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Discussion Starter · #1 ·
1973 Datsun 240 Z - No oil pressure after timing chain change.

After replacing my timing chain (and put on a new oil pump while at it) I noticed that while the car ran nicely, the oil pressure was zero. I naturally shut off the car

No oil was getting up to the cams, and even the new oil filter was dry

I pulled off the new oil pump and primed it like folks suggested. I also took some
speaker wire and ran it up the oil passeges to make sure the gaskets had not
slipped. I then took a hunk of hose and blew into the oil pump outlet and
heard oil gush from the oil filter port (oil filter was off). I then used a
hand pump and drew some oil from the oil pan. Everything seemed OK save for
a small shard of old gasket material that must have been hiding in the front
cover.

I put the old oil pump back on and cranked the engine with my remote starter . .
no oil came out of the cam oilers. I pulled off the whole oil filter and nothing
came out there when I cranked either (pretty drastic)

I repeated the process 3 times. Finially I saw some oil coming out of the
oil filter inlet. So I put the oil filter on the car and started it.

NOW IT GETS BETTER . . . after 10 seconds or so the oil pressure came up . .
slowly . . . to about 40 psi (half way) . I sat and watched it for a few
minutes, then thought "gee, I better set my timing". So I ran around to the
front of the car and diddled with the distributor. The idle dropped
somewhat, so I looked back at the dash mostly to check the idle RPMs . . . AND THE PRESSURE WAS BACK TO ZERO AGAIN.

I stopped the car and FREAKED OUT. The car could have
been idleing for 2 - 3 minutes with no oil pumping. I checked the oil level
in the pan and it was low (I guess the oil passages filled up at least) but
this could not have been particularly good for the motor. And I STILL HAVE THE OIL PRESSURE PROBLEM.

I guess I should take the front cover off at this point and try to figure out
what is going on. I just hope I have not destroyed the rings / bearings. The cam is probably OK . . I kept pouring oil in it in between cranking the engine.

I still don't know what the problem could be. The front cover is not
leaking, it is tight, the oil passages are clear and not blocked by a gasket.
I've got my old oil pump that was working when I took it off, and the new
one I bought to replace it with for "better performance".

I think I'm going to take a few days off from working on the car. This is not so fun for some reason . . . .

Any suggestions ?
 

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Find out for sure

What I would do is remove the plugs, remove the oil pressure sending unit and remove the rocker cover. Try and borrow or rent an oil pressure guage and attatch it to the hole where the sending unit was. Providing the pump is primed have someone turn the engine over and watch for pressure. Seems to me you've checked everything. As I mentioned on your last post the problem could be the gaskets, maybe it's worth double checking. It will take quite a bit of turning over to get the oil up to the cam oiler, If the engine was running there should be a puddle of oil in the head if the cam oiler was charged.
 

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Re: Find out for sure

bE careful when you remove the sending unit, I once(2 months ago) had the dang nipple break off in my motor. Caused Alot of trouble for me, broken screw exctractor in nipple, had to drill, got shavings in galley, spun bearing, had to swap motors, and many more problems had followed that i really dont want to get into because it just get me mad. I still haven't got my dang Z up and running. All I was trying to do was hook up a mechanical gauge and next thing I know my Z has been down for 2 months now

steve
83zxt
 

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the pump sucks the oil through the passage in the cover. I am guessing that the gasket did not seal against the block, and the pump is sucking air through the gap. did you remove the pan in this process? what about the oil sump. the sump may have a leak where it meets the block, if you removed it . did you run the car with the old oil pump? If so and pressure was still low, and the only thing removed was the front cover, then the leak is definitely there.
 

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hello i was looking through my how to rebuild your datsun OHC engine books and noticed it states the oil pump/drive gear should be installed on to the crank nose ( shaft ) with the CHAMFERED end first.. and up against the chain sproket ..im not sure exactly what they mean by CHAMFERED end but its states this is critical for correct instalation..i dont know just trying to help you out with some ideas here since this drives the oil pump ??? ofcourse you have to take the front cover off to check this YIKES!!!! i hope you get this figured out!! good luck michele
 

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Discussion Starter · #6 ·
Hi -

Thank you for your note. We must have the same manual because I read that section a number of times. I took out the dictionary and found out that Chamfered means tapered. That was a good observation that you made, but I think I got that right, too.

I was talking with a person out in Washington state that said it just takes a few minutes to get the engine pumping oil properly. He told me to just take the spark plugs out, disconnect the coil (I'll probably block-offf my fuel line too) and use a remote starter to let the engine crank over for about 4 - 5 minutes. It won't be running so it does not cause any damage to the engine.

I'll do this later this week. Thanks for the follow-up note : )
 
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