300Tdi crank pulley Nm +90

Hi folks
Could someone please explain in plain English that what does that +90 means?
Does that bolt needs to turn further 90 degrees manually?
Or that 27mm bolt needs to be tightened to 80 Nm first then once again tighten to 90 Nm?
Thanks

Usually means torque to xx nm then +90degrees on the bolt

J

Bolts that compress two parts together that are subject to repeated and often changes of temperatue will loosen over time,
You torque them up and they don't last, unless you 'stretch' the bolt so that the bolt itself is under tension whilst it holds the two things under compression.

The clever engineering types have determined that this requires a 0.375mm 'stretch'.
The bolt has a 1.5mm thread, so after it has been tightened and is clamping the head to the block (for example), it then needs to be rotated another 90 degrees to achieve the tension in the bolt itself.

In these situations, it is very important that you fit new bolts as the old ones have already been stretched and won't be the same again. It is also important to fit the original manufacturers bolts (OEM) as others may be of a different steel/alloy that won't stretch the same.

Yes tighten to spec then 90 degrees

In reality you will need the crank locking tool and a 6 foot tube to go on your breaker bar to even get close to that

You will almost certainly need the special tool to get the crank pulley off too

Last few I've done up ft with my dealt impact gun turned up high and they've been fine but that's just me (plenty loctite and you shouldn't need to replace the bolt)

That is the way I have done it as well, impact gun and loctite.