S.O.S.: i need your help, please.

pierodn · Apr 29, 2015

I know, i am not a mechanic, only a fan, but i have already mounted a lot of Commando cylinder/head for me and for my friends, and the bikes run great, no oil leak!
I did this because I have a problem with my Fastback that i can't seem to solve.
I have had a copious oil leak from the right side of the push rods.
I had mounted a AN flame gasket with wellseal glue (like M.E. says) and tight with the values predicted by the manual with the torque wrench.
Now, I have disassembled again the barrells and the cylinder head, and did do skimmed both faces.
Then I have used a AN flame gasket dry (no glue) and tight like x manual.
The bike runs great but....... there is the same problem!.
Oil leaks from the side of right pusrods.
As before the leak is severe, almost sprayed!.
It is as if there is too much pressure in the engine which finds an outlet from the head gasket!
I have to add:
-the bike mount the large oil tank of the early Fastback;
-oil line passes through the oil filter (the line is correct);
-the oil returns from sump to the oil tank;
-the oil tank is very hot;
-oil filter is very cold;
-the motor is fitted with a breather under the sump instead of his original sump filter body and i can't reassemble the original breather on the plugged drive side crankcase because i did not left the spring into;
-there is no leak frome the the hose that goes from tank out on the air (the line from sump breather goes into the oil tank.
I dont believe any more the problem is the gasket.
Please, i need your help.
Thank you.
Piero

comnoz · Apr 29, 2015

pierodn said:
I know, i am not a mechanic, only a fan, but i have already mounted a lot of Commando cylinder/head for me and for my friends, and the bikes run great, no oil leak!
I did this because I have a problem with my Fastback that i can't seem to solve.
I had copious oil leak from the right side of the push rods.
I had mounted a AN flame gasket with wellseal glu (like M.E. Says) and tight with the values predicted by the manual with the torque wrench.
I disassembled the barrells and the cylinder head, I did do a flat skimmed to both.
This time I have used a AN flame gasket dry and tight like x manual.
The bike runs great but....... there is the same problem.
Oil leak on the side of right pusrods.
As before the leak is severe, almost sprayed!.
It is as if there is too much pressure in the engine which finds an outlet from the head gasket!
I have to add:
-the bike mount the large oil tank of the early Fastback;
-oil line passes through the oil filter (the line is correct);
-the oil returns from sump to the oil tank;
-the oil tank is quite hot;
-oil filter is very cold;
-the motor is fitted with a breather under the sump instead of his original sump filter body and i can't reassemble the original breather on the plugged drive side crankcase because i did not left the spring into;
-there is no leak frome the the hose that goes from tank out on the air (the line from sump breather goes into the oil tank.
I dont believe any more the problem is the gasket.
Please, i need your help.
Thank you.
Piero

Piero,
The fact that your oil filter is cold would indicate that the scavenge pump is not working to keep the excess oil from the crankcase.
It is likely a plugged passage on the inlet side of the scavenge pump or maybe a damaged scavenge pump.
Can you watch the tube in the oil tank to see if you have oil return from the scavenge pump? Jim

dennisgb · Apr 29, 2015

Something doesn't seem right that the oil filter is cold, but not sure that is the problem...just sounds odd like the hose routing isn't right.

If too much pressure there are a lot of places oil will come out of before the head.

I'm sure other's will have other ideas but is it possible there is porosity in the casting?

batrider · Apr 29, 2015

Sometimes the oil squirts out of the rocker spindle covers and then through a valley in the head to the front of the engine. The leak is almost undetectable at the spindle covers but a huge amount of oil will pour out the front and it looks like the head gasket is leaking. These little bolts have to be pretty tight. The latest 750s and 850s had copper washers under the bolt heads which can't hurt - and also there are one piece covers that might be more rigid. There is high pressure oil under those covers.

This won't help the cold filter problem. It sounds like plumbing. Is there an in and out marked on the filter housing?

