oil pump rebuild

[adriangsmith]

I rebuilt my oil pump alongside my engine rebuild.
I now cannot get any oil up to the main gallery.
The scavenge side of the pump is working well as it picked up the pint of oil i tipped down the rocker cover and deposited it back in the tank.
But what ever i do i cannot seem to get any thing from the pressure side of the pump.
Is it possible to put the rotors back together wrong?
I know i matched the dots on each pair of rotors with both facing upwards during assembly.
The pressure relief valve moves easily, maybe a little to easily but still has pressure against it.

Any ideas anyone??

[Gixxer-18]

I read somewhere that you should fill the pump with Vaseline to prime it before trying to start the motor?
Nigel.

[K2-K6]

Worth having a look over on the thread "oil pressure motor rebuild" by MrDavo as toward the end of the thread it discusses exactly this, so there's quite a walk through it on there.

The pressure side of the pump is only fed by the oil line coming down from the oil tank so you can only look at that for your feed, and not the sump.

Vaseline packed into pump head will often get reluctant pumps sucking again so worth doing.

If you have air on both sides of a pump (in and out)  it will quite often not want to start. Another way that may get it to prime is to drain the oil tank and feed pipe if the oil's cold and thick, then get the oil warm and slowly pour it in as it's more likely to run through the pump head and get it filled.

Simpler method maybe to point a fan heater onto the oil pipes and base of engine for half an hour to get the viscosity down.

Once going, they never have a problem, but can be slightly reluctant to get primed.

[Trigger]

I rebuilt my oil pump alongside my engine rebuild.
I now cannot get any oil up to the main gallery.
The scavenge side of the pump is working well as it picked up the pint of oil i tipped down the rocker cover and deposited it back in the tank.
But what ever i do i cannot seem to get any thing from the pressure side of the pump.
Is it possible to put the rotors back together wrong?
I know i matched the dots on each pair of rotors with both facing upwards during assembly.
The pressure relief valve moves easily, maybe a little to easily but still has pressure against it.

Any ideas anyone??

Did you put in new O rings ?
Have you primed the pump ?
And don't try to turn the engine on the starter motor until you can see oil at the top end.

[adriangsmith]

yes new o rings fitted to the pump.
Didn't prime the pump though. so i guess sump off, pump out and vasalene time! 
I have also tried reverse filling by filling the main gallery with oil. letting it sit and kicking it over every 2-3 hours to try and release any trapped air.

[K2-K6]

Thinking about it a bit more laterally, filling the main gallery (the one behind the barrels with cap on clutch side) will only provide oil sooner to the head area once the pressure comes through. Don't think it will run back via the filter to the pump head.

I think it's the oil filter that will give an outgoing restriction to the pump regarding air lock, ish. So if you took off the oil filter and just keep slowly turning the engine with the kick start you may see oil come out of the filter feed. If that's successful, refit the filter and it should start to build pressure if the pump has filled.

[MrDavo]

Been there done that, was driven to visit Boots for a tub of Vaseline after Trigger told me how many motors he has re-rebuilt after they were started with no oil pressure and posted a link to someone selling up in disgust as a result.

Take the pump apart and pack it full, I then packed it the ports until it emerged into the chamber. I then turned it a bit, packing Vaseline in as it rose from the outlet. Back in place, oil in, the red light went out after only a few kicks, much to my relief.

A bit more kicking and it was running out of the gallery. I'd packed both sides of the pump, I also noticed Vaseline floating in the oil tank, which could only have got there up the return pipe.

[Trigger]

Boots for vaseline ? I always get the big budget tubs from the 99p shop

[philward]

I have been following the various start up oil pressure threads and having had difficulty getting pressure on the last rebuild, am picking up tips for the next start up (some time off yet). I am obviously going the multi recommended vaseline route but am intrigued at what point do you change the oil tp get shut of the residual vaseline from the oil - we are all so particular about our oils/viscosity, given that vaseline isn't made to lubricate with the loads on a hot engine, won't there be bearing damage if you don't change the oil ASAP?
Over to you SOHC experts!

[K2-K6]

As a proportion of the oil it's insignificant I feel.

Of far more concern for me in oil properties is the dilution caused by running on choke for any appreciable accumulated time for these engines. For any engine of this type I don't think it's good practice to start it and not let it warm up fully, for the bores, oil condition and any of the standard pipes really.
The incompletely burnt fuel and condensation containing acid byproducts of petrol combustion aren't good at all.

One of the biggest advances in petrol engines is to run them so lean when not under load nowadays that even the exhausts can last to 200,000miles or more. They just didn't do that on carbs.

[MrDavo]

The pumps are little marvels of precision engineering, I wonder if the factory primed them before assembly, or did it somehow when installed, say with a pressurized oil feed?

[Trigger]

I have been following the various start up oil pressure threads and having had difficulty getting pressure on the last rebuild, am picking up tips for the next start up (some time off yet). I am obviously going the multi recommended vaseline route but am intrigued at what point do you change the oil tp get shut of the residual vaseline from the oil - we are all so particular about our oils/viscosity, given that vaseline isn't made to lubricate with the loads on a hot engine, won't there be bearing damage if you don't change the oil ASAP?
Over to you SOHC experts!

The Vaseline will just melt when the oil is hot and mix in with the oil, along with other lubricants that you have used on the build. Just change the oil and filter after running in, 300 to 500 miles. 

[adriangsmith]

I fear I must be doing something wrong.
Sump and pump off, dismantled pump and packed pump with vaseline, reassembled and filled ports with vaseline and it was sucking it in well, fit back onto bike fill with oil and still absolutely no oil making it to the main gallery.
Oil was flowing well out of the tank with the pump off.
What else would stop the oil flow?
plunger valve was moving easily.
Could i have put the rotors in incorrectly? both drive pins were in and located properly.
Maybe I blocked an oil pathway when i reassembled the engine cases?
Also just found this diagram that I found useful to explain the flow and return routes.

[adriangsmith]

Starting to get the feeling this oil pump is shot even though rotors show very little wear and are well within limits.

[Trigger]

Are the jets in the head unblocked ?
The oil travels up the head studs, are these oil ways clear ?
Is oil getting to the oil filter bolt ?
Do all the main oil ways have there caps on tight and is the oil pressure switch nice and tight ?
Did you put a new O ring in were the crank cases fit together and the O ring fits round a dowel ?