Retorque procedure

[Walter Pearson]

My A-4 files have at least three different methods for retorquing head nuts after the intitial reassembly. I assume they might have been for different gasket configurations used at different times. What is the current suggested procedure for the dual gaskets now used?

[Don Moyer]

Walter,

Our own shop practice is to start with the center stud and circle our way out through the rest of the studs. We start with 25 foot pounds, then 30, and finally 35 foot pounds. The only controversy with which I'm familiar among the experts is whether or not to lubricate the threads on the studs before torquing. Our practice has been to lubricate these studs with a light oil, feeling that this method will provide better consistency during the torquing process.

Regards,

Don Moyer

[Walter Pearson]

I wasn't clear enough with my question. I was referring to after the engine is running after assembly. In your early newsletters, there was reference to tightening nuts again while hot after the engine first reached operating temp, letting cool, and repeating. I believe a Westerbeke bulletin advised no re-torquing was needed. Some say to run for 30 minutes and retorque hot. Others check torque after cooling down. This is where I am confused.

[Don Moyer]

Walter,

I can't speak to Westerbeke's rationale that re-torquing is not necessary. Every engine manufacturer that I know of recommends some form of re-torquing after changing a head gasket. I replaced the head gasket in the four cylinder GM engine in our little fishing boat last winter, and their manual
suggests re-torquing after initial start-up, and then after 20 hours.

In our work with the Atomic 4, we follow the recommendation of the manufacturer (Victor Gasket Co.), as well as the general historic advice of the Universal Technical folks which is/was to re-torque the head studs after the engine is initially started and brought to operating temperature.

In our own rebuilding operation, we also re-torque a second time after the engine cools, and sometimes a third time if any of the nuts show movement on the second torquing. We take this extra precaution so that we do not have to ask our engine rebuild customers to re-torque after installing the engine in their boats. We are aware that access to the engine would make re-torquing difficult to impossible after installation, and that most of our customers would have a difficult time finding a torque wrench.

Hope this helps,

Don

[Walter Pearson]

Thanks for re-torque procedure - that makes sense and it worked OK. The Westerbeke document I referred to was Bulletin #223, 15-May-1996. You included it in your Newsetter No. 22. That was when they went to the graphite gasket, but used only one (and you expressed concern about compression increase with that method). The backside of Bulletin #223 contained the torque sequence diagram and you included that in Newsletter No. 23.

I found the torque sequence diagram to be very helpful. Perhaps for us graphically oriented, a small diagram could be included in each gasket set.