Russ

pierodn · Apr 29, 2015

comnoz said:
pierodn said:

I know, i am not a mechanic, only a fan, but i have already mounted a lot of Commando cylinder/head for me and for my friends, and the bikes run great, no oil leak!
I did this because I have a problem with my Fastback that i can't seem to solve.
I had copious oil leak from the right side of the push rods.
I had mounted a AN flame gasket with wellseal glu (like M.E. Says) and tight with the values predicted by the manual with the torque wrench.
I disassembled the barrells and the cylinder head, I did do a flat skimmed to both.
This time I have used a AN flame gasket dry and tight like x manual.
The bike runs great but....... there is the same problem.
Oil leak on the side of right pusrods.
As before the leak is severe, almost sprayed!.
It is as if there is too much pressure in the engine which finds an outlet from the head gasket!
I have to add:
-the bike mount the large oil tank of the early Fastback;
-oil line passes through the oil filter (the line is correct);
-the oil returns from sump to the oil tank;
-the oil tank is quite hot;
-oil filter is very cold;
-the motor is fitted with a breather under the sump instead of his original sump filter body and i can't reassemble the original breather on the plugged drive side crankcase because i did not left the spring into;
-there is no leak frome the the hose that goes from tank out on the air (the line from sump breather goes into the oil tank.
I dont believe any more the problem is the gasket.
Please, i need your help.
Thank you.
Piero

Click to expand...

Piero,
The fact that your oil filter is cold would indicate that the scavenge pump is not working to keep the excess oil from the crankcase.
It is likely a plugged passage on the inlet side of the scavenge pump or maybe a damaged scavenge pump.
Can you watch the tube in the oil tank to see if you have oil return from the scavenge pump? Jim

Hi Jim,
Thank you.
Please, can you explain me what means "scavenge"?
Where it could be plugged?
With the bike starting the oil return into the oil tank.
The oil tank is very very hot!
Is it right?
Please, what is the way to control the breather works?
Believe me, i cannot think is the head gasket.
Please, help me, let me understand better where i can watch the plugged oil passage.
Regards
Piero

htown16 · Apr 29, 2015

Do you have the oil filter in the feed line from the tank to the engine or in the return line from the engine to the tank? It wasn't clear from your post. It should be in the return line from the engine to the tank. That might explain why it is cold.
Maybe this will help
http://www.oldbritts.com/oillines.html

pierodn · Apr 29, 2015

htown16 said:
Do you have the oil filter in the feed line from the tank to the engine or in the return line from the engine to the tank? It wasn't clear from your post. It should be in the return line from the engine to the tank. That might explain why it is cold.
Maybe this will help
http://www.oldbritts.com/oillines.html

Hi and thank you.
I mean, but the oil line is like x manual.
Ciso
Piero

guest76 · Apr 29, 2015

Hi Piero,

I think I am right in saying that in one of the official manuals, the diagram is wrong.

The filter must be inline on the return FROM the engine TO the oil tank.
The collection from the engine and moving oil back into the tank is called scavenging the oil.

It is not correct if it is installed inline on the feed FROM the oil tank TO the engine

The oldbrits link above has the correct diagram.

pierodn · Apr 29, 2015

gtiller said:
Hi Piero,

I think I am right in saying that in one of the official manuals, the diagram is wrong.

The filter must be inline on the return FROM the engine TO the oil tank.
The collection from the engine and moving oil back into the tank is called scavenging the oil.

It is not correct if it is installed inline on the feed FROM the oil tank TO the engine

The oldbrits link above has the correct diagram.

Hi and thank you.
Sorry, but the oil line is correct like x the above manual.
From the oil pipe junction the left return hose goes to the right body filter pipe and from the left to the tank.
I repeat, the oil return to the tank, the tank s very hot, the filter is very cold.
What means "damage scavenge pump"?.
I dont understand "scavenge".
Pieo

pierodn · Apr 29, 2015

pierodn said:
gtiller said:

Hi Piero,

I think I am right in saying that in one of the official manuals, the diagram is wrong.

The filter must be inline on the return FROM the engine TO the oil tank.
The collection from the engine and moving oil back into the tank is called scavenging the oil.

It is not correct if it is installed inline on the feed FROM the oil tank TO the engine

The oldbrits link above has the correct diagram.

Click to expand...

Hi and thank you.
Sorry, but the oil line is correct like x the above manual.
From the oil pipe junction the left return hose goes to the right body filter pipe and from the left to the tank.
I repeat, the oil return to the tank, the tank is very hot, the filter is very cold.
What means "damage scavenge pump"?.
I dont understand "scavenge".
Pieo

comnoz · Apr 29, 2015

pierodn said:
gtiller said:

Hi Piero,

I think I am right in saying that in one of the official manuals, the diagram is wrong.

