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I notice a slight water leak on the middle bolt at the back of the cylinder head. Does this mean pulling the head and replacing the gasket immediately or when summer is over?

I assume from your description that water is also now entering the combustion chamber, and that does present some issues. Some of it will find it's way past the rings into the crankcase and you sure don't want coolant in the oil. Somewhat more remote is the possibility that you'll get enough water into the chamber to hydrolock the engine when turning it over and the result of that can be a rupture of the piston head. Changing a head gasket is at most a full day job for the novice, probably 3-4 hours for someone who has done it a few times. Were it mine, I'd fix it now, why take any chances? And change the oil when you're done and before you restart the car. Don't forget to check the cylinder nut torque after perhaps 30 minutes of running, again after a couple of hundred mines, and again at the end of the season.

If you've not done the job before, here's a primer which might be useful reading.

packardclub.org/forum/viewtopic.php?f=14&t=863

Hi Willis:

From your description I assume the leak is coming up around the stud. I assume this is a monoblock eight. Anyway, if it is coolant and the motor is old throwing parts at it probably will not be productive. I would leave the radiator cap loose and drive around for a while. This will allow some sediment to plug the leak if you are lucky.

As well, I would leave the radiator cap loose when the vehicle is not being used.

Whether the leak is into the combustion chamber can be checked by having a cooling system leak test done and looking at the spark plugs. If number 8 is much cleaner than the rest that is a problem.

Sometimes when those motors are old blow by gets around the studs. That can be checked with a compression test.

So I would first do some analysis of the engine vitals and plan based on that. Don't rule out an external crack as well.

A plan of remedy depends upon the budget. I remember the late Paul Lamb left a 34 Su8 in in his garage with a cracked valve seat and the motor seized. The car had no symptoms other than the occasional need for water, but he didn't oil the cylinders when he stored it.

Thanks for the tips. I have 2 car shows in May and will do the job in June or July. I will leave the cap loose until then and for sure check the plugs.