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98cobra+75280z

rebuilt l28et has no oil flow

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Hey guys, hopefully someone can lead me in the right direction.  I recently rebuilt my l28et that is in my 77 280z.  I took my time with the rebuild and checked all the bearing clearances and replaced any and all gaskets.  I also cleaned all the oil and coolant passages and made sure to triple check everything during the rebuild.  I purchased a new turbo oil pump to ensure that everything in the motor was at least mostly new.  Well fastforward and the motor is back in and I am attempting to prime it for first start and break in.  I took the oil pressure sending unit out as well as all the spark plugs and oil fill cap.  I crank the motor (or have my brother crank it) while the other looks for oil flow through the oil pressure sending unit port as well as oil on the cam.  Well we have neither!! I cant figure out what it could be as the oil filter is a new bosch which I have never had problems with bosch filters pre-rebuild.  And the pump is brand new and the dizzy shaft gear and pin seem fine.  Any ideas would be greatly appriciated.

 

 

Thanks guys

 

 

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One thing I would like to mention is that during tear down there was now gasket between the block and oil pick up tube.  Is there suppose to be, I modified a gasket out of my gasket set to put one there but it took a little cutting.  I am certain it isnt leaking or allowing air to pass through but i was curious why I found now gasket, Is there one there from factory?

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To prime the pump I followed the directions in the "how to rebuild your datsun L series".  So I put oil in the pump an rotated the gear around to get oil on both sides.  Does oil need to be in both the pump and pickup tube?  I also pumped oil down the oil galley to the pump when it was installed.  I didnt take the galley plug out of the block.  I didnt have it hot tanked or anything, just cleaned it and tried to keep it as clean as possible. 

 

Maybe I will install the old pump and see if maybe I just got a bad pump.

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Yes,  the gear is on the crank as well as the oil slinger.  The dizzy shaft is all in good shape and all the tolerances checked out, the gear on it is not missing any teeth and has no play in it.  I can take the dizzy cap off when I get home to double check that it spins but I am pretty sure it will since everything was in good shape when I installed it. 

Edited by 98cobra+75280z

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If you add up the total volume of all oil passages, it would probably be more than a quart.

There is a secret squirrel technique to backfeed the pump.

I used some clear plastic tubing and used a plastic tube connector to fit it to a funnel.

Then I removed the oil filter and stuffed the clear tubing into the oil gallery that feeds the filter (not the one in the center but the hole in front of it) by stuffing it in pointing toward the front of the car as much as possible.

I removed the T fitting from the block and screwed the sensor in it's place to ensure no air was being drawn in.

I got it in about 1/2 an inch by squeezing and prodding it after carving a taper into the end with a razor blade.

Then you put a bit of oil in the funnel and crank the engine by hand backwards.

CAREFUL!! some engines with very worn timing chain or tensioner might not like being turned backwards and could possibly skip the chain because turning it backwards will compress the tensioner inward.

You should see the oil going down the clear tube if you leave a bit of an air bubble to use as an indicator of flow.

If you crank half a quart or more and fill the filter, you should get pressure once you put it back together but you might want to do more.

After the priming, I took out the oil pressure sender, reinstalled filter, and watched while cranking with a remote starter switch until I saw oil coming out and quickly put the sender back into the T fitting and reinstalled the turbo oil supply tubing......and cracked loose the 17mm line on the turbo.

Then I cranked it until I saw oil at the turbo.

 

I actually had to do this twice since I did it once and got zero pressure.......because the fully primed pump was bad.

If that happens then you have a bad pump or a pickup that is sucking air since you just guaranteed oil is in the pump by the above proceedure.

I replaced the pump with another I had lying around and repeated the process and got pressure right away while cranking.
 

Edited by HowlerMonkey

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From my experience it just takes a long time to prime. I spun the engine with the starter with no spark pugs. I rebuilt mine a few years ago and recently pulled the head and oil pan and inspected the bearings. They still looked new. However, modifying an oil pump shaft to drive to pump with a drill would be better. I know some cams can become damaged before the engine ever starts. Mine did not though.

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Yay! oil pressure.  Took off the pump and filled it with oil and vaseline and spun it with a flat tip screw driver. Bolted it back on and filled the filter. Cranked it for about 20 seconds and oil came out at the turbo banjo and then a few seconds later the cam holes.   MORAL VICTORY.

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So I worked on the car today and didnt get any results.  I took the pump off and made sure it was full of oil, I also pushed oil down the oil passages to ensure plenty of oil.  I then cranked the car and got no oil.   I then switched the new pump out for an oil one that I know worked but didnt flow as much as I wanted.  I put that pump on and got no oil flow.  I then took the oil pan off to check the pick up tube and it was clear and looked good.  I put it back together and changed the oil but I still have no oil going anywhere.  I cant figure it out as the engine passages are all clean and the pump is brand new.  Any idea?

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Tonight I made a shaft to spin the oil pump to use a drill on.  I took the oil pump shaft out and primed the pump then put the pump back in and spun it with my drill... Still no oil anywhere.  So I then took the front of the engine apart to make sure the passages were clear.  I took a funnel and poured oil into the oil pump feed passage and then took the oil pan plug out and poured oil down the funnel.  The oil poured out of the pan as quickly as I could pour it in.  That makes me sure that the oil passage is clear and the pick up tube is fine.  I have no clue how the pump refuses to pump oil. Is there any other things that can possibly cause a oil pump to not pump.  Both the pumps aren't working.   Please any suggestions would be greatly appreciated.  I am sorry to ask so many questions about this but I can't figure it out at all and am completely baffled by the lack of oil pressure with both a new and good used pump.

 

Thanks again guys.

Edited by 98cobra+75280z

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Thanks newzed on catching my mistake. I flipped the direction of the drill and sure enough I got oil to flow. I pumped it until my gauge read around 60psi and the cam was flowing oil. My question now is that when I put the front end back together and cranked the car I still see no pressure. Is the starter motor just to slow to get the oil to flow?

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Thanks newzed on catching my mistake. I flipped the direction of the drill and sure enough I got oil to flow. I pumped it until my gauge read around 60psi and the cam was flowing oil. My question now is that when I put the front end back together and cranked the car I still see no pressure. Is the starter motor just to slow to get the oil to flow?

You have the plugs out, yes?

 

If so, and there is no compression, your starter should be spinning the engine like a top!   YOU tell US if it is spinning quickly enough.

Edited by BlueStag

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