I know why I adjust the valves cold. It takes me too much time to do it and you don't know if you are going to get pulled away from the job. When the Engine is cold the temp is extremely stable.

When the Engine is hot and you take a long time to do the job the temp changes faster.

That means I do what is easiest and surest for my own situation. Also a hot engine can be uncomfortable if you put your hands in the wrong place.

If you lived someplace where it is extremely like the Sahara hot it could be would be a good idea to adjust hot. Or just adjust cold and wait till it is the hottest part of the and after longish drive pull the valve cover off and check what the hot clearance is.

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84 300D, 82 Volvo 244Gl Diesel