners. The automotive industry should make more use of them.

--Tanuki.

[Jode]

I think I am right in saying that as the first part of tightening them is torque and the next 2 settings are rotation degrees, you would have to undo them and redo them to get the correct settings anyway. Unless there is a known torque value for the bolts when they are done up fully?

Presumably there isn't as the manual indicates the use of a degree torque wrench as you noted.

[western]

Unless there is a known torque value for the bolts when they are done up fully?

no such figure supplied in the workshop manual, just the angle tighten procedure.

[JimAttrill]

And the 300Tdi bolts are not 'stretch' bolts. This is why you can use them 5 times. The TD5 bolts are 'stretch' bolts and you can feel them reaching their elastic limit at the end of the angle-tightening procedure. They must only be used once because of this. We used to drill holes in the workshop wall and bash the bolts in and then used them to hang stuff on