The age old question which seems to split forums. Do you lube the head bolts or keep them dry when torquing down? Only a light wipe of oil as you don't want a pool at the bottom preventing the bolt moving down any further.

I've had 2 sets of bolts, both from different manufacturers. One set came with lube and the other did not.

What is the official Fiat word on this? How do they do it?

I was taught to always lightly lubricate head bolts.
Haynes says to do this.
The Fiat official manual on CD does not mention lubricating the bolts, it just says "fit them".

The bolts are first tightened to a low torque figure, then turned 90degrees, twice. During this the bolts need to turn in their threads in order to stretch them and give the required pull. If the threads are tight, they are likely to twist instead of stretch, so I'd always oil them lightly.

The gasket should be in a sealed bag. During use it glues itself to the head and block. It needs to be kept in its bag until ready to fit, then the head should be put on without delay. Head and block faces must be clean and oil-free to avoid contaminating the gasket, so care needs to be taken to keep the light oiling of the bolts away form the gasket.

why head gasket needs to be stored in air tight container?

flisko said:

why head gasket needs to be stored in air tight container?

Click to expand...

That is not what I said.

The gasket should be supplied in a sealed bag, and should remain in it until ready to be fitted, then fitted without delay between clean faces.

To quote Haynes: "The new gasket should not be removed from its nylon cover until required for use. Fit the gasket dry, and make sure that the mating surfaces of the head and block are perfectly clean."

From Fiat manual on CD:
"Because the gasket is made out of special material, it undergoes a polymerisation process during engine operation and hardens considerably during usage.

In order for the polymerization process to take place the gasket must be kept in its sealed nylon container and only taken out just before fitting to prevent getting oil on it."

Clean and dry headbolt in the block
(Brake clean + airline it dry)

I personally light lube my headbolts after cleaning if they are to be reused


Ziggy

The torque is not really what is important. The object is to stretch the bolts by enough so that no matter what happens the head will stay on and sealed. Think of it like an elastic band around a Jack-in-the-box. You need the band tight to keep the lid on.
In an ideal world you would measure the length of the bolt before and after. In some applications the bolt is electrically heated to a temperature that produces the required stretch, the nuts snugged up finger tight, with oven gloves, and then left to cool down.
Traditionally torques are tested on dry fasteners. Well good luck getting that on a head rebuild. Lube will reduce the friction on the threads and the same torque will stretch the bolt more than intended.
Angle tightening takes this out of the equation. Ninety degrees is one quarter of a turn which stretches the bolt one quarter of the thread pitch which is back to where the designer wants to be, i.e. specifying an extension or amount of stretch. The torque required to produce the stretch is then irrelevant.

Angle tightening is only another proxy measurement for bolt preload, just like torque. Both have pluses and minuses.


The way to be as sure as possible is to follow the manufacturer's specification. If they say lubricate, do that, if they say not to, do that.


After all, they have designed and manufactured the product.

changing head gasket on 8v, reusing old head bolts and was wondering if that 90 degree torque stuf also applies to used bolts or should they be torqued by feel?

It applies to new or used bolts.
It uses the angle method to apply a little stretch into the bolt, presumably to keep pressure on like a spring.
Doing it by feel will lead to gasket failure sometime soon.

thanks for that old buddy