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Discussion Starter · #1 ·
So my 998 has more oil pressure issues. I replaced the pump and no oil comes out of the feed line to the cooler or the line going to the heads. I’ve been testing with the plugs out by the way.
Before buying yet another pump, I am considering other culprits. In an older thread, Davey j mentioned the oil bypass spring. So I had a look and it looks as if it’s…peeling? What is going on here?

The other potential culprit I guess is the ring on the clutch cover which is also slightly torn.

I’ve checked the o rings and even replaced two that were missing.
Any help would be greatly appreciated. I have two many red herrings.
I’m beginning to think I’ll never ride it again.
Wheel Tire Automotive tire Automotive lighting Motor vehicle
 

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Looks pretty normal , is the diverter sealing the hole ? That should send the oil into the cooler .
Have you verified you have no blockages?
NOT common to have multiplepumps bad so something seems up I would start tracing your oil pathways to make sure you do not have a clot somewhere. Years ago I was the 3rd shop to rebuild a 996 motor by 10,000 miles, I found a good amount of non-oem RTV built up inside the crankshaft where it blocked oil to the rods. Don't panic yet but they a manual and start verifying your passageways are all open and correct.
 

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Discussion Starter · #3 ·
So this morning, the oil pump that had been on the bike sent oil through the cooler. I verified that it was coming out of the feed line to the heads. However, it was NOT getting to the horizontal head as I had the cover off to verify. Furthermore, the light stays illuminated. In that instance, it was like it had some oil pressure, but not enough to pump to the heads.

When you mentioned RTV build up, it reminded me that I found some RTV sealant in one of the water jackets of the heads so its quite possible that one of the passageways is blocked. What is the best way to verify they are all open?
 

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Discussion Starter · #5 ·
Yes Namor. In fact I had a spare and hooked it up at the bottom end but didn’t attach the lines that would normally go to each head. Oil seemed to flow well for that experiment but once I hooked it up to the heads, it hasn’t worked as well.
 

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Discussion Starter · #7 ·
Yes, the sensor seems to be working. Also, like I said, I can verify that oil isn't reaching the horizontal head because I have the cover removed.

I suppose its possible that I have two faulty oil pumps, but as Ducvet said, that seems unlikely.
 

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Discussion Starter · #9 ·
It is definitely possible Ducvet. I will check tomorrow.

What I dont understand is how it had enough pressure with the first pump to send oil through the cooler but yet the sensor doesn't register oil pressure and when I disconnect the sensor, no oil comes out. Its very strange.
 

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Are you saying with no sensor just a hole the oil is not coming out?
If yes that is a issue that needs solving asap.
Besides the used pump has anything else been changed since this problem showed up?
Any chance side cover o-ring is missing?
when side cover is off is there clear passage in the cover?
feed to that sensor is also feed to the crank , both through the side cover and O-ring.

I will try and trace the path in a set of cases to see if there is anything that makes sense.
 

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‘05 749R, ‘89 851/926, 749R/999RS project
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Wouldn't it be easier to replace the engine with another one ( or a 1098..) ? if I remember correctly you've been having issues with this for a while ?
Hmmm, that's a big call. You're talking, what, at least $1500 to fix what may just be a bit of RTV in the wrong place.

I dunno, personally I find it hard to see how even a bad pump can't supply enough oil to at least push something somewhere, even if it is a reduced flow/pressure. It's not an electrical component that works or doesn't work, it's just a pump that will slowly degrade not (fingers crossed!) catastrophically fail.

Much smarter folks on here than me (obviously), but I'd be finding some sort of oil/lubrication diagram then using an air line to confirm the flow paths. If all looks good then it must be the pump, or the drive to the pump. It's like a crime investigation: instead of follow the cash, follow the oil.
 

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Discussion Starter · #14 ·
Are you saying with no sensor just a hole the oil is not coming out?
If yes that is a issue that needs solving asap.
Besides the used pump has anything else been changed since this problem showed up?
Any chance side cover o-ring is missing?
when side cover is off is there clear passage in the cover?
feed to that sensor is also feed to the crank , both through the side cover and O-ring.

I will try and trace the path in a set of cases to see if there is anything that makes sense.
Correct. No oil is coming out with the sensor unplugged.

Which o ring for the side cover are you referring to? I looked at the parts diagram to make sure i wasn't missing one, but I could have overlooked it.

How about the ring separating the clutch case from the pump location? It doesn't leak oil, but if it allows air in, wouldn't that affect pressure? It looks as if it needs replaced.
 

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dry clutch seal should not do anything.

under the right side clutch housing, right next to the oil pump should be a o-ring.
3 o-rings under that side cover.
2 under the pump and one under the cover itself.

That cover o-ring does feed the crank and pressure sensor passage.
 

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Discussion Starter · #16 ·
Wouldn't it be easier to replace the engine with another one ( or a 1098..) ? if I remember correctly you've been having issues with this for a while ?
Yeah, thats exactly what I would like to do especially with a 1098 engine. In fact, I found a 999 engine near me on marketplace and i messaged the guy about it this weekend. He has yet to respond, but he had someone looking at it so he probably sold it.

dry clutch seal should not do anything.

under the right side clutch housing, right next to the oil pump should be a o-ring.
3 o-rings under that side cover.
2 under the pump and one under the cover itself.

That cover o-ring does feed the crank and pressure sensor passage.
Thanks. All the o-rings are accounted for.

Now the cover o ring had fallen out but i put it back in its place and it is still there. But perhaps it isn't sealing properly? Especially since it feeds the cranks and pressure sensor passage. Ive got some spares. I will replace it just in case. I didn't think o rings went bad unless they were nicked or torn. But perhaps I am wrong. I hope I am!
 

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I dont find them nicked and causing such a large drop in pressure but a missing one might. Normally if you turn the motor over by hand you will pump oil out the pressure hole.

Also not to nag but to be clear, you are not just unplugging the sensor but removing in entirely?

On the side cover if you put a hand over crank feed and apply air pressure to the pressure sensor hole does it come out the small hole in the cover where the o-ring sits?
 

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Discussion Starter · #18 ·
I dont find them nicked and causing such a large drop in pressure but a missing one might. Normally if you turn the motor over by hand you will pump oil out the pressure hole.

Also not to nag but to be clear, you are not just unplugging the sensor but removing in entirely?

On the side cover if you put a hand over crank feed and apply air pressure to the pressure sensor hole does it come out the small hole in the cover where the o-ring sits?
Yes, I am unplugging the sensor but I did eventually remove it entirely and there was no oil shooting out of it.

I will use an air compressor this afternoon to test as you have suggested. I will report back.
Thanks again for your help.
 

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You should never see oil through the sensor itself unless one is failing, do your testing with the sensor completely removed and if possible a actual gauge inserted in the hole, a cheap harbor freight oil pressure gauge is warranted at this point.

As I mentioned when turning the motor over by hand I would expect oil to pump out of the hole, spin the motor over with a crank turning tool or a high gear plugs out of the engine. If you are getting a bunch of oil coming out of the hole then install a actual gauge into the hole and with the motor spinning read pressure you should see about 75psi on cold oil at idle.
 
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