head gasket oil leak?

[corax]

ok, after an extensive period without my beloved 79 gs850, i finally got the engine together. turns out after tearing everything apart looking for burnt valves or bad piston rings (i had no compression) that all i had to do originally was set valve lash . . . live & learn. so i have the engine back in the bike & do my initial start-up. after about a minute i noticed the headgasket leaking. everything was torqued to spec, checked for warpage, & thoroughly cleaned during assembly.
so my question is if my specs of 30 lb/ft for the head bolts is correct & if i should retorque the bolts once the engine is hot? is it normal for the head gasket to "seep oil" until everything settles?
Any ideas?

[duaneage]

It is not normal to leak a lot of oil. I would expect it to not leak at all. The head was straight and true, right? Were there O-rings in the head or block that could have been squished or forgotten? I think there is a small bolt on each end of the head, did it bottom out and not tighten up because it was the wrong length or had debris in the hole??

I am not sure since I have a 650G. I have small bolts outboard on my head that are 10 mm and are a special length.

Sorry t hear valve lash was the problem. We had a member on here that was days away from a teardown but doing the valves saved him. A PO had incorrectly adjusted the valvetrain.

[corax]

the o-rings at the top & bottom of block were new, everything was resealed. the bolts on either side & 1 in front are all open holes. head bolt threads were all cleaned.
it looks like the oil was actually bubbling out of the gasket itself (kinda seeping through, but enough for a slow drip).

[argonsagas]

I don't know your experience, but, after the necessity of a lack of cleanliness of all parts before assembly, perhaps the most common reason for newly-installed gasket leaks is that the bolts were not tightened in a proper sequence, and/or because maximum torque was applied right away.

Either one can keep the gasket from seating properly.

Presuming you used a metal gasket, it may still be recoverable.

Loosen all the bolts and try doing it again. I have not done your engine, and do not know the bolt pattern, but a general idea would be like this:

Start with one bolt at the centre of the head, then the second one would be opposite it. The third would be ahead of the first, the fourth would be behind the second.


Fifth would be beside the third and sixth behind the first.

You are doing the tightening in a criss-cross manner.

It is VERY important that you do not apply maximum torque at once.

It must be applied in the criss-cross manner at a light pressure, then done again at a higher pressure, following the same tightening sequence, and on the third you can apply the pressure.

A fourth torquing is still needed , always in the same sequence, to ensure everything is even.

Yes, it is time-consuming, but it saves gaskets and a lot of headaches.

Final point, use a light coating of oil on every bolt before beginning the work.

Some people disagree with the oil, saying it is better done dry.

I disagree completely, as you cannot be certain of accuracy using dry nuts and bolts due to the irregularity of friction between the threads at each bolt. The oil minimises friction and allows a more accurate torque application on all bolts.


I would put a trace amount of oil on the metal ring around each cylinder...both sides. A drop of oil on the finger is sufficient quantity.

Remember always, cleanliness of all parts is vital.

[corax]

bolts were oiled, sequence is cast into the head (makes it really easy), & the torque was done in 10 ft/lb increments (three times round at each torque). my main concern is that i have the correct torque spec. my clymer manual says ~ 28 ft/lb. i went to 30 ft/lb to conpensate for old bolts. i think this weekend i'll try retorque to 35 ft/lb.