'68 Datsun 1600 Roadster head gasket replacement

[Matthom]

Hi all,

My coolant overflow is pushing out coolant due to air pressure from a bad head gasket. Oil is still clean. When the overflow cap is loose it's better, but still running rough.

Is there a step by step guide to removing the head correctly? I pulled the motor and trans to swap a rebuilt trans this summer and someone had a guide that was perfect for a first timer. YouTube has a video of a Z engine teardown, was hoping someone had a 1600 head gasket replacement documented.

Thanks!
Matt

[Gregs672000]

It should be in the manual in the tech wiki. May have to work past some Japanese to English translation issues... not hard.

[RustBucket]

Hey Matt,
It's not too hard. Just takes a little time....
1.Drain coolant and disconnect upper hose from head.
2.Disconnect plug wires and temp sender gauge wire
3.Remove intake manifold (I like to leave the carbs attached, but it is hard to get at the nuts underneath the manifold though, a long wrench is your friend, or someone with small hands)
4.You can leave exhaust manifold attached to exhaust, just pull it off the head studs
5.Remove cam cover, loosen valve rocker adjustments fully (you can remove the rocker assembly if you want and pull the push rods, but it isn't necessary)
6.Remove head bolts or nuts depending on setup
7.Tap head with leather or rubber mallet to loosen.
Be gentle cleaning the old gasket off the two surfaces. Make sure they are both smooth and free of oils before reinstalling. I normally wipe mine down with thinner or acetone a few times before putting the new gasket in. I've also had some leaks around the rear oil hole. so this last time I put a very small ring of sealant around it (which worked well), but is probably not necessary. Some folks like Copper Coat too. Install a new exhaust gasket upon reassembly for good measure.
Good luck,
Rustbucket

[SOUPY]

I would add #8 in there....spend the extra duckets and take it a machine shop and have them check for cracks and do a very lite mill to the head.

[spl310]

On reassembly, take note of the head bolts if you are reusing them. One will be slightly longer with a circular mark on the head. That bolt goes on the rear most intake/exhaust side with the slinger (lifting hook) mounted underneath of it. They get mixed up and put in the wrong place a lot and that causes head gasket leaks as the bolt bottoms out and gives a false torque reading. Also, clean out the holes all the way down to the bottom. A surprising amount of crud in there. But then again, what do I know - I have been accused of not working on Roadsters.

[Mochi]

I would add #8 in there....spend the extra duckets and take it a machine shop and have them check for cracks and do a very lite mill to the head.

i second this! i pulled my head from a blown headgasket. the vacuum test came back and failed everywhere and found multiple cracks that i did not see when i pulled the head off. worth every 60 dollars spend.

[Fairlady5150]

All good advice. And I second SPL310's comment about using a bottoming tap to go through all the head bolt holes in the block. A very minimal cost and time investment, and it's surprising how much garbage you'll pull out of there. Also a good time to brush through all of the cooling passages.

[Matthom]

Guys,
Thanks for the feedback, this is exactly what I was hoping for! Going to start the teardown either tomorrow or Sunday. My first time opening a top end, I was concerned about timing chain and alignments and anything that had an order of removal or a do not touch recommendation.

Completely agree on taking the head in for a professional review, I have a local guy with an excellent reputation and who specializes in classic heads. What is the recommendation on replacing the head bolts? I know the head has been opened before because the head bolt with the circle (longer) is in the wrong spot. My assumption is to get new as they have been retorqued more than once.

Thanks again for the comments! Let me know if anything has been missed.
Matt

[redroadster]

Use a fill funnel to get it completely full ...very important and /or park on a steep up slope filling after the new gasket , head checked

[Dreymar]

Hey Matt,
It's not too hard. Just takes a little time....
1.Drain coolant and disconnect upper hose from head.
2.Disconnect plug wires and temp sender gauge wire
3.Remove intake manifold (I like to leave the carbs attached, but it is hard to get at the nuts underneath the manifold though, a long wrench is your friend, or someone with small hands)
4.You can leave exhaust manifold attached to exhaust, just pull it off the head studs
5.Remove cam cover, loosen valve rocker adjustments fully (you can remove the rocker assembly if you want and pull the push rods, but it isn't necessary)
6.Remove head bolts or nuts depending on setup
7.Tap head with leather or rubber mallet to loosen.
Be gentle cleaning the old gasket off the two surfaces. Make sure they are both smooth and free of oils before reinstalling. I normally wipe mine down with thinner or acetone a few times before putting the new gasket in. I've also had some leaks around the rear oil hole. so this last time I put a very small ring of sealant around it (which worked well), but is probably not necessary. Some folks like Copper Coat too. Install a new exhaust gasket upon reassembly for good measure.
Good luck,
Rustbucket

Good guide here. My friend might deal with the head gasket replacement job on his incoming Roadster project. We'll take a closer look at it after we finished installing the headache rack, nerf bars, and bed cover on the truck and clear the garage.

[Matthom]

On reassembly, take note of the head bolts if you are reusing them. One will be slightly longer with a circular mark on the head. That bolt goes on the rear most intake/exhaust side with the slinger (lifting hook) mounted underneath of it. They get mixed up and put in the wrong place a lot and that causes head gasket leaks as the bolt bottoms out and gives a false torque reading. Also, clean out the holes all the way down to the bottom. A surprising amount of crud in there. But then again, what do I know - I have been accused of not working on Roadsters.

Found my circular marked bolt in the wrong spot, guessing it's my leakage problem! Finally opening it up tommorow. Thanks for the info!

[redroadster]

On reassembly, take note of the head bolts if you are reusing them. One will be slightly longer with a circular mark on the head. That bolt goes on the rear most intake/exhaust side with the slinger (lifting hook) mounted underneath of it. They get mixed up and put in the wrong place a lot and that causes head gasket leaks as the bolt bottoms out and gives a false torque reading. Also, clean out the holes all the way down to the bottom. A surprising amount of crud in there. But then again, what do I know - I have been accused of not working on Roadsters.

Found my circular marked bolt in the wrong spot, guessing it's my leakage problem! Finally opening it up tommorow. Thanks for the info!

Did you retorq it after 500 miles ?

[spl310]

On reassembly, take note of the head bolts if you are reusing them. One will be slightly longer with a circular mark on the head. That bolt goes on the rear most intake/exhaust side with the slinger (lifting hook) mounted underneath of it. They get mixed up and put in the wrong place a lot and that causes head gasket leaks as the bolt bottoms out and gives a false torque reading. Also, clean out the holes all the way down to the bottom. A surprising amount of crud in there. But then again, what do I know - I have been accused of not working on Roadsters.

Found my circular marked bolt in the wrong spot, guessing it's my leakage problem! Finally opening it up tommorow. Thanks for the info!

That is a likely culprit. Glad to have helped!