New Oil Pump ?

Status
Not open for further replies.

Paul1972

Joined
Oct 28, 2008
Messages
28
Country flag
After not running the Commando for three weeks I found the oil level was about a pint low. This is not uncommon after a few weeks laid up so I decided to drain the sump. However oil continued to drain from the sump and on investigation I realised it must of been draining from the oil tank and did not stop until I replaced the plug. Is this a definite indication that the oil pump needs an overhaul or may it be due to another problem. Thanks in advance :)
 
Paul1972 said:
After not running the Commando for three weeks I found the oil level was about a pint low. However oil continued to drain from the sump and on investigation I realised it must of been draining from the oil tank and did not stop until I replaced the plug.
Click to expand...


If the oil could drain down through the pump as fast as you've described, then the tank would not have been "about a pint low", it would already have emptied-two weeks and six days earlier.

So how much oil continued to drain from the sump, and over what length of time and did you notice if the oil level in the tank also dropped by a similar amount?
 
Nope, Tank was still showing oil on the stick. The fact the plug was out may of made a difference?

I left the bike for a few mins to drain and the 3 pint jug was almost full. I will try again tomorrow with a larger jug but I am sure if I had not replaced the plug the oil tank would of drained completely.
 
Paul1972 said:
The fact the plug was out may of made a difference?
Click to expand...

Unless the breather was blocked, then the crankcase would already have been at atmospheric pressure before the sump plug was removed, so there should have been no residual pressure within the crankcase to reduce the rate of oil drain from the tank, and even if the breather was blocked, any pressure within the crankcase would get out past one or both sets of piston rings.



Paul1972 said:
I left the bike for a few mins to drain and the 3 pint jug was almost full. I will try again tomorrow with a larger jug but I am sure if I had not replaced the plug the oil tank would of drained completely.
Click to expand...

Please give us the results, as something seems seriously wrong if the tank was in fact draining at such a rate, as I doubt anywhere near 3 pints of extremely hot oil would be capable of passing through the oil pump over a few minutes and certainly not if it was stone cold.
Possibly the relief valve has stuck open (as it connects to both the inlet and outlet sides of the feed pump) but that still wouldn't explain why only a pint drained in three weeks.

I'd say the loss of one pint from tank to sump over a three week period is quite low.
 
Thanks L.A.B , I will fully drain the sump again tomorrow and see how much oil I get.
 
FWIW, I reconditioned the oil pump several months ago when I installed new valves/seals/piston rings. I surfaced everything per the manual so there was essentially no clearance between the cover/rotors.

It reduced the wet sumping but it did not eliminate it. I was in the US for 2 months, just returning to Mexico (and the bike) a couple of days ago. Pretty much the entire contents of the oil tank was in the sump. So don't expect oil pump rebuilding to eliminate the problem. It can certainly reduce it considerably if the pump clearances are sloppy but the nature of the system is to drain the oil into the sump. There is no way that the oil pump can be sealed so well that oil won't seep through over time.
 
Paul, Are you sure it was all oil or was it oil-gas mixture from a petcock leaking or left on. Jim
 
MexicoMike said:
There is no way that the oil pump can be sealed so well that oil won't seep through over time.
Click to expand...

I think many owners also overlook the fact that oil from the tank would not necessarily have to pass through the pump to get to the sump.

A faulty seal between the timing case to crankcase joint, or the OPRV jammed open (not MkIII) or leakage around the OPRV threads (not MkIII) could result in oil flowing "backwards" through the recirc. gallery and either leaking into the timing chest at the timing cover joint, or in the case of a leaking OPRV-passing into the timing cover gallery, then through and out of the crankshaft into the sump.

Or a leaking pump gasket?

Or is it possible there was simply too much oil in there to start with (the oil tank was topped-up when there was a couple of pints already in the sump)?
 
MexicoMike said:
FWIW, I reconditioned the oil pump several months ago when I installed new valves/seals/piston rings. I surfaced everything per the manual so there was essentially no clearance between the cover/rotors.

It reduced the wet sumping but it did not eliminate it.
Click to expand...

Also remember that it's not just the end play that can allow it to leak, the clearances between the gears is also important.
 
If oil is touching most Commando dipsticks, its too full of oil.
Some try to leave pistons at top of bore on shut downs to
stifle some of the easy oil path flow into sump via crankshaft.

Many if not most last 3 decades of motorcycles use a vacuum
valve to flow fuel and shut off with just engine motion.
About as failsafe as it gets but may need to valve manifold
for the amount of oil vs fuel flow needs.

hobot
 
Hey L.A.B , I drained the sump again today and only got a pint out. I must of massively miscalculated how much oil was in the sump. Sorry about the silly question from a non engineer amateur and thanks for all your replies :oops:
 
Paul1972 said:
Hey L.A.B , I drained the sump again today and only got a pint out. I must of massively miscalculated how much oil was in the sump. Sorry about the silly question from a non engineer amateur and thanks for all your replies :oops:
Click to expand...

Hi,

I've driven lads mad on this forum with all my questions about oil level. I was confusing myself draining the sump pouring oil back into the tank & trying to figure out oil consumption.

The 'proper' way of checking oil level is to run the bike for 3-5mins, take a reading with the dip stick and that's your actual oil level. On my bike, 75 MK3, there always seems to be 1/2 pint of oil in the sump even after a spin, others may differ?

My bike tends to drain about 1/4 of a pint each day (24 hours) so after two days there's a about a pint in the sump (1/2 pint already in there + 1/2 pint drained in from the oil tank).

It's been said by lots of guys on this forum, the best cure for wetsumping is . . . . . . . ride the bike more :mrgreen:

Kevin
 
If oil is touching most Commando dipsticks, its too full of oil.
Click to expand...

Okay hobot, let me try to understand this, you don't want oil to show on the dip stick??? I find I seem to need to run my oil level at or just slightly above the "L" mark on the dip stick or I get oil all over everything. You don't want any oil to show on the dip stick???
 
Yes Steve, exactly how did you determine that oil touching the dip stick is too much oil?
What happened to your motor that was so negative, what damage, when oil registered on your dip stick?
 
I just did a 4 day check on mine re wetsumping - this after I rebuilt the pump a few months ago. With the eng on compression, using straight 40 wt oil, it drains 3/4 OZ per 24 hours with temps in the 70's.

Like others, I have found that the best oil level for my bike is at the "L" mark on the dipstick.
 
MexicoMike said:
I just did a 4 day check on mine re wetsumping - this after I rebuilt the pump a few months ago. With the eng on compression, using straight 40 wt oil, it drains 3/4 OZ per 24 hours with temps in the 70's.

Like others, I have found that the best oil level for my bike is at the "L" mark on the dipstick.
Click to expand...

How do you even measure 3/4 ounce?
 
Oil drain open, measuring cup under hole - 4 days, 90ml. I converted it to OZ for us metric-challenged types. ;)
 
MexicoMike said:
Oil drain open, measuring cup under hole - 4 days, 90ml. I converted it to OZ for us metric-challenged types. ;)
Click to expand...

So you drained the sump. Then 4 days later drained it again and got 3/4 oz? Not bad. I think I can spit more than that.
 
No, sorry if I was unclear. I opened the sump drain and drained what was in there. Then I left it open with a measuring cup underneath. 4 days later there was 90 Ml (a little less than 3 OZ) in the cup so it wet sumped about 3/4 OZ EVERY day (24 hours).
 
Status
Not open for further replies.
Back
Top