Oil Pump rebuild, anyone tried it?

[bmf]

Hi All,

My oil pressure is 20 PSI at 3000 RPM, well out of the range of 28 to 71 indicated by the book.

A quick question. I do not feel like splitting the crank to check big end bearings (nor buying a new oil pump - 140$).

A quick question - has anyone tried to rebuild the oil pump - I am thinking it is a first port of call.

Bike is a 2003 GS E , 40000 km on the clock and I recently did a top end overhaul. New filter and oil BTW (10W40)

Might just go to 20W 50 to get through the summer before a winter rebuild.

Anyone else have any other ideas RE the low pressure?

Thanks

Brett

[sledge]

Are you 100% certain the gauge is reading accurately?

I would drop the sump and check gauze filter on the oil pick-up is not clogged first.

[gsJack]

Could be a restriction ahead of the pump like sledge suggests or lack of back pressure downstream of the pump.  You mention recent top end overhaul, any chance there's an internal leak causing it?  Did you have any hint of the oil pressure problem before overhaul?

40000 km, only about 25k miles is hardly more than broken in for a GS.  I put 80k on my 97 and have 98k mi on my 02 so far without any hint of an oil pressure problem so haven't given it much thought.  Never saw the light with engine running.  There is a pressure regulator in the system but that's just a pop-off I think so pressure doesn't get too high.

My first thought when I saw your post was to try some heavier oil, only cost 3 qts to try some 20W-50.  The GSs do run a bit hotter with a 20-50 than they do with a 10-40 or 15-40 though.  Shop manual says oil pumps are not serviceable so you'd need a new or good used one to replace yours.

[weedahoe]

I would not try to rebuild it but rather buy a new one as there are many all over ebay

[prmas]

It is possible that the pressure relief valve is stuck slightly open due to a bit of carbon, clutch plate material or such like. Perhaps you accidently dropped a small piece of gasket material or similar inside the engine when you were doing the top end rebuild. That scenario is not uncommon. This can cause low pressure readings at lower engine speeds but may not cause much of a drop in the maximum pressure due to the increased volume of oil flow which may mask the problem. I would try flushing the engine with heavier oil a couple of times to boost the pressure and cause the by-pass valve to open at revs and perhaps you might be lucky enough to flush out the problem.  Just use the cheapest oil as it will only be in there for a few minutes.

Macka

[bmf]

Hi Folks,

The gauze filter is fine was washed out before reinstalling recently.

I have tried 20W50 in the bike, pressure shot up to 50 psi in the first few minutes but after 15 minutes it is back down to 20 psi at 3000 RPM (and around 5 at idle ).

I cranked the starter with the valve cover off and I only got oil coming out of a single cam journal. (i did plastiguage the cam journals and they are all fine- well within spec) 

I have ordered a 2nd hand oil pump and will try it before I then pull the engine to check the  oil bypass valve. It's a PITA that it is located in the crankcase!!!

With the oil pump off I imagine I can try to wash out

Will keep you updated

[The Buddha]

The oil pressure is dismal ... I've seen it drop to where a guage wont read it @ 2k when its warmed up.
The oil pump I am sure is not defective ... atleast it wasn't in my case ...
What it needs is a bumped up gearing on the pump.
Cool.
Buddha.

[bmf]

Did you run the bike on such low pressure for any length of time?

How can you change the gearing?

Thanks

Brett