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240zadmire

1977 280z prepup for smog check

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Engine sounds pretty good.

I don't like that your oil pressure gauge is at "0". Pull the valve cover cap a bit and see if there is any oil slinging around in there. Do it quick, your engine will try to stall out if there are no vacuum leaks.

Edited by rcb280z

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At rest, the oil pressure needle is about 1/8” left of zero.  Cold start, it move up about 1/8” or so and keep it dead zero on idle when engine is warm.  If I rev up to 2-3000rpm, then the needle move to shy of 1/8”.  It’s kind of misleading on the gauge to have 90psi but I don’t think it’s every get more than 10psi.  Will check FSM again.  But I worried before as well but I do see oil sling around.

from what I read, our car love cheap oil. Music to my ears!  What I had in right now is the quake from Home Depot and running 87 octane.  What your recommend oil for our car?

 

regards

 

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From the schematic diagram, seem like the oil sending unit is connect/relate to the temperature gauge.  Btw, the old oil sending unit and the current new installed behave the same thing.  Might be a connector corroded somewhere !?!??

read that it should be some where in the 35-40psi on normal cruising.  I might need to get a heavy weight oil, say 10w40 instead of Quaker 10w30

 

regards

 

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The battery has been bother me a while as it is freely moving around when turning... 

poor man’s billet battery tie down.

Should help the visual smog check

 

material:

- 1 1/8” width x 1/8” thickness and aprox 10” length.  My battery width is 7”

- grinder with cut through blade

- sanding disc for grind the sharp edges

- old battery rod with end screw and hook

- some left over aerosol paint can

- a gallon of sweat

Be sure to bend the middle a bit upward to create a “spring” to help tie down without too much force at one end 
 

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6B7B9C80-2E87-46B3-B5D4-89E8B44A2844.jpeg

Edited by 240zadmire

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I have a little exhaust leak right at the connector from the end of the catalytic toward the muffler.  Boy, it took me couple of days to find it.  It’s embarrassed, I know.
 

Then old one were paper like instead of the new ones I installed.  The new ones are fel pro and feel like aluminum/metal.  I notice the flange is not flat anymore.  Perhaps due to heat/cold it deformed.

 

what is your recommendation? Paper or metal exhaust gasket?

 

new ones look look like this.

image.jpeg

 

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 The metal FelPro gasket is my choice. Have you considered trying to straighten the warped flange? An oxy-acetylene torch, hammer and dolly would probably get it close enough to seal.

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read somewhere people prefer paper gasket but for the manifold to the head.  Some say soak into water half an hour or so to soften so it will mate nicely to the cylinder head.

as for my problem, yes.  Hammer, dolly and a torch did make the flange straighten better.  Of course oxy-acetylene would be nice.

down the road, I will need to replace from the catalytic and new muffler.  Also, read somewhere that I cannot touch exhaust manifold and the down pipe to the catalytic.  Something with the smog rules in California.  This makes me worries.  I probably understand the exhaust manifold being stock as it keep helping the heat and recirculate the unburned  gas.  But what if the down pipe to to catalytic is too rush, were doom?

 

regards

 

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While waiting for the DMV permission slip to take the car for smog... bought the mechanical oil pressure gauge because my oil pressure gauge on the dash doesn’t seem to response.  At cold start, maybe 1/8” from zero and as the car warm up, the needle almost point to zero.  
 

- new single pin sender or the old one behaves the same.

- oil weight is 10w-40 Lucas high zinc

- oil filter is K&N

 

hook up the mechanical gauge and at cold start, around 25PSI and as the car warms up and idle, around 8PSI.  Rev up the engine seem to be very responsive.

I guess there is something wrong with the gauge on the dash? Perhaps a resistor need to replace? But resistor don’t fail that often.  Any thoughts? Am I too annoying? Just forget it ?

 

regards

 

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It might be time for a new oil pump, it's a pretty easy job to do, drop the sway bar down from the rail mounts and you have access to the 4 bolts holding the pump on.  8psi at idle is the lowest you would ever want to see, I'm sure there are engines that function on less but why risk it.

The engine looks great.

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@grannyknot

you mean I just wasted a new $0.50 oil pump gasket?!?! ?

Folks here seem to incline a turbo oil pump from 280zx of 1982-1983.  I don’t think any definitive of auto or manual trans turbo oil pump.  What’s the recommendation? Get an oil pump from a auto trans or a manual?

 

regards

 

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That movie is way too big to download easily.  Lower the resolution or just make it shorter.  It was 520 MB.  Took a few minutes and I have decent internet speed.

