New Owner of a 720 (with many problems)

[datzenmike]

Seems Rotella T is now re-labeled T4. Apparently same thing. T5 is a synthetic blend and T6 is full synthetic. I wouldn't run these synthetics in an old Datsun, they are better suited for newer closer tolerance engines. All diesel oils are higher detergent than gas engine oils but they do still have the higher ZDDP levels.

 

I'm running the 14w40 which is thicker and there was no problem with temperatures down just below zero. I didn't know it came in 10w30 but will stick with the thicker as I drive mostly in the summer.

[captain720]

No RTV.

[Lockleaf]

The only thing that matters is which valve cover you have.

 

If cast aluminum you HAVE to use the cork version of the gasket.

 

If stamped steel, you have to use the rubber gasket.

 

They are not interchangeable. Sometimes it requires having them look up a different year truck to see both options.

[Charlie69]

The aluminum valve cover comes om some Z20 and all Z22 engines I have seen.  81 to 83 720s had Z22 engines.  Lockleaf is correct on the cork and the rubber gaskets.

[Brandon.fair]

Well a magnet sticks to it so Im pretty sure it's not aluminum. But as far as brands go it there any recommendations? I'm currently looking at these APEX with semi circular plugs

 

https://www.rockauto.com/en/catalog/nissan,1985,720+pickup,2.4l+l4,1210352,engine,valve+cover+gasket,10710

[datzenmike]

The Z20 was used the same years as the Z24 truck ('83-'86.5) so stamped steel valve cover. The Z20 used in the HL510 and the S110 200sx were cast aluminum as were all Z22 engines.

[Charlie69]

Thank you for dialing ing the valve cover vintage Mike.

 

As far as gaskets I would spend the $0.42 more and buy the Fel-Pro set.

[Brandon.fair]

Fel-pro it is.

I see in the tune up data of the fsm it says valve clearance (hot) should be .30mm. I'm assuming this is valve lash. Does the "hot" meaning the engine needs to be warmed up first? Some videos I watched said you should let the car sit over night. 

 

[datzenmike]

The references are always in metric followed in inches in brackets. 0.30mm and (0.012")

 

Yes running temperatures.

 

 

On a Z series turn the engine to TDC on the compression stroke of #1 cylinder. You can get close enough by bumping the starter. Both front two cam lobes will be pointing downward with the first at about 8 o'clock and the second one at 4 o'clock as viewed from the front.

 

Quickly set these valves...

 

1, 2, 4 and 6Tthese valves are closed and the clearance can be set.

 

Turn the engine ONE turn and back to TDC. The front two cam lobes will now be 2 nsd 10 o'clock

 

Quickly set these valves...

 

3, 5, 7, 8 These valves are now closed and the clearance can be set.

 

 

Done.

 

 

If you do it this way there is no need to constantly bump the engine around and you are done before it cools down..

[Brandon.fair]

Thanks Dmike

 

I'll post a video of the sound the engine makes for a reference to how it sounds after. 

 

Gasket ordered should be here by the 16th I'll be in Florida with a rental car that weekend so I might have to do it the following week if it gets here after the 13th. 

 

Are Z2.4L prone to oil leaks from any certain gasket? (oil pan, rear main gasket ect.)

 

Next question, is there a good way to flush the gas tank? My "bogging down" issue is back, although not as bad yet. I opened the drain of the gas tank and the gas was kinda brown with some debris. I think it's clogging the filter already. I'd prefer not to buy a new tank.

[captain720]

You can take the pump housing off on front of the passenger side rear tire, then there is a couple hose clamps. If you take off the right one then you can turn the key and make it pump into a bucket. Or just siphon it out. I prefer the pump itself version.

[datzenmike]

The electric pump has a twist off bottom with a filter and a magnet.

 

Z24s don't leak oil any more than any other engine.

[Brandon.fair]

Once I get all the gas out, I guess ill just flush out the crap with more gas? What can I do with the contaminated gas? Is the standard size tank on a 85 King Cab 16gal?

[Charlie69]

According to this list the US King cab 720 held 13.2 gallons.

 

http://www.carfolio.com/specifications/models/car/?car=31625

[Brandon.fair]

Maybe my gauge isn't wrong lol I was assuming it was 16 gal, because I've seen 16gal tanks for sale.

