A bitter sweet moment

[paulbell6]

Thanks for that Milothedog, gearbox will be off at the weekend so at £6.95 delivered I have ordered a double lip seal from BK and I will swap it out regardless.

Thanks


Paul

[NickA]

<snip>
.. as you know some Stags run with the fan quite close to the Radiator and others have a larger gap <snip>

With a supergill rad the gaps so small you can't even change the belts without first removing it

[V Mad]

Just a thought, if the crankcase breather on the RH cam cover was blocked you may get pressure build up which would push oil out through the seals.

[paulbell6]

I think I will leave the rad in place and put a piece of thin piece of plywood across the rad so if the blades do touch the rad then hopefully they will deflect accordingly, but I will keep a good check on it.

Paul

[wilf]

Before you go pulling things apart:

If the leak only happens when the engine is running - well that crank rear seal isn't seeing actual oil pressure, just oil leaking out of the rear main bearing, that won't be at full pump delivered pressure. It seals against "splash" if you like. If the leak starts immediately the engine does, then I personally think there is summat else amiss, and you may have put your finger on it earlier when you questioned things like oil gallery plugs. What is the oil pressure like?

Are you sure the crankcase isn't pressurising? Is the crankcase breather system OK?

And lastly, because like others, I have pulled engines apart only to find a leak was coming from something external - are you totally, absolutely, and 100% happy that there are no leaks from the usual areas, like oil pump, oil transfer housing, cam covers. They really can be a sod to spot.

Not trying to teach you to apply suction to eggs here, just want to make sure you don't waste time tracking down this leak.

If the engine has only just been started after a rebuild, has it actually run for long enough for the various parts to get to know each other?

If I suspected that rear main seal, I might try one of the snake oil "seal expanders" before I got down and dirty with the gearbox.

[milothedog]

Wilf's suggestion about a seal swell type product is worth considering Paul,

Me and Dean (Deanoed) fitted a +20 crank when we did his bottom end rebuild, the crank came with a speedy sleeve that we fitted as recommended and the seal still leaked. we checked/tried everything including engine crankcase pressure which was fine and still it leaked despite 3 different seals from different suppliers. I admit all from the same origin I suspect. we even run the engine up with no G/box attached to confirm the seal leaking which was proven once the flex plate was taken off after running it up. in the end a bottle of "Snake oil" (£10) was put in for the drive up to ND, not a 100% cure but I would say a good 90+%. Deans now has the double lipped seal ready for when the box comes out again but at the moment it's acceptable.

Ian

[paulbell6]

Wow, plenty of grist at this mill. If the crankcase breather is deemed as the wire mesh under the cam cover then yes this has been cleaned out. All the pipes on the engine are brand new.
to use a footballing phrase, I am 150% certain that the oil is not coming from any other part of the engine. The engine is freshly painted and the sump cover bright zinc plated and yellow passivated and they are both spotless, with no signs of any oil spillage. I would say that the engine has only run for about 10 minutes in total and I would estimate that I have lost about an egg cup full of oil, so the drip is quite severe, and as I said before it only leaks with the engine on. I can't tell you what the oil pressure is as I don't have a gauge, but the oil light does go out almost instantly. When the oil pump was out during the rebuild I measured all of the lob tolerances as per the ROM, and if I didn't know better I would say the pump was brand new. My gut feeling is that the oil is coming from one of the studs that hold the flywheel to the crank. When I assembled them I did use copious amounts of thread sealant, I didn't use new bolts - which I subsequently found out that I should have, but the thread sealant should have done the trick as it apparently seals up to 10 Bar. Am I right in saying that the centre of the crank see full oil pressure ergo that is also seen at the six mounting holes at the rear?
I have never heard of seal swelling products before, would they seal a major leak?

Thanks guys

Paul

[milothedog]

Wow, plenty of grist at this mill. If the crankcase breather is deemed as the wire mesh under the cam cover then yes this has been cleaned out. All the pipes on the engine are brand new.
to use a footballing phrase, I am 150% certain that the oil is not coming from any other part of the engine. The engine is freshly painted and the sump cover bright zinc plated and yellow passivated and they are both spotless, with no signs of any oil spillage. I would say that the engine has only run for about 10 minutes in total and I would estimate that I have lost about an egg cup full of oil, so the drip is quite severe, and as I said before it only leaks with the engine on. I can't tell you what the oil pressure is as I don't have a gauge, but the oil light does go out almost instantly. When the oil pump was out during the rebuild I measured all of the lob tolerances as per the ROM, and if I didn't know better I would say the pump was brand new. My gut feeling is that the oil is coming from one of the studs that hold the flywheel to the crank. When I assembled them I did use copious amounts of thread sealant, I didn't use new bolts - which I subsequently found out that I should have, but the thread sealant should have done the trick as it apparently seals up to 10 Bar. Am I right in saying that the centre of the crank see full oil pressure ergo that is also seen at the six mounting holes at the rear?
I have never heard of seal swelling products before, would they seal a major leak?

Thanks guys

Paul

Paul, there is no oil pressure at the rear flange of the crank it's just splash (boundry lubrication) and what is lost from the rear, rear main bearing. If you sealed the flywheel bolts it's also unlikely they are leaking. The seal is there to contain the oil as it gets flung about.


Ian.