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Discussion Starter #1
Just bought a 75 280Z with a blown head gasket. Haven't taken head off yet to inspect but found oil/water froth when I drained oil. Former owner reported that engine overheated and blew the head gasket. What should I look for when I remove head? What are the chances the head is warped? Apparently the head has recently been milled and rebuilt. If it is warped can it be re-milled a second time? Does this model of Z have a tendancy to overheat? What are most likely cause of overheating?
Thanks for any help you can give me.
 

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Remember this car is 24 years old. First check to see if the radiator has been replaced, if not don't waste your money or time going to a radiator shop, buy a new one.

If the motor got extreamly hot it might have warped the head. I would question the quality of the rebuild on the motor if it over heated so soon after being rebuilt.
 

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Discussion Starter #3
How do you know it has a blown head gasket? I wouldn't jump to any
conclusions until you pull the head. A few years back, my '76 over heated
and dumped coolant into the oil also. Turns out the head was cracked. :-(.

Radiator and/or hoses and thermostat are likely culprits.

ross

> Just bought a 75 280Z with a blown head
> gasket. Haven't taken head off yet to
> inspect but found oil/water froth when I
> drained oil. Former owner reported that
> engine overheated and blew the head gasket.
> What should I look for when I remove head?
> What are the chances the head is warped?
> Apparently the head has recently been milled
> and rebuilt. If it is warped can it be
> re-milled a second time? Does this model of
> Z have a tendancy to overheat? What are most
> likely cause of overheating?
> Thanks for any help you can give me.
 

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Discussion Starter #4
Head Info

> Just bought a 75 280Z with a blown head
> gasket.

A guy's put together a web page you might be interested in. It gives pretty good info about the heads for Z-cars:

<A HREF=http://www.geocities.com/MotorCity/2824>http://www.geocities.com/MotorCity/2824</A>/

If you find that your head needs a lot of repair, you should consider getting a replacement one from a junkyard. I looked for heads here in the L.A. area junkyards over the last 3 weeks, and I found that most of the junkyards want between $50 and $75 for a head (in the pull-your-own-part yards).

If you pull the head, MAKE SURE YOU USE A TIMING CHAIN WEDGE BEFORE YOU REMOVE THE CAMSHAFT SPROCKET (you can buy a wedge from Motorsport Auto for only a couple of bucks). I learned that lesson the hard way recently, and I still haven't been able to reassemble my engine so it runs right. If you don't use the wedge to hold the tensioner in place, the tensioner will tighten. Trying to hold tension on the chain instead of using the wedge won't work (I thought it would, and I was wrong). The wedge physically holds the tensioner in place. I mistakenly thought the wedge was to hold the CHAIN in place on the lower sprocket, and I didn't think the tensioner would move by itself. I was dead wrong. If you don't use a wedge and the tensioner tightens, you'll have to remove the entire front cover assembly, a real pain in the neck to do...

-Rob
 
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