i was on the long drive back from my z car club yesterday, and my z started overheating and i didn't notice until it was too late. long story short, she'll start up but there's water in the exhaust now, and a steady leak coming from between the head and the block, right in the center. i'm hoping it's just a blown head gasket, but i may have warped the head. does it sound like anything else to yall? can i unbolt the head and look at the surface of it without removing the manifolds? if i end up needing to replace the head, what can i expect to pay for one for a '76 280?

i still don't know why she overheated in the first place. i just checked my coolant a few days ago, and i've never had any problems with it before. suggestions?

Well, head gaskets are a wear item. While it may be that your gasket has simply worn out, it may also be that you've got some buildup in your cooling system, and it just got to be too much and the coolant found a path of lesser resistance.

I would imagine you could remove the head enough to check the surface for trueness, but in all reality, it would be much, much easier to pop off your manifolds, pull the head and have a shop check it out.

Sully,

It may have overheated because the head gasket blew first. Or it may have been something else that caused the overheating and blew the head gasket. Either way, you'll need to replace it. And since you've got to pull the head, it's probably likely it was warped, you'll want to take it to a machine/auto shop to have it checked out. No sense in going through all the work to remove it, just replace the gasket to find out that the head was warped and you have to do it all over again.

Depending on the miles on the motor, this may also be a good time to have the valves done.

As to can you remove the manifold without taking all the other items off. Probably not. I don't think you're going to be able to get to all the bolts to loosen the exhaust manifold, but I've got a 240z, so a 280 with f/i may be different. Also, it's going to make lifting and positioning the redone manifold a lot harder.

Sorry, but you're in good company. A lot of us have done this one!

Best,

Bob

Edited May 17, 200915 yr by bobc

Check your oil too if you haven't already. Sometimes when the head gasket goes, you end up with water in the oil.

When you do take it apart, check your exhaust ports too. They do tend to eat thru the exhaust ports from the water jacket. Especially on # 6.

ok, i pulled off the head and manifolds yesterday. the cylinders were full of antifreeze, and there was a small chewed up spot on the gasket that corresponds with the leak pattern, though it seems kind of small to have caused that kind of leak. i'm gonna post a new thread asking about local machine shops if no one recs one here pretty soon. i am in dallas/ft. worth.

i did manage to get the head off without removing the manifolds, which may make things easier in the long run. it's been a pleasure to remove them from the head while it's sitting on my coffee table as opposed to leaning over the fender for an hour. i will check my oil before reassembling everything. check out my flickr set for photos of the job.