Wet Sumping

[bigskyforever]

I am having issues with wet sumping on a 1973 TX. I have checked the check valve near the oil pump and it does seem ok. 

Anyone had some issue with this problem. I have a 1974 TX and it has no wet sumping issues. Any comments would be appreciated.

[retromech]

funnily enough my tx had the same issue when I first owned it,suddenly and for no apparent reason it cured itself,however I have just completed an engine rebuild incorporating many of the known mods and the problem has returned,despite checking and cleaning the check valve,I will have a look into the problem when time allows.

[retromech]

Hi All,
Can anybody confirm for definite which way the rubber part of the check valve should face, that is should the smaller diameter end face inwards or outwards ? the parts manual appears to show the smaller diameter facing inwards, I can find no other reference to this item.

[bigskyforever]

I removed three different valves from three different engines. The small end goes to the inside, the three were that way.

[bigskyforever]

Just a comment: A few weeks ago I plugged the engine oil pump line from the tank and confirmed that wet sumping was occurring through the scavenger pump. Within an hour or two all the oil had drained to the bottom of the engine through the scavenger pump. I then tore the pumps out and resealed them. Unfortunately there was no improvement in the wet sumping. The wet sumping from the scavenger pump is considerably quicker than the sumping through the engine lube pump. Probably because the scavenger pump is wider. Both pumps have had some trash through them. I have read that new pumps will help. I am considering making a check valve to reduce the sumping through the scavenger pump.

Any comments on this issue would be appreciated.

[retromech]

Thanks for that, to confuse things when I rebuilt my engine I too refitted the rubber part with the smaller diameter inwards, within 24 hrs the oil tank was empty, previous to this work the check valve had been performing correctly, bike had stood unrun for up to 5 weeks,no significant drain back occurred.I have then run the bike for a while covering at least 500 miles in total,if left for 24 hrs oil tank is nearly empty. out of desperation I removed the check valve and inserted the rubber part with the small diameter end facing the rear (in other words inside the outer sleeve). I have ridden the bike for 50 miles,all seemed O.K.,also it has stood for 4 days with no drain back !!!!,I am not suggesting anyone else does this as I do not think this is how it should be,also engine appears to run quieter especially when hot,will check oil pressure when I have the chance,I am now totally confused and concerned.

[retromech]

Hi All,Due to the occasional malfunction of the check valve system can any body give an accurate account of exactly how it works ?,I am assuming the valve is closed when no oil pressure is present,oil pressure assumedly uncovers the port and allows oil to flow from oil tank,if this is so what is the relevance of the shuttle valve and rubber part ?.

[bigskyforever]

retromech

A late follow up from your last posting on this issue. Are you still running the plug with the smaller end inside the shuttle valve. Are you still having limited drain back to the sump.

[retromech]

yes is the answer to both your questions !!,so now I am totally confused, to re cap, before engine work I had no noticeable drain back with the plug fitted the "correct" way, even after 5 weeks non use, after engine work including cleaning/inspection of the valve assy. within 24 hrs there would be no sign of oil on the dipstick, after turning the plug the other way round it now takes about 7 days for the level to be off the dipstick, clearly I am not understanding how this valve works and how to rectify it's problem. as regarding your coil rewire I will send an in depth reply to that shortly.

[bigskyforever]

Sept 22, 2015 6:56:09 GMT -5 retromech said:

yes is the answer to both your questions !!,so now I am totally confused, to re cap, before engine work I had no noticeable drain back with the plug fitted the "correct" way, even after 5 weeks non use, after engine work including cleaning/inspection of the valve assy. within 24 hrs there would be no sign of oil on the dipstick, after turning the plug the other way round it now takes about 7 days for the level to be off the dipstick, clearly I am not understanding how this valve works and how to rectify it's problem. as regarding your coil rewire I will send an in depth reply to that shortly.

Retromech;

Having my own issue with wet sumping. Same issues your having. Is there something we are missing. I did some engine work also. I do not know the history of this engine, I have changed the scavenger pump, shaft, shaft seals. I have unhooked the input  pump hose and plugged it and left the scavenger pump hose attached opened the drain plug and oil will drip one drop at a time. Did the same with the return hose (scavenger pump), plugged it and left the oil pump feed line attached and oil drips. I have the shuttle valve installed with the plastic side against the inside housing. 

[retromech]

Hi, my bike is presently sitting in a friends garage and has been for some time, I have only started it once in at least 2-3 months, before starting oil level in tank was full, having run it for 30 mins. the oil level dropped slightly as you would expect, after 2 weeks standing oil level in tank on full mark !!!,rubber plunger is still fitted the "wrong" way round, I have thus concluded (rightly or wrongly !!!) that the critical part of the cause of wet sumping is the sealing of the crankcase oil way by the rubber plunger, this is my thinking, I stand to be corrected by someone who understands the system better than me ,any comments on this subject appreciated !.

 Kind Regards Paul

[argo1974]

There is a slight leak of oil from oil tank to oil sump of the engine during storage. This will happen through scavenge pump. Generally, this is not a problem since oil tank will never empty. While engine is running, oil pumped from oil sump to oil tank by scavenge pump, will flow through oil hose and overflow pipe inside oil tank. I don't have exact length of the overflow pipe in hand, but it's around 2/3 of the overall height of oil tank. In case of oil leakage through scavenge pump, this particular pipe prevents oil level sinking below a certain level.

So any significant oil leakage should be sought after in oil feed passages.

[bigskyforever]

Argo;
Thanks for working through this oil sumping problem. I guess you are stating the shuttle valve sealing point is the major leak point. Any other possible location oil will drain? Through a shaft seal at the engine oil pump and then through the outer scavenger pump housing seal is that a possibility? It would have to leak through two seals if that were to happen? If I remove the oil filter and oil drips out of there is this a sign the oil is bypassing the shuttle valve?

Let me know your thoughts.

[retromech]

Thanks for the input from both of you, if I had to guess I would have thought that when my bike has this problem in a big way that the tank has less oil in it than to the height suggested by Argo, as would happen if oil was returning to the sump via the scavenger circuit, my thinking (and I may be wrong !!!)is that oil is entering the sump via the shuttle valve failing to seal, my own view is that the "rubber" component is the issue, a very interesting subject !!!.

[bigskyforever]

Retromech;

I will be shopping around for a rubber stopper of some type to replace the old stock shuttle stop. I will try to make some type of mold for a pattern. For sure a lot less oil draining back if I keep the reservoir level bellow the return pipe inside the tank.