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My project had been going well http://www.bmw2002faq.com/topic/134019-73-fjord-with-megasquirt/page-2

but today i hit a major setback. I cranked the engine over with no plugs in, after a few 15 seconds bursts the oil pressure warning light was still on so after searching the forums i 

 

i) Removed the oil sender unit and cranked the motor for 20 seconds - no oil spurting out.

ii) Ran oil down the oil sender hole, cranked, ran more oil, repeated 4 or 5 times - still no oil.

iii) Removed oil filter (that i had previously filled with oil) it was empty, i then cranked the engine for 20 seconds and only 150ml of oil came out, repeated this 6 times each time with the same result, oil came out but not alot.

 

At this stage i tidied the garage, walked away and pondered the next step which is probably to drop the subframe, sump and remove and inspect oilpump. Before i do i thought i would ask

 

a) Is 450ml of oil per minute less than it should be?(Im guessing it is)

b )Is there anything else i can do before disassembling?

c) Will i have damaged bearing shells by cranking probably about 5 minutes in total with no plugs in ( its not a newly rebuilt motor, has plenty of miles on it already

 

Sorry about the long winded post but trying to give the full story!

 

Cheers Chris

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Without plugs there isn't that much load on the bearings. I wouldn't be too worried. It's often hard to get the pressure up when running with starter. I've found that filling the filter makes it even more difficult. Just put it all together and start. If the light doesn't go off in 20 seconds then be worried.

 

If it's all new engine where I've invested everything I own then I'm more careful.

 

   Tommy

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I've just been in a similar position. With a new engine/oil pump/m3 starter i got the oil light to come off in about 5 seconds without the plugs in. Obviously an old engine is going to be different, but surely you should be getting more pressure??

 

Would a missing o-ring from the pump cause this low pressure?

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I wouldn't worry about the bearings. I have seen a VW Bug driven 50 miles on the freeway before the bearings started making noise, when someone forgot to add oil after draining it. There is lots of machinery that runs for decades and is lubricated only by an oil-soaked wick. You might try overfilling it temporarily so the pump will have an easier time priming itself .

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However, I WOULD worry about the pump not emptying the pan in a minute of cranking-

it should make a pretty big mess in that amount of time with the filter off.

 

The bearings will be fine.  If they were before...

 

I'm not sure the pump is, and at this point, I'd drop the pan to find out.

 

t

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Thanks for the replies guys, good news about the bearings, but as Toby commented the oil flow rate doesn't seem anywhere near adequate. I think the plan will be to drop the front subframe and sump, remove and check oil pump and while the subframe is out do a refurb with new rubbers, something i was hoping to do in a few months but may as well do it now.

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It's not the o- rings.  They won't leak much without some pressure, and if the filter's off, there's no pressure.

 If it's not really flowing and your starter's spinning at a good cranking speed, the only thing I can think

of off hand is that sometimes the dipstick gets whacked by the crank, then it cuts a hole into the pickup right

about at normal oil level.  Only seen it once, and it didn't seem to have hurt the motor it was on, but man, did it

put the fear of the dipstick into me.  Just like those stupid Castrol ads that drove me to change oil brands...

 

t

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Subframe dropped and pump removed, measuring with feeler gauges showed clearances were within spec but there is some wear and tear -

IMG_2223.JPG

Outside of outer rotor

IMG_2226.JPG

Face of housing cover

 

Is it usable in this condition and is it possible to flatten the face of the housing cover by rubbing it on wet and dry paper on glass?

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Subframe dropped and pump removed, measuring with feeler gauges showed clearances were within spec but there is some wear and tear -

IMG_2223.JPG

Outside of outer rotor

IMG_2226.JPG

Face of housing cover

 

Is it usable in this condition and is it possible to flatten the face of the housing cover by rubbing it on wet and dry paper on glass?

Re: Scoring on back housing cover -  Examine CD's diagram above.  Look at pc 4.  Your pump may not have this because this wear plate came later.  A plate will fit in this pump and avoid having to flatplate lap the housing.  The wear plate is stainless and is present in E21 and S14 pumps which are interchangeable with this engine (I am referring to the pump not the pickup).  The plate does not change any of the internal dimensions and pumping capability will be same or better.

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You don't show the gear surfaces, but I've torn out ones that were much worse that still made decent pressure.

 

Jim's right on with that plate- it works great, and adds a few psi to a 'pretty good' pump that has side plate wear.

 

Add to Jim's list of donor pumps the E30 M10 (318 i from 83-85) which are the same except for the pickup end.

 

But you didn't find any blockages or other problems that would have restricted flow?

 

t

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Thanks for all the replies guys, the relief piston was free in the bore and moved up and down smoothly, spring was correct (68mm) length. Gear surfaces looked good and measured to spec, no obvious blockages noticed and the pickup wasn't damaged so atm the mystery remains. I plan today to pull the oil pump from my other motor, compare and choose the best one, bolt it back in, temporarily bolt sump back on crank it and see how much oil spurts out the filter housing - not very tech but hopefully will reveal an improvement? Ill also blow through the block oilways with compressed air before putting the pump back on. Fingers crossed!

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