How soon after an engine rebuild does one need to retorque.

[Mervyn Spencer]

Hi Folk,
As per my subject line "How soon after an engine rebuild does one need to re-torque the head"? Even after the engine was refitted to the Dexta and warmed up the head was not retorqued. The Dexta has less than a hour on the tachometer and not done any work other than slow cruising around the tractor club Shark.
Mervyn

[Billy26F5]

It tends to depend a bit, but you should always do it after the first warmup (when the tappets also need resetting) then officially at 50 hours, but I would do it more to get the best sealing.
Sandy

[Mervyn Spencer]

Cool, thanks Sandy.

[shepp]

Our Cheshire club member Phil Moston is a Perkins engine enthusiast and specialist, and what he doesn't know about the earlier engines is not worth knowing. His recommendation for the 3 cylinder Perkins and Perkins derived engines (Dexta), which can have a tendency to blow the head gasket between cylinders, is to torque down at least 4 times after a rebuild with a few hours running between each tightening. If you have fitted new head bolts and studs, in addition they will stretch as the engine is used, so at least 4 tightenings in that case.

[Mervyn Spencer]

Hi Shepp,
Thank you for that valuable information. I must admit that those thoughts of blowing a head gasket has haunted me for several months now. Unfortunately/fortunately my Dexta is not a working unit but an exhibition unit that does very little running. We have a club social/work day in ten days time where I was planning to do the first re torque. I will need to find some heavy work like pulling a disc harrow or something. Its going to be a long while before I will be able to complete the four re torques as I live 60 miles from the tractor club. Nothing ventured nothing gained
Mervyn.

[Billy26F5]

Very handy rule Shepp, hope Davie never needs it but if he does we now know it.
Don't forget to reset the tappet clearances after retorquing the head.
Sandy

[Mervyn Spencer]

Will do, thanks Sandy.

[Mervyn Spencer]

In hind site I don't recall us renewing the head bolts, is that a sin

[Billy26F5]

It depends on the engine, but older engines generally don't need new bolts or studs (if they're in good condition) but check manuals about that for each engine. I can confirm that neither Major's nor Dexta's need new bolts or studs.
Sandy

[Mervyn Spencer]

Thank you for your input Sandy, much appreciated.

[Jerry Coles]

To be honest I rebuilt my Dexta engine 18 years ago and never re-tightened the head bolts!!
I worked it hard topping straight from rebuild and since then it's been as good as gold. Maybe I was lucky!

[Billy26F5]

I think you have been very lucky! Probably worth doing anyway though.
Sandy