I need some opinions on what to do about replacing a freeze plug on the back of the head. I really don't want to take off the head to get to this freeze plug and so the rubber expansion freeze plug looks tempting. Are there draw backs to using the rubber expansion plugs or are the pretty good fix in a tight spot like that? Or am I basically looking at taking off the head?

Cheers!

Rubber expansion if you don't want to remove the head. In the industry the steel plugs are called 'cup' plugs, but commonly referred to as freeze plugs by mechanics. Their job is to plug a hole that was necessarily drilled in the head casting to allow machining chips to flush out during manufacturing. The rubber one will be ok - try your best to make sure the hole is cleaned of any loctite that may have been used when the original cup plug was installed.

Note: if you do remove the head to put a new steel cup plug in carefully use a screwdriver or square ended punch to tilt the old cup plug in it's bore just enough to get some needle nose pliers on the lip to pull the old one out - can be a devil to find if you push it all the way thru. Clean the hole, apply some anaerobic loctite around the ID and then use an appropriate size socket to tap the new one squarely in place. The depth of the new one should sit 1mm - 1.5mm below the chamfer of the diamter in the head.

The rubber plug is the easy fix but I would think with heat and age it will eventually fail. Maybe someone else has some experience with the rubber plug.
Dan

My memory is kinda soft, but, without going to the basement to look at heads, I remember NO frost plug on the back of (or anywhere else on) the head.

There is a seal on the rear of 240s, to block the spot where 700s mounted a distributor on the cam.

You can search here on "cam seal retainer" (or similar) to see what people have done about its tendency to loosen. (And also clean your flametrap, to decrease the pressure that helps force the seal out.)

There are two "freeze plugs" in the back (at the firewall) side of the head. One goes to a chamber where coolant is and the other goes to a chamber where oil is. I thought it was quite odd that Volvo would put two plugs in the back but c'est la vie.

Ooops! Wow! Meas culpa.

Live and learn.

I was think of big mutha frost plugs, as on the block.

Now I see 2 candidates -- what you mention -- on both the front and back of the head, each ABOUT 29 mm diameter. And very deep cups they are. And aluminum, I suppose.

Which I have no intention of removing! :-)

When WOULD someone need to deal with them?

In my case? When they leak. :)

Oh... like when my neighbor asked my younger daughter Maddy when she would be 3 years old. "On my next birthday." :-)