carbon1993

Hi guys ive rebuild my 2.8 cologne engine and also put in some new headgaskets.

Ive seen some manuals say torque it to step 3 80-95 ft lb and thats it.
But some manuals even have a step 4 80-95 ft lb after the engine had run for about 15 minutes.

Now my question is is this a necessary step and if so should i let the engine cool down or should it be torqued when the engine is hot?


it has no stretch bolts.

costina

iTrader: (1)

cold then do valve clearances.

MrEngineerdat

The manuals are not always correct. Fact! But the manual you read could be implying that its a good thing to re tighten to 80-95 after the engine has had a run, having heated up for expansion movement, and cooled for contraction movement, but thats not to say it should be hot when you tighten it up. Metal changes shape and load carrying capacities when its hot, so you could cause irrepairable damage by tightening when hot. Also bear in mind that a hot expanded bolt and thread is under the stress of 80-95 in a hot situation, then it cools and the bolt wants to shrink due to temperature, increasing that 80-95 to an overloaded snap or crack. Always do your fits and clearances in the cold. Also threads can be more vulnerable to stripping off when they are hot, so be aware, especially if its a bare metal thread and its not helicoiled.