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Forum newb and his 34K original miles '80 Datsun 720 4x4


Gradyfest

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Hey Grady, you talked to an idiot at your local O'Reilly (no surprise, most of my co workers are). I've worked for them for ten years and I know for a fact we rent the block tester. I will get the part number from work and post it for you tomorrow if you want.

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Cold cylinder pressure test results:

 

1- 149

2- 150

3- 159

4- 152

 

 

 

 

I would warm the engine up and do this test. It uses coolant when running not when cold. Test under similar conditions. Metal expands when hot, clearances increase.

 

Possibly the intake is leaking from the coolant hole into the #4 port (far left) but it's a long way to go, maybe 5/8" or more. Water holes and cylinder are much closer on the head gasket.

 

DSCN1047_zpsf00533f1.jpg

 

If you can't find which one but you are sure it's one or the other, remove the head with the manifolds, take the manifolds off and look. Clean it up and put the head back on. Bubbles will likely be the head gasket. Compression may be 160 but when a cylinder fires, it's higher.  Even higher when you step on it.

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I did it, pulled the head off with the intakes on. Needed help to lift it off. The only snag was I needed and ordered another valve cover gasket and had to buy a 10mm hex socket for the head bolts. Needed help from two people when putting it back on. One to help hold, and one with tiny hands to pull the timing chain up as it all came down. Other then that, went smooth. I had a Chiltons and the actual Nissan book to help guide me.

 

I found the bad spot on the head gasket between a water jacket and the cylinder. The piston was steam cleaned like I read it would be!

 

All in all took me 7 hours. Not bad for the first time and having all that emission stuff to unhook I think. A big portion of that was cleaning. I took a gasket scraper to both surfaces first, then followed with a Dremel and rags until it was shiny and clean on the rags.

 

It runs great again!

 

 

I'll get some photos up. It got dark so I only have some from the beginning.

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I am sure there's a better way but I got piston one to top dead center on the compression stroke by manually rotating it at the camshaft watching the valves and felt with a barbecue skewer through the spark plug hole when it was TDC. It worked.

 

 

 

 

image_zpsg62skprc.jpg

 

 

 

image_zpsoiz7zchu.jpg

 

 

 

image_zpse0tpfr6q.jpg

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Done dididly done.

 

 

After torquing down of the head bolts I ran it for a few minutes and let it get hot. Then I pulled the valve cover and did a valve lash adjustment and retorqued the heads like one of the manuals said too. Two of them needed to go a little more so glad I did that.

 

 

I haven't done a valve lash adjustment since I did that cold one the last job so I thought it needed done. My intakes where at .09 so I just left them alone being so close. Then according to the manual my exhaust should be at .012, the temperature change from cold to hot must be drastic because the exhaust was .08 measuring hot. So I figured I should adjust them to .012 like the manual said. I did.

 

 

And I thought I had valve ticking before! I kind of wish I would've set them at .010 now.

 

 

Like it really ticks. When I leave from a stoplight that's the only thing I hear now with my exhaust buttoned up is that ticking. Are these engines known to just be like that?! Do you guys deal with ticking all the time after a proper valve lash adjustments?

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Better re-torque the head again when it's cold and the metal has cooled and contracted. Always re-torque head on a dead cold engine to get the proper clamping pressure when it heats up.. No harm done, but get 'er done..

 

Great feeling isn't it???

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  • 1 month later...

So it's been a while. I have so much stuff to update on topics I've started. All good info.

 

But...

 

 

This is the pretty much the only original topic started by me that ol' King Rat hasn't locked, WTF bruh?

 

 

 

No new members with ideas welcome? I've been respectful and have delt with the trolls on the site very well I thought. Regardless, all I've done is try and spread learned information to the masses like this sight has done for me and be kind in the process.

 

 

The Datsun is still making a noise but I've got her diagnosed I think, (I'd love to talk about it on the thread I started regarding it, nope it's locked; why?) I have stuff to talk about on it and ask for help, someone in the future might even learn from it all; but no, it's locked and what do I do?

 

Start a new topic on it and hope dumb ass trolls don't get me locked out being jackasses with nothing more but ignorant I'm a badass and dont question my authorities on this site comments.

 

 

 

 

 

 

 

 

 

No progress will ever happen with everyone stuck in the same ways here.

 

 

 

 

 

 

 

 

I love this site and the help it and its awesome generous members have gave me.

 

 

Trying to do the same.

 

 

 

 

 

 

Go ahead and padlock this one to Mike.

 

 

I'll focus on the other forums I'm a member of with my other vehicles of and bid y'all adieu!

 

 

 

 

 

 

 

 

 

 

 

 

 

Nothing to learn from me, you obviously know it all partners.

 

 

 

 

Keep the Datsuns on the road friends!

 

 

I'll keep honking at y'all.

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