 

Im starting to think the bogging is more of an ignition  issue. It's hard to describe with words but it like brrrrrrrrrrrrrrr (issue starts) brrp brrp brrp brrp brrp then I shift or get off gas. Then brrrrrrrrrrrrrrr and repeat (Those are engine noises)

It happens while accelerating.

 

My currently thought train is that the vacuum switch above, that detects low manifold vacuum and cuts exhaust ignition to reduce noise, is activating and cutting ignition to exhaust side and my intake side is not working. Idk. I can't imagine that the fuel filter is clogged again.

[datzenmike]

Once I get all the gas out, I guess ill just flush out the crap with more gas? What can I do with the contaminated gas? Is the standard size tank on a 85 King Cab 16gal?

 

Unplug the switch and see!!!

 

I gravity fed my old gas through a filter and it cleaned it from orange to clear lightyellow color. Worked just fine.

[Crashtd420]

I do the same add alittle dry gas and octane boost just incase and just throw in my daily driver chevy....

[Brandon.fair]

On my lunch break I unplugged a vac switch and drove it. I did this for all three one at a time and still the problem remained. I got back to my work and adjusted the float level again (it's was low) and sprayed out the Jets again...... it drove home fine....... FML I think it's time for a carb rebuild.

 

How about this one

[Charlie69]

If the plug for the carb has 6 wires on it it is California emissions and that carb kit is not correct.

[Brandon.fair]

Do you have a link to a decent rebuild kit? I don't know what makes one better than others. 

[Brandon.fair]

Does the choke heater stay on the entire time the truck is running? What controls the heater if not? Computer under the driver seat? 

[Brandon.fair]

So I just adjusted the valve lash on my truck. It took about 4 hours, and here's how it went. I followed Dmike's instructions. Put it all back together and it ran really shitty, it would not idle. But it was really quite! So thinking I tighten a valve(s) to much I started over and re adjusted all the valves. And made sure the didn't spin when I tighten them. Again it ran like crap. So I did it a third time and loosened the valves alittle more and when I finished I realized that I had left a vacuum line disconnect I tried running the engine without the vac hose and it ran like crap. Plugged in that vac hose and it ran great. (Palm.....Face) FML I wasted all that time and there still is alot of valve noise. I guess I will get to do it again next week. YAYYYYYYYYYY............ <_<

 

Update: I redid the valve lash and it seems to run alittle more quite, idk if it is placebo or not. Video I made of the before and after, doesn't seem to make a noticeable diffrence

[Brandon.fair]

Any ideas on how to tell if the secondary barrel is opening on my carb? I don't hear any noticeable change in sound and it seem to rev slower past 3.5kRPMs. Does the secondary open. Off vac pressure or mechanical?

[datzenmike]

With all that practice you should easily be able to set the valves hot before it cools down too much. I recently set mine and I guess I was too slow. Stopped in at Len Robertson's after Canby and borrowed some tools. Wow it is ever quiet now! .

 

Does the choke heater stay on the entire time the truck is running? What controls the heater if not? Computer under the driver seat? 

 

Yes it does. It is powered by a relay that requires a charging alternator. Here's why... say it's cold out and you go out and start your truck and go in to finish your coffee while it warms up. Unknown to you it stalls. The engine is stone cold but the choke heater has fully warmed up and turned the choke off. You go out and try to start it but without a choke to richen up the mixture either you can't, or it won't keep running by itself. With the relay if the engine stalls the alternator no longer charges, the relay shuts off power to the choke heater and it stays cold also. Restart is easier.

 

 

Any ideas on how to tell if the secondary barrel is opening on my carb? I don't hear any noticeable change in sound and it seem to rev slower past 3.5kRPMs. Does the secondary open. Off vac pressure or mechanical?

 

I would just hold the throttle open (at least half way) and push up on the diaphragm linkage to see if it is stuck. (engine off) Take a look down the secondary side it watch the butterfly open. If not used much it could very well just be sticky.

 

The throttle has an interlock that won't allow the secondary to open unless about 1/2 open. It also forces it closed when you let off the gas. The secondary is pulled open by a combination of vacuum signals from both venturies on a diaphragm in response to heavy engine load.

[Brandon.fair]

 

push up on the diaphragm linkage to see if it is stuck.

 

What does said diaphragm look like?