1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

No oil pressure after rebuild. Help me avoid having to pull off front cover again!

Old Mar 24, 2022 | 01:10 PM
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No oil pressure after rebuild. Help me avoid having to pull off front cover again!

Dug deep on the forum history, but final check before I remove a bunch of parts and front cover to get to the oil pump and see if I missed something in the rebuild. Back already aching from two water pump re-installs!

Boils down to this... any methods I have missed to prime the oil pump? Any tests to verify the oil pump is working or not?

Stock unmodified 12A, oil cooler under radiator not beehive. Engine rebuilt with new everything using Atkins kit and video. Atkins video did not mention packing or priming the oil pump during the build, so did not do anything special there. Trying for first start. Stock oil pressure gauge on dash connected to stock oil pressure sender on engine does not move when engine cranked (plugs out and fuel pump fuse removed). Have run a dozen 10 to 30 second cranks over two days. Grounded oil pressure gauge wire at engine to test it and gauge moved all the way to right which I believe means gauge is working. After rebuild oil was filled through the outside port of the oil filter base with the front oil line uncoupled from the engine. Once oil started coming out of front oil line connected it back to engine and finished filling oil through the normal oil filling hole under the oil cap that leads to the center iron. Total oil right around 9.5 quarts, but oil cooler is not OEM so volume need may be different so finished by using dip stick. Oil level now at just over the L mark on the dip stick.

Don't have an oil pressure tester, so connected a milk carton to the Atkins oil pressure / oil temp base I already have on there with some flared copper pipe. (Just happen to be running copper pipe in my van right now). Cranked the engine 30 seconds, not a drop of oil in the carton. Realized I was missing something obvious and removed the oil filter... its dry inside.

Could the fact that I had the front wheels up on ramps when I did the first part of the oil fill (through oil filter base with front line uncoupled) mean I screwed up the priming? Maybe now the car is level I should drain the oil and start again on the oil fill?

And... Should I worry about repeated cranking of the engine? Have pulled the plugs to reduce load on the starter, but concerned that the only thing lubricating the brand new seals is the vaseline I used to hold everything together.



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Old Mar 24, 2022 | 02:04 PM
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Did some more digging online, and found suggestions to test the pump by uncoupling the oil line that runs from the front cover to the oil cooler. Went ahead and undid the line at the cooler, dangled it down in to a catch basin and cranked the engine for 15 seconds. No oil pumped from the disconnected line. New oil pump time? Or is there more I can do to try to prime it that does not involve taking it apart? If I need to remove the front cover I am probably going to get a new oil pump just in case.

Did find my missing oil pressure wire terminal though, had fallen off and had lodged in the front suspension. Small blessings.
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Old Mar 24, 2022 | 05:16 PM
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You could take the oil pan off and ensure the oil pickup is in place and has a gasket. This will also allow a very little access to the oil pressure regulator, but, with the cross member not much room to see much.
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Old Mar 25, 2022 | 11:05 AM
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From: https://www2.mazda.com/en/100th/
i had one that just would not prime the pump, and i had to take the upper oil cooler hose off and fill the oil pump that way. after that it worked fine. you might try that.

hold the top/front cover oil cooler line up, vertical, and just pour some oil in it, when it gets to the oil pump, it will get full. then you can move the engine, and watch it go up and down
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Old Mar 25, 2022 | 03:16 PM
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Thanks J9fd3s! That was one of the most satisfying things ever. Picked up one of these from OReillys for $7 and rigged it to the front line using a Pex fitting. Filled the hose with oil and held the funnel in place using a camera tripod. Cranked the engine backwards using a ratchet on the big bolt on the end of the eccentric and BINGO! oil starts going down in the hose. Cranked the other way and BADA BING BADA BOOM! oil starts going back up the hose. I could do that all day! However I cross threaded the oil line putting it back on so got me another task before I try to start the engine.

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Old Mar 26, 2022 | 09:07 AM
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From: https://www2.mazda.com/en/100th/
Originally Posted by Slow_sevens
Thanks J9fd3s! That was one of the most satisfying things ever. Picked up one of these from OReillys for $7 and rigged it to the front line using a Pex fitting. Filled the hose with oil and held the funnel in place using a camera tripod. Cranked the engine backwards using a ratchet on the big bolt on the end of the eccentric and BINGO! oil starts going down in the hose. Cranked the other way and BADA BING BADA BOOM! oil starts going back up the hose. I could do that all day! However I cross threaded the oil line putting it back on so got me another task before I try to start the engine.
i don't know what happens, but like of all the engines i've done, they all self primed, except this one and yours. not sure why...
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Old Mar 26, 2022 | 05:09 PM
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Thank you guys. Priming the pump via the front line worked! Tapped the damaged thread on the cooler, reattached the lines, cranked the engine and (cue chorus of angels) dash oil pressure gauge registered after about 5 seconds of cranking.

Next.... spark. I am as unhappy messing with electricity as I am crawling under the car so not looking forward to this bit.
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