I saw it get up to 40 psi but it should have been higher.  Could be the oil pump but the other reason for low pressure is low resistance to flow from worn parts, like crankshaft bearings.  But an oil pump change is worth a shot, to start.

Turbo pumps are high volume pumps, to make up for the oil diverted to the turbo.  You shouldn't really need it.  You might just drop the one you have and check it.  There are specs in the FSM.  Take pictures if you find ravaged parts.  Entertainment for the audience.

image.png

image.png

 

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@Zed Head  thanks for the pointers ! The darn app to convert mov to mp4 didn’t work I guess.  

All the bearings clearance I did check and they are new as well.  I did not check the clearance of the oil pump when I dismantled, clean.., replace the gasket of the oil pump itself and the gasket when mating to the engine.  I didn’t check the oil spring length.... it’s one of those thing “I’ll get to it later” and later is now ?. Sucks but will pull it off and see what’s the problem.  Hopefully still within specs and only need few more $ for the gasket and we’re good! But most likely a new pump seem to be in order! 

Edited by 240zadmire

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Hi all,

I believe I screwed up, again.  Nothing new to me I guess ?

Been reading a lot of threads and I believe Tony D. and many people recommend to use turbo oil pump to get more volume ... apologies if I misquoted. @Zed Head and others in this thread, not that I don’t value your recommendations... I just feel a bit more volume won’t hurt...

 

anyway, as @Zed Head predicted, took the old one apart and seem there are scores on the rotor top and the holder.  However the rotor and holder seem to be pretty flat. My thinest gauge is 0.038mm and won’t slide through.  The clearance of the outer rotor and holder is tight.  Don’t have gauge for it...

what I meant I screw up is that the spring pressure is already out of specs. On top of that, I replaced the washer that is thicker than the stock which make it even less pressure.  Been reading a lot and folks suggest to put a thinner washer inside the bolt to make it more tight/higher pressure.... since I bought the new pump, might as well use it. After all pump is like our heart pumping blood to other organs.

Stock washer

1856C40E-E795-4934-8A0E-34ACA02BF773.jpeg

I screwed up and replace with this thicker one 

8590A76E-EA7B-4108-B9A9-FF71ADA0811E.jpeg

spring out of specs of 52.5mm

BD326C60-3F0C-486D-A2DE-E91D1B103952.jpeg
 

it look like when cold start, pressure got to around 45-50 psi.  At idle is roughly 10psi. When the car warm up a big, rev to 2k rpm seem to get pressure to 30psi or so.  I did not see this with my older pump.  I’ll hook up the mechanical gauge tomorrow to see how high it gets.  I’m pretty sure psi would be more higher and more responsive.  

I reduce the movie quality and it’s about 60mb for 3 minutes or so.

 

Stay tune.  I think I’m at ease a bit and ready for the pre smog

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531324BD-A77D-41A4-A315-08EE7BA0BDE6.jpeg

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Old pump on the right and new pump on the left.  As soon as I see the washer. I new I screwed up without open the old pump.

 

experts, please confirm my theory so that anyone read this won’t make mistake as I did.  

3147F36F-D74C-43EB-B3C6-BAFF699DC7B1.jpeg

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4 hours ago, 240zadmire said:

what I meant I screw up is that the spring pressure is already out of specs. On top of that, I replaced the washer that is thicker than the stock which make it even less pressure.  Been reading a lot and folks suggest to put a thinner washer inside the bolt to make it more tight/higher pressure.... since I bought the new pump, might as well use it. After all pump is like our heart pumping blood to other organs.

What you are calling the washer is actually the crush washer or seal, the washer that your reading about would go between the spring and the cup that screws into the pump housing.  Find a small washer the same diameter as the spring and place it in the cup that the spring sits in, put the spring in place and put everything back together.  Now that the spring is being compressed more than it was the oil won't get through the bypass valve as easily.

The mechanical gauge will give you a much more accurate reading on what the pressure is, if the pressure is still low with the new pump then as ZH says, the next thing to check is the main bearings and conrod bearings for wear.

The amount of oil your getting while cranking the starter is good,  the head looks very clean, maybe some work was done on it recently?

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Since one end of the spring pushes against the threaded in plug, increasing the thickness of that spring could (under certain circumstances that aren't in play here) reduce the oil pressure. The thicker that washer, the further the inside surface is from the overpressure relief, and the easier it will be to open that bypass.

The only thing that bypass valve does is limit the upper end of the oil pressure. If the oil is thick (cold) and the engine is tight, that bypass will open and limit the pressure to an upper psi. If the oil is thin (hot) or the engine is worn, or the RPM's are low, that bypass valve will be closed and not be doing anything at all.

