TOPIC:

Hi guys, finally about to replace my head gasket, got all the parts, is it ok to just do the head or will the base be disturbed/damaged while removing. The engine ran well, no smoke or noises, just a slight oil leak at the head, there was a little oil at the back by the base gasket but it may have run down from somewhere else. I want to keep it simple for now if possible ie just do the head gasket and be prepared for doing a full refurbish in the future.

If it was me with this situation, the first thing I'd do is check the cylinder head nuts for torque. You're reporting that the only issue here is a minor oil leak out the back of the cylinder /cylinder head gasket area and that everything else is fine and you want to delay a tear down until later. Quite often a minor leak like this will seal itself up with a retorque of the head nuts. What you want to do is back off each of the head nuts ONE AT A TIME Put a drop of oil on the stud and ensure that there's oil around the head area where the nut will contact, then retorque the nut. Can't stress enough that when doing this you want to do one nut at a time and not loosen off all the nuts and then retighten.

Torquing nuts and bolts is a science unto itself and I could spend half a day on the subject but the general rule of thumb is when torque down a bolt or nut, you need a light film of oil under the bolt or nut face to provide a bit of lubricity. Also of importance, there should be a light film of oil on the threads to lubricate the sliding surfaces of the thread. If you torque down a nut or bolt dry, you won't meet the required stretch of the bolt or stud to achieve the required pinch on the sealing surface.

The most common problem we had at the nuclear plant that I worked was failures of sealing faces due to under torqued bolts and nuts. All of the mechanical maintainers had to go for an 8 hour course on torquing and the importance of following the procedures for each and every different type of torque spec. Bottom line here, make sure you know the torquing requirements for assembly and don't cut any corners. If it calls for a certain type of lubrication on certain surfaces before torquing, then that's what you do. Otherwise, you'll end up with over torqued and possibly stretched bolts or studs which will fail or under torqued bolts and studs and have failed sealing surfaces.

Thats great advice thanks, I hadn't considered that as an option and it will only take time rather than money, I didn't mention that there are traces of oil in the coolant but compression is ok and it doesnt overheat or loose coolant but presume this could still be a weep from the gasket that could potentially reseal when retorqued, I will flush the system before refitting, thanks again.

I would skip the base gasket for now. If you do change it, it also means replacing all the piston rings and re-honing the bores. All of this gets expensive quick.

Change the head gasket, seal the water passages on it with Yamabond, clean it up real good, bolt it up, and ride it. If it still leaks, you'll be able to tell.

Kawboy , one last question from a very non engineer/mechanic, the manual states 29 ft lbs torque, I put this on my old torque wrench and tried it on a middle head nut , it "felt" to me as if it would be more slack than the torque it was already under, I have little experience with these technical issues but wouldnt want to follow a procedure without overtightening only to make it worse, thanks for any thoughts

Thanks Lucien ,have the gaskets and hoping to pull as little as possible off so thats number 2 option