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1991 Toyota MR2 2.2L
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Discussion Starter · #1 ·
I recently posted about how to prime the oil pump, but was told that wouldn't help. I've pulled the pan and done some basic checks so I figured this warrants a new thread with an accurate title, if not, I'll delete this and you can reply here instead: How To Prime Oil Pump - Pressure gauge is reading 0psi

My low oil pressure light came on. The engine has been rebuilt. No sludge build-up. The car is a 1991 MR2 5sfe with 128k.

List of things I've checked/done
  • Checked oil level - Full
  • Replaced pressure sender sensor - Still have a light on
  • Hooked up a mechanical pressure gauge - Read 0psi with no movement on the meter
  • Removed plugs, cranked for 10 seconds to see if meter on pressure gauge moved - Nope
  • Checked bypass filter on oil filter - It is closed
  • Dropped Oil Pan
    • Oil all over the lower end (crank, rods, bearings) car hasn't been run for a few days so the lower end seems to be well lubricated by the looks of it.
    • Looked at the pressure relief valve - Nothing unordinary but did attach a picture
    • Checked Strainer on pickup tube - Little bit of sludge but not clogged and can see through screen
    • Removed pickup tube and blew a little air through pickup tube from the strainer side, air comes through fine and no sludge inside pickup tube. (Pictures of pickup tube attached)
    • Put oil in a cup, placed pickup tube strainer inside oil, used other hand to crank the crankshaft in a tightening direction to see if it would pick up oil out of the cup - Oil stayed at roughly the same line (Residual dripping all over strainer) Hand cranking may not be enough to pull oil I guess
  • Removed valve cover to inspect camshafts and presence of oil - Very little residual oil in low spots (Pictures attached)
  • Ensured pressure sender port was not clogged up - stuck a long zip tie in and actually pulled out oil on the end of it.
I think that is about it. Does anyone have any other ideas? Possible culprits before I get an oil pump? How would I check the oil pump since the above method did not work? Can I simulate it pumping oil and if I removed the oil filter would it come out there? If the bottom end is lubricated why isn't the top? Can the oil pump clog? ..I now only have more questions after looking into it.

I really hope someone has some advice because I feel like I've tried everything and I can't afford another pump right now and I'm not sure if this one was replaced with the rebuild.
 

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There is no oil in the head at all? And there is rust on the cam shafts.

The way to simulate the oil pump working without removing the cam belt is to crank the starter motor with the EFI fuse removed so the engine won't start. This should bring the rpm up to around 500 which is plenty to make the pump work. It's a typical thing after major engine work or sitting for a long time to crank the engine a while to circulate oil with the engine unable to start so there is no load on the rotating parts.

This will show you if any oil is able to get to the head. If there is no oil in the head there is no pressure at the sensor. The sensor is just a switch. It doesn't take much to deactivate the light.
 

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Is it possible to install the head gasket backwards on the 5SFE? Sometimes that will result in most passages lining up, except the oil passage. Which would give you oil to the bottom end, but no oil in the head and the oil pressure light on.

But if I remember from your other thread, you said it was OK for a while, then lost pressure?

That oil pump looks brand new, FYI.
 

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91t gen5
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Removed plugs, cranked for 10 seconds to see if meter on pressure gauge moved - Nope
I only mentioned removing the plugs so your starter will be able to turn the oil pump faster and to take some of the load off of your bearings. Plus your battery will last longer before it dies and the starter won't get as hot. This wasn't a test of any sort, just a preventative measure.
 

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1991 Toyota MR2 2.2L
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Discussion Starter · #6 ·
Won't have time to look at more until later but here are some replies.

GDII - The engine sit for 4 years, not sure if this was before, after, or in between rebuild so that may explain the slight surface rust on the cam. I'll clean that up before putting it all back together. I was initially worried about cranking it without oil up top but 500rpm makes me feel a bit better about it.