The filter must be inline on the return FROM the engine TO the oil tank.
The collection from the engine and moving oil back into the tank is called scavenging the oil.

It is not correct if it is installed inline on the feed FROM the oil tank TO the engine

The oldbrits link above has the correct diagram.

Click to expand...

Hi and thank you.
Sorry, but the oil line is correct like x the above manual.
From the oil pipe junction the left return hose goes to the right body filter pipe and from the left to the tank.
I repeat, the oil return to the tank, the tank s very hot, the filter is very cold.
What means "damage scavenge pump"?.
I dont understand "scavenge".
Pieo

The oil pump is divided into two sections.
The small section supplies oil to the engine. [supply side]
The larger section picks up the excess oil from the bottom of the crankcase and pumps it back to the tank. [scavenge side]
If there is damage to the scavenge side gears the pump may not work. Jim

pierodn · Apr 29, 2015

Hi Jim,
if the oil returns to the tank it means that the scavenge side of the pump works?
Or this is not right?.
Maybe the return of the oil into the tank that i can see comes from the breather and not fom scavenge pump?.
If is damaged the scavenge pump may be true that the oil comes out from the head gaket?.
Thank you.
Piero

comnoz · Apr 29, 2015

pierodn said:
Hi Jim,
if the oil returns to the tank it means that the scavenge side of the pump works?
Or this is not right?.
Maybe the return of the oil into the tank that i can see comes from the breather and not fom scavenge pump?.
If is damaged the scavenge pump may be true that the oil comes out from the head gaket?.
Thank you.
Piero

That is correct.

If the scavenge side of the pump is not working then the sump plug breather will still return oil to the tank -but not well. The extra oil left in the crankcase may be blown out through the head gasket.

Check the scavenge side of the oil pump and the passages to and from the oil scavenge pump. Jim

htown16 · Apr 29, 2015

Are you sure you have the correct filter? If the oil in the tank that has returned is hot and the filter is cold then it sounds like the oil is not properly circulating through the filter. My understanding is that most filters have a bypass that lets oil through if the filter is clogged. I would try a different filter.

pierodn · Apr 29, 2015

comnoz said:
pierodn said:

Hi Jim,
if the oil returns to the tank it means that the scavenge side of the pump works?
Or this is not right?.
Maybe the return of the oil into the tank that i can see comes from the breather and not fom scavenge pump?.
If is damaged the scavenge pump may be true that the oil comes out from the head gaket?.
Thank you.
Piero

Click to expand...

That is correct.

If the scavenge side of the pump is not working then the sump plug breather will still return oil to the tank -but not well. The extra oil left in the crankcase may be blown out through the head gasket.

Check the scavenge side of the oil pump and the passages to and from the oil scavenge pump. Jim

Hi Jim,
That sounds good.
The breather works well but not the oil return.
Please, what is the better way to take a control of the oil passages from oil scavenge pump?
And for the pump?
If i will have the good luck to solve this problem do you think i will must change again the head gasket because dirty of oil?
Thanks fir helping me.
Piero

Hobot · Apr 29, 2015

OIl return by breather route that skips the normal route via oil filter could explain hot oil in tank but not filter.
Implies a lot more intimate bonding with your Commando too soon.

baz · Apr 29, 2015

i think the oil filter has a one way valve built in so make sure you have the feed and return hose the right way round ,,,,,,,,,

Bob Z. · Apr 29, 2015

The stock filter housing is labeled IN and OUT.

Maybe this helps?

I suspect that the oil pump is not picking up (scavenging) the oil from the bottom of the crankcase and sending it thru the filter and to the oil tank.
Perhaps blocked pick up hole in the bottom of the crankcase?

Happened to me once; blob of silicon sealant blockage in the oil passage.

Suggest to pull off the oil hose leading to the filter, kick over or briefly start the motor and see if oil comes out.

Good luck.

Matchless · Apr 29, 2015

Make sure the oil tank is full. Remove the filter from the housing & start the engine for a minute or so. Oil should flow out of the outer drilling, not the threaded boss. This will prove if the return side of the pump is working & also if the filter housing is connected up the right way.

pierodn · Apr 30, 2015

Hi.
The oil line is right.
No oil return.
Pump or oil paggages plugged?
Thanks
Piero

S.O.S.: i need your help, please.

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