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Discussion Starter #21
I used a whistle and my socket wrench on the crankshaft to help me set TDC. I then, per the manual and videos on the internet used the crank shaft pulley timing marks and the location of the points in the distributor to make sure I was at TDC. I still got tons of leakage. I set TDC multiple times to make sure I was at TDC: just before the whistle stopped, when the whistle stopped and just after the whistle stopped, and let the whistle stop then back up the engine just a little (socket wrench on the crankshaft nut counterclockwise). I also called Lang and spoke with their technical support.

Just like SMJ said you don't need much pressure for a leak-down test. You can pump up the cylinder with less then 100psi. Watch the gauge which will indicate the percentage of leakage. An engine in great condition should generally show only 5 to 10% leakage. An engine that's still in pretty good condition may show up to 20% leakage. But more than 30% leakage indicates trouble.
Got it thanks! I thought it had to be 100PSI. I follow what you are saying. I may try it again with the PSI set below the compression readings I got for each cylinder.
 

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Discussion Starter #22
I have a few questions about my engine. I noticed my engine has a 5 hand written on the valve cover. Why? My hunch is this was a replacement engine which was put into the truck at some point?
 

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Discussion Starter #23
Another question, how do I know if my engine is actually a Z24i? My understanding is there is a carbureted version, a fuel injected version and a throttle body injected version of this engine correct?

The sticker on my door says Z24i, but I am skeptical.
 

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Discussion Starter #24
Third question: are the parts from a Z24 interchangeable with a Z24i? There is a 1981 Z24 engine near me for $350 and I was wondering if an older engine like this would be useful as a parts engine. The engine looks to be carbureted.
 

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NF Mod/Nissan Master Tech
2006 Pathfinder LE, 2003 Frontier SVE
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The Z24i had throttle body fuel-injection. The Z24S was carbureted. The only version used in the D21 Hardbody in the US was the Z24i and it was only used a couple of years before being replaced by the KA24E engine. The Nissan Z-series engines, sometimes called "NAPS-Z," were hemi-head engines and, if my memory is correct, used the engine block from the ol' L-series 4-cyl. that appeared in a number of Datsuns, like the 510, 610, 710 cars and 620 truck. While NAPS-Z engines aren't talked about much these days, they were a pretty innovative engine in their day---Popular Mechanics Magazine even did an article on it---due to their ability to recirculate a large amount of exhaust gas ("NAPS" stands for Nissan Anti-Pollution System). It came in 2.0, 2.2 and 2.4-liter displacements, some with 4-spark plugs and most with 8-spark plugs. Some had single-row timing chains and others had double-row timing chains. So, not all NAP-Z engines are the same. There are probably a number of parts on the '81 engine that would interchange with yours, but I don't think I would pay $350 for spare parts engine. Not unless you are considering swapping your throttle body injection for a carb setup, but that would be a mistake in my opinion. The "Electro-injection" throttle-body Z24i is a pretty stout engine! Yeah, it's not big on horsepower, but it does a pretty good job of getting a Hardbody truck around. You don't run into many timing chain issues with them, although you may run into a failed head gasket once in its lifetime or an occasional failed throttle body gasket or intake manifold gasket. There's a whole bunch of vacuum hoses, as you found out, but that was par for the day; they were nothing compared to the vacuum hose mess that Honda used on old Accords! Avoid aftermarket ignition parts water pumps and do basic maintenance and they tend to last a long time!
 

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Discussion Starter #27 (Edited)
I broke a bolt on the upper exhaust pipe to exhaust manifold connection. No big deal. I can retap it when the exhaust manifold is out. FWIW: the nut had been scrubbed with a wire brush then soaked liberally with PB Blaster. I let that soak in for a couple days before wrenching. See below.
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But, how do I get the other bolt off of the pipe (I suspect it will break too)? It is very difficult to get my socket wrench around this location and get leverage. I have to use a universal socket drive just to attach my socket.

This is a view of the next nut (13mm) through the driver's side wheel well. I have thought about using a nut splitter, but I don't think I can get it to slip behind the nut (because of the exhaust piece that is in the way). Your thoughts? Thank you for your help. Dremel drill w/a cutoff wheel? A torch is difficult in this location.

I can always cut the entire exhaust pipe. No big deal; it can be easily rewelded.

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Discussion Starter #28
My hunch is this is throttle body injection? So that confirms my engine is a Z24i correct?
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