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Discussion Starter · #1 ·
First, let me say I am new to Triumphs.

Just got my pre-unit rebuilt and it is leaking oil. To me, it looks bad. I know "it's a triumph and they all leak", but even then it just doesn't seem right. I have taken it back a couple times to the guy that rebuilt it and am told it is actually good for a pre-unit. Maybe he is right, but I figured I would see what you all think.

They did a full engine rebuild. The bike has been ridden about 150-200 miles since. After riding and the engine is shut off, it will leak about 20 drops of oil. This picture is how much oil that has leaked in 2 days of sitting. It is about a 7" circle on cardboard.

If this is good or normal, I can live with it. But I guess I just needed some opinion from those with experience.

Thanks for your honest opinions.

 

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If it is leaking out of the primary then you will probably just have to deal with it. Those primaries never had gaskets so we tend to seal them with our sealer of choice. It is still gonna leak out of the back of it though, since there was never a good seal where the mainshaft goes through.

If it is leaking out of the breather in the back of the intake camshaft that is also normal, that is what it looks to me like in your picture. Stockers had a big long hose that went back to the oil tank and let the excess oil from the crankcase breather vent back into the tank. You can add your own hose and vent it back to somewhere around the back of the bike so you don't get it under the bike and on the tire when riding.

If it is leaking out of the center of the crankcase, where they are sealed that is bad. It is also very difficult to seal the bottom of the motor at the sump plate. It is a big square hole in the bottom of the motor where the oil collects when at rest. I use a good sealer but since it is so very difficult to clean that area, they will leak after you break the seal for an oil change.

If you could isolate where the leak is coming from exactly, it would help us make a determaination. Sometimes shop guys are not very articulate, but very capable.
 

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Discussion Starter · #4 ·
Thanks for the replies. I will see if I can possibly figure out what area it is coming from. I will clean it all off the bottom and see what's going on exactly.
 

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That's not really bad - the cardboard soaks up and spreads the oil.

The rule of thumb is 'a quarter on the floor overnight'. If its more than that - yeah. It should be looked at. Clean and degrease the bottom of the motor, don't just wipe it down. The exterior should be dry. Fire it up, run it for a few minutes, stop and look at the underside of the case. Look at the parting lines for the main cases, look at the primary and look at the breather. Keep doing this until you see where it's leaking from.
 
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