In other words, if you've got low oil pressure, changing the bypass valve spring won't do anything to help. When the oil pressure is low, that valve is already closed and not having any impact at all on the pressure. So unless that spring is so weak that the bypass is being opened accidently at a very low pressure (unlikely), it's got nothing to do with the oil pressure level.

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So you're worried about maybe using the wrong washer in the pump?   The video looked good to me.  The pressure is higher, stays up when the engine gets warm, and there's good flow to the cam shaft.  I'd leave it and move on to the next issue.  I think that every Z owner worries about their oil pressure. 

Although, and this might be for someone who's been deeper in to their lubrication system, I notice some bubbles coming from the cam shaft when you stopped cranking.  I don't know where you could suck air in to the system except maybe at the gasket surface. Or the pickup tube in the oil pan.  That would "suck" if it was there.  Not sure how you'd diagnose that.  You might try cranking again with the valve cover off and confirming that the bubbles are constant and not just residual air in the system.  If you don't get bubbles, assume it's fine and just use it.

It might not be worth worrying about though, just an observation.

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@grannyknot yes, I torn down the entire car, engine, head ...etc and replaced all wear and tear parts.

 

@Captain Obvious Thanks for the great explanation.  I learnt something as always.

@Zed Head you have a keen eye.  I noticed it put didn’t pay much attention as I thought air still in the system as I just replaced the oil pump.... checked the oil dipstick and yes, very loose.  Temporary solution was to wrap around with electronic tape... open valve and crank again and no more bubble.  Thanks

 

so I hooked up the mechanical gauge.  Cold start, psi around 40ish.  It drops down to 10ish PSI as the car warms up and idle.  The PSI is very responsive as I rev up the engine and it could reach up to 60psi.  If I rev up more, might go higher.

I guess as you suggested, leave it alone as the gauge on the dash might not tells the whole thing.  Btw, I have new oil sender unit as well.  Both the old and new one behave the same way.

The Video is 105mb and around 5 minutes long. 

 

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That's a great video. The pressure seems lower than most at idle but jumps up quick so is probably fine under load.   It's a tough call, I can't think of what you would do about it except a rebuild.  The pump looks fine based on how the pressure jumps when you rev it, but the 10 psi at idle seems low.  I'm only guessing but it looks like you might just have a worn, or loose, engine.   A perfectionist (no offense to those out there) might tear the engine down and rebuild it because it's not "as-new" but it looks like it's supplying oil with back pressure at the higher RPM, so should run fine and last many miles.  Maybe run a thicker oil than standard.

I'd just run it as it is until you hear a rod bearing knocking.  I'm not an expert though, one of the guys who's rebuilt a few might see clues of impending doom there.

 

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Thanks @Captain Obvious.  That's encouraging!

@Zed Head, don't freak me out 😉 

Let me try to get the smog pretest going on and hopefully pass the smog test as well.  I really want to enjoy it a little while.  I'll keep an eye out for the short block and see if I can do a better "rebuild" next time.  I'm a bit of worry freak myself if I know something is wrong ... though I'm not a perfectionist and I'll never be.  At least in this mechanical/electrical areas.  They are above my brain can comprehends.  Like you say, I have other issues I need to attend to....

 

Say, what should I be looking out for the next rebuild? bearing clearance, piston wall ...

 

regards,

 

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Hi everyone,

After followed all the tips, advices... 
Took the courage and brought the car for the pre smog test.  Unfortunately the car did not pass.  It failed on the too much CO.  

The technician commented the car run a bit rich and need to dial the air/fuel mixture  a bit lower.

as you noticed on other thread and in this thread as well I believe, the car run a bit rich.  I don’t really know how to go about measure the air/fuel mixture after adjusting the air flow meter.

please see the report and any advice you can give.

9B52FF7E-78AB-4802-A9E1-7EF1E25BCB56.jpeg

 

as always, much appreciate all the help.

 

regards

 

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That is super-close.  Don't do anything drastic.  

Have you been driving the car much?  Have you given it a good hard run or two?  Your first post in this thread shows that you've basically rebuilt the engine.  The rings are probably not even seated yet, so some of that "richness" showing could just be oil burning.

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Failure of CO is usually high fuel delivery, excess fuel.  I have a CA 75 and it has always run rich. I would usually lean out the AFM  and that would usually do the trick.  Also,  check your PCV valve and make sure it's working and not stuck.  OOPS, didn't see zed's comment. That's a good idea to drive it at HWY speeds for 10 miles or more before going to smog .

 

Edited by zclocks

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