Alex W. - Well I didn't notice that gap.. seems obvious now, pump could just be sucking air through that. Looks like they used a sealant, there is some residue on the pick up tube as well. I have a new gasket on the way. Does anyone recommend even using gasket sealer on an internal part like this? Also, you're correct, I've had the car for 2 months, started, and drove quite a few times (not far cause I've been fixing/test driving). But this problem just now arose during the most recent test drive. Thanks for mentioning the pump looking new. Looks new on the outside too so I may just leave that alone for now.

J Harris - I tried it to see if I'd get any pressure at all but got worried about the lack of oil up top. Makes sense that there will be less load since there will be no compression resistance with the plugs out so I'm not so worried anymore. Priming seems like that won't help until I get that pickup tube gasket sealed and know that isn't stopping it.
 

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Discussion Starter · #8 ·
Update: I replaced the gasket, torqued everything is torqued to spec, put a little oil on the cam lobes/gears. Cranked for a minute (twice) without plugs and with efi fuse removed, still no pressure. Removed the valve cover, no oil flow to cam, removed the oil filter, no oil flow to the filter. Had a second person at the engine bay inspecting everything.

I suppose the next step is removing the timing cover and at least ensuring the oil pump gear is attached to the shaft. The diagram looks like it is attached by a nut so maybe the nut came loose. If not then maybe my oil pump has failed even though it seems new.

Not sure if it's an issue, but when I remove the oil filter I can hear bubbles popping inside it, like air is being removed from the fluid. Could just be where it is in upside down and then tilted right side up upon removal. Or maybe the pump is still sucking air somehow.
 

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Discussion Starter · #10 ·
Based on this image of a new oil pump, it looks like the gear slides on and is only held there by the torque of the nut itself? I don't see any spline or anything that would hold the gear in place.
 

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Based on this image of a new oil pump, it looks like the gear slides on and is only held there by the torque of the nut itself? I don't see any spline or anything that would hold the gear in place.
There is a little notch on the pump gear and shaft that locks it in place. It doesn't show in that photo.

You can see it on my 3SGTE pump here.

Silver Bicycle part Automotive wheel system Rim Font
 

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Like GDII said its very unlikely the gear has come off as this would cause cam belt to fail. A remote possibility is that the oil pump was defective and possible internal shaft broke. This would disrupt any oil pressure. Pic of my pump taken when installing new O ring and shaft seal.
76728
 

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Discussion Starter · #14 ·
Thanks for the info guys! I should have looked at more than one photo.

Update: I've removed both belts, crank pulley, passenger engine mount, and timing cover. What I found was quite odd. The belt was tight, but the oil pump gear can easily wobble a lot around the shaft if I try to move it. The shaft stays stationary. I didn't have any more time to look at it but I will update when I can.

I think either the gear backed away/loose nut, or the shaft connection is worn. It could be both, it could have backed off from being loose and then shaved/wore down the shaft connection with all the cranking I've done on it. All speculation at this point.
 

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Discussion Starter · #18 ·
Update, I was finally able to get the nut off (nut thread was stripped). Looks like the gear is completely rounded out.
Pictures attached.

Shaft doesn't look damaged apart from threads messed up a bit. Does anyone know if the shaft can spin freely? I couldn't get it to spin at all and wondering if it locked up causing the gear to shred itself. I wanted to see if the shaft would spin, then somehow attach a drill to it to see if the pump works. If anyone knows how to attach a drill to it I'd appreciate that information as well.

Don't want to remove the pump if I don't have to. But I guess I'm already this far-right.
 

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You certainly found the problem. Any speculation on how it occurred?
My guess is an internal fault with spindle in pump possibly from a broken bit of metal getting jammed inside causing it to sieze. You need to take cover off to investigate.
 

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That's definitely the issue. But yes, why has this happened.
If the engine is this fresh then you should be able to reuse the pump o ring (which is more spaghetti than O shaped) and take a look at what stopped the pump from moving. Jim is probably right with a bit of metal getting in there somehow.

If you can't reuse the o ring as they can swell or go hard then they are available new from most places. I don't expect it to be hard being fresh